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How to modularily mount a projection lens

Dr Klaus Schmitt

Well-known member
This is to show how to mount a projection lens. The front adapter can be changed, as well as rear camera mount (can be basically any camera).

Remark: This is mainly intended to test and use a variety of lenses and not does not replace a full conversion of such a lens (adding iris, focusing, camera mount),
as it allows to switch lenses in seconds using an Allen wrench.

Works from infinity (depending on lens back focal length) to very closeup. Setscrews allow to calibrate the infinity position. The basic idea is to allow the lens to
"dive into" the larger helicoid, hence quite a short optical length can be achieved using such a contraption.

Lens --> Lens Adapter to M65 --> M65 to M42 Helicoid --> M42 to Camera mount Adapter (the latter two may be just one M65 --> camera mount X)







It is not a slim elegant and lightweight solution, but the benefits are:

1) no lens modification needed
2) non rotating front for sunshade/filter (needs additional clamp holder)
3) accepts a variety of lens types and lens diameters, switch within seconds
4) mount may hold ND filter (better in front though using variable ND) or adjustable iris
5) allows a variety of camera mounts (M42, Nikon-F, Sony-E, Canon EF, m4/3, Hasselblad V, Mamiya 645 etc.)
6) needs only about 15mm net optical length (plus camera register) for lens diameter 62.5mm or smaller
7) safes money and time for not having to go to the gym, as it is quite heavy :)

The design is basically made to accept 35mm russian film projection lenses with a standard 62.5mm diameter.
Smaller ones (52.5mm etc.) are possible using a different front plate, also some larger ones, but infinity focus
may often not be reached using the latter, as such lenses then cannot dive into the helicoid.

The M65 helicoid is made in China and may be found on ebay.

Those two adapter rings (front and back) are made by rafcamera.com based on my design.
The front one has three hex nut setscrews which hold the lens in place and allows to adjust infinity focus (only if the lens has enough back focal length)
Rafcamera offers several camera adapter plates for the rear one incl. Nikon-F, Sony-E, m4/3 etc.
Orders may be done directly through their site or through amazon.com
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dphoto&field-keywords=rafcamera+M65&rh=i%3Aphoto%2Ck%3Arafcamera+M65

(I have no connections with Rafcamera except that I'm a happy customer...)

[my name is on the rings was a curtesy of rafcamera and is a non standard feature]
 

Asher Kelman

OPF Owner/Editor-in-Chief
Thanks so much Klaus for so generously sharing your extensive expertise and for free!

Much appreciated!

Asher
 

Doug Kerr

Well-known member
Hi, Klaus,

Thank you so much for sharing with us this elegant design and execution.

Best regards,

Doug
 

Asher Kelman

OPF Owner/Editor-in-Chief
Klaus,

One might have a variety of lantern lenses for your recommended setup.

Do you have a recommendation for a useful "set" of adapters for the front of the M65 helical main adapter and do you think the the Sony APS-C sized E mount camera camera end of an M65 adapter is sufficient for FE cameras or will there be vignetting?

I guess to be safe one could use an M65 with an integral M42 adapter at the back and then use the M42 to Sony FE adapter to mount to the camera.

Asher
 

Dr Klaus Schmitt

Well-known member
Thanks so much Klaus for so generously sharing your extensive expertise and for free!

Much appreciated!

Asher

So I guess I made a mistake it seems - "for free". Every heard that famous word "what comes for free has no value"? Wise words....

Hi, Klaus,

Thank you so much for sharing with us this elegant design and execution.

Best regards,

Doug

Most welcome Doug, hope you make good use of it ;-)

Klaus,

One might have a variety of lantern lenses for your recommended setup.

Do you have a recommendation for a useful "set" of adapters for the front of the M65 helical main adapter and do you think the the Sony APS-C sized E mount camera camera end of an M65 adapter is sufficient for FE cameras or will there be vignetting?

I guess to be safe one could use an M65 with an integral M42 adapter at the back and then use the M42 to Sony FE adapter to mount to the camera.

Asher

I'm rather bad on guessing and I really detest being possibly blamed for things I'm not responsible for, so please have you own thoughts and decisions based on my proven-to-work (for me) design. Well, "I can cook a soup, but you have to eat it" is another famous word ;-)
 

Asher Kelman

OPF Owner/Editor-in-Chief
Dr Klaus Schmitt;164906 I'm rather bad on guessing and I really detest being possibly blamed for things I'm not responsible for said:
Makes sense!

You are already generous enough, Klaus! I was wondering if there were sets of adapters for the front of the device that one can buy and have in reserve. I'll contact the M65 seller.....and measure the diameter of my lenses!

Asher
 

Dr Klaus Schmitt

Well-known member
That's why I have added the amazon link to the seller, as he offers many front and rear adapters. What he has is all listed there, just have a look, if that isn't too much asking for ...
 
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