[MJB DIGITAL]

Hey guys. I have never shot a format larger than 35mm.

I'm wondering if the size of the sensor/film has an effect on the speed of exposure.

Just curious.

Thanks.

Mitch

[Wheatfield]

The speed of the lenses sure do.
Oh wait, most of us are used to slow lenses now with all the zooms, I suppose an f/4 maximum aperture doesn't really seem that slow to most people.
What slows down shooting speed with a medium format is the physical weight of the equipment and the generally slower to recock speed with winding the bigger film.
Move to sheet film and a good days shooting is a couple of dozen exposures.

[Ben_Edict]

Hey guys. I have never shot a format larger than 35mm.

I'm wondering if the size of the sensor/film has an effect on the speed of exposure.

Just curious.

Hi Mitch, the film format has no effect on exposure times - except, that you run into mechanical constraints for the shutter with large formats.

Many LF shooters use their DSLR as "advanced" lightmeters to make test shots at the same ISO, the LF film has. Much easier and more accurate than even multiple spot readings with a handheld lightmeter.

What I wrote about mechanical constraints is something different. The larger the film format gets, the bigger (usually) the lenses get, if they have a decent fast aperture (a 300/5.6 for instance). The bigger the lens gets, the larger the diameter of the shutter needs to be. So a typical Copal shutter for a 180mm or 210mm standard lens (for 4x5 inch) reaches 1/500s at the fastest shutter setting. on a bigger lens, like a 380/5.6, the fastest shutter speed is only 1/50s -because the shutter blades get so big, that they wouldn't allow a faster acceleration.

If you use behind the lens shutters, like the old-fashioned (but still useable) Packard shutter or a bellows shutter, you typically have 1/10s as the fastest shutter speed.

But all that has nothing to do with the fact, that any film with the same ISO sensibility needs exactly the same exposition (combination of aperture and shutter speed), independend of film format.

Ben

[MJB DIGITAL]

ok cool thanks.

i've been looking for some specs on what 'high iso' is on a medium format digital...

i cant find any tonight but i remember researching before, and they seem to only go up to 400 in many cases

[MJB DIGITAL]

nevermind i found the specs of the hd32.

iso: 100-200-400-800 only

shutter speed: 32sec to 1/500

compared to all of the new super DSLR's, the specs seem to be limiting...except the resolution.
i dont really stray outside of that range of specs though, unless im shooting in terribly harsh sun (read: hellfire) where i have two wireless flashes giving me fill set to max ev comp and shutterspeed at `1/4000 (all on highspeed flash mode)

i think i could hang with this hd32 during a wedding...

now if i could just come up with a few hundred thousand dollars for a wedding kit AND computers that can handle the files...

Maybe instead ill try and pick up a 645n2 8) i like the specs of that one

[Class A]

compared to all of the new super DSLR's, the specs seem to be limiting...except the resolution.

Yes, from what I've read current digital high-ISO performance beats film for image cleanliness.

Regarding your original question, I'm assuming that you want to compare with respect to equivalent images, i.e., same FOV, same DOF, same exposure, same output size.

In this case, larger formats don't buy you any speed. Note that they don't buy you any enlargement factor either, in other words, you cannot print a larger format bigger than a smaller format without introducing more noise.

For an equivalent image from a larger format you either need to get closer to the subject (when using the same focal length) or use a longer focal length in order to obtain the same FOV. In either case you need to increase the f-ratio to obtain the same DOF, hence the aperture becomes smaller. This reduces the amount of incoming light. However, the larger light sensitive area cancels out the loss of incoming light. The images from two formats will be hence equivalent when scaled to the same size.

If you want to exploit the enlargement advantage of larger formats while retaining the same exposure, you either need to use lower shutter speeds or higher ISO. You'll find many sources claiming that larger formats need higher ISO to allow equivalent images but that is only because they implicitly assume that you want the enlargement advantage.

[MJB DIGITAL]

Exploitation is exactly what I'm up to.

I have another question: At, for example 150mm and f/4, would the DOF be thinner on a larger format if you were comparing to 35mm or aps-c formats?

[Gooshin]

Exploitation is exactly what I'm up to.

I have another question: At, for example 150mm and f/4, would the DOF be thinner on a larger format if you were comparing to 35mm or aps-c formats?

for reference: Online Depth of Field Calculator

proposition:

you are standing in spot X, shooting a subject 15 feet away, with 150mm lens @ F4 using your 645

1. standing in the same spot, to achieve the same field of view on a FF camera, you would need to use a focal length of 100mm, and to achieve the same depth of field, you would need to set your aperture value between 2.5 and 2.8

2. standing in the same spot, to achieve the same field of view on a APS-C camera, you would need to use a focal length of 66mm, and to achieve the same depth of field, you would need to set your aperture value between 1.2 and 1.4 (good luck)


(also, as a tid bit, if you wanted to replicate the field of view and dpeth of field capabilities of a 150-200 dollar FA 75mm F2.8 lens for the 645, on APS-C, you would need a 33mm F1.0 lens (well, actually, somewhere around 0.90 ish), heh.. )

also, using a 45mm F2.8 lens on a 645, shooting something 15 feet away, can give you a DOF coridor of only 9 feet!

to replicate that on APS-C, you need an F1.0 20mm lens, which doesnt exist.

the more readily available 21 F3.2, gives you a depth of field corridor of 80+ feet when shooting something 15 feet away, ie, everything is pretty much in focus.

this is the (in my opinion) true power of the medium format, the ability to shoot wide, encompasing photos, while mainting a thin depth of field, seperating your subject from the background.

the resolution and all that stuff is secondary.

[MJB DIGITAL]

for reference: Online Depth of Field Calculator

proposition:

you are standing in spot X, shooting a subject 15 feet away, with 150mm lens @ F4 using your 645

1. standing in the same spot, to achieve the same field of view on a FF camera, you would need to use a focal length of 100mm, and to achieve the same depth of field, you would need to set your aperture value between 2.5 and 2.8

2. standing in the same spot, to achieve the same field of view on a APS-C camera, you would need to use a focal length of 66mm, and to achieve the same depth of field, you would need to set your aperture value between 1.2 and 1.4 (good luck)


(also, as a tid bit, if you wanted to replicate the field of view and dpeth of field capabilities of a 150-200 dollar FA 75mm F2.8 lens for the 645, on APS-C, you would need a 33mm F1.0 lens (well, actually, somewhere around 0.90 ish), heh.. )

also, using a 45mm F2.8 lens on a 645, shooting something 15 feet away, can give you a DOF coridor of only 9 feet!

to replicate that on APS-C, you need an F1.0 20mm lens, which doesnt exist.

the more readily available 21 F3.2, gives you a depth of field corridor of 80+ feet when shooting something 15 feet away, ie, everything is pretty much in focus.

this is the (in my opinion) true power of the medium format, the ability to shoot wide, encompasing photos, while mainting a thin depth of field, seperating your subject from the background.

the resolution and all that stuff is secondary.

Love it. Thats one thing I was pretty sure of. Thanks for the input.

[fs999]

I think the age of the photographer has a lot do with...
As you know that older you are, that bigger is your toy

[Digitalis]

"Old-fashioned Packard shutter or a bellows shutter" - just reading those words brings back memories....

[Peter Zack]

Funny MJB, for different reasons I'm also considering a 645 or 6x7 for next year. Still undecided but I do miss the 6x7 I sold a few years ago. Digital just can not reproduce B&W like these cameras could. So I've been thinking about offering it as a feature for certain clients that want something more.

But as others have indicated, these are slower cameras to use because of weight and shutter speed/ISO limitations. It's why these cameras were always considered portrait or landscape units vs action or sports. But there's no question they can render an image with greater dynamic range and 'texture' than a digital camera can. Especially in B&W.

[pingflood]

If you use behind the lens shutters, like the old-fashioned (but still useable) Packard shutter or a bellows shutter, you typically have 1/10s as the fastest shutter speed.

Or you could use something like a Speed Graphic with a 1/1000 focal plane shutter.

[Ben_Edict]

Or you could use something like a Speed Graphic with a 1/1000 focal plane shutter.

Yes, there are a few faster behind the lens shutters (Sinar and Copal also offer more modern varieties), but they are cumbersome to use and very expensive. The Speedgraphic is a nice camera by the way, but I prefer my CrownGraphic (the same, but without the shutter assembly), because it can be used with shorter fl lenses. With these old press cameras, movements are pretty limited, but they are a nice, cheap and very useable replacement for a typical field camera.

Ben

[pingflood]

The Super has some pretty decent movements, but yeah, nowhere near a view camera.