Dof

[Leonard Evens]

But that assumes you use the same film speed. Following the same argument, you can allow a grain that is roughly 4x as large linearly in 4x5 vs. 35mm for the same size print with the same graininess (that this is usually not desired for LF is a different matter). So by going from ISO 25 in 35mm to ISO 400 in LF you have the same shutter speed...

You have a point. But I don't usually go that low in ISO when shooting 35 mm. In fact, I no longer shoot 35 mm, but use my Nikon D80, which has a 24 x 16 mm format, which is between one fifth and one sixth the size of 4 x 5 format. I usually shoot at ISO 200, bu t I could go as low as 100. With 4 x 5 Ilford HP 5, I usually shoot at about 320, so at best there is an advantage of a bit over 3 times for b/w, and for color it is even less. In practice, I find that using my D80, I would shoot at 1/125 and for the same shot with my 4 x 5 I would be using at best 1/60, but usually 1/15 to 1/32. So my experience confirms that lower exposure time can be an issue.

[Vaughn]

Always interesting discussions on this forum! And like usual, most of the info is of questionable use by the average photographer when one is actually out there photographing. After all, we can see the dof increase or decrease on the GG as the three factors (f/stop, focal length & distance to subject) are changed. Few of us actually have to compute the dof!

It all comes down to one's particular bent. Techophiles love this stuff, technophobes run and hide, but most of us just make photographs.

Vaughn

[BetterSense]

But that assumes you use the same film speed.

You have to! There are no ultra-high-speed films available for LF. Paradoxically, most of the films available for the slowest cameras are slow films. I use 400 speed films in 35mm, but I don't have the option of using anything faster since Delta3200 is not available in 4x5. Probably because that would just be too awesome.

[Arne Croell]

You have to! There are no ultra-high-speed films available for LF. Paradoxically, most of the films available for the slowest cameras are slow films. I use 400 speed films in 35mm, but I don't have the option of using anything faster since Delta3200 is not available in 4x5. Probably because that would just be too awesome.

Well, yes, of course. I know that the highest ISO for LF is 400, and I actually would LOVE Delta 3200 (which is an 800 film for me) in 4x5, too. The previous points by Emmanuel and Leonard discussed the topic in general and I wanted to mention that there was one more variable or boundary condition that had not been mentioned before. To stay in the realm of the possible, I chose the ISO 25 (35mm) vs. 400 (4x5) example, because that is the only realistic one: Rolleipan/Adox Pan 25 vs. TMY, for instance.

[Lenny Eiger]

A few points ..
I think that part of shooting in large format is shooting slower. One has a tripod (almost always) and can contemplate the shot and make sure to get all the angles right before proceeding. It can go too far, where all the image are boring, or all centered, etc. I have taught myself to shoot fast, but the exposure is the exposure - one has to get those details in there or the print will be lousy.

I shoot mostly at 45 or 64 with my 8x10. I expect exposures of 5-30 seconds or more... I don't use a calculator, as I am going to get what I am going to get with the lens closed down.. I much prefer DOF to super-critical sharpness.

I think it's ok that foliage moves, as it does this in real life...

I use Ilford Delta and TMY. I don't like the huge grain of HP5.

Lenny

[Mark Barendt]

I have been shooting large format for a short while and reading everything I can about it when I am not taking pictures. There is a lot of talk about depth of field being shorter in 4x5 vs. smaller formats. Why is this?

Technically I can't answer the question, but in purely practical/experiential terms think about what you have seen in your 35mm experience; the longer the focal length you use in a given situation, the shorter the depth of field. Stand 6-feet from any subject with a background a fair bit furthar back, focus exactly on your main subject. Take one shot with a 20mm lens and one with a 150mm lens, one with a 300mm lens, take all three at f-5.6. The 20mm lens will give you a shot with most everything in acceptable focus, at least easily recognizable, the 150mm lens may render the background recognizable but now part of the bokeh, the 300mm lens will probably be well on the way to making the background unrecognizable.

Now think about a LF camera with a 150mm lens focused on that same subject at 6-feet.

Behind that 150mm lens on your 4x5 camera you can put 4x5 film, or switch to a roll film back and use MF film, or with a bit of ingenuity you could even use a roll of 35mm film. The DOF won't change with any of these combinations because you do not need to change focus distance (for a given camera-subject set-up the distance from the center of the film to the center of the lens remains the same regardless of the film format used in the camera).

What does change with a change of format is the angle of view that can be captured on a given piece of film.

To get a "normal" angle of view on a normal 36x24 35mm frame you use a lens close to 50mm in focal length, for 6x7 you need about a 100mm focal length lens, your 4x5 film needs something close to a 150mm lens to get a similar view.

So, for the same angle of view the larger formats have shorter practical DOF because the focal length has to be longer.

How does this effect everyone's large format compositions. I have spent most of my life shooting 35mm and I feel like I am still composing for large format as I would with 35mm.

For a given angle of view, i.e. "normal", why should the basic composition change?

I don't think it should.

The compositional advantage of LF for me is to be able to use movements to "fix" a given composition where most smaller format cameras cannot. Simply put I can point the camera up at an angle and still get the trees to stand up straight on the negative.