large format lens coverage.

[calbee]

question.

I'm interested in building a 5x7 foot camera. (not inches, I know it's crazy.) I know this can be done, I'm not saying it will be cheap or easy to build or shoot with. I have all the room and WS power I need and then some. (GO Speedotron!!!) Now all I need is a lens… I know pinhole would work for most applications, but I would like something a "little" faster. If anyone knows of a 3000mm lens with a 5x7 foot coverage let me know, some were built to shoot from B52's I believe, or maybe an email of a good lens builder who might be crazy enough to take me on as a client.

[Bill_1856]

Talk is cheap. Come back when you've successfully built an 8x10".

[calbee]

I have made 8x10's before, and an 11x14. I also assisted on building a really great 16x20 while in school. I was also a professional assistant for 10 years so photography is not a new hobby for me. Besides this monster will be more like a fixed focus closet with a lens on the end so construction will be about as hard as a closet, which I've done before and might add is quite easy. The lens on the other hand is the trouble. And your right talk is cheap so enless you know anything about lens design or construction why talk shit?

[Ralph Barker]

I guess the big question (in keeping with the camera) would be what do you intend to photograph, and at what distance? Although not an expert in the area, I suspect that most of the long focal-length lenses made for the military were of telephoto design, and covered much smaller formats - i.e. typical aerial camera sizes. In contrast, for your purposes a conventional lens design might be better, allowing you to take advantage of the relatively extreme extension. There are, for example, 24" and 36" Artars floating around occasionally that might work for you. Assuming, that is, you want to do extreme macro work.

[Tracy Storer]

Melles Griot has some long focal length meniscus lenses in the 2000mm and 4000mm range if I recall correctly, which might serve you well(and cheaply). I'm on the road right now and don't have their website bookmarked on my laptop. Keep us posted on your progress. Tracy

[calbee]

I had planned to do full lenght portraits at 1:1 hopefully.

[calbee]

Thanks Tracy, any help would be amazing.

[Bill Laidley]

Science World in Vancouver BC has (had? It has been a while since I last visited...) a view camera that must measure at least 8 foot by 10 foot. You walk inside to focus on an image projected onto a screen. I never looked, but I don't think it was designed for film holders... so presumably if one had wanted to actually take a picture on film or paper you would have to tape or pin it into place while standing in the dark.

There was a lens - really big - of less than stellar quality. Images would have been similar to some of Sally Mann's moody landscapes from the last ten years.

By the way, kids thought it was really, really cool to be inside a camera and look at the image on the back screen.

[John Kasaian]

There was an article awhile back in View Camera Magazine on Douglas Busch in the July/August 1990 issue that might help you out. Good Luck!

[John D Gerndt]

If you parameters allow perhaps you could have one made. A four element Guass wide angle or even a Protar (f18) might be possible. I see people make their own lenses for telescopes - there are sites on the web. A prototype machine shop could probably mount the glass if you could find someone to grind it and the specs to do it. I am guessing the Protar design might only be 6 inches across...that seems doable.

Cheers,

[Chris Gittins]

I don't think a meniscus lens is what you want for 1:1 imaging. They're optimized for imaging at infinite conjugate ratio, i.e., imaging objects off at infinity. For 1:1, a symmetric biconvex spherical lens might work for you. (For 1:1 imaging, I believe the spherical aberration introduced on the object size of the lens gets undone by the image side. Check me on that though. That may be wishful thinking and lousy memory on my part.) Actually, there's no reason you couldn't put two meniscus lenses back to back, but I don't know if the combo would be better, worse, or the same as a single element biconvex.

Melles Griot is a good source for glass, although fairly pricey. You might also try Edmund Scientific. Also Esco Products.

Good luck, Chris

[tim atherton]

Hasn't it been done? That big Polaroid cmaera take 4'x9' film or some such and makes life sized portraits and uses an old spy camera lens form a U2 or something.

Maybe contact the polaroid studios that use the camera (I think there are 2 or 3?) and talk them or the Polaroid techs about the lenses

[Chad Jarvis]

The book "Portraits of 9/11" was shot with the room-sized Polaroid that uses roll film. As Tim suggested the folks at Polaroid could probably make a suggestion.

[David A. Goldfarb]

I think for this purpose, Tracy is "the folks at Polaroid," no? Here's the web page for info on the 40x80" camera: http://www.polaroid.com/global/detail.jsp?PRODUCT%3C%3Eprd_id=845524441760009&FOLDER%3C%3Efolder_id=2534374302023748&bmUID=1090677745748&PRDREG=null.

[jnantz]

some photographers in providence, ri made a room size camera obscura a few years back. i'm not sure if they only used it with a pinhole or if they had a lens for it too.

http://www.erikgould.net/camera%20ob/aboutCO.html

erik sometimes posts here, maybe he'll be able to tell us more ?

[Martin Courtenay-Blake]

Hi

I noticed an absolute monster lens on US Ebay yesterday...front cell in excess of 12inches in diameter. It is clearly from some kind of military camera...possibly from a B52?????

May be worth checking out.

Martin

[jonathan smith]

You might consider a lens made for eyeglasses. In uncut form, they are about 70-75mm in diameter, and ones made of glass are available.

I experimented with these in a darkened room with a window one day at work (I'm an optician, and we stock the lenses) and what you want is a very weak plus lens, a +.50 would actually give you 2000mm focal length, and a +.25 would give you 4000mm.

They would not be perfect, but better than a pinhole.

[Bill L.]

Check out ebay - 100 inch infrared ektar:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=50540&item=3828033308&rd=1&ssPageName=WDVW

Only 17 hours left, but it is only at $25 at the moment. I'd hate to see the shipping though - IIRC, it weighs about 75 lbs.

They said it would cover 5x7, but that appeared to refer to inches rather than feet.

Bill

[calbee]

yeah the lens on ebay is tempting but I'm not sure about it and I can't find anything online about it to see it's area of coverage or what it will really cover.

[Michael S. Briggs]

Kodak practice was to label military aerial lenses with the intended format in inches. The IR lens on ebay is thus designed to cover 5x7 inches, not feet.

Your format of 5 x 7 feet is 152 x 213 cm, with a diagonal of 261 cm. Your desired focal length is 300 cm. With your goal of a life size image, both the subject and film will be 600 cm (19.7 feet) from the lens. Some simple trigonometry gives the required coverage (full angle) as 24.5 degrees. This isn't a challenging design requirement! Modern plasmats typically cover more than 70 degrees. There were 19th Century designs covering more than this, and having adequate resolution for contact prints. So unlike many DIY questions that appear on the forums, I think your goals are realizable.

The symmetry of a life size image means, by simple optical arguments, that the lens should be symmetrical. Without getting into true mathematically lens design, you could simply arrange two two-element achromats symmetrically about a stop. This would give you something crudely similar to the Rapid Rectilinear lens design. The Rapid Rectilinear is a symmetrical design invented by Dallmeyer in 1866 which proved to be very successful. See pp. 59-60 of "A History of the Photographic Lens" by Rudolf Kingslake.

There is much more to a Rapid Rectilinear than using two identical two-element lenses: indices of the glasses, thicknesses, curvatures and spacing. Rudolf Kingslake works through the design on a Rapid Rectilinear in "Lens Design Fundamentals". Unlike "A History...", this book is technical, with numerous equations.

As a cheap approach that might be good enough, you might just want to buy two achromats and arrange them symmetrically about a stop. One source of larger diameter achromats are suppliers to the market of amateur telescope makers. A really cheap source would be the objective lenses from a binocular, but the focal lengths and diameters from common binoculars are probably too small. You could buy some binoculars on ebay and experiment with the lenses. A good source of surplus optics in the Surplus Shed, http://www.surplusshack.com/. They have a changing inventory of lenses, and frequently have binocular objectives.

[Tracy Storer]

Thanks David, yes, when I lived in Boston and the 40x80 camera was there I sometimes worked as one of the camera-men for that studio, but the 20x24 has been my main "axe" for years. The folks at "Moby C" the current owners of the 40x80 in New York bought the camera (and lenses) from Polaroid a few years ago, and the original guys in Polaroids' Optical engineering department that did the work on that lens (the one for 1:1) are almost certainly retired, or have passed away. If you could find them, they might not be interested... I'm not sure how well the meniscus lenses will perform at 1:1, the magnification hadn't been stated yet. I remember them being in the $40 range from Melles Griot (http://www.mellesgriot.com/) so that's certainly cheap enough to experiment a bit. (they were 2" diameter lenses, so you'll be talking dim focusing at f/64 or worse) Calbee, you've got some great responses above, I agree with you that it could be built simply, and that using it may not be easy. Could be very cool to do it anyway though. More than happy to help out a little more off board if you want. Best,