Nikon Optiphot Projection Lens Magnification

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Melch
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Nikon Optiphot Projection Lens Magnification

#1 Post by Melch » Thu Apr 07, 2022 2:40 pm

Hi

I have a Nikon Optiphot microscope with a camera tube. It came with a 5X and 10X projection lens. Both these projection lenses significantly crop the image when taking photos.

Does anyone have experience with this setup and know what projection lens magnification I should look for to get close to full frame on a DSLR camera (3/4 sensor) or where I could look for this information.

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zzffnn
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Re: Nikon Optiphot Projection Lens Magnification

#2 Post by zzffnn » Thu Apr 07, 2022 2:48 pm

With 3/4 sensor and “10x projection lens”, you may try a 28mm prime lens in between. A zoom lens set at 28mm will produce a much smaller image circle.

I don’t know about your “10x projections lens” and trinocular tube length. But with the correct tube length setting (that is parfocal with visual eye tube), a 10x visual eyepiece will work there for sure, with 28mm prime lens and 3/4. I tried that before and it worked well for me.

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Re: Nikon Optiphot Projection Lens Magnification

#3 Post by PeteM » Thu Apr 07, 2022 4:31 pm

Nikon used a 2.5x projection lens to image from their trinocular heads direct (no camera lens) to a 35mm camera. So that's ideal for today's full frame sensors. These are readily available used, but will magnify a bit too much for something like an APS-C sensor.

Nikon also made a 2x projection lens - closer to what you want. While a bit harder to find, they're out there and somewhat affordable compared to Olympus' rare and pricey 1.67x projection lens.

So if you want to go direct and avoid the extra glass and complication of a camera lens, look for a 2x and maybe settle for a cheap 2.5x in the interim if your desire to take pictures ASAP exceeds your luck in finding one. There are also generic 2x relay lenses available (AmScope and other dealers of China-made optics), of somewhat lower quality in my experience, but well under $100.

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Re: Nikon Optiphot Projection Lens Magnification

#4 Post by Scarodactyl » Thu Apr 07, 2022 6:11 pm

The 10x at least is not meant to be used as a projection lens. It is designed to be used afocally, with a lens focused to infinity above capturing the image. In my testing it gage a clesner image than the pl 2.5x projective (which added a fair amount of CA), though the coverage was a bit worse. The pli 2.5x is a lot better than the pl 2.5x on that front.

Melch
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Re: Nikon Optiphot Projection Lens Magnification

#5 Post by Melch » Fri Apr 08, 2022 7:40 am

Thanks everyone for the helpful feedback.

First of all Ill try using my slr with a 28mm lens and 10X projection lens in the photo tube and see how this works but it sounds like it will suit my needs (hobbyist hoping to get some photos of what I see). It will be great not to have to buy more equipment at this stage so this is good news for me.

If that does not work I will look for a 2.5X or 2X projection lens.

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Re: Nikon Optiphot Projection Lens Magnification

#6 Post by zzffnn » Fri Apr 08, 2022 1:03 pm

With your 2x crop four thirds camera sensor, you can use 24mm prime lens as well, but 28mm is ideal. Any vintage manual lens will work. Try the lens at widest aperture first, then step down 0.5-1 stop to enhance contrast without producing a smaller image circle.


Move camera up / down and left / right to align to center and ensure a large image circle on camera sensor.

If your 10x eyepiece works well that way, you may try gluing the eyepiece to a 28mm-30mm lens (step-up) adapter reversely (at the 30mm thread end), then connect said 28-30mm lens adapter to other lens step-down adapters such as 42-28 or 58-28. Use high tensile strength export putty and lots of them to hold eyepiece with 28-30mm lens adapter.

Many eyepieces can fit onto the 30mm end of 28-30mm lens adapters as they are or when you remove their outside shells. Some eyepieces don’t fit. I remember Labophot / Optiphot eyepieces have thick rubber surrounds and don’t fit 28-30 adapter, but older HKW10x fits quite well once outside she’ll is removed.

Some telescope eyepiece - camera / smartphone adapters would work as well. I have a plastic 3 prongs version similar to this one and it works well for me: https://www.ebay.com/itm/383448535488?h ... SwwAVbZHNh

Or use a smartphone lens:

https://www.ebay.com/itm/384224732119?h ... Sw3XtgyYsO

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Re: Nikon Optiphot Projection Lens Magnification

#7 Post by sreynolds » Sat Jan 14, 2023 1:55 am

Scarodactyl wrote:
Thu Apr 07, 2022 6:11 pm
The pli 2.5x is a lot better than the pl 2.5x on that front.
If I were looking for a projection lens, am I to understand the 'PLI' is for infinity objectives, and 'PL' is for fixed-length 160mm systems?
Steve

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Re: Nikon Optiphot Projection Lens Magnification

#8 Post by Scarodactyl » Sat Jan 14, 2023 2:07 am

In theory. In practice their eyepieces are cross-compatible as long as the diameter matches, but the older pl 2.5x adds aberrations of its own which the updated versions do not.

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