Charles 46277 Loc: Fulton County, KY

I still have a fair amount of large format equipment, though I use digital for the most part (amateur). I have a question about large format focusing. I bought an Aristophot reflex back (by Linhof). This is a box that goes on the back of 4x5 cameras (or on the 4x5 back of an 8x10), and gives 5 inches of additional extension, as well a reflex mirror that is lifted manually. The extra extension is for very long lenses on 8x10, or for macro work, which is fine. The box has its own ground glass, which is said to be expensive and rare (the gadget cost $450, old and second hand but in fine condition). It gives a sharp image for sure, with focusing circle in the center, but it also has (and here is my question) thin crosshair lines, corners to corners, of unfrosted clear glass. These let you see the focused image not on ground glass but "in the air." How is this used? Do you have to squint a certain way to see this image in perfect focus? Somebody said something about "airy image," but I am not sure that applies here...

rmalarz Loc: Tempe, Arizona

The use of this back seems to be for macro use. I've found a manual that might be helpful to you. I've done macros with my 4x5, but it was extremely difficult, as I had to kneel or stand on the table on which the camera and mount were located. This back would have been a big help. The description of the glass you provided reminds me of the fiduciary "screen" installed on the NASA Hasselblads. However, that was placed in front of the film, not in the viewfinder.
http://microscope.database.free.fr/Accessories_manuals_files/Aristophot%20Instructions.pdf
--Bob

RWR Loc: La Mesa, CA

You’re focusing on an aerial image. Move your head slightly while focusing - when there is no displacement of subject and cross-hair, you’re in focus.

wrangler5 Loc: Missouri

IIRC, you focus an aerial image by moving your head slightly while looking at the image and the crosshair. If the image and the crosshair are not in the same plane, they will appear to move relative to each other as you move your head. When they stop moving, they are in the same plane and the image is in focus.

Charles 46277 Loc: Fulton County, KY

Thanks malarz--I did not have manual or instructions, though I had no trouble using it for my purposes. Apparently, just looking at the image in the clear crosshairs is all there is to it for maximum clarity of focus. In a view camera, it allows composing and focusing by looking down (and seeing the image right side up), which is not always an advantage (but sometimes it is). The main thing for me is the additional bellows extension--long lenses or macro with long lenses.

Using the digital camera, I have two macro lenses--a Canon 60mm, which is good, and a Fuji 240mm F9 A (large format), which can be used on a large format camera for bellows, with digital camera attached on back. The Fuji lens is much better (and of course only the central area of the image is used, even with some movements of the large format camera. But I have a couple of large format graphic arts lenses that are much longer--one is a Schneider Repro-Claron 485mm that takes about 19.5" extension for infinity focus--more for close-up. The Aristophot reflex housing gives the extra needed extension (a digital camera adds two more inches). As I recall, this is the setup I used for my avatar photo here, the rex begonias (shot on my front porch in north light). (Sorry, it is in PowerPoint, below, and I posted that.)

Attached file:
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Charles 46277 Loc: Fulton County, KY

RWR and wrangler5, thanks--that answers my question--I did not know what I was looking for.

nadelewitz Loc: Ithaca NY

Why are you using the "graphic arts lenses" (also known as process camera lenses)? I'm a former graphic arts/process camera operator from way back (47+ years)in the printing field. I learned early-on that the concept of using smaller apertures for greater depth of field, in general photography, was not applicable to the graphic arts camera. The reason....a process camera is photographing FLAT surfaces only. Process lenses are (were) not intended or optimized for three-dimensional subjects. They have an "optimum" best-performance aperture, which was 2-3 stops down from wide-open.

That's probably what differentiated enlarger lenses from camera lenses also.

Ron Dial Loc: Cuenca, Ecuador

When using a macro setup on a large format camera, remember that if the length of the focal plain is longer than the mm of the lens ( you have to measure this with a metric tape) then add one f-stop to the shutter to account for the difference in light inside the camera.

Charles 46277 Loc: Fulton County, KY

People use process lenses as long lenses for general use because they are cheaper, yet still give excellent results. Their use is limited in some ways, but my need for a 610mm lens on a view camera is rare, and the Nikon 610 process lens does the job. Most people using large format are using small apertures, 22 being a common default setting. My 19-inch Repro Claron is also fine for what I would use it for. I have a Packard shutter that accommodates the Nikon, and the Claron has a #5 shutter.

All lenses focus on just one plane, though it can be curved (or not). Depth is found only by the aperture, not the lens design. Since we want a picture of people standing in a row to be sharp from end to end, any fine lens is meant to be reasonably flat-field. But you are right that flatness of field is not the issue in general three-dimensional work, while in process work, it is.