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06/17/2004 08:16:29 AM · #1 |
| I am using a coolpix 5400 at work for measuring distances through macro shots. But I would like to increase the resolution achieved (200 pixels per mm at 1cm of distance). Could it be possible?. What kind of accesories do I need (adapters, etc). |
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06/17/2004 09:20:51 AM · #2 |
I assume that 200px/mm is your target? I calculate the maximum resolution of the 5400 by itself as 81px/mm, based on data from DPReview.
Since the 5400 already focuses down to 1cm, a using a diopter (providing closer focus) will do yo no good. Reversing an SLR lens, say, a 50mm, in front of the 5400 may give you enough additional magnification. If not, you may be forced to use a stereo microscope and do eyepiece photography. That's not a cheap option, though.
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06/17/2004 01:13:57 PM · #3 |
I don´t know how the DPreview guys calculate this resolution, but with the coolpix 4500 I have achieved such resolution (about 90px/mm) at 2cm with 4Mp.
The problem with the microscope is that I can´t put the sample under the microspcope. I have to do an in situ photography. ¿Any idea of a decent cost solution? (apart from the coolpix 5400).
Thanks kirbic. |
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06/17/2004 01:48:02 PM · #4 |
Oops I thought you were using the 5400, not the 4500; very little difference in either case. The 4500 has a 28mm front thread, though, making it tougher (though not impossible) to mate an auxiliary lens. If you must do an in-situ photo, I'd try a reversed 50mm SLR lens. You could find an (older, manual)used one for very little money ($10-20??) at a camera store, you just have to find a way to mate it. You could test it by just holding them together to get "proof of concept".
Assume you find a lens with a 49mm front thread; you'd need a 28mm-49mm "macro coupler". I don't necessarily think such a thing is available, so you might have to create something. That wouldn't be difficult, especially if you have access to a machine shop with even modest capability.
Message edited by author 2004-06-17 13:48:38.
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06/17/2004 02:19:55 PM · #5 |
I have a 4500 and tried a reverse lens setup with my Canon 50mm f/1.8.
I ended up buying a 28-37 step up ring and a 37-52 step up ring and a 52-52 macro coupler. As you can imagine, the extra distance with 3 rings, plus the fact the the Canon lens has the glass element set back pretty far, made vignetting a real problem and I lost about 60% of the frame. I am going to keep experimenting by trying other ring combinations and maybe a different lens.
Another alternative I'd recommend, however, is the Crystalview 8x32 Sharpshooter monocular. It's not the greatest quality glass, but with a tripod mount and setting your 4500 on macro setting and manually focusing the Crystalview, you can get some decent shots. I have used it more as a telephoto than for macro work, but I have a sample spider picture (not that great) I could show you, if you'd like to see the quality. You can get the Crystalview from //www.ckcpower.com/crystalvue.htm
Dave
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06/17/2004 02:54:25 PM · #6 |
One thing you want to be careful of when using any imaging system to do measurements is that you account for lens distortion. If you have significant barrel or pincusion distortion, and you measure distances across much of a frame, you may wind up with errors as great as a couple percent due to distortion.
Luckily, the eye is pretty sensitive to this. If you photograph a grid straight on, and you can easily see the distortion, you probably need to compensate for it. you can do so by either "doing the math" to correct the results, or by correcting the distortion in the image prior to making the measurements.
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