View Full Version : Hyperfocal Distances Beyond 8x10

Michael Kadillak

11-Nov-2003, 13:49

My internet search for hyperfocal distances beyond the 8x10 format was fruitless. Just curious as to the 11x14 and 12x20 format with lenses of 210mm, 355mm, 450mm and 600mm. I realize that judicious utilization of movements are critical, but I just want to get a tactile feel for the numbers. Any assistance would be greatly appreciated.

Cheers!

David A. Goldfarb

11-Nov-2003, 14:15

This raises an interesting question: If you contact print, does the hyperfocal distance change with format? Hyperfocal distance depends on the figure chosen for the acceptible circle of confusion, which presumes a certain maximum degree of enlargement with normal viewing distances, but if you are using large negatives and contact printing, there is no enlargement to think about, so I would think that hyperfocal distances for 8x10" are valid for larger formats as well, if you're not enlarging.

Michael S. Briggs

11-Nov-2003, 14:27

As David mentions, a calculated hyperfocal distance is based on the value used for the acceptable circle of confusion, which is usually determined from several assumptions. One common assumption is that prints are viewed from a distance equal to their diagonal. Under this assumption the acceptable circle of confusion would be larger for contact prints made from larger formats and thus the hyperfocal distance for a given aperture would be smaller. I think it more likely that today's LF photographer making contact prints will want to examine their prints closely regardless of size. This means a small viewing distance independent of format/contact print size. Under this assumption the circle of confusion and hyperfocal distance would be the same for 8x10 and larger formats used for contact printing.

There is no One True Answer for the hyperfocal distance, e.g., a fanatical LF photographer will probably notice blurring that a casual observer wouldn't notice or care about, and so for the LF photographer a smaller circle of confusion would be needed to correctly calculate a hyperfocal distance that the LF photographer would be happy with.

Alan Davenport

11-Nov-2003, 15:42

f/calc includes 11x14 in its hyperfocal calculations

http://www.tangentsoft.net/fcalc/

Michael Kadillak

11-Nov-2003, 16:28

Great web site Allen. Great contributors who are beyond gracious with their time and knowledge are what make this forum the best!

Witold Grabiec

12-Nov-2003, 11:50

We could probably go on forever with COC and what it should be. COC is indeed the most determining factor for the depth of field (hyperfocal distance being a special case of DOF problems).

For those who would like to delve into the fine points of optics I strongly suggest getting a copy of Applied Photographic Optics by Sidney Ray. It's pricey and the $100 I spent was actually considered a bargain for a new copy. It is some read though, complicated and a bit disorganized for starters. But once you get through a few chapters, formulas will start to make some sense and eventually things get a lot easier.

Having said the above, there is no agreement on what the COC should be and it'll likely remain a subjective matter. Some references still use f/1000 for an acceptable COC (where f is focal length of the lens). However, this leads one to believe that different focal length implies different enlargments, which is simply not the case. COC is now viewed as a constant depending on negative size. I'm still in a search for a comprehensive list on this subject and if anyone knows of one, please let me know. Formulas for calculating Hyperfocal Distance or DOF are simple and it all depends in the COC chosen.

The f/calc is a nice little applet where he uses a "zeiss formula" of d/1730 to find the COC (d is diagonal of the negative in use). It is in fairly close agreement with some sources and for sure a good starting point. The only thing that bugs me about f/calc, is its approach to finding angle of view. It arrives at three different angles for any focal length. There is only ONE angle of view for a non-zooming lens. While I can see how it's calculated, why would one need to know all three? If the idea is to cover the format, then wouldn't it be only the diagonal we shuld care about?

Dick Roadnight

12-Nov-2003, 12:02

f = focal length N = f number = aperture (relative)

a = Max COF diameter

Hyperfocal distance = f +ff/Na

If you want it to look sharp through a 10 x loupe, or in a big enlargement, then the max COF is what your film can resolve.

Many pictures - e.g. groups, town scapes will be examined closely - if you do not need the reslolution, why bother?

David A. Goldfarb

12-Nov-2003, 12:13

Regarding the angle-of-view calculation on f/calc, I find it useful not for determining coverage required, but for comparing lenses on different formats with different aspect ratios. Comparisons like "a 50mm lens on 6x6 is like a 35mm lens on a 35mm camera" are kind of vague, while knowing the horizontal and vertical angles of view gives more of a sense of what the lens sees in a given format. The question I'm usually interested in is "what lens in an unfamiliar format has about the same horizontal angle of view as X lens in a format I'm more familiar with."

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