Question about infinity space (plus basic photomicrography inquiries)

Starting out in microscopy? Post images and ask questions relating to the microscope and get answers from our more advanced users on the subject.

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Question about infinity space (plus basic photomicrography inquiries)

Post by smimo »

Hi, I’m looking to get into photomicrography but I’ve yet to put my finger down on a set up. I’m probably going to use a reversed raynox dcr-150 as my tube lens and a Nikon CFI 10x as my objective but the science behind infinity spaces confuses me and is proving somewhat of an impasse re my progress. I see some places advising me to minimize infinity space as much as possible, but other websites displaying set ups with infinity spaces north of two inches. I’m unsure how to proceed at the moment.

My rough plan is to build my tube out of m52 extension tubes, plus a short helicoid for minute length adjustments, but any input (and gear recommendations) from more experienced photomicrographers apropos building a set up is definitely welcome. I’m hesitant to use bellows because I can be somewhat clumsy with my gear and I currently don’t have a controlled equipment storage environment, but if push comes to shove I might get them. My current camera body is a Nikon d7500, and I plan to get a rail (most likely a motorized one e.g. stackshot) after I’ve figured this all out.

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Re: Question about infinity space (plus basic photomicrography inquiries)

Post by rjlittlefield »

smimo, welcome aboard!

The reason you see a wide range of lengths for the infinity space is that the very best length depends on which tube lens is being used.

In some cases it also depends on the photographer's personal preferences for trading off one aberration against another, because changing the length can make some some aberrations worse while making other aberrations better.

Purpose-made tube lenses from the major microscope manufacturers are generally designed to prefer larger lengths, or at least to tolerate them. The reason is that for microscope use, the infinity space is a handy place to put large accessories such as beam splitters and filter cubes.

Other lenses that have been repurposed as tube lenses usually prefer shorter infinity spaces.

To get the absolute best length for your own equipment and preferences, there is no substitute for experimentation.

On the other hand, in my experience the differences in image quality caused by infinity space length are seldom very large compared to the plethora of other issues that impact image quality. So, given that I only have so much time to spend on tinkering, I generally just pick some convenient length and don't worry about it.


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