another weird question ...asap replies if possible

melekalikimaka · 21-01-2009 10:03pm #1

if you have a camera with a 105mm lens, and you set aperture priority (so the camera selects the correct speed) and you set it into 1/125 and f4, and then you change the lens and put a 35mm, but you still have f4, which speed will the camera choose, 1/15, 1/60, 1/125 or 1/10?

this is a exam question... i'd say 1/125... but surely its lens specific....

ThOnda · 21-01-2009 10:08pm

Theoretically, the exposure should be the same. However if the camera has TTL metering, the difference if amount of lenses (glass, plastic, transitions among lenses and air) could affect the final measured exposure. So yes, you can get different times for the same Aperture.
Not to mention that it depends also on the way how the exposure is being measured/calculated, because you'll get different scene (and variations of tonal range) with each focal length.

Fajitas! · 21-01-2009 10:10pm

It depends on what you are metering on and for - The 35mm lens will take in more of what's in front of you, so you'll most likely need to adjust your metering to suit, unless in a controlled scenario.

Valentia · 21-01-2009 10:11pm

I suppose, strictly speaking. BUT it depends on the metering that you use and the subject. If, lets say, the centre of the frame has a dark object with the 105 and when you put on the 35 the scene changes so that the dark object is now only a small part of the subject then the camera metering may change the exposure values. So the question should be more specific I would say if they want a short answer.

Hope this makes some sense.

Valentia · 21-01-2009 10:12pm

SNAP!!!

DaireQuinlan · 21-01-2009 10:13pm

Theorhetically it ought to be identical. Though in practice you'll probably get slightly different results for a couple of reasons. First of all different lenses have different transmission characteristics. Nowadays this isn't such a big deal, typically you'll lose anything up to a third of a stop through a lens. I'd be surprised to see any difference in real terms. The other difference might be down to the focal length. A wide angle will be metering off a much larger FOV, and so might take in much brighter sources for example, that might not be included in the metered scene for a telephoto.

melekalikimaka · 21-01-2009 10:13pm

yeah well thats all thats in the question... ultipla chice so i assume the answer is the unchanged option....

DaireQuinlan · 21-01-2009 10:14pm

hahahaha

aren't we all quick off the mark this evening ?!?

Fajitas! · 21-01-2009 10:16pm

melekalikimaka wrote: »

yeah well thats all thats in the question... ultipla chice so i assume the answer is the unchanged option....

Piss them off, draw your own box, and let 'em know the truth :pac:

melekalikimaka · 21-01-2009 10:33pm

Fajitas! wrote: »

Piss them off, draw your own box, and let 'em know the truth :pac:

i am considering that on alot of question tbh... multipal choice doesnt make sense in photography, no answer is right or wrong if you talk bout it enough hehe

another weird question ...asap replies if possible

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