I want to make a special lens adpater...

[yuri_sopko]

Any ways, I want to put something like a relay lens within a tube so I

can project the image from my lens into it, but, have the oprion to

move said relay lens around to achieve certain focal changes. Like I

have seen what those MF and LF cameras can do.

 

I think I can pretty much use a relay lens in between my camera lens

and film, but, I have been looking around this board and some

telescope sites but have yet to find exactly what I want to make.

 

Any one have any technical experience with this or anything?

 

Thanks....

[plattro]

Could you be more specific exactly what you want to do?Relay lenses aren't exactly a simple subject!<BR>

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For focal length changes, maybe consider a zoom lens?<BR>

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For more information, read <U>Applied Photographic Optics</U> (Sidney F. Ray). I hope you aren't afraid of math!<BR>

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For some examples of what can be done with relay lenses:<BR>

See http://www.naturfotograf.com/D1_fisheye_1,html.htm<BR>

and http://www.nearfield.com/~dan/photo/wide/fish/index.htm<BR>

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Personally, I have only produced one even close to useful use of relay lenses, to produce a picture of something just inches away together with something at infinite focus, both perfectly focused, but everything in between blurred. See my previous answer on the thread on "extreme depth of field". But you need a small fortune in spare lenses and adapter rings to produce something even close to workable!<BR>

[david choo]

Yuri, are you a lawyer? =)

[yuri_sopko]

Nope, I am not a lawyer... why do yu ask?

 

Ok, basically I want to have a semi-tilt/shift lens, but, have the T/S done within the lens assembly. Or, maybe a PCS type lens that Minolta and some other companies have made in the past that allowed a rear element to be moved around to create interesting effects. I don't want to magnify or reduce any given focal length, I just want to be able to select what part of the image circle is produced and how so on the film plane.

 

I have some smaller relay lenses that are used for c-mount cameras. But, like I said, they are small. Maybe 1/2" in diameter. And playing around with it I can make some cool stuffs. This being hand holding the lenses and then projecting the image on paper. I can't find a larger one at reasonable cost, but, I know telescope/microscope people make these things all the time for adapting a camera to their item.

 

I was just wondering if anyone had any experience in such things.

[Brian1664876441]

Some quick thoughts: A quick, cheap way to do some of this may be to use the optics from a teleconvertor in a tube of your own making that allows for the pan and tilt. The teleconvertor will project and magnify part of the image; usually the center when used as is designed. As a 2x convertor only projects 1/4 of the total image circle, you have some room to move around and you will get a full frame picture.

 

If you want to pan and tilt from without magnification, you will have to get some large format optics adapted for your camera.

 

I have been experimenting using some lens elements from an extreme wide-angle lens that was unusable. Placing the negative elements in front of the lenses extended the back-focus and gave a wider view. I have my 24mm Lens picking up almost 180 FOV. A Nikon K1 adapter was required to fixup the back focus. I have also played with putting some elements behind the objectives as well. EBay is a great place for junk lenses.

[david choo]

<<have the oprion to move said relay lens around >>

 

Because you said, have option to move SAID relay lens..... HAHa im not being mean. I have a lot of lawyer friends and I catch them talking like they're writing their contracts and I tease em about it all the time. ;) Happy New Years. hehe

[Brian1664876441]

I asked an Optical Engineer at work about relay lenses. He explained to me that they were often used in Periscopes and other such applications. He referred me to MIL-HDBK-141 and pulled out his copy. I have found it online, available for download at:

 

http://www.azmackes.net/astronomy/mil_hdbk_141/index.html

 

Long Story Short: The book suggests that a pair of Doublets (each made from a positive and negative element) be placed back-to-back. Objects at the focal length of the doublet get "converted" to parallel rays, strike the second identical element, and are then focussed into an image.

 

At work, this engineer did the same with to identical 25mm F1.4 "normal lenses" for a C-mount camera. He connected them at the filter ring and mounted them onto the C-Mount sensor for 1:1 imaging.

 

This may do what you want. I have also used the front group (negative diopter) from Xenar/Tessar formula lenses to extend the back-focus of various lenses. the extended back-focus allows for some "post-processing" of the image.

 

Have fun. If the thread is still around tomorrow, I will post some images made with my "trash-can" lenses. Basically, pulling elements and groups out of junk lenses and using them in conjunction with standard lenses. I made my Canon 50mm F0.95 into a 35mm T1.4 with a 60mm Back-Focus and a 24mm Nikkor into a 150 Degree FOV full-frame fish-eye.