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Thread: Want advice on using Projector Lens as taking lens

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    Thor from California notaspammer3948797432's Avatar
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    Want advice on using Projector Lens as taking lens

    Hi, I've got a couple f3.5 7" projector lenses lying around that I want to test out on a speed graphic because they're pretty fast and should should create some interesting bokeh swirl.

    First off, what's the difference between mounting the lens normally vs reversed? I've read that in theory reversing a lens makes it behave as a macro lens, but I couldn't really tell there was much of a difference, except reversed seemed to project a larger circle of coverage... I assume this is because the lens elements are all at the far half-end of a long narrow plastic tube. Could I increase the circle of coverage by sawing off the excess tubing?

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    Re: Want advice on using Projector Lens as taking lens

    I have an old 5.5" Bausch and Lomb 35mm movie projection lens that I use for both 4x5 and, in a pinch, 8x10. The lens did have a tube at the rear that caused vignetting so I sawed this off as close to the rear element as was feasible and the coverage improved. Not the quality of the coverage, just the actual circle of illumination. Cutting through that thick brass tube with a hacksaw is not something I will ever do again! But if yours is only plastic you should have an easy time of it.

    I also have a Buhl 35mm slide projection lens that will cover 8x10 at portrait distances with its rear tube removed. These lenses can be lots of fun. Give it a shot. Sounds like you haven't much to lose. I can't speak to reversing these lenses, though. Mine are clearly meant to be used in one direction and that's the only way I've ever used them.

    Jonathan

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    Re: Want advice on using Projector Lens as taking lens

    I have an Ediphor 310mm f/2.8 projector lens that I plan on using for wet plate. I dont know about reversing the lens, but I do know that my projector lens is AWESOME.
    The bokeh is very strange, cant wait to use it with wet plate. I say go for it and cut that thing, whats there to lose?

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    Thor from California notaspammer3948797432's Avatar
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    Re: Want advice on using Projector Lens as taking lens

    I sawed off the excess tube (within a cm of the lens) and now the lens covers 4x5, but unfortunately not with room for much movement. I wonder if the remaining lip is the limiting factor or whether the optics are. (I guess I could check to see if light is being projected onto the remaining lip and if so try sawing even closer...)

    It does look really cool. The large focal length/aperture ratio makes for very nice DOF separation from background, even on distant subjects.

    Reverse mounting this lens appears to have some interesting effects. First off it appears that the focal plane (if you can still call it a "plane") becomes somewhat spherical instead of flat. !!! Also, the bokeh has strange zoom-like distortions (as opposed to the typical swirly distortions of a Petzval). I'm not actually too fond of the look of these quirks.

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    Re: Want advice on using Projector Lens as taking lens

    Here is an image taken on my pack porch with a little 4.25" B&L Cinephor Petzval projection lens on 4x5 film. No hacksawing was needed with this one! What's strange is as you move outward from the center you get the usual Petzval swirlies but when you move beyond even that you get the more zoom-like effect.



    Jonathan

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    Re: Want advice on using Projector Lens as taking lens

    Don't be afraid to use just the front or back half of the lens. This photo was taken with the front half of an Ilex Projection lens. It is a petzval lens but the image size is only about 4". Using the front half, the image size goes way up to easily cover 8 x 10 and the focal length goes from about 4" up to about 9". Don't get swirls anymore, but very unique look - sort of sharp in very center of image with lots of blur as it goes towards the outsides. I like this little half lens a lot.Click image for larger version. 

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  7. #7
    Les
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    Re: Want advice on using Projector Lens as taking lens

    While on similar subject...I'm hoping someone will chime in. I just dug up my slide projector lens (Kodak) Ekta....something...C and it's a 102-152/3.5 zoom lens (in excellent condition).....naturally after reading this post....and having this moose drool oozing out of me. It may have enough of a circle to cover 4x5...and certainly I could use wider lens...well, lets just say several lenses in one. Sure, I can easily hack the rear portion that protrudes out. However, would it make sense or would it be feasible to have this wild-looking-thang to try to install it in a shutter....and be able to stop it down to say F22/32/45 ? Well, how often does one see a zoom on a LF camera ? Should I contact SK Grimes or this place in SF that installs shutters ? I realize this is bit nutty, but any advise would be appreciated.

    Les

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    Thor from California notaspammer3948797432's Avatar
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    Re: Want advice on using Projector Lens as taking lens

    Here's a shot with the sawed-off f3.5 7inch Kodak Ektanon Projection lens. Being a full stop faster than the stock lens, shooting indoors on this 3x4 fp-100c film becomes almost possible.



    All the dust and noise caused by the "photosmart" scanner. Subject blurriness due to my mom not standing still, but you can see there's sharpness in the shirt. I think the bokeh is quite nice. I couldn't explain why the extreme vignetting is only on one side -- even if I mounted the lens a bit off center and crooked, it's still quite strange.
    Attached Thumbnails Attached Thumbnails 6869749042_cae8fc0c1e.jpg   6869749042_cae8fc0c1e_b.jpg  

  9. #9

    Re: Want advice on using Projector Lens as taking lens

    I thought I want to contribute. Here's a wet plate 4x5 normal light night shot using 5 inches Luxtar Anastigmat f/3.5, and I took off the back tube for better coverage. pardon for my crappy digital shot on the wet plate picture frame . It has a really nice blur away from center. The Luxtar is cheap I bought for $5 they go for $3 on fleebay I believe :-)


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    Thor from California notaspammer3948797432's Avatar
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    Re: Want advice on using Projector Lens as taking lens

    another shot with the Kodak projection lens. (these are really easy to find for under $10) I sharpened it a bit, since the instant film isn't terribly sharp, nor is my scanner. the lens probably isn't too sharp either, but what the heck, sharpness isn't everything.



    Compressed tele-photo look, with petzvel-style swirl at the bottom. I'm sure this $7 lens will find its uses!

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