stupid question about exposure for MF

[simonSE15]

this is probably really stupid but... are exposure times the same for medium format film as 35mm?

to put it another way, say I have a my Oly 35SP and my Mamiya 6 both loaded with portra 160VC. will they produce the same results at say, 1/125 f5.6 in the same light?

 

[furcafe]

Yes, if both cameras are operating within specs, the same settings should produce the same exposure (perceived depth of field, etc., on the film will be different because of the different formats).

 

[simonSE15]

thanks. I read somewhere that large format needed longer exposure times because there was more of it. is that wrong?

 

[furcafe]

I don't shoot LF, so I'll let someone else chime in, but that sounds wrong, too, like somebody confused the issue of reciprocity failure w/format size or something.

thanks. I read somewhere that large format needed longer exposure times because there was more of it. is that wrong?

 

[rogue_designer]

thanks. I read somewhere that large format needed longer exposure times because there was more of it. is that wrong?

Yeah, that's wrong. If the f-stop, and film speed are the same, your exposures will be the same regardless of format.

 

[Debusti Paolo]

maybe it means that large format usually takes longer exposure time (and needs tripod) because lenses are much slower (f 4.5/5.6) than 135mm format (f2/2.8).😉

 

[Turtle]

sometimes the emulsions are not the same between formats, but more often the user wishes for a different looks so exposes differently (i.e a harder contrastier look in 35mm, achieved by less exposure and more development) compared to fine art work on a LF camera (so more exposure and less development). this is just an example.

Some films have different dev times in different formats. The only way to be sure is to test yourself what works for you. Generally the 35mm/120 times are darned close if not the same.

The other issue is metering. My Leica MPs all agree perfectly, but indicate 2/3 stop different to my other cameras so i rate the film 2/3 stop slower (TriX at 200) than I would in my mamiya 7 (320). I then end up with the same exposure on film. If using an external meter then you will end up setting the same exposure and should get the same.

 

[chippy]

thanks. I read somewhere that large format needed longer exposure times because there was more of it. is that wrong?

yeah, as mentioned already that is incorect (in as much as it is because there is more of it), although large format is different. its not something you have to worry about between standard cameras in small and MF. In large format there are circumstance when the exposure is lengthend and you cant use the same reading to shoot as you would for 35mm or MF, it needs to adjusted (longer speed or wider aperature)

when the bellows/front standard are extended beyond the focal length of the lens, normal reading cant be used and a few adjustment are necessary.

cameras like these ones with the bellows extended, which i often do to take close up images

this old houghton/butcher camera has about a 260mm lens on it but the bellows are extended near twice that or more in this pic. the aperature scales on the lens are calculated when the lens is focused at infinity, which means the bellows/front standard would be extended only 260mm from the film...the closer i focus on something the further the lens gets from the film so the aperture scales are no longer acurate and the readings alter..there is some complicated math to it all and it gets more complicated if filters are used...but i have a marginaly less acurate way that is very quick and easy...but people all have their own methods for working it out or they write it down to keep with the lens

or this old 9x12 Welta Dubla with triple exstention to about 360mm, and on this particular camera it has a 165mm lens. great for ultra close ups but once i go much past 165mm extension its time to start making adjustments to the exposure.

 

[macmx]

Exposure will be the same on all cameras unless you use bellows. Large format is slow because DOF is different at a given aperture. Therefore LF lenses need to be stopped down. Example: percieved DOF of a 2.8 MF lens is aquivalent to 2.0 on 35mm.

 

[chippy]

Exposure will be the same on all cameras unless you use bellows. Large format is slow because DOF is different at a given aperture. Therefore LF lenses need to be stopped down. Example: percieved DOF of a 2.8 MF lens is aquivalent to 2.0 on 35mm.

its a windy slippery road when you start to talk about DoF and LF. what do you want to achieve...i take your point that if standards are left square and you want the same DoF then smaller formats have greater DoF so the LF needs stoping down.

, but just because they 35mm has greater DoF doesnt mean thats what you want, if it was important then why not shoot 110, APS or use small point and shoot digi ..half the reason (my view) people buy fast lenses in 35mm is so they can have the shallow DoF option easy with LF (the other half for available light--oh and some because they like the fast numbers 😀), this is easy with LF..but if you want greater DoF its not hard to acheive either, even on the same f stop; tilts, swings and other movements gain what your trying to acheive....when the lens in most formats are focused on infinity at say f16 there is little diferance in DoF (maybe 6 or 10 feet from memory-correct me if i am wrong) and this is in the forground, again this is easily adjusted with movements to have greater than 35mm, so on the basis of Dof i would have to respectfully disagree, even though i appreciate where you are comming from

 

[Leigh Youdale]

LF Exposures?

LF Exposures?

Chippy is right, and therefore it also applies to 35mm cameras WHEN YOU USE BELLOWS for closeup work. Same principle, and the format itself really doesn't make any significant difference if focal lengths are equivalent.