Silly Question . . . What makes a LF Lens?

In the process of building a DIY (design it yourself) 8x10, I have gone through a number of lens configurations. Please understand, I can't spend $300, $600, $1000 for a quality shutter and glass (okay, I won't). But, I have been very successful putting spare parts together, and making them work. I am sure I'm not alone here . . . . I'm calling all inventors!

on to the nitty-gritty . . . Having acquired a number of Kodak No. 3A model C cameras, I pulled a shutter/lens and placed it on my 8x10. To cover the 8x10, I removed the rear elements. Seems to work, to a certain degree. My question then . . . has anyone been successful using pieces and parts to make that LF lens from scratch? Any ideas to share? Thank you. Dann

If you can live without a shutter plenty of barrel lens for not much money. They won't have a fancy name and they won't be easy to mount in a shutter but both are over rated.

This doesn’t directly answer your question, and you may consider it a silly answer, but consider starting off with a pinhole lens, which will get you going until you can find a suitable lens/shutter.

There are various older lens/shutter combos that were designed to be used "in parts" - called convertibles. Often, however, it is the front element that is removed, resulting in a different focal length (usually longer) for what's left. In most cases, there is also a substantial difference in optical quality or characteristics, usually a degradation. Sometimes the effect is "interesting" - so, if the lens is really inexpensive, no harm in trying it out that way. A yellow filter over the opening often helps reduce some of the abberations that result.

For pure economy, look for inexpensive older lenses in barrel (no shutter), and use the old lens-cap or hat-shutter technique.

The best deals I've gotten have been on barrel lenses. Kowa, Eskafot, and JML lenses in particular. Most process lenses over 300mm will cover 8x10. (A careful web search will turn up information on a lot of lenses. Not all are documented on the web, but it's surprising the number for which you can find data if you look carefully.)

Note that process lenses are inexpensive if they're tough to put into shutters due to their size. The ones that can be screwed directly into shutters usually cost more (for the obvious reason).

The sizes that are difficult to put into shutters usually go for reasonable prices. Last year I picked up three JML lenses that will cover 8x10 for under $50 total. JML lenses have become a little better known since then, but they're still inexpensive compared to famous lenses like the Nikon APO-Nikkor process lenses.

If you use slow film and stop down, it's pretty simple to keep your exposures in the 1 sec. and greater range, which you can handle with a lenscap or a hat.

Best of luck.
Dave

To cover the 8x10, I removed the rear elements. Seems to work, to a certain degree

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Perhaps my ignorance will be yet again on display in this, but I'll take a chance.
When shooting with half of a convertable lens, aren't you supposed to put the cells you use behind the shutter, that is, remove the front elements or put the front elements on the rear to shoot?

I will second the JML process lenses. I have 2 and both are exellent performers. Coverage in line with plasmats, as thats is what I think they are. I use barrels on a packard shutter.

Whitey's question matches what I've read, as well, though the test is in the resulting image. If it's a Rapid Rectilinear or similar symmetrical design, you'll probably find you like the results better using glass behind the aperture instead of in front, though...

But the answer to your original question is, "A large format lens is one that produces an acceptable or desirable image quality with a large enough image circle to cover 4x5 or larger film."

FWIW, I've recently (when shopping for a lens for 4x5) seen lenses advertised in the APUG classifieds that will easily cover 8x10, well under $200 including shutter. No, they aren't the latest multi-coated wonders in a shutter with last year's date code, but they are a great deal better than good enough for contact prints and portraits. And, some are convertible, giving you two or even three focal lengths (sometimes with slight degradation of image quality, but again, still more than good enough for contact prints) from a single purchase. Dig back a few months and check with the sellers for lenses that look up your alley.

Thanks y'all, for the ideas / info. I've learned a ton. The lens is a Rapid Rectilinear Baush & Lomb and may work best with the elements behind the shutter as Whitey thought. In my amateur tests last evening (and up close ~ 5'), the results appear satisfactory on the front or on the back (to me). This morning as a test, with the elements only on the front of the shutter, I focused on a filling station at about 1/8th mile. I could read the "Beer Prices" on the station's window, using a loupe on the ground glass (acid etched 8x10). It's definitely clearer than my previous configuration with an old copier lens. I like the fact the focus rolls off everso gradually to the edges of gg. Whereas the copier lens has a more defined "area of focus". Note: With this Rapid Rectilinear the FL changes from 400mm with the elements on the back to 350mm with the elements on the front. Very interesting. The ultimate test will be taking some shots this weekend in the daylight. ;-) Here's another cool observation. I replaced the glass elements with a single element (plastic) from an old Polaroid Land camera (210). Nice "wide angle" and nearly a "fish-eye" and the FL drops to ~200mm. The Polaroid element is a "perfect" fit in the Kodak shutter, also. Ralph mentioned using a yellow filter, and I did. Things do appear cleaner on the gg with a filter. I shoot paper only "Ilford MGIV RC Deluxe". Will filtering in yellow effect the contrasts?

Filtering in yellow will be like shooting through a 0 or 00 contrast filter. The gain of the yellow filter relative to image quality is in cutting down on uncorrected chromatic aberration, which shouldn't really be a problem with even half of a Rapid Rectilinear; both halves are achromatic.

FWIW, the image quality you see on the ground glass is what you'll see in a contact print, give or take, but if you were shooting on film to be enlarged, you'd want sharpness much better than what you can make out with a loupe.

Dann...we're all now dying to see what you get with this setup when you finally shoot with it. I hope you'll share your results. (You make me want to dig through my stash of "abandoned glass" to see what kind of odd combinations I can put together...)

Be well.
Dave

Mongo said:

Dann...we're all now dying to see what you get with this setup when you finally shoot with it. I hope you'll share your results. (You make me want to dig through my stash of "abandoned glass" to see what kind of odd combinations I can put together...)

Be well.
Dave

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I have actually had the opportunity to shoot twice. (a 3" dia. copier lens configuration) As I continue to add nuts, bolts, and whistles to the DIY camera . . . it's becoming harder and harder for me to find a crew of people to help move it. LOL! No Joke. ;-) I think the coolest results will come when I insert a polaroid element in this kodak shutter.

Both test shots below were shot on Ilford MGIV RC DeLuxe Paper 8x10. Nothing impressive at all. Then converted and adjusted on the computer.

This was my very first attempt (indoors - first light) ~ one week ago
Paper Negative, 10 second exposure - ~ 15mm aperture
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This was my first outdoor attempt . . . last Saturday
Paper Negative, ~18 second exposure ~ 3mm aperture (suspected settings) both scans from same negative
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Focus could be better, but that's what happens on a limited budget. ;-)

If I'm beaking rules here by inserting links, please let me know. I find rules at different forums do vary.

I've never seen an objection to an in-line link here...APUG'ers tend to be pretty easy going about such things. (And I'm sure that if I'm wrong I'll be told in a nice way.)

It's pretty much impossible to evaluate an image from a scan on a web page unless there's something seriously funky going on (like swirly bokeh or vignetting...that sort of thing). The images you posted all look plenty sharp. (On my monitor the indoor shot actually looks overly sharp, but again, web page...monitor...scan...impossible to tell.) It looks like your exposure guesses were pretty good, considering what you were up against.

Keep an eye on Surplus Shed (www.surplusshed.com)...sometimes interesting lenses show up there and some of them can be very inexpensive. I've picked up a couple of old Wollensak copy and graphic arts lenses for very few dollars there, and even picked up a 6" metrogon clone there cheap. (No iris...I'm building waterhouse stops for it.)

Best of luck with your experimentation. If you're looking for an interesting read and you've not seen it yet, you might want to get a copy of "Primitive Photography". Great stuff for do-it-yourself folks. (Make your own cameras, lenses, paper negatives, and printing paper...who cares what Kodak does?)

Be well.
Dave

Be well.
Dave

If you can find an old "Xerox" copier you may be able to salvage the lens. I expect $5-$10 would be a typical price. You can make an apperature by unscrewing the element and inserting a Waterhouse stop (hole in the paper) made of opaque paper or plastic. If the aperature is small enough a lens cap can serve as a shutter. If you need a faster shutter build a guillotine shutter. Use a black board with a slit that passes in front of the lens and is powered by gravity.

The optical quality will be better than using pieces of "not so good lenses".