exposure question

[jim_panzee]

This question has confused me for a long time, and I hope someone can clear it up for me, without getting too technical. So here goes, say you have two 50mm lenses a 1: 1.4 and a 1: 3.5, plus a light meter. When you look through the view finder of a camera with TLM the 1.4 lens gives a reading of say f 5.6 and a shutter speed of 125. Point the light meter in the same direction and it gives the same reading, although the light meter has no setting for the difference in the lens type (1.4 or 3.5), so if you set this reading on a camera with no auto exposure or shutter speed and the 3.5 lens, would the exposure setting be correct. If so why?

[nnpc]

The "1:1.4" designation on the lens tells you the lens' maximum apeture (how "fast" the lens is, lower being better). f5.6 on the 1:1.4 lens lets through the same amount of light as f5.6 on the 1:3.5 lens. If your meter said you needed f2 for 1/125, then you couldn't use the 1:3.5 lens because it can't open up that far.

[jim_panzee]

OK, fine, but apart from really low light situations hand held without flash etc, you would not gain very much if anything between the two. So if 90% of your shooting involves normal outdoor shots in daylight, it makes one wonder with two lenses of different aperture value, and if they are of the same build quality, why you would need a faster lens, and pay possibly up to three times as much for the advantage, or are we talking snob value. I have gone down this road several times in my life with various cameras and lenses, and when I recently analysed my photographs and found that only a very tiny percent were taken below f4, I wondered did I really need these lenses in the first place, maybe I could have saved myself a great deal of money. Just a thought!!!!!!!!

[framewerkz]

For broad daylight stuff, there's absolutely no need for anything less than a f/5.6. Then again, if you had a f/1.4, you have a great deal more flexibility, and the ability to shoot indoors without a flash.

It's a bit of a circular argument really - when you say "when I recently analysed my photographs and found that only a very tiny percent were taken below f4.." - it's probably because you haven't had a lens that could open up past that.

Because I shoot Av most of the time, it's certainly given me an additional dimension of flexibility. I had a similar argument at a time when I was debating getting a f/1.4 when I already had a f/1.8 - was the extra third of a stop worth it?

Unequivocally, yes.

[jim_panzee]

It's a bit of a circular argument really - when you say "when I recently analysed my photographs and found that only a very tiny percent were taken below f4.." - it's probably because you haven't had a lens that could open up past that.

Ah. Sorry to disappoint you, but over the years as I said, I have had lenses that would open out from 1.1 and up-wards, even now I have two Canons both with 28 and 50mm 1.4 prime lenses, I also have a Leica with a 5cm 3.5 Elmar, and was contemplating a 2.8 for this also but the price even s/hand, is out of this world.

Ps. The indoor shots I take in a year, you could count on one hand, and if a shot needs flash, I don't take it. If you don't believe me have a look at some of the phtos on my galerie. http://www.pbase.com/jim_panzee/galleries

[framewerkz]

OK, I sit corrected (but you didn't say, y'know). Still, I like the additional flexibility offered by having a fast lens.

*psst* If you're really not that keen on them, I'll take the 28/f/1.4 off your hands

[jim_panzee]

why you would need a faster lens, and pay possibly up to three times as much for the advantage, or are we talking snob value. I have gone down this road several times in my life with various cameras and lenses,

Read between the lines I didn't say I don't use them, of course I do if the situation demands it, all I was saying is "do I really need them for the bulk of my shots" the answer to that is "NO". And the answer to your question framewerkz is also a big NO. Well not yet anyway.

[framewerkz]

Sorry, not so big on between-line interpretation, what with English not being mother tongue and such.

I suppose it's down to horses and courses then.

PS Great travel galleries.

[wyk]

The faster the lense, the more shallow your depth of field can be, especially at close focal distances. Faster 50mm also tend to be quality lenses, giving a great 'bokeh' effect as well as a great depth of field.

http://www.pbase.com/wyk/image/12582 Is an example of a 50mm F1.4 Minolta lense on a Maxxum 9 with the lense wide open to f1.4.

[jim_panzee]

Nice photo Wes, I would have liked to have seen the photo taken at a larger aperture, say f3.5. But then again I don't know what your intentions were.

Like the lens as well

JimP.

[llung]

I might add that what extra you may get at one end you may lose at the other. My 1.4 only stops down to f16, while my 3.5 stops down to f22. You might at times find it desirable to get that extra depth of field. It's also helpful when you've been shooting inside or in dark alleyways with 400 ISO film and step out into the bright daylight with a thirty year old camera that has a max shutter speed of 1/1000.

I spent a couple of years in Egypt where the difference between the sun and the shade at mid day could be a half dozen stops or more (too lazy to get up early in the morning; too much smog in the late afternoon/early evening). This makes for interesting contrast, but it's hell on the light meter. If you're interested, see HERE.

I guess my point (if I have one) is that there are different lenses for different situations...

[installer]

The f/1.4 lens will allow shallow depth of field, when you want it to keep a background out of focus. Like this:

http://www.pbase.com/installer/image/45023296/original

Also, it will allow you faster shutter speeds in the morning and in the evening.

[kodan_txips]

Even if you always use f11 for every shot, an f1.4 lens will make the viewfinder much brighter and clearer than an f2.8, so it will be easier to compose your shot. If you are using an SLR, that is.