Circle of Confusion query

[Tobias Key]

The CoC is defined as the point where what was a point now becomes a disc - that's the point where an image becomes blurred. Lessening the CoC reduces the effective depth of field, and the bigger the print the shallower the depth of field if you are viewing the print from a near distance. So you could define the CoC as the smallest point an lens could resolve or whatever you need to get away with to print at a certain size. It's not an absolute measure. A real life application is the image we can print up to a certain size but not larger because you *just* missed focus. The missed focus means the optimum CoC hasn't been reached but the number is small enough to yield a good 5x7 for example.

[Drew Wiley]

The whole point of view cameras isn't just the large negative, but how you can control depth of field issues in more ways than just stopping down, hyperfocal etc. Tilts and swings are there for a reason.

[Bob Salomon]

The whole point of view cameras isn't just the large negative, but how you can control depth of field issues in more ways than just stopping down, hyperfocal etc. Tilts and swings are there for a reason.

Plane of focus and subject shape. DOF is still controlled by aperture and focus point and CofC.

[Oren Grad]

Only you can decide what works for you.

But FWIW, I bought a Hobo designed for fixed-hyperfocal use with a 120mm Super Angulon, did some tests at f/45, examined the results as I would normally examine contact prints, and concluded that the pictures would be acceptable only when I lucked out and the main point of interest in the picture happened to be at the fixed focus point or very, very close to it. Otherwise, it was a great way to waste 8x10 film at $4-5 per sheet. So I had the Hobo remodeled to include a focusing helical.

To put it differently, I concluded that even with a focal length short enough to give an ultra-wide field of view, the concept of hyperfocal distance was of no practical use to me on 8x10. Even in contact prints, given the way I view them, the effective image magnification is just too large to get away with cheating on the point of focus.

To better grasp the theory and how it relates to the way the pictures come out, I agree with ic-racer that Merklinger is worth a read.

[Tin Can]

Oren, you just saved me a lot of time.

Thank you

[Peter Collins]

FWIW, I am usually IN a CofC....

[Tin Can]

Is it the snow?

FWIW, I am usually IN a CofC....

[Drew Wiley]

Don't get fancy telling me something we all know anyway, Bob. I just don't care. I compose in relation to exactly what I want to draw the eye to in the composition by being in precise focus, and what I might want to de-emphasize by being ever so subtly out of focus. I don't give a damn about rules or charts. I do know how to make very very crisp prints. I cut my teeth on big Cibachromes. But that's just half the story.

[Pere Casals]

The application is a box camera so it will have a fixed focal length

If I understand well, you have to decide what hyperfocal settings you are to use, the problem is that when using fixed hyperfocal you are to have distant subjets in the worst case...

You can use this app:



...to understand how the system will behave across subject distance, to decide what f/ and what focus plane distance you want.

[Drew Wiley]

Doesn't Dramamine or Pepto Bismol cure circle of confusion issues?