Mounting a projector lens on a 35mm film camera

[David Bigeleisen]

I've seen some interesting images where people have mounted projector lenses onto mirrorless digital cameras. I'm wondering whether I can make this work with my Nikon F mount film cameras. I've been told that this won't work; the the rear element of projector lenses is too close to the focal plane of the film to work with a film SLR. Has anyone anything helpful to say on this subject? I don't have a digital camera and I'm not in the frame of mind to get one.

David

 

[Chan Tran]

You can try with a film SLR and see if you can achieve focus in the viewfinder but I think you can't put the lens close enough to the film plane to achieve infinity focus

 

[AnselMortensen]

You would need a projector lens with a long enough focal length to allow for clearance of the mirror.
You also would need some sort of focusing device, such as a helical or a macro-type bellows.

 

[David Bigeleisen]

Dear Ansel:

Thank you for your reply. How long a focal length will i need to clear the mirror? I have a Nikon bellows, but i think that a helical adapter will be more useful. Have you experimented with this setup?
Thanks in advance.
David

 

[Bill Burk]

Our friends son in middle school worked with me to make a camera from scraps of junk around my garage. We used a projector lens and it worked well as a demonstration

 

[AnselMortensen]

David,
My experiments with projector lenses have been with a 4x5 view camera, which has bellows focusing.
Projector lenses come in a bunch of shapes & sizes, some with long barrels (that might need to be trimmed).
Too many variables to be very specific.

A few guidelines:
You can't have anything obstructing the operation of the SLR mirror.
Focal length of a lens is determined at infinity focus... the nodal point of a 5" non-telephoto-design lens is 5" from the film plane at infinity focus.
How thick is your Nikon body?...add the thickness of your compressed bellows.
Maybe start with an inexpensive 5" Wollensak or Revere slide projector lens and play around with mounting it on your bellows with gaffer's tape, try different focusing distances & see what you get.
Projector lenses have no aperture adjustment..wide open only.
Have fun, lots of experimenting & testing to do.
Hope this helps.
Maybe others can chime in with suggestions, also.

Edit: 5" = ~127mm

 

[xkaes]

It depends on the design of the projector lens and the flange focal length of the camera -- and the depth of the "adapter(s)". I adapted a Tamron pro flat-field 1.5" (38mm) projector lens onto Minolta film & Sony digital cameras (all with mirror) using an M42 thread on the rear. I have two step-up rings in-between -- as a very limited helicoid -- which lets me get closer than infinity.

On a mirrorless camera, a real helicoid could be used.

 

[OAPOli]

I've adapted projector lenses to medium format SLRs. Infinity focus is impeded by two factors: focal length and lens diameter. Short focal length equals short back focus, and fast projection lenses will have large elements which not fit in the lens bayonet opening or in a small M42 helicoid adapter. The faster the lens, the shorter the back focus.

You can find Nikon-F to M65 adapters. Combining that with a M65 helicoid and clamp adapter to the projection lens would be a good start. You will need the projector lens in hand to check the specs and dimensions.

 

[wiltw]

Dear Ansel:

Thank you for your reply. How long a focal length will i need to clear the mirror? I have a Nikon bellows, but i think that a helical adapter will be more useful. Have you experimented with this setup?
Thanks in advance.
David

There is no single mathematical relationship between FL of a lens and the distance between rear element and the focal plane position...look at the fact that the flange distance of different SLR manufacturers' designs vary from one another, or the fact that Canon 135 format FD lens flange distance is quite different from Canon 135 format EF lenses is different from flange distance of Canon 135 format RF lenses! And the fact that medium format 50mm FL has a different flange distance than 135 format 50mm FL.
Similarly, an adapter to mount a projector lens onto an SLR body will be variabnly dependent upon the specific projector lens vs. the specific camera body being paired.

 

[Dan Fromm]

Nikon F-mount FFD is 46.5 mm.

 

[Bob Merlin]

It depends on the focal length of the projector lens.
Will you need to stop it down or focus it?
You can also buy focusing helicoids and diaphragms on ebay if necessary.

 

[David Bigeleisen]

Dear Bob:
Thank you for your reply. Please let me be more specific. I'm looking for a medium telephoto of a focal length of about 75mm to 100mm or so. I'm looking for a very large aperture to give shallow depth of field. And I want to achieve swirly bokeh if possible.
I'll be grateful for any suggestions.
Thank you.
David

 

[MattKing]

Threads combined, and resulting duplicates deleted.
@David Bigeleisen ,
It isn't necessary or desirable to post threads asking the same question in more than one place. People who visit Photrio generally see new posts, wherever they might be in the sub-fora.
We hope you find what you seek.

 

[koraks]

I'm looking for a very large aperture to give shallow depth of field. And I want to achieve swirly bokeh if possible.

Look for a generic, old Petzval type lens; they're around and not necessarily expensive for the smaller ones that are around f/4 and cover ca 4x5" (which is way more than you need). They are often a little longer than what you're specifying; e.g. 125mm or thereabouts. You should be able to hack one onto your camera using some ingenuity and bits of cardboard and tape, or (better) 3D print an adapter/interface. For the camera mount you could cannibalize a defective lens and graft your adapter onto it.

An easier solution to your problem is to purchase a new Petzval-type lens specifically made for modern cameras. There's one or two of these products around. You may have to obtain a camera body that accepts the lens in one of the mounts it comes in. Lomography markets a couple of types in various focal lengths, including something around 75mm. There also appears to be at least one Chinese option that's quite affordable and looks easy to use.