Typical f/stop setting with a 240mm lens on an 8x10?

[Keith Tapscott.]

For those of you who use an 8x10 Camera and regularly use a 240mm lens for photographing landscapes, trees or nearby subjects, which f/stop do you find that you use the most for good depth of field? I have a Sinar Norma with a 240mm Nikkor which is the only lens for 8x10 that I own.

[Geary Lyons]

Wow! That kind of asking "How long is a piece of string!" It really depends on the composition and the required depth of field to deliver your personal visualization. You have to factor the exposure relationships of film speed and aperture versus shutter speed. So, really hard to give a definite answer without the defining parameters.

That being said, my 240mm is a Docter with a max aperture of f9. I generally shoot f22-f32 if possible. Seems to consistently be the "sweet spot"

Cheers,
Geary

[David A. Goldfarb]

My lens in that range is a 10" Wide-Field Ektar, and I try to get around f:22-32 when I can in those situations, but will stop down more if I need it for the coverage or less if speed is more of a priority.

[Jim Galli]

Keith, there is a phenomenon called diffraction that says the more you stop a lens down the less detail it can record. That's why most will land at f22-f32. That is the tip-over point where things start to digress for most LF lenses. That said if your composition includes both near and far objects that precludes using camera movements to help you get it all in focus near the same place, you either stop down further or don't take the photo. Group f64 were not dummies. They knew about diffraction and trade-off's just as we do. For a contact printed 8X10 you can use f64 to get it all focused. For a 40X50 inch print you might see the diffraction. Look for a book called "image Clarity" by Williams to read and understand all the tradeoff's you will have to deal with to obtain the maximum resolution in each case scenario.

[Capocheny]

Keith,

I'll second and third what Geary and David said about the aperture setting... I've been shooting with a 240 G-Claron and have just started with the Doc Germinar.

F22-32 seems to be the sweet spot but I wouldn't hesitate shooting at 45 either. :)

Cheers

[Mark Sawyer]

The "optimum" is usually in the f/22 to f/32 range, as diffraction sets in at smaller stops, but...

Unless you're making considerable enlargements, it's not something to worry terribly about. In contact printing (whichis all quite a few 8x10 users do), go for whatever f/stop gives you the desired depth of field. I tried f/256 on an Apo-Ronar just out of curiousity, and the negative was quite sharp for contact printing. Weston made very small stops for his peppers and other still lifes to get sufficient depth of field. I don't know what size they were, but the exposures in his studio (where there was sufficient light for portraiture) ran eight hours.

You can also use camera movements to give better depth of field, but that sometimes works against the composition's perspective.

[Kirk Keyes]

Read this - from our own LF home page - http://www.largeformatphotography.info/fstop.html

it is the easiest and best way to decide which f stop to use. There's a little math, but you can just skip it and go straight to the f-stop table.

[walter23]

For those of you who use an 8x10 Camera and regularly use a 240mm lens for photographing landscapes, trees or nearby subjects, which f/stop do you find that you use the most for good depth of field? I have a Sinar Norma with a 240mm Nikkor which is the only lens for 8x10 that I own.

f/64!

[Chauncey Walden]

Does anyone remember ever reading something about a "rule of 4"? It was something like if you take the focal length and divide it by 4 that would give you an f stop that would be probably the smallest you would want to use with that lens so as to not have excess diffraction effects. So, is there something magic about a 4mm hole that having a smaller one would start dramatically increasing the effects of diffraction?

[Walter Calahan]

Depends.

The Nikkor 240 mm is one of my favorite lenses, but I never write down f/stops and shutter speeds. I choose my settings for the moment. Once the image is made, I don't care anymore.

That said, it is always good to shoot somewhere near the middle of the aperture scale. This isn't my harden fast rule. Yes there are times I really want to shoot wide open, and others times when stopping down to the minimum f/stop is because the image needs it.

So the best of my poor memory says, without pulling the lens out, that I try for the f/11 through f/22 area. But don't quote me. Ha ha ha ha ha

[Peter K]

Since the fifties LF lenses are designed to get the best resolution at f/16. With older lenses it was f/22 and and f/32 with realy long focal lenghts.

[Chauncey Walden]

Oh, by the way, Weston said he used 256 for "the pepper" but that was probably US 256 on his old Rapid Rectilinear which would be f/64.

[Brian Ellis]

There is always an optimum aperture for any given situation, that optimum being the aperture at which you obtain the desired depth of field while striking the best compromise between keeping diffraction to a minimum (wider aperture) and eliminating some lens aberration the name of which escapes me (smaller aperture). I believe Tuan's article dealing with focusing the view camera in the articles section of this forum goes into all this. It requires that you measure the distance your front standard travels between focusing on the nearest and farthest objects in the scene that you want to appear to be "in focus." And you need a table of optimum apertures at various distances.

I don't have time to discuss this in detail now but it's actually a very simple method to use, it's the way I've been focusing and selecting apertures for many years. The first I heard of this method was in an article by Paul Hasma that appeared in Photo Techniques magazine around 1995. I've been using it ever since. But as I said, I think Tuan's article also goes into the methodology. If not, search on "Hasma" here and you'l probably find threads dealing with it.

If you don't choose to use this method then I'd suggest that your main concern should be with obtaining the necessary depth of field ("necessary" being the depth of field needed to make the print you want to make). Those "rules" you often read about in different places (including this thread) about opening up one or two stops because most lenses are at their "sharpest" at those settings or trying to never use an aperture smaller than f32 are applicable to smaller formats, especially 35mm where you're enlarging almost 8x just to get an 8x10 print so that diffraction is always a potential problem. Believe me, with 8x10 film you're not going to have to worry about diffraction until you start making prints in the 30x 40 range so you can stop down as far as you want to obtain the neeeded depth of field (consistent of course with the desired shutter speed).

[Ed Richards]

Think of it this way - as the aperture opening gets smaller, you converge to a pinhole camera, with its infinite depth of field and overall fuzziness.

[Daniel_Buck]

I've only been shooting 8x10 for a little bit now, but 240mm is my main lens. I usually end up at f32, but if I'm un-sure that my movements will adequately bring everything to focus at f22-f32, I'll go f64 just to cover myself as I don't have enough experience to know exactly what stop combined with my movements will bring sufficient focus to everything.

With the 8x10 sheets though, diffraction isn't much of a concern of mine, so I don't hesitate to go to f64 if I'm unsure. My 240 does have an f90 on it, but I have yet to shoot stopped to f90 (probably because physiologically I think f64 is enough?). I Haven't broken out a 40x loupe on the negatives, but my f64 negatives don't look any less sharp than my f22 negatives. I'm aware of diffraction though, so I would suspect that fine details (grass blades in a landscape maybe?) wouldn't be quite as cutting sharp when looking at it blown up 3 or 4 times.

[Don Hutton]

Unless you're making very large prints, the effects of diffraction (slight softening and slight loss of contrast) are way less noticable than soft fuzzy areas which you did not get into focus. I'd suggest you stop down more and worry less! Everytime you make an 8x10 image, it's likely you are diffraction limited anyway, it's generally going to be a question of how much... Remember, 8x10 film can bulge a bit in the holders too. I've drum scanned an 8x10 negative shot with a Germinar 240mm at f64 - it would print very comfortably at 40x50 - possibly larger.

[Peter K]

With modern lenses like the Nikkor 240 the diaphragm is limited at the value before diffraction limitations begins. Of course on can unscrew this stop and add other f-values to the f-scale. With lenses made for graphic arts work like the Germinar it's different, diffraction is used to influence the size of the pattern used for printing.

[Don Hutton]

With modern lenses like the Nikkor 240 the diaphragm is limited at the value before diffraction limitations begins.
Where did you get that information Peter? - I'm curious as that particular lens is marked all the way to f64 I'd bet the house that it shows plenty of diffraction at f64. As an example, most of my 4x5 lenses stop down to f45, but almost all of them are diffraction limited by f22.

[E. von Hoegh]

When using a "star" image, I can see diffraction rings on the GG with all of my lenses, starting between f22 and f32.
Granted, this is a rough & ready test, but these lenses are 80 to over 100 years old. (8x10 outfit)

I should check my "new" 1960 vintage Schneiders; I'm sure I'll see the same.

I try to stick to f22 to f32, unless the scene says otherwise.

[Keith Tapscott.]

It seems from the replies that f/22-f/32 is around the `sweet-spot` although as mentioned, it depends on many factors. After mostly using 35mm and 6x7MF, the 8x10 is definitely a different beast altogether. I guess I will soon get to learn how to get the best from it. (Maybe not).

Thanks for the replies,

Keith.

[E. von Hoegh]

It seems from the replies that f/22-f/32 is around the `sweet-spot` although as mentioned, it depends on many factors. After mostly using 35mm and 6x7MF, the 8x10 is definitely a different beast altogether. I guess I will soon get to learn how to get the best from it. (Maybe not).

Thanks for the replies,

Keith.

Just pick a lens and go shooting! It's not like a pool, you can't drown.:) :) :)

[Peter K]

Where did you get that information Peter? - I'm curious as that particular lens is marked all the way to f64 I'd bet the house that it shows plenty of diffraction at f64. As an example, most of my 4x5 lenses stop down to f45, but almost all of them are diffraction limited by f22.
Don, by comparison of LF-lenses data-sheets made after the fifties one can read the optimum f-stop is two or three steps down. Rodenstock and Schneider writes of f/16 for optimum resolution and f/22 when the maximum image circle is needed together with best resolution. With pre-WWII lenses like the Angulon the optimum diaphragm is f/22.

[Ole Tjugen]

... With pre-WWII lenses like the Angulon the optimum diaphragm is f/22.

Is that the pre-WWII Angulon, or the post-WWII Angulon? They are quite different in both construction and performance...

[Peter K]

The optimum diaphragm, f/22, is the same. As I know the different construction was made because some optical glasses weren't aviable anymore. This happens sometimes and the lens has to be recalculatet. And sometimes the performance goes up too.

[Brian Ellis]

With modern lenses like the Nikkor 240 the diaphragm is limited at the value before diffraction limitations begins. Of course on can unscrew this stop and add other f-values to the f-scale. With lenses made for graphic arts work like the Germinar it's different, diffraction is used to influence the size of the pattern used for printing.

Diffraction "begins" at all f stops with any lens, even at f1.4. Diffraction is the result of light rays bending as they strike the outer edge of the aperture opening. Even with a lens wide open some light rays will be bent before they hit the film. But with a wider aperture the proportion of "bent" to "unbent" rays is very low so the effects of diffraction (generally a very slightly soft overall look to the print) aren't noticeable. As the aperture becomes smaller more light rays are bent and the proportion goes up.

However, even at very small apertures where there's a high proportion of bent to unbent light rays the effects of diffraction aren't noticeable until the enlargement factor becomes pretty large. Which is why 35mm lenses, which will typically be used to make prints of at least 8x10, often don't have an aperture smaller than f22, whereas LF lenses often go to f64 or even f128 as my 300 mm Nikon M does. An 8x10 print from a 35mm negative has a mag factor of roughly 8x. A print enlarged 8x from an 8x10 negative would be a 64x80 print, a size that was virtually unheard of in darkroom days and is still pretty rare.

That's why I said earlier in this thread, and have said often in other threads, that in my opinion many people here seem worry too much about diffraction. It just isn't that big a deal with LF film for most of us. Obtaining the necessary depth of field is much more important because the effects of inadequate depth of field will almost always be far more noticeable than the effects of diffraction with LF film. There's certainly nothing wrong with trying to stay around f22 - f32 when that produces the needed depth of field. What's wrong is never using a smaller apeture because of an unfounded fear of the effects of diffraction and losing needed depth of field as a result.

[Keith Tapscott.]

An 8x10 print from a 35mm negative has a mag factor of roughly 8x. A print enlarged 8x from an 8x10 negative would be a 64x80 print, a size that was virtually unheard of in darkroom days and is still pretty rare.

That's why I said earlier in this thread, and have said often in other threads, that in my opinion many people here seem worry too much about diffraction. It just isn't that big a deal with LF film for most of us. Obtaining the necessary depth of field is much more important because the effects of inadequate depth of field will almost always be far more noticeable than the effects of diffraction with LF film. There's certainly nothing wrong with trying to stay around f22 - f32 when that produces the needed depth of field. What's wrong is never using a smaller aperture because of an unfounded fear of the effects of diffraction and losing needed depth of field as a result.
Brian has made some interesting points and I agree that depth of field is more important than diffraction, particularly when using a large film size.
I can only make contact sheets with 8x10 and I would have to send these to a commercial lab for enlargement. A print size of either 20x16 or 24x20 inches is large enough for me.