May Need Help

[rdenney]

I really hope someone jumps in about 8x10 Studio Camera with the Big Barrel lens, Dave Wooten lent me a 8x10 Cambo with a 300 mm lens, I plan to use this camera for a few landscapes and as well use it up north at my daylight studio at the trailer. It would be impossible to take the Studio Camera up there so I need to figure how to do macro with the 8x10, not sure Dave would like me reversing the elements like Rick suggested.

Is the 300 just a standard plasmat?

I just checked shutter threads, and the No. 0 shutter your 90 is in, and the No. 3 shutter the 300 is probably in, both have the same threads front and rear. A No. 1 shutter does not. A plasmat doesn't project down into the lens as much as a Super Angulon, as I recall, and the aperture should be pretty centered between the cells. Shouldn't be a problem at all--the front and rear cells are very similar on a plasmat anyway. If it's a process lens, it's already optimized for 1:1 and won't see any advantage to being reversed.

My calculation is that to use the same bellows draw on the 8x10 camera as you have used to get 1:1 with a 48cm lens (which is 38 inches or so), you need a 190mm lens to get 4:1. The 210 would need a bit more, but not that much. So, use that lens. Coverage is not an issue--you'll have enough.

But the 210 is probably in a No. 1 shutter, so you can't reverse the lens cells on that one--the threads are a different size. Try it as it is.

If you try to do it using the Cambo 8x10 camera, you may not have 38" of bellows draw. For that one, you may need to use a shorter lens. Even the 90 will work--you'd need 450mm of bellows draw. The image circle at 4:1 is about five times what it is at infinity--coverage won't be a problem (even a 90mm lens for 35mm might be enough to cover 8x10 at 4:1).

Rodagons for enlarging small format are optimized for 1:10, and for large format are 1:2, based on reading I did last week. The shorter ones will benefit from reversal more than the longer ones, and the longer ones may be fine just as they are.

Rick "suggesting two tripods, if not an optical bench setup" Denney

[bob carnie]

Rick

It is a fujinon . w 1:5.6/300 Copal shutter.

[rdenney]

Rick

It is a fujinon . w 1:5.6/300 Copal shutter.

Yup, standard plasmat in a No. 3 shutter. Should be no problem reversing those cells, but I'll bet you'll need a shorter lens if you want to do 4:1 magnification.

Rick "not thinking an 8x10 Cambo has that much bellows draw" Denney

[bob carnie]

Thank you all for your help, my brain hurts now, before today all I new was I was using a 210 for the 4x5 and a big boy for the 8x10.

I will consider all advice and modify my existing gear, and give the small objects a go and post some results in a couple of weeks.

[Bill Burk]

Could you use an enlarger? Maybe just put the film on an easel and the object to be photographed in a negative carrier.

Ok not literally, but to keep your head from hurting it might be easier to imagine the entire setup this way.

[bob carnie]

Now you are talking my language.

Could you use an enlarger? Maybe just put the film on an easel and the object to be photographed in a negative carrier.

Ok not literally, but to keep your head from hurting it might be easier to imagine the entire setup this way.

[Jim Jones]

Yup, standard plasmat in a No. 3 shutter. Should be no problem reversing those cells, but I'll bet you'll need a shorter lens if you want to do 4:1 magnification.

Rick "not thinking an 8x10 Cambo has that much bellows draw" Denney

According to S. K. Grimes http://www.skgrimes.com/products/new...standardcopals the Copal #3 thickness is 32mm and the front to iris dimension is 17.7mm. Other Copals have similar differences between front and back. Thus, the iris is not centered between the cells. This may be a problem in reversing the cells. I tried reversing a 90mm Optar in a Wollansak shutter with dismal results.

An old Leitz 21mm Angulon reversed on a 4x5 gave about 4X magnification. With three dimensional subjects the DOF is quite small, even with the lens stopped down to an indicated f/22 (working aperture about f/90). At that aperture, diffraction raises its ugly head. This might not be as distracting in Solarizated images as in straight photography.

Most enlarging lenses work well when reversed for greater than unity magnification. Mounting by screw-in or Kodak series filter rings epoxied into lens boards is easy. To keep people from stopping down more than a few stops less than optimum aperture, most enlarging lenses can't be stopped down very far. They are even worse than camera lenses when seeking maximum DOF. Edward Weston had to have the aperture on an inexpensive Rapid Rectilinear modified for an aperture of f/256 (according to some sources) for some of his macro photography. Hmm. Maybe a junk box RR is the answer!

[rdenney]

I just tried it with a 90mm f/5.6 Super Angulon, which is, of course, in a No. 0 shutter. It doesn't work--the front cell in the rear threads screw in too far and interfere with the aperture. A quick look at a Grandagon layout suggests it will have the same problem. But it should work with plasmats and double-gauss lenses, except that the most useful of those will fit in a No. 1 shutter that does not have the same threads front and rear. So, you're probably right in enough cases that I should just withdraw the suggestion.

The Rodenstock enlarging lenses specifically can be reversed, but most of them have an optimal range down to 1:2 and might be fine without reversal. If I could not reverse a standard lens, I would switch to using an enlarging lens. At 4:1, exposures are going to be long enough not to need a shutter.

But 4:1 will also reveal a range of sub-optimalities not visible at 1:1.

Rick "noting that 4:1 is four times as challenging as 1:1" Denney