Alternatives to official photo projection lenses?

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Seta
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Alternatives to official photo projection lenses?

#1 Post by Seta » Wed Mar 10, 2021 3:45 pm

Hi,
I am using a Olympus BHT with nikon CFN lenses via direct projection on a Sony NEX camera; as corner performance is far from perfect and Nikon lenses do the corrections on the lens I wonder what alteratives do we have to official manufacturer projection lenses.
I have used manual teleconverters sometimes, I do own a vivitar 1.5X and a M42 2x but they behave more like a 1.9x and 2.4X. I am looking for something between 1.3 and 1.5 ideally.
Would something like the achromatic pairs Edmund optics has do the job?

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hkv
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Re: Alternatives to official photo projection lenses?

#2 Post by hkv » Fri Mar 12, 2021 7:23 am

Yes, I have been thinking about these myself, but I have not tried them. They should do just fine is my conclusion after doing some research. The tricky part will be to get a lens setup with the correct focal length and distances so that you also achieve parfocality with the eyepieces. It is on thing to just connect a camera and view everything from the screen or viewfinder, but to capture (on camera) exactly what you see in the eyepieces, both light trains needs to be in focus at the same time. I guess you will have to calculate exactly what lens setup you would need to achieve this.
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apochronaut
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Re: Alternatives to official photo projection lenses?

#3 Post by apochronaut » Fri Mar 12, 2021 12:55 pm

I may be interpreting your post incorrectly but I think you are looking for a photo eyepiece that is compatible with your CFN objectives? You are therefore thinking the Edmund relay lenses should be absolutely neutral in their corrections and work as a projection lens?

PeteM
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Re: Alternatives to official photo projection lenses?

#4 Post by PeteM » Fri Mar 12, 2021 4:37 pm

Probably a bit cumbersome to adapt to your Sony, but Nikon made F mount teleconverters in 1.4x, 1.6x, 1.7x, and 2x. Since you don't care about exposure automation and auto focusing, most any old converter (cheap but with the glass in mint condition) could be worth a try. Only gotcha for Nikon owners is that some of the oldest converters (non AI) won't safely mount on their modern DSLR's.

I'd assume others make quality and relatively plan teleconverters that could be adapted?

Seta
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Re: Alternatives to official photo projection lenses?

#5 Post by Seta » Fri Mar 12, 2021 5:37 pm

hkv wrote:
Fri Mar 12, 2021 7:23 am
Yes, I have been thinking about these myself, but I have not tried them. They should do just fine is my conclusion after doing some research..................
As long as the offer good performance I can adapt them, maybe inside M42 tubes. Sent a message to Edmund support, still waiting for them to answer
apochronaut wrote:
Fri Mar 12, 2021 12:55 pm
I may be interpreting your post incorrectly but I think you are looking for a photo eyepiece that is compatible with your CFN objectives? You are therefore thinking the Edmund relay lenses should be absolutely neutral in their corrections and work as a projection lens?
I would expect them to be, as most modern optical systems; I asked support, we´ll see
PeteM wrote:
Fri Mar 12, 2021 4:37 pm
Probably a bit cumbersome to adapt to your Sony, but Nikon made F mount teleconverters in 1.4x, 1.6x, 1.7x, and 2x.................
I have and used a Vivitar 1x5 F mount teleconverter and an old and cheap M42 2xTC; with the mitutoyos they seem to perform well but with the nikon lenses I have noticed a drop in performance, corner quality anbd resolving power. The 1.5X behaves more like a 1.85X and the 2x more like a 2.4X; maybe I did not get the distances right.


Here is a full size picture of a Papilio blumei scales at 48X with mitutoyo 20/0.42, Raynox DCR-150 as tube lens and 10$ M42 TC.

Problem with 1.4xTC I have tried is they suffer from a hot spot in the center of the frame, with my vivitar I can fix this adding a short extension tube I have (maybe is the rectangular window it has that fixes it)

Reason to look for a relay lens is because I am aiming at a 1.25x to 1.5x maximum magnification

"Our 15.0mm and 30.0mm Mounted Achromatic Pairs combine our popular TECHSPEC® achromats into common configurations used for relay and projection applications. Packaged in a slim-line aluminum housing, each pair is ready for integration into a host of OEM applications, eliminating the need to handle loose optics. Our 15.0mm pairs can be coupled into our C-mount components using our Helicoid Barrel Accessory. Each lens has also been oriented for optimum system performance. All lenses AR coated. Lower f/# pairs may not be ideal for imaging applications depending on the performance requirements. Cylinder lenses can be incorporated into empty barrels in order to generate lines or sheets of light. Mounted Achromatic Pairs Kits also available."

I am not that good at reading specs sheeets..

Image

There is two housing diameters 15mm and 30mm; focal lengths for doubles range from 14mm to 100mm and magnification from 1x to 3.33x but there are some interesting ones like 1.2X, 1.25X, 1.33X, 1.5X, 1.67X (Like a famous NFK) and so own

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lagoonatic
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Re: Alternatives to official photo projection lenses?

#6 Post by lagoonatic » Fri Jun 04, 2021 7:10 pm

PeteM wrote:
Fri Mar 12, 2021 4:37 pm
Probably a bit cumbersome to adapt to your Sony, but Nikon made F mount teleconverters in 1.4x, 1.6x, 1.7x, and 2x. Since you don't care about exposure automation and auto focusing, most any old converter (cheap but with the glass in mint condition) could be worth a try. Only gotcha for Nikon owners is that some of the oldest converters (non AI) won't safely mount on their modern DSLR's.

I'd assume others make quality and relatively plan teleconverters that could be adapted?
John White can convert non-AI lenses and converters to fit modern Nikon DSLR mounts - https://www.aiconversions.com/

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