Subject: DOF issues with sizes larger than 4X5

[audioexcels]

I hope not to make too much of a redundant topic here and hopefully this is posted into the correct category.

I have spoken with a few highly valueable members regarding the subject, but want to get further information relating to the subject of DOF with format sizes larger than 4X5

1) From what I have read, 5X7 and up tends to involve a similar practice as 8X10. I will not be getting into ULF sizes greater than 8X10 for this subject, but rather focus on sizes 5X7-8X10.

Is it true that once you go from 4X5 to 5X7 or 8X10, that working with 5X7/8X10 DOF issues are a wash, meaning, those shooting with 5X7 or 8X10 are going to face similar DOF issues and have to deal with similar consequences OR is DOF an even more difficult issue to deal with when shooting 8X10 vs. 5X7 or even 6.5X8.5?


2) How often are timed exposures required when working with 5X7-8X10, meaning, how often does one need to use a long time exposure with these larger formats? Lets say we have a sunset photo where the sun has just gone down, but there's still quite a good deal of light with tons of beautiful colors and clouds in the composition, with the sea/ocean well lit. Do shots like these require timed exposures due to having to stop down a lot?

3) A slight side topic, but how difficult is it working with movements, especially with an 8X10 camera vs. 5X7 or 4X5?

[Nick_3536]

The issue is you use longer lens.

210mm normal for 5x7
300mm normal for 8x10.

5x7 isn't much longer then 4x5. Some people even use 210mm for 4x5 normals.

Exposures? You tend to use smaller F/stops with bigger cameras. But once again 5x7 isn't that different from 4x5.

Movements? Other then the camera ease of use? That bigger screen can't hurt IMHO.

[Ron Marshall]

There are online depth of field calculators, but I will run through one scenario for you, making the assumptions that you wish to maintain the same circle of confusion in both formats, no swings or tilts are considered, and focal lengths equal to the film diagonal are used on both formats.

There is a 300mm on the 8x10 and a 150mm on the 4x5.

To get the same DOF with a 300mm lens as a 150mm (with the same circle of confusion, and no swings or tilts) you would need to multiply your f-stop by four: ie. f11 on the 150mm would give the same DOF as f45 with the 300mm.

With those assumptions, you lose four stops with the 8x10. Assume at sunset an EV of 8 and an EI of 400. Your exposure would be about 1/8 sec at f11 for the 4x5 and about 2 sec. at f45 for the 8x10 (assuming no reciprocity failure correction is required with a 2 sec. exposure).

Unless you are planning to make prints larger than about 24x30 or contact prints, you might find you are just as happy with negs you would get from the 4x5 as those from an 8x10.

In reality, you often can make do with a larger circle of confusion and can apply some tilt or swing, so you might only forfeit two stops or less.

What formats are you currently shooting?

For further info see the link below:

http://home.online.no/~gjon/davisdof.htm

[audioexcels]

Hi Nick and Ron.

Thanks for the input. Right now it is digital (uggg) and some 4X5. Have other cameras around, but not the useable type. My main camera is in the shop.

Am I correct by saying 5X7 or more appropriately, 5X8 (since it is a true 2X greater surface area as 4X5), costs you two stops more than shooting 4X5, with 6.5X8.5 being 3 stops, and as you said it, 8X10 being 4 stops?

I.E. For your example, F22 for 5X8, F32 for 6.5X8.5, F45 for 8X10...

And obviously with a different focal length used along with movements applied, things will change with respect to how many stops are lost when shooting the larger film, particularly 8X10 that you mentioned...

Final print size I would want to have=30X40-40X50 maximum with the majority of prints somewhere in the 11X14-24X30 range (yep, quite a wide range, I know).

Last thing-I like to shoot on the wide angle side of things, so a 300mm would likely be the longest lens I would use on any format.

[Ron Marshall]

Hi Nick and Ron.

Thanks for the input. Right now it is digital (uggg) and some 4X5. Have other cameras around, but not the useable type. My main camera is in the shop.

Am I correct by saying 5X7 or more appropriately, 5X8 (since it is a true 2X greater surface area as 4X5), costs you two stops more than shooting 4X5, with 6.5X8.5 being 3 stops, and as you said it, 8X10 being 4 stops?

I.E. For your example, F22 for 5X8, F32 for 6.5X8.5, F45 for 8X10...

And obviously with a different focal length used along with movements applied, things will change with respect to how many stops are lost when shooting the larger film, particularly 8X10 that you mentioned...

Final print size I would want to have=30X40-40X50 maximum with the majority of prints somewhere in the 11X14-24X30 range (yep, quite a wide range, I know).

It is not the area so much as the ratio of the film diagonals, or more correctly, the ratio of the focal lengths to obtain the same perspective on both formats. A direct comparison is possible with 4x5 and 8x10 because they have the same aspect ratio. To get the same perspective as a 150mm lens on 4x5 with an 8x10 you would need a 300mm lens. DOF decreases with the square of the focal length, and is directly proportional to f-number.

The approximate diagonals of the film formats: 4x5 = 150mm; 5x7 = 210mm; 8x10 = 300mm.

300/150 = 2; 2 squared = 4 stops

210/150 = 1.4; 1.4 squared = 2 stops (these are approximate values)

You can do the math for the other formats!

[robert fallis]

I have a 300mm lens on a half plate camera, so it's good for portriats and close ups. I'm usless at landscapes, I also use slow ortho film or paper negs, on a bright sunny day if I want to use maximum depth of field the then it's 2secs at f64, In portrait I often use the lens at F4.5 as this puts the background
very much out of focus, there are some advantages to small depth of field,
bob

[Brian Ellis]

Here is all you need to know about depth of field with any camera in any format using any film under any circumstances:

(1) Depth of field doubles as the f stop doubles (e.g. going from f16 to f32 doubles depth of field).
(2) Doubling the lens-to-subject distance quadruples depth of field, tripling the distance increases depth of field by a factor of nine.
(3) Reducing the lens focal length by half quadruples depth of field, doubling lens focal length decreases depth of field by a factor of four.

That's it. Depth of field discussions become more complicated and even acrimonious because some people insist on bringing endless variables into the discussion that don't relate to depth of field as such but rather to acceptable "sharpness" in the print, such as print size, enlargement factors, cropping to obtain the same image from one focal length lens as from another, print viewing distance, lighting under which the print is viewed, and who knows what all else. But depth of field (as in size of circles of confusion) is only affected by the above three factors in the above ways.

Applying those principles, you can see that moving from a 4x5 camera to a 5x7 or 8x10 camera doesn't, by itself, have any effect on depth of field. What does affect depth of field with larger format cameras is that to make the same image (i.e. same angle of view) with say an 8x10 camera as with a 4x5 camera from the same camera position and using same aperture, the lens focal length has to be doubled, which causes a loss of depth of field by the factors described above. So it isn't the fact that an 8x10 (or 5x7) camera is being used by itself that causes loss of depth of field, it's how the camera is used (i.e. lens focal length, aperture, and subject distance).

[Ken Lee]

Here is all you need to know about depth of field with any camera in any format using any film under any circumstances:

(1) Depth of field doubles as the f stop doubles (e.g. going from f16 to f32 doubles depth of field).

(2) Doubling the lens-to-subject distance quadruples depth of field, tripling the distance increases depth of field by a factor of nine.

(3) Reducing the lens focal length by half quadruples depth of field, doubling lens focal length decreases depth of field by a factor of four.

Bravo !!!

[Oren Grad]

2) How often are timed exposures required when working with 5X7-8X10, meaning, how often does one need to use a long time exposure with these larger formats? Lets say we have a sunset photo where the sun has just gone down, but there's still quite a good deal of light with tons of beautiful colors and clouds in the composition, with the sea/ocean well lit. Do shots like these require timed exposures due to having to stop down a lot?

I just took a peek at my negative log to make sure I was remembering correctly. For formats larger than 4x5, my shutters spend the vast majority of their time on B and T - my exposures are usually in the range of several seconds to several minutes at apertures of f/32 and beyond, usually on HP5 Plus. Yes, definitely in reciprocity correction territory.

You should know that I'm usually out with a big camera toward the end of the day, when the light is fading (and the bugs are biting - ). YMMV.

[David A. Goldfarb]

That's it. Depth of field discussions become more complicated and even acrimonious because some people insist on bringing endless variables into the discussion that don't relate to depth of field as such but rather to acceptable "sharpness" in the print, such as print size, enlargement factors, cropping to obtain the same image from one focal length lens as from another, print viewing distance,

Would that it were so. DOF is a calculable value, based on the above factors and a figure for acceptable circle of confusion, which depends on format size, enlargement factor, viewing distance, and assumptions about the limits of human vision. You can determine the size of an actual circle of confusion without deciding upon a value for acceptable circle of confusion, but you can't describe it as DOF without deciding at what subject distances for a given aperture produce a circle of confusion that is no longer acceptable, and that depends on format size, etc.