I have a set of 58mm close up lenses that I got for christmas back in 2006. I knew there was a reason I never gave them up, even if I only used them twice...I just checked, and it looks like the no. 1 would easily cover. That's amazing. I never would have thought of that.
Originally Posted by Nicholas Lindan
I never looked at the education lenses section of Surplus Shed, but they have a hell of a range. And that's a hell of a lot of possibilities.
Originally Posted by Allen Friday
(Oh great, now I'm gonna spend the whole evening browsing their catalogue again)
Can anyone reccomend a basic introduction to the topic that would help me understand what combining this element with that element might result in?
I'm generally from the "well let's just see what that does when I do this" school of science...
I've got an old overhead projector from a friend that I'm currently taking to pieces - it looks promising too, it seems to be a nice 255mm f/3 lens. That wont cover my format, but it will be good to play with.
Originally Posted by michaelbsc
Is focal length the main variable determining the image circle?
Again, thank you everybody for all of the information.
If you want to aactually make one, che ckout dbOptic software for free design.
On a lathe you could cut a wooden 2D curve template and apply a cheap diamond tip glass cutter to cut the curve from the template, and fire polish the glass surface on the lathe too.
Focal length alone has very little to do with image circle. For example a 250mm M42 mount lens will likely only cover the 35mm negative area. But a 250mm LF lens will cover much more.
There\'s far more about lens design that I don\'t understand to explain this. Maybe someone has a good reference work that can help.
Last edited by michaelbsc; 11-10-2010 at 06:47 AM. Click to view previous post history.
Can I make a suggestion? Look for an old bromide/repro camera.
They are often given away/sold off really cheap. I picked up 3 lenses when the one we had at my old work was thrown out - all Rodenstock lenses that could cover just about 20 X 30.
I also have a Nikon 560mm APO Repro lens (and a Rodenstock APO Repro lens) at home as well - many of the repro lenses are a wide field lens that will cover far more than you could expect..send me a PM if you have any questions
A friend of mine got his Ultraviolet exposure unit (with vaccuum back) through a local graphic arts supplier, one of their clients was getting rid of it and he picked it up for $150. I imagine old copy cameras could be found via similar avenues...surely there's some out there...
Originally Posted by Andrew K
I'll start my experiments with this No.1 closeup lens and work forward from there, a real lens would certainly be nice.
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Many tele lenses do cover a lot more than 35mm in a lot of case.
Originally Posted by michaelbsc
And strangely... the Canon 17mm TS-E will cover the 645 format (and more) with a lot of movements.
35mm lenses are generally designed to cover a 35mm frame, and that's about it. In fact if they did cover more it would potentially make them more vulnerable to flare. The TS lens needs to cover more to allow movements, although it sounds like it covers even more than it has to.
Originally Posted by Athiril
Now, for view camera lenses, a given lens design will have a consistent angle of coverage. As a longer focal length lens needs to be further from the film plane to focus it will cover more area of film.
This is all a bit off topic really though as I can't really help with which lenses will cover 20x30" sorry!
Many lenses will cover at 1:1, few will cover at infinity.
APO Artars, APO Ronars, APO Germinars and APO Nikkors 24" (610mm) or longer will cover at 1:1, as will 305mm and 355mm G Clarons and the 360mm WA APO Nikkor. f9 Computars in the 240mm, 270mm and 305m focal lengths will cover at 1:1, as will a 14" Goerz Blue Dot Trigor. Basically, any lens that has an image circle approaching 500mm, or more, at infinity, will cover 20x30" at 1:1. Process lenses that are optimized for 1:1 reproduction work will probably perform better than general purpose, or wide angle designs, but since you likel won't be enlaring (or will you?), that shouldn't matter much.
At infinity, you're much more limited. A 42" Red Dot Artar, or 1070 APO Ronar will probably cover, as will a 19" or 24" Dagor. A 1000mm APO Germinar should also cover 20x30" at infinity when stopped down.
I'm sure there are others I've missed, especially at 1:1, but that will give you a few ideas on what to look for.