Kaleun96

I don't think we can do it quite the way you suggest as the 20um and 12.5um figures would change when we change the parameters of the camera sensor, i.e. they're all related and not held constant just by using the same lens. Your example might be possible if we're talking about taking two images from the setup I used for the USAG testing and then edited the photos so that they were both 1200x1200px, but I don't think this is what you intended. Let me know if it was though! The closest way of doing this example in-camera, so to speak, would be as follows: assuming the full-frame sensor size is 24x24mm with 20um pixels, we can assume the APS-C sensor size is about 0.65 of that, or 15.6x15.6mm (with the same 20um pixel size). The resolution of the resulting images is then 1200px square vs 780px square. Scenario 1: same pixel size, different sensor size A coin that takes up the full frame on the FF sensor at 1x magnification would have an lp/mm on the sensor of about 25. This on the sensor lp/mm is the same for the APS-C sensor, but it changes when we think about the lp/mm on the subject. Because the APS-C sensor is physically smaller, we need to decrease the magnification from 1x to 0.65x for the coin to fit to the APS-C frame. That means that a feature that in real life measures 1mm on the coin (and takes up 1mm of space on the full-frame sensor), now only takes up 0.65mm of space on the APS-C sensor. The inverse of this means that 1mm on the APS-C sensor is covering 1.54mm (1/0.65) on the coin. So the sensor's 25 lp/mm, i.e. 25 line pairs per 1mm, is now spread across 1.54mm, thus decreasing the lp/mm of the image to 16.25 (25*0.65). So in that sense you would see a difference between full-frame and APS-C. But I think where you might be getting confused is that you're assuming the sensor size, pixel size, and field of view are the same for both APS-C and full-frame, which isn't possible. Above I assumed the pixel size stayed constant but in a real-life scenario it's probably more likely that the pixel size would be smaller for the APS-C sensor, so let's take a look at that example: Scenario 2: different pixel size, different sensor size The only way to have a 1200x1200px image from both full-frame and APS-C where the field of view is the same is to decrease the pixel size for the APS-C camera from 20um to 13um. This would increase the lp/mm to 38.46 on the sensor for the APS-C, but the APS-C sensor is still much smaller at 15.6mm vs 24mm. So what I describe above still applies: the APS-C would need to image the coin at 0.65x magnification for it to fit the frame. The lp/mm of the image is then 38.46*0.65 = 25, the same as that of the full-frame. So assuming the lens used for both sensors was capable of, say, 50 lp/mm, holding everything else equal, the detail should be about the same in both images. So I don't think you can really say there's a certain size of coin or resolution at which APS-C and full-frame differentiate because you can't keep all the parameters the same and compare using the earlier lp/mm measurements I took. When you get to real-world examples of cameras, scenario 2 is also not going to help balance out the disadvantaged APS-C sensor because (1) the difference in pixel size likely wouldn't be as dramatic, and (2), it would require that the APS-C sensor's lp/mm capability be much higher than any lens you're going to use will be capable of. That would mean the lens would limit the resolution and the full-frame would win out on lp/ph due to the larger sensor size and higher magnification for the same field of view. There's maybe a way to make a comparison similar to what you suggest purely in the editing of the photos afterwards. If you're resizing a full-frame image down to 1200px, then yeah you probably will lose out on a lot of the benefits in resolution it provided and it would be more similar to the APS-C image resized down to 1200px. One difference, though, will be that the resized full-frame image would maybe be sharper because it more accurately resolved the detail. Not sure if that's true though...

@dougsmityour experiment reminded me I could do something similar but keeping both the camera and lens the same. My Sony A7R III has an APS-C "crop mode", for those who aren't familiar, it essentially just "crops" the sensor as if it were a smaller size. It's essentially the same as having an actual APS-C sensor so is perfect for this comparison. I also happen to have a 1951 USAF Resolution Chart for measuring lp/mm. You take a photo of the chart on a glass slide and observe the smallest group in which you can identify distinct line pairs within an element. A look-up table then tells you then corresponding lp/mm for that group and element. I took a photo in normal full-frame mode at approximately 1x magnification. I used a ruler in the frame to measure the field of view. I then changed to APS-C mode and did the same, but needing to zoom out to approximately 0.65x magnification to have the same field of view (i.e. the ruler in the frame measured the same distance). At this magnification I took another photo of the chart. Here's an overlay of the two images in their respective sizes. The APS-C image is the smaller photo in the bottom left corner, while the full-frame image is the larger photo taking up the whole image. So you can see from this just how much larger the FF image is, even though they have nearly identical field of views. I had the USAF chart near the top-right of the frame as that's where my light would reflect just right off of the smallest groups in the middle. We're now going to zoom all the way in there and compare the results. This next image is showing the area of the USAF chart we're going to zoom in on... yup, on that tiny area consisting of "groups" 4, 5, 6, and 7. So here's a crop of that tiny area. The first is the APS-C version, and the second, full-frame. For the APS-C one, I would say I can make out a distinct line pair up until Group 5 Element 5. For the full-frame version, I can make out a distinct line pair up until Group 6 Element 3. APS-C: Full-Frame: Group 5, element 5 corresponds to an lp/mm of 50.8 Group 6, element 3 corresponds to an lp/mm of 80.6 So, there we have it. Even though in both modes the sensor's theoretical lp/mm is the same (~110 lp/mm), because the height of the effective sensor is different (24mm in full-frame vs 15.6mm in APS-C), the line pairs per picture height is also different (2661 lp/ph vs 1724 lp/ph). Thus, the full-frame image resolves more detail than the APS-C as evidenced by the higher lp/mm measurement on the USAF chart.

Interesting comparison! It presents a good opportunity to follow up on the lp/mm discussion with some real examples. Canon R7: 156 lp/mm, 2313 lp/ph Canon RP: 87 lp/mm, 2087 lp/ph The R7 has smaller pixels so naturally a higher lp/mm but it's crop sensor so it doesn't do as well on the lp/ph comparison even though its theoretical lp/mm is nearly twice that of the RP. But as I mentioned earlier, the lp/mm limit at the sensor doesn't mean much if the lens can't match it. DXOMark has the lp/mm of the Canon 100mm f2.8 at just 37 lp/mm, which is not surprising given only the best lenses seem to reach 100 lp/mm or more. Though we'd really need the MTF chart to know whether the 37lp/mm is at a high contrast value (~70%) or somewhat low (~30%) and how it varies across the image. N.B. something I forgot to account for before, is that I was assuming the same field of view in my previous comparisons and this means the magnification is different. For a coin that fills the frame at 1x on full frame sensor to fill the frame (and not any more) on a crop sensor, the magnification would have to be less (e.g. 0.65x for the A6600 vs A7R III). The lp/mm value for the crop sensor cameras should be adjusted by their magnification assuming we keep the same FOV, thus the lp/mm values should be significantly lower than I quoted earlier. But let's continue with the sensor lp/mm values I've already given for now and the 37 lp/mm value for the lens. This would adjust the R7's lp/ph to just 548 and the RP to 888 lp/ph. We'd therefore expect the RP to produce an image of the coin with more detail, assuming everything else is the same (which it's not given they're different cameras with different sensors). As you mention it's a bit hard to compare given the different focus points and lighting. The first photo is definitely the better photo but it's also the most in focus. Theoretically, the RP would have a shallower depth of field for an equivalent field of view compared to the R7, which points to the second image being the RP. But that could also be explained by missing the focus a bit on the 2nd image; e.g. if only the back of the focal plane is just touching the top of the portrait the surfaces would appear more blurred than if the front of the focal place was touching the top of the portrait. So The third is easiest to tell because of the chromatic aberration 🙂

You're not hijacking at all, I see this thread as the perfect place for these discussions! Apologies in advance for another long post but in case it's useful for helping you or others make a decision, here are some more of my thoughts: It might help to make a decision on crop-sensor (e.g. APS-C) versus full-frame, rather than just MP. I say that because it's probably unlikely many APS-C/crop sensor cameras will get 40MP+ sensors anytime soon. They're often seen as the entry-level to prosumer cameras for these companies and they want to reserve the higher MP sensors for full-frame cameras, which are of course more expensive. Best you could do on a crop-sensor is probably 32MP or so, which the Canon M6 mk.ii has (and a few of Canon's other mirrorless cameras). So if you want 40MP+ it means you likely need to go for a full-frame camera (and FF lenses etc). But if that's too much investment and you want to stick with crop-sensor, then Canon's 32MP mirrorless cameras are your best bet for most megapixels. Canon's M6 mk.ii as an lp/mm of 156 and an lp/ph of 2328, which is not far behind the Sony A7R III. The difference is that a macro lens that does 156 lp/mm is going to be difficult to find (I don't think any consumer lenses do this). Which means the Canon's effective lp/ph is probably much lower, with an lp/mm the same as the Sony A6600 (127 lp/mm), the lp/ph would be about the same (1892 lp/ph). So, in a way, the extra megapixels of the Canon may not be that useful because (a) the lens will likely be the limiting factor; and (b) the Canon's sensor is actually a touch smaller than the Sony A6600 so for the same lp/mm the Canon will do worse than the Sony. But that's not to say don't buy the Canon, it's still a very capable camera and lp/ph isn't everything!

In case others are interested, I just want to use your Note20 as an example of why more MP doesn't always mean better. Not that you're saying that yourself, it just makes for a good example 🙂 Similar to my previous post, it comes back to sensor size being the more important factor. So while the theoretical max lp/mm of the Note20's 108MP lens is 625(!!) due to the tiny pixels (0.8um), and equates to a lp/ph of 4,500 (nearly double the Sony A7R III), the camera will probably still take less detailed photos than the Sony A6600 with the 24MP camera. This is where talking about the theoretical maximums becomes less relevant due to the share number of pixels crammed into such a small space. We're talking about 3x more pixels in an area 12x smaller than the A7R III's sensor 😵 So some factors that will then degrade the resulting photo from the Note20 are: noise, light, diffraction, and lens limitations. I mentioned earlier that very good sharp lenses will be capable of 100 lp/mm, yet here the Note20 sensor can manage up to 625. What this means is that even with a very capable cellphone lens that somehow can do 100 lp/mm, we're still "throwing away" roughly 525 lp/mm that goes unused. And that's if manufacturers managed to build such a lens for a cellphone and fit it inside the case, which they of course can't. I don't know what realistic lp/mm values might be for a cellphone camera but 30 lp/mm is perhaps a fairer starting point. But let's assume the Note20 had an amazing 100 lp/mm lens, we're still throwing away the extra 525 lp/mm the sensor is capable of, so let's calculate the lp/ph again to see how it compares. At 100 lp/mm the Note20 now has a lp/ph of only 720 (100*7.2mm), which is about a third of the Sony A6600 and 3.6x less than the A7R III. I won't get into the other factors I mentioned, safe to say that when you have very, very, very tiny pixels, they need proportionally much more light to be illuminated properly. Likewise, these cellphone cameras have pixels that can only store a fraction of the number of photons as bigger sensors in DSLRs and Mirrorless cameras, limiting the dynamic range and the ability of the pixel to separate signal from noise. Lastly, these phone camera lenses are tiny and have very fast apertures that are already approaching diffraction territory. I read that the f1.8 lens of the Note20 is already in diffraction territory, meaning stopping down the lens (if possible) would reduce the resolution of the image. A macro lens with a maximum aperture of f1.8 would have a very small depth of field as well, making it useless for macro photography without focus stacking. I'm not particularly well versed in the physics of this stuff so hopefully didn't making any glaring mistakes and that others will find this useful when thinking about upgrading a lens vs upgrading sensor size vs upgrading megapixels.

In terms of the theoretical limits, as I understand it, this is sort of correct but in practice not always so. So for example, both the Sony A6600 on an APS-C crop 24MP sensor and the Sony A7R III on a full-frame 42MP sensor have a maximum resolution of a bit over 100 lp/mm (line pairs per mm). In fact, the A6600 has a higher lp/mm of 128 vs 110 for the A7R III at 1x magnification. This is because the A6600 has smaller pixels than the A7R III. An excellent lens would be able to resolve 100 lp/mm at 1x so we may conclude from this that the lens is usually the limiting factor... ...However, that is the limits at the sensor and is really only useful for comparing sensors of the same size. If we think about an image of a coin at 1x magnification taken with the same lens on the A6600 sensor vs the A7R III sensor, the A6600 image will be projected on a sensor that is 16mm high versus 24mm high for the A7R III sensor. The coin is taking up the same field of view in both images, i.e. both images are at the same magnification. As we know, the A6600 sensor can resolve 128 lines pairs per mm and the A7R III can do 110 lp/mm. So we take the photos and then compare the two images... perhaps to our surprise, the A7R III camera with the lower lp/mm shows much more detail than the photo from the A6600 camera! Why is this the case? Well as the image takes up the same field of view on both sensors, the camera with the larger sensor is able to resolve more absolute line pairs than the camera with the smaller sensor - even if the lp/mm were the same for both cameras. To show this, we need to multiply the lp/mm by the height of each sensor to get the lp/ph (lines per picture height). For the A6600, this is (128*15.6mm) 1,996 lp/ph and for the A7R III this is (110*24mm) 2,640 lp/ph. So the A7R III is theoretically able to resolve 2,640 line pairs across the height of its sensor while the A6600 can only do a touch under 2,000. Because the photos of the coin are at the same magnification, the A7R III is resolving more detail of the coin than the A6600 can. Using the very same lens on each camera, we find that the A7R III is capturing much more detail, even if the lens had an lp/mm rating much worse than the sensor is capable of. This is largely why I upgraded from a crop sensor camera to full-frame, you just can't beat the extra detail you get. But that doesn't mean the sensor is always the limitation either. If your lens is not taking advantage of the sensor's resolution, then upgrading from crop sensor to full-frame probably doesn't make much sense unless you plan on buying a new lens as well.

Thanks for those photos Curtis! From the get go I had a hunch Naumann wasn't close to being right with their attribution so after a brief search I moved on from looking at the suggested Lanz types but it's nice to have examples of each one just to be sure. Re: Naumann 115, I was actually the underbidder at the time on it and was a bit sad to have missed out. I wonder if the buyer didn't pay as 119 is about 3 months after 115 and I believe 3 months is their "grace period" before cancelling an invoice. I had a suspicion they might've called it Celtic for the same reason so I had been looking specifically for examples of both official and Celtic issue with no controls but it can be hard to get the search terms right. Great find with that particular example and the note about why they thought it was Celtic. I can see why Naumann might jump to that conclusion but without any other hints in the style that it may be Celtic, it's perhaps a bit too far of a leap for me to be convinced. For a minute I was thinking the dotted borders is a bit unusual for an official type but it does seem that official types from a very early point do occasionally have dotted borders. Sometimes, even, one side has a solid border and the other a dotted border. On mine I see hints that both sides had dotted borders, perhaps that might be useful for narrowing down the exact period in combination with the style etc as well.

Thanks for the photo of Le Rider! His work is a die study right, so you're saying my coin is obverse die 235 and reverse die 381? If so, neither my obverse or reverse seems to match those. The portrait is quite easy to spot the differences due to the locks of hair curling in opposite directions below Zeus' ear. On the reverse, the tail is different and the second half of the legend starts too far down the right side. Looking at an example of D235, I also feel that the style is fairly different from mine. The portrait of Zeus appears sterner with harsher features, whereas I feel the Zeus on mine has a more softer expression and rounded features. It does seem that Le Rider 462 is without a control mark so if you were just meaning mine might be the same type but not the same dies that makes sense. Though unfortunately I couldn't find any other examples of D462 on PELLA or ACSearch and no examples of R381 either so it's hard to know what kind of stylistic variation to expect for this type.

Certainly could have! Though everything is also relative to 1) what you're used to and 2) what you're able to detect. By the first point I mean that it's very hard to compare lens performance without having another lens to compare it to. The second point can mean you won't notice some issues if you're not using a lens to its capabilities, e.g. using a 1x macro lens to take photos at 0.5x isn't going to necessarily tell you what the sharpness is like at 1x. It can also mean that if you don't need those capabilities, then any issues that only surface at a particular setting are not important for your use case and thus not a factor. The last bit is the most important for you when it comes to deciding whether you want a dedicated macro lens IMO. If you're happy with what you have and it's working for you, there's no reason you should change. So if you don't have any complaints with the photos you're getting, a dedicated macro lens is mostly going to offer convenience in things like: ease of focusing, better light transmission (extension tubes require more light due to the extension), and increased depth of field for a given aperture. Almost certainly, a dedicated macro lens would also be sharper and able to resolve more detail at its optimal aperture versus an extended lens not optimised/corrected for close focusing but, again, if you don't feel you need that or that it will make much difference at the magnification you shoot at, then maybe stick with what you have. The difference you'll notice with a proper macro lens will depend a bit on the camera you have too. On an APS-C or Micro 4/3 sensor, it might not make as much of a difference compared to full-frame. Though I did start with extension tubes on APS-C myself, then later bought a dedicated macro lens, and ultimately upgraded to full-frame. If you can borrow a macro lens from someone you know it might be worth giving it a try just to see how it compares.

I picked up a lovely Philip II tetradrachm the other week at Naumann and while it was attributed to being a Celtic imitation by Nauman, I personally have my doubts. The style is quite good and different to the style of the better Celtic imitations, in my opinion. Some of the Celtic tetradrachms have great style but it is a different style in how the Zeus and horse are rendered. I think at "worst" it must be an early Celtic imitation with dies engraved by someone who clearly was familiar with the style of the Philip II tets and had the ability to copy that style very closely. I think there's still a decent chance it's an official issue, however. The trouble is there doesn't appear to be a control symbol on the reverse so it's very hard to compare it against any official issues that might be similar in the more minute details. It's possibly one of the types with a spearhead in the exergue, though I think I can see the signs of a dotted border below the exergue and that wouldn't leave much room for a spearhead. http://numismatics.org/pella/id/pella.philip_ii.35 http://numismatics.org/pella/id/pella.philip_ii.37 I've been through hundreds of both official and imitative examples on ACSearch but haven't really come close to a good style match for the obverse, let alone die match. Some of the "tells" I've been using are the two curly locks of hair below Zeus' ear and the horizontal curls of the bottom half of the beard. It's possible I've missed some close matches due to the wear on my example making the locks of hair appear thicker than they may really be without the wear.

I've gone through a few iterations myself, though haven't yet tried a copy stand or the WeMacro. Someone on photomacrography.net turned me on to the Thorlabs XT66 rails and I've never looked back. What I love about them is that they're plenty strong, can be assembled and disassembled easily, and have dovetails that are compatible with ARCA clamps so you can attach a clamp anywhere one is needed without having to thread it into a breadboard or similar. I also like how I can easily change between a vertical and horizontal setup: I just loosen the rail clamps at the bottom and rotate the L-shaped XT66 rails 90 degrees: I wouldn't normally recommend them but since you're looking at copy stands in that price range, and this setup can be made cheaper, I thought I'd suggested it just in case. You'd need: 2x XT66 750mm rails = $225 1x XT66P2 rail carriage = $76 2x XT66P3 mounting plates = $120 1x XT66RA1 right-angle clamp = $55 1x Optical Breadboard (I have the 6" x 18") = $136 That's a total of $612 before tax. Not cheap but a quality setup that can easily be adapted down the road. You could also save $75 on the XT66 rails by buying the raw extrusion (unanodized) in a 2m length for $150. Then you could have different cut-off lengths for the L shape for when you need a small setup or the extra length and working distance.

Excellent write-up and coins too! I love your Salamis one in particular, it has such a unique style to the Zeus.

No problem! Feel free to PM me if you find one and have any questions about it. Newport and Thorlabs are the two current big names when it comes to this gear, Melles Griot is a third but IMO the equipment is usually a bit older. Misumi and Suruga Seiki are both respectable brands as well and you can't go wrong with them. But there will be lots of no-name / small time brands out there that are likely good enough for this purpose too. Re: your macro lens question. Extension tubes are likely good enough for most people but there are a few downsides: 1. It's a pain if you want to change the magnification of the setup for a smaller/larger coin. You could find a sweet spot magnification that works for all coins but of course it means you're not getting the most out of the system (which maybe OK depending on your needs). 2. Optical issues. Macro lenses are specifically designed to work within their magnification range and will try to correct for common issues such as chromatic aberration and curved image fields (where only the centre of the image is in focus at one time). An extension tube setup may or may not have these problems, it would depend on the specific lens and extension. 3. Focal length. Extension tubes tend to work best on smaller focal lengths (e.g. <50mm) and are less effective on longer focal lengths (> 80mm), where instead a close-up diopter would be better. What this means is that your working distance with extension tubes is likely to be very small, it's even possible to have a negative working distance (i.e. the focal point will be inside the extension tubes) if you have too much extension. Smaller working distances make it more difficult to light the coin properly. 4. No lens EXIF data, auto aperture, or auto focus if you use extension tubes without electronic contacts. That being said, my macro lens, the Laowa 100mm 2x, actually doesn't do any of those things so it's not a big problem IMO. But these aren't problems that can't be solved, and in fact many macrophotographers use extension tubes combined with particular lenses that solve a lot of the issues above. For example, extension tubes paired with a cheap enlarger lens can work quite well. You could even use a bellows instead of solid tubes to allow you to easily change the extension distance.

Yeah the last one I would trust less to support a weight without shifting. You also could have some issues with vibration in the arm and difficulty in ensuring it's actually perpendicular to the surface and not tilted in any one of three axes.

As you say, autofocus isn't needed for coin photography and I never use it myself so don't worry about buying a lens without it. In terms of focal length, I would aim for 60mm as that would give you about 120mm full-frame equivalent focal length. I use a 100mm full-frame lens and you really need that focal length to give you enough space to light the coin. In that case, either the 40mm or 60mm micro full third lenses should be OK for this purpose, but the longer the focal length the better so I'd personally go for the 60mm. The 7Artisans lens seems to have decent reviews so that sounds like a good option but it's worth reading a few reviews about it online to see how people find the experience of using it as well as the photo quality.

There's usually two methods for doing this with a standard tripod. 1. The first is to use an extension bar to get the camera out horizontally from the top of the tripod and point it downwards. The extension bar is needed to clear the legs so they're not in the frame but if you have a proper macro lens, this is likely not an issue and you can just tilt the camera down using the standard tripod ball head (i.e. no extension needed). Pros: it works Cons: takes up a lot of space, may require a somewhat expensive tripod if you have a heavy camera+lens, often requires a counterweight (see briefcase below). 2. Invert the centre column of the tripod and attach the camera to it so it's placed between the legs. Pros: it works, takes up less room than the other method, doesn't require a counterweight, ensures your camera is perpendicular to the surface if the tripod legs are extended all the same amount. Cons: requires a tripod with an invertable centre column (a common feature on mid-tier and above tripods), still takes up a reasonable amount of space, the tripod gets in the way and makes it harder to adjust settings on the camera (less of an issue if you tether it to a computer). A better option would be a "Copy Stand" like this one. It does exactly what you need it to and no more (downside is it's not useful for other types of photography). You can generally find cheaper ones on Amazon too. The things you want to check are: the vertical column height (will it give you enough room with the camera + lens length + minimum focus distance of the lens), the weight the mechanism on the vertical column can support, and how the adjustment mechanism works. Ideally you'd want a mechanism that can be loosen so that you can twist a knob to adjust the height up/down but also so that the mechanism can be tightened to "lock it off" and prevent movement. Worst case is a mechanism that can't support itself and the camera so that when you want to move the camera up/down, you have to hold the camera and physical move it and then lock the mechanism in place. Nothing wrong with that, just a convenience factor. Similar to the copy stand, but perhaps even better, is the WeMacro vertical stand. These are very affordable and good quality and are widely used in the macro photography community. One problem I heard is that if you mount the camera directly to the stand (i.e. without the motorised linear rail shown in the photos), the camera may not extend far enough out to place it over the XY table below it, which allows you to centre the subject below the camera. This is easily fixed by buying some extra camera adapters from Amazon to make up that distance but requires a bit more fiddling than some might like. Lastly, and I think this is what Doug has done, is to build your own stand out of wood + some camera adapters. This is the most affordable option and virtually gives you all the features you would find in the above solutions, it just requires a small bit of know-how in terms of designing and assembling it. What I would do in that case is to buy one of these long double-sided arca rails and screw it to the vertical wood column and then buy one of these double-sided arca clamps to attach to the rail, then you just need a small arca plate to attach to your camera's tripod thread and to the double-sided arca clamp. You then adjust the bottom part of the arca clamp that is attached to the long arca rail to adjust the camera's vertical position. I recommend the long double-sided arca rail so as to provide clearance between the wood and the arca rail as the clamp needs a bit of room to run in the dovetail grooves. Downside of this method is that the adjustment is not very precise but that likely won't be needed unless you have a proper macro lens.

This is probably the best you can get for $50 without being patient and stalking eBay for a few weeks, though shipping is $20: https://www.ebay.com/itm/202662699439 It's a 40x40mm stage with +/- 10 degrees of rotation and a height of rotation of 40mm (anything placed 40mm above the stage will not translate in a horizontal direction as it is rotated). It's small but enough if you're just putting a coin on top of it. One issue for US folks is that it's metric, so the hole spacing and threaded diameters are both metric, but that may not be too much of a problem. Though it would probably be worth offering $70 on something like this instead as it's imperial and has a micrometer, which will be much easier for adjusting the angle than the knob on the other one. The range is only +/- 5 degrees but that's plenty and the center of rotation is ~35mm above the stage.

If you're just using the goniometer and are in the US, you have a bit more flexibility than me and don't need to be so picky as the vast majority on eBay are sold from the US and have imperial threads. For a Thorlabs, Newport, or Suruga Seiki goniometer, I'd look to pay $60-$90 if I were you. But it depends a bit on the size too, often the Thorlabs and Newport models have stages only 40mm / 1.5" wide / long, which may be enough for some but I really wanted the bigger 60-65mm stage so I could attach the rotation stage to it. There will be other branded or no-name goniometers on eBay that may be cheaper and are probably fine too. For these, I'd aim for something that's like $40. Main thing to check on the specs is that the rotation is enough (some will only do +/- 3°, which might be just about OK), the size of the device, whether you have an easy way of attaching something to it and it to something else, and how you adjust the angle - some have small knobs which may be hard to turn due to limited clearance between the knob and the surface the goniometers will sit on. Also, if it's being sold by some seller who typically guts industrial parts from warehouses or factories and sells them on eBay "as is", expect to be able to get a 50% discount on asking price in some cases. I got mine for $75, down from $150, and it was DHL couriered from Thailand for $10.

It has scaled correctly to the page for me but because the orientation is portrait rather than landscape, it's possible for the image to be longer than the height of the viewport of your device so you may have to scroll to see all of it. In that case, the solution suggested IanG is ideal since it rescales the image for display but opening the image in a new tab will show the full size original image. Whereas if you reduce the resolution and then upload the file, there's no way for someone to see the image in its original resolution and detail is lost. If someone forgets to use the forum tool for resizing and the image is longer than the viewport, you can also click on the image to open the "lightbox" and this will resize the image so its height is less than the viewport and you can see the entire image on your screen without having to scroll. This shouldn't be a problem for most photos in a common landscape aspect ratio as the aspect ratio will ensure the image is never scaled so that it is too "tall" for your device and requires scrolling.

I've been using a variation of the coin platform setup as shown above for about a year and a half now but have decided to try something new, partly because I have Gear Acquisition Syndrome when it comes to photography 😁 But kidding aside, I wanted to improve on a few limitations with my prior setup. It did let me adjust the coin platform in two key ways: I could move it up or down and I could tilt it back and forth so the coin was at an angle relative to the lens. The problem was that there were more degrees of freedom to this setup than just these two: I could also swivel the platform around the vertical post and I could move the horizontal post forwards and backwards. The problem is these are all manual adjustments and it's difficult to get everything perfectly centred and at the right position. So I did something I've wanted to do for awhile and I bought some optomechanical equipment designed for the job. eBay is full of this kind of gear as industrial warehouses and research facilities use them like candy and, when the place is shut down, the gear gets sold off cheaply as no proper facility is going to buy this kind of thing second-hand. I managed to pick up a Newport M-481 rotation stage and a Suruga Seiki B58-60 goniometer for a fraction of their retail prices (though not as cheap as one might hope). The rotation stage provides smooth and precise 360 degree rotation of the coin platform to help orient the coin without having to fiddle with how it sits on its little pedestal. Previously I used an M8 bolt for this, which I would turn from underneath the platform, but there is a lot of slop in such a method and it was a bit too imprecise for my liking. The rotation stage has a built-in micrometer to provide "fine" adjustment of the rotation to +/- 5 degrees. Beneath that is the goniometer, which is simply a device that rotates a stage around an imaginary fixed point above it. Typically they don't have more than 3-10 degrees of rotation and in my experience you only need about 2-3 degrees of tilt for a coin. Anymore than that and the distortion of the coin's dimensions becomes too apparent. I 3D printed some adapter plates so everything would fit together. A happy little accident of my design is that the point of rotation for the goniometer is 7.5cm above it and that turns out to be nearly exactly where the coin sits. What does this mean? Well it means that when you adjust the tilt of the goniometer, the coin doesn't move forwards or backwards, it stays exactly where it was but is simply tilted. With my previous setup, rotating the coin platform would cause the position of the coin to shift relative to the camera because it was not aligned with the axis of rotation. This gear is all way too overkill for this kind of purpose but it does help when it comes to using the mirror background technique I've discussed earlier. If the mirror is not close to perpendicular to the axis of the lens (i.e. parallel to the camera sensor), it can create bright areas on parts of the edge of the coin, making background removal difficult. Since my previous setup wasn't particularly precise, I ran into this issue frequently and had to be careful to align things just right. With the new setup, however, everything is perfectly aligned with the camera and I can make minute adjustments if necessary.

Side note but that's a great Alexander tetradrachm. I love how the sceptre extends so much higher than the dotted border, I don't think I've seen it go that high before. Particularly interesting they'd make it so when it doesn't look like it would fit on the flan if struck perfectly centered. Also interesting that it isn't topped with a lotus flower, which usually a lot of the ones that do extend past the border have.

Can you check what the resolution of these photos are on your computer before you upload them? According to the dev tools in Chrome, the forum software is reducing the resolution of the image from 3000 pixels wide to just 1094 pixels wide (for my device, at least). To me it doesn't look like the forum software is increasing the size at all, particularly as it wouldn't make sense for it to upscale an image to 3000 pixels from whatever the original resolution was and then downscale it again to 1000 pixels. But this is a good example of another point worth making for @Topcat7: if you export a photo from Photoshop that is 3" by 3" at, say 300 PPI, what you get is a 900 x 900 pixel image that will be displayed at different sizes depending on the screen/device of the user. So even when you export an image to a specific dimension, it does not mean that is how it will appear to all users. Case in point, the above image is rendered to 1094 pixels wide on both my 32" 2560 × 1440 screen and also on my 16" 3072 × 1920 screen. The 16" screen is smaller in physical dimensions and has a higher resolution, so the 1094 pixel wide image measures in at 21cm, but on my larger 32" monitor, the image measures 29.5cm. So the dimensions of the file don't guarantee how much physical space it will take up on your screen when measured with a ruler. Combined with responsive web design, not only is your image going to appear to have different physical dimensions for different users, the resolution of the image served to the users will be different as well.

Strange, the images should resize to fit the viewport. In the screenshot below you can see an example where I attached a photo with a width of 2560 pixels but my screen is only displaying it at 1094 pixels. If I reduce the width of the Chrome window, it becomes even smaller. This should be done automatically by the forum's CSS to ensure that the forum is scaled to fit your screen and the content within the threads is scaled to fit within the bounds of the thread. It should also work if you have any accessibility settings set within Chrome to increase the font size / zoom. Though it's possible accessibility settings set on your device (e.g. via Windows' settings or such) may not play ball. @Topcat7Can you link us an example so we can test it and see if it's limited to your device or if it appears that way for everyone? Ideally the scaling of images is done entirely by the forum (and as far as I can tell it is) because making people resize images manually is not a great experience for everyone. For some people, a non-scaled 500x500 pixel image on a screen may be too large, for others it may be much too small. The best method is for the device/client to serve the correct size of image for each user depending on the resolution of their screen/viewport. Most websites and apps do that today ("responsive design") as it's fairly easy for them to do and results in the best experience for most people.

There are a lot of great tools out there for storing collections online but the problem I had with them is that the functionality is often very limited. Since you're digitising your collection, it'd make sense to be able to take advantage of that data and use it in different ways, such as: using it to plot your coins on a map, aggregating weights/diameters by different denominations or weight standards, analysing your purchases to see the effects of changing exchange rates or different fees/shipping costs between auction houses add up in the long-run etc, plotting your collecting habits over time, calculating your profit/loss on coins you've bought and then consigned etc. So for this reason, I did two things: (1) use Google Sheets to track this info and run any analysis I like on the data, and (2) start a website so I could do more complex things and have a way to visualise and share my collection. I disagree strongly with @Alwin when he says "Excel and Word are not suitable for this use" as Excel is perfectly suitable (though I'd recommend Google Sheets instead myself). Microsoft Access of course has some benefits but so does Excel/Sheets and if you're good at spreadsheet tools you can easily create a UI for data entry, enforce database conditions like unique keys, make a "lookup" page for displaying a coin and its info in a nice way, etc and leverage all the spreadsheet functions like historical foreign exchange rates for converting prices to a base currency etc. Google Sheets also has the added benefit of having a version history so you can easily revert to a prior state if you screwed something up. Though there may come a point where using a proper database is needed, and I'm not saying those cases do not exist, only that the vast majority of people would likely not see much benefit from them. In my case, the problem was keeping the data in my website's database up to date with the data in Google Spreadsheet. So just recently, over this past 2 weeks, I decided to switch to using my website's database as my primary database and to build a UI from scratch so that I can interact with the database more easily: But this is something that mainly makes sense for someone who has a website like myself because my website's database is the one used by many of my plugins, such as the Ultra Zoom, the coin galleries, the coin map, and my ANS-like user-facing database with filters etc. So having my Google Sheets out of sync with my website would mean my website doesn't have all the information until I sync the two and I'd essentially be managing two separate datasets. The syncing of Google Sheets to my website is a bit of a manual process where it is easy for things to go wrong as well, so it made sense to stick with one primary database linked to my website, the problem was just that there's no good UI for that database and PHP MyAdmin is not a fun way to manage such a database.

I've had similar problem in the past with Noble's live platform as well. I've had it no register my bids at all in the back platform (where it says which lots you bid on), to also "winning" a lot as it closed live only to find out after it didn't record me as the winner.