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# Thread: Calculating Optimal F-stop for 8x10

1. Alex & George, I totally agree with you that's the way I've always worked except I rarely if ever use the the lens minimum stop. It's also the way everyone else I know using LF uses.

However there is some logic behind this Hansma system and it may be potentially useful working with 10x8 or large formats particularly when you want to work with faster shutter speeds and know you still have sufficient DOF.

While the greats like Weston, Adams etc were capable of working exceptionally well without Hansma tables, its only a small bit of card in the backpack, and mental arithmetic.

Ian

2. Originally Posted by gbenaim
Hi all,

When using 4x5, I used the defocus distance method for choosing optimal f-stop. Now that I'm using 8x10 for contacts, I've been using the same values, though I know I can be more liberal. Does anyone have a chart listing f stop values for 8x10 to use the defocus method? I'm often in need of more than the 10mm listed in the LFF article, and don't really know how much dof I'm getting beyond f64. Thanks,

GB
g'day gb
as a non (traditional) 8x10 user i assume you are talking about techniques to increase DOF to the max, something like hyperfocal distance focusing

regardless, shouldn't one always focus on what is important and let DOF sort out the rest?

i would assume that at f64 pretty much everthing is in focus if you actually focused just shy of infinity

plz explain further if i have this wrong

Ray

3. Originally Posted by Alex Hawley
IMO, throw the charts and calculators away. Life is much simpler without them. Use the ground glass. It doesn't lie.
Yes. Forget gurus' calculations. Take pictures. Do not look for more precision than exists in the system.

Cheers,

R.

4. Originally Posted by Ray Heath

regardless, shouldn't one always focus on what is important and let DOF sort out the rest?

i would assume that at f64 pretty much everthing is in focus if you actually focused just shy of infinity

plz explain further if i have this wrong

Ray
Obviously there is not a "right or wrong" answer to this but in terms of my own recent work (and that's not to say it won't change tomorrow) everything in the image is important or it wouldn't be in the picture. I've also found that, with 8x10, focusing near infinity and stopping down doesn't cut it. I'm almost always using movements of some kind and just rely on the ground glass for my DOF... as Alex said, "it doesn't lie." All the best. Shawn

5. Yeah, once Scheimpflug enters the equation it's better to just inspect the ground glass and stop down a little bit more than seems necessary. Do you really want to calculate your DOF wedge or whatever for every tilt & swing angle and focus distance and all that? Tilt movements are why I haven't bothered with DOF calculations for LF. That and the nice ground glass & focusing loupe.

I admire those who take the time to work it out, but it's just not necessary for me. You can probably optimize sharpness a bit over what I'm doing, but my 16x20s look razor sharp when I want them to be and that's all I would ever ask from a negative.

6. Originally Posted by walter23
I admire those who take the time to work it out....
Why?

I'd only admire them if they got better pics. As far as I know, they don't.

Rather, pity them. Photography is about taking pictures, not making calculations that have only a tenuous connexion with the real world.

Cheers,

R.

7. Originally Posted by Roger Hicks
Why?

I'd only admire them if they got better pics. As far as I know, they don't.

Rather, pity them. Photography is about taking pictures, not making calculations that have only a tenuous connexion with the real world.

Cheers,

R.
I agree with Roger. Read as much as you can about DOF and diffraction, then practice a lot. If you do this, your work in the field will be intuitive and you won't have to worry about such tedious calculations.

I think you will also make better images because you will concentrate more on the really important things, i.e. relationship of objects in the scene and tonal values.

Sandy King

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