How to modularily mount a projection lens

[Dr Klaus Schmitt]

Thanks, Klaus, for the details of the adapter.  Hope the filter I intend to use is of a thin-frame type.

I have been told the max. thickness (w/o thread, just frame height) is 5mm (not too bad actually), max. outer filter diameter 54mm

[Akira]

I have been told the max. thickness (w/o thread, just frame height) is 5mm (not too bad actually), max. outer filter diameter 54mm

Thanks for the additional info.  5mm should be thick enough to accommodate virtually any filters, and I don't intend to any polarizing filters like PL or vari-ND.

[Dr Klaus Schmitt]

Thanks for the additional info.  5mm should be thick enough to accommodate virtually any filters, and I don't intend to any polarizing filters like PL or vari-ND.

Just one CAVEAT: there has to be ALWAYS a filter inside as otherwise there will be significant focus shift, based on the old Astronomer's rule, Focus Shift = 1/3 Filter Thickness, so a 2mm thick filter will shift focus 0.6mm backward.

As I use filter (stacks) of different thicknesses, this is a major drawback. Using gel filters would solve that (as those are very thin and not made of glass), but not possible for my type of photography.

AF shooters will have the camera balance this out most likely, but for MF it is cumbersome, especially when using a color corrected quartz fluorite lens w/o focus shift.

[Akira]

I'm going to shoot very distant subjects.  So long as I can focus at infinity, that would not be a major problem, as I can adjust the focus ring to the closer distance.  Thank you for the note.

As the adapter disables the AF function, the user will have to focus manually anyway.

[Dr Klaus Schmitt]

I'm going to shoot very distant subjects.  So long as I can focus at infinity, that would not be a major problem, as I can adjust the focus ring to the closer distance.  Thank you for the note.

As the adapter disables the AF function, the user will have to focus manually anyway.

Actually you will be able to focus a bit beyond infinity, once the filter is installed!
I just wished the filter holder would sit a bit tighter...

[Frank Fremerey]

I see a lot of Pentacon 3.5/140mm projection lenses on Ebay chaply like no 222677170669 . Are these suited for your adaptation?

I like to try shooting shots like these: https://previews.123rf.com/images/yokokenchan/yokokenchan1608/yokokenchan160800195/61336876-smoke-tree-Pentacon-lens-Bubble-bokeh-Stock-Photo.jpg

[Dr Klaus Schmitt]

I see a lot of Pentacon 3.5/140mm projection lenses on Ebay chaply like no 222677170669 . Are these suited for your adaptation?

I like to try shooting shots like these: https://previews.123rf.com/images/yokokenchan/yokokenchan1608/yokokenchan160800195/61336876-smoke-tree-Pentacon-lens-Bubble-bokeh-Stock-Photo.jpg

Sorry, but I don't know this specific lens, but as lomg as it is not thicker than 62.5mm, I don't see a problem!

[Snoogly]

How to mount a projection lens, front adapter can be changed, as well as rear (can be basically any camera).

Works from infinity (depending on lens back focal length) to very closeup. Setscrews allow to calibrate the infinity position.

Lens --> Lens Adapter to M65 --> M65 to M42 Helicoid --> M42 to Camera mount Adapter







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

1) no lens modification needed
2) very durable
3) non rotating front
4) accepts a variety of lens types and lens diameters
5) allows a variety of camera mounts
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 film russian 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 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.
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 them except that I'm a happy customer...)

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

Sorry to revive such an old thread!!!

I can't seem to find the M42 to Nikon F adapter on the rafcamera site. Will any M42 to Nikon F (without a lens inside) adapter work at the rear end of this wonderful contraption?

[Akira]

Sorry to revive such an old thread!!!

I can't seem to find the M42 to Nikon F adapter on the rafcamera site. Will any M42 to Nikon F (without a lens inside) adapter work at the rear end of this wonderful contraption?

If you live in Japan (or even in Tokyo), you may want to check out BORG accessories.  This cameramount:

https://www.tomytec.co.jp/borg/products/partsDetail/summary/180

combined with this 49.8mm to M42P1 adapter:

https://www.tomytec.co.jp/borg/products/helicoidDetail/summary/47

will make a neat M42 to Nikon F adapter which may be a bit pricey but will serve as a handy and expandable system.

[Akira]

Here is how the adapters mentioned above look (three rings on the right).  The mounts are for m4/3 and Sony E, but BORG offers many other mounts including Nikon F.

[Snoogly]

Great. I will become absorbed into the BORG ...

Both rings are available from Yodobashi, so already ordered!

Many thanks for the info.

[Akira]

Great. I will become absorbed into the BORG ...

Both rings are available from Yodobashi, so already ordered!

Many thanks for the info.

Glad to be of any help.  If you need to examine BORG parts at a retailer, I would recommend Kyoei shop near Akihabara.  This shop specializes in astronomical telescopes and keeps more BORG parts in stock than Yodobashi does:

http://www.kyoei-tokyo.jp/

[Dr Klaus Schmitt]

Well any parts will work as long as you follow the principle idea. Rafcamera also offers these,
as it basically has been turned into a "product" by him, which many now use as the hype for
using fast projection lenses is still on..

Mine still is this, but many helicoids are on the market now...