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How to modularily mount a projection lens
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PostPosted: Thu Mar 12, 2015 8:06 am    Post subject: How to modularily mount a projection lens Reply with quote
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 Smile

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]

Last edited by kds315* on Mon Aug 31, 2015 6:20 am; edited 1 time in total


PostPosted: Thu Mar 12, 2015 8:55 am    Post subject: Reply with quote
Interesting! That's way more elegant than most of adaptations I do Very Happy

But one question, what is "Lens Adapter to M65"? Is it an adapter like T mount? (with 3 screws)


PostPosted: Thu Mar 12, 2015 9:01 am    Post subject: Reply with quote
BurstMox wrote:
Interesting! That's way more elegant than most of adaptations I do Very Happy

But one question, what is "Lens Adapter to M65"? Is it an adapter like T mount? (with 3 screws)


It is a ring which has three setscrews to lock the lens into position (use an Allen Wrench to adjust hex nut set screws). Has M65 thread to attach to helicoid.


PostPosted: Thu Mar 12, 2015 9:42 am    Post subject: Reply with quote
Looks like a very nice elegant solution, more so if you have many similar lenses to mount.
Is it easy to get the lenses centred and with no tilt?


PostPosted: Thu Mar 12, 2015 9:48 am    Post subject: Reply with quote
Lightshow wrote:
Looks like a very nice elegant solution, more so if you have many similar lenses to mount.
Is it easy to get the lenses centred and with no tilt?


Yes, as the adapter ring is rather long and the fit is very smooth, so no tilting (if the set screws are operated the right way that is)


PostPosted: Thu Mar 12, 2015 11:57 am    Post subject: Reply with quote
This is something I am planning to do myself as soon as I'll get helicoid. I have one question - why not use an M42 to M42 helicoid? Is there a special point of using M65 to M42 one?


PostPosted: Thu Mar 12, 2015 12:01 pm    Post subject: Reply with quote
Not really, just could not find a suitable adapter with a negative length to fit 52.5mm or 62.5mm to :BIGGRIN:


PostPosted: Thu Mar 12, 2015 12:35 pm    Post subject: Reply with quote
Snowcat wrote:
This is something I am planning to do myself as soon as I'll get helicoid. I have one question - why not use an M42 to M42 helicoid? Is there a special point of using M65 to M42 one?

Easier to adapt down to the needed diameter, but if the lens is 45mm in diameter and needs to be closer to the sensor then the flange for infinity, the wider version may still prove useful.


PostPosted: Thu Mar 12, 2015 4:50 pm    Post subject: Reply with quote
Snowcat wrote:
This is something I am planning to do myself as soon as I'll get helicoid. I have one question - why not use an M42 to M42 helicoid? Is there a special point of using M65 to M42 one?


More specifically, it is beneficial if the lens to be adapted allows to penetrate into the helidoid, than attaching a helicoid just to the rear of a lens (it is also called "sunken mount"). This way the rear lens group can be brought usually much closer to the sensor. Member Lightshow has mentioned that.


PostPosted: Thu Mar 12, 2015 6:55 pm    Post subject: Reply with quote
Can we get a link to the helicoid you have? At the moment i am using old Hanimex lens parts for my 16KP 1.2 and its not bad. Smile


PostPosted: Thu Mar 12, 2015 8:12 pm    Post subject: Reply with quote
ebay, found it there a while ago. I'm sure there is more...


PostPosted: Thu Mar 12, 2015 11:50 pm    Post subject: Reply with quote
http://www.ebay.com/itm/62-5mm-to-M65-adapter-to-use-LOMO-projection-lenses-on-focusing-helicoids-/141239547719?pt=LH_DefaultDomain_0&hash=item20e2887747


PostPosted: Fri Mar 13, 2015 12:06 am    Post subject: Reply with quote
How cool , thank you!!


PostPosted: Fri Mar 13, 2015 3:31 pm    Post subject: Reply with quote
Ingenious!
Thanks for sharing!


PostPosted: Fri Mar 13, 2015 3:35 pm    Post subject: Reply with quote
Most welcome Spyros!


PostPosted: Fri Mar 13, 2015 6:52 pm    Post subject: Reply with quote
Very neat and elegant, even ND filter mounted.
Btw. is it easily removable ?

Those mounting lens screws, do they touch the lens, I found they can scratch the lens barrel or even the lens mounting thread when in the way. The remedy is a protecting cut sleeve even of a cardboard, do you use one ?

Many projection lens have standard mounting diameter of about 42,5 mm so it is rather convenient to produce one sleeve for them - I use outer barrel with helicoid of Helios auto 44 lens and a cut sleeve of 1 mm aluminum sheet, it fits almost perfectly.

macheck


PostPosted: Fri Mar 13, 2015 10:11 pm    Post subject: Reply with quote
Sure, use a sleeve if you need to, to protect a precious EUR15 lens....

Or simply do what you do with a certain feeling for it and not use brute force, that's what I do - and never had any damage.


PostPosted: Sat Mar 14, 2015 10:43 pm    Post subject: Reply with quote
My notion was of informative purpose for those who would wish to repeat your well done job.

The cut sleeve is rather common when mounting moveable components in optical equipment by the means of screw fixture in order to protect the surface being fixed.

The value of an object is irrelevant, since we are about no longer in production lenses, so susceptible to extinction when improperly handled or modified.

I have my Trioplan 2,8 100 mm for more than thirty years and remember times it was worth less than now and nobody valued it that much, so Heavens protected me from mutilating Him Wink.
Who knows what will be tomorrow so I stopped madly converting lenses but rather looking for appropriate system to handle them or making reversible modifications.


PostPosted: Thu Jun 18, 2015 9:27 pm    Post subject: Reply with quote
Thank you very much Klaus for your share and Woodrim for link to Adapter - 62.5mm to M65x1.

Next Visionar mod from Poland made by ebay user - pk674:






Last edited by Kamosor on Fri Jun 19, 2015 7:54 am; edited 2 times in total


PostPosted: Fri Jun 19, 2015 6:37 am    Post subject: Reply with quote
Nicely made, looks good to me!!

(please place your ebay ad in the "For Sale" section here and use the English ebay site, not polish, not everybody speaks that here...)


PostPosted: Mon Aug 31, 2015 6:20 am    Post subject: Reply with quote
(updated original posting to current state)


PostPosted: Mon Aug 31, 2015 1:31 pm    Post subject: Reply with quote
yes mounting top quality projection lens is a very rewarding and satisfying passion for me,

This is my Canon rig for movie shooting





PostPosted: Mon Aug 31, 2015 1:33 pm    Post subject: Reply with quote
Looks rather professional Wink Wink Wink


PostPosted: Mon Aug 31, 2015 1:39 pm    Post subject: Reply with quote
Thank you!

Of course today, we can enjoy the supreme quality of 3x Oscar winning lens for such little cost.

https://www.schneideroptics.com/pdfs/projection/Cinema-Lenses.pdf


PostPosted: Mon Aug 31, 2015 4:31 pm    Post subject: Reply with quote
JohnBar wrote:
Thank you!

Of course today, we can enjoy the supreme quality of 3x Oscar winning lens for such little cost.

https://www.schneideroptics.com/pdfs/projection/Cinema-Lenses.pdf


Yep, even one with adjustable Iris, saw one on ebay but was way to pricey.... Neutral
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