Originally Posted by Julius
Both the 24-105f4 and 70-200f4 are very appealing to me. Believe me, in cost and size, they are VERY appealing over the 2.8 versions. But the main point of me jumping to FF is for better low light performance. So it almost seems a waste to get f4 lenses when I need to maximize my low light potential. Am I wrong in thinking this way?
The full frame automatically gets you more than a stop. 1.6x applies to the effective equivalent aperture.... So f/4 on full frame is 'faster' in effect, than f/2.8 on a crop sensor.
But, really, the issue on f/2.8 sans IS vs. f/4 with IS, is better stop motion, and thinner depth of field, more pronounced bokeh, vs. better handheld with available light of stationary objects. The difference in zoom is significant, but not extreme, in my opinion, and the 24-70 is better on the wide side at equivalent apertures, as I recall.
Well I think I'm going for the 24-70 2.8 or 28-70 2.8 for sure. That being said, I'm more uncertain about my longer focal lengths. 135L? 70-200 f4 IS? 70-200 2.8 IS? The last one mentioned would be great, but I think the pure size and weight of the lens will limit the places I'd take it. Not to mention the price tag.
The 'crop factor' applies to aperture in terms of effective depth of field, but not light-gathering ability - in other words, you'll have the same exposure settings at f/4 on full frame and a 1.6x crop body. But, the full frame sensor will have less noise, so performance in low light will be better.
The 'crop factor' applies to aperture in terms of effective depth of field, but not light-gathering ability - in other words, you'll have the same exposure settings at f/4 on full frame and a 1.6x crop body. But, the full frame sensor will have less noise, so performance in low light will be better.
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Maybe my words were chosen poorly. The sensor itself is, in total, gathering more light, however, the light intensity per area of sensor does not change, so, yes, in terms of exposure requirements for a given ISO sensitivity, yes, that doesn't change. you see it in being able to (all else being equal) use a higher ISO sensitivity for a given noise level.
I never claimed to be Daniel [8-|]
Well, that depends on how you define "light-gathering ability". If you mean "per area", then you're right. But if you look at "total" light gathering ability, then it's clear that full frame does have more.
Which definition you use will depend on what your purpose is. If you're advising a novice on how to get a good exposure in daylight, talking about per-area light makes more sense.
On the other hand, if you're trying to determine which camera+lens combination has the most light (and least amount of noise), then the amount of light per area is completely immaterial: all that matters is the total amount of light (and sensor technology).
For example, if you looked only at per-area light, it would dictate that f/2.8 on a digicam has more light (and therefore less noise, AOTBE) than f/5.6 on a DSLR. But in reality it does not, which is clear if you look at total light: an integration of light per area and total amount of area, where it is clear that f/5.6 on a DSLR has more light and less noise than f/2.8 on a digicam.
I'm sure you know all of this already, but I just wanted to point out that "per-area" is not the only valid way to interpret "light gathering ability".
This shot was with the 5D(12.8MP), 24-105 @ f5 and 55mm, 1/25, ISO 800, hand held with IS on.
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Here is 100% crop
[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.24.67/IMG_5F00_0142_2D00_100_2500_.jpg[/img]
Mark
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