50mm/f2.8 versus 90mm/f2.8 macro lenses for coin photos?

I have been telling myself that I would do that for a couple years now. I wonder if I could make a limited edition 1 of 1 and sell it for $26.

 

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Viva Ott lights.

 

This has been a fascinating thread. I was sure that I had some extender rings and went looking. What I found was diopter lenses, +1, +2 and +3. This didn't seem to be right as there was glass in each of them. Then I remembered that something came free with my ring light. Described as a macro extension, there are three sizes 28mm, 14mm and 7mm.

I have got over the shaky camera by using a remote clicker thing and if necessary, have found the page in the manual related to mirror lockup.

My biggest problem at the moment is that when I am photographing a larger coin, the camera needs to be towards the top of the copy stand. This means in order to look in the view finder, I need to get the step ladders out.

 

Have you thought about putting the whole thing on the floor?

 

Thank you Doug for sharing your knowledge.

 

It is a question of space and two dogs who like to "help".

 

Diopter lenses come in +1 to +10 strengths with each number slightly more powerful than the one before. They degrade the image slightly if they are the expensive two element versions and a lot if they are one element versions that usually come in sets for very low prices. They should be used with cameras which do not allow the lens to be removed. The image below shows results on the edge of a serrate denarius (top right). The right part of the close up was shot with a one element cheap diopter. The left part used a very high grade multi-element accessory diopter. Single elements can not correct chromatic aberration so you get some color fringing. You get what you pay for.


Extension tubes have no glass and reduce the quality very little (depending on the lens design, possibly none). They go between the lens and the camera so can only be used on interchangeable lens models. Only buy models with electric contacts (brass pins in image of this Canon model) so your auto diaphragm still works.

The other (much cheaper) type can be used with manual lenses (like enlarger lenses) to good effect (especially for very large magnifications) but it takes some care to learn to use them. Examples:


Extenders (1.4x, 2x usually) have glass and magnify both the image and the faults of the lens. Some do better than others but the main reason people use them is to get a telephoto lens cheaper than buying a real one. You could use one with a short macro lens to turn it into longer macro and get the advantage of the greater working distance. I have done it with very small coins but usually the quality loss is about the same or greater than just cropping. I do not recommend them.

The rules have really changed in the digital age. Sharpening routines, properly used in postprocessing, can improve some lens problems. Misused, they can wreck images. Focus stacking can make depth of field problems much less a problem. I am not saying that learning all the tricks will mean you can use lousy lenses but I'm wondering if that might be coming to a generation in the not so distant future.