f/2.8 vs f/4

rabidcow wrote in post #2269926
I was at ISO3200 and yes the lens was wide open (f/4) As for how far away I was, I don't know, I forgot my tape measure. but I was on the sidelines.

What noise software do you use? That shot is very good, well exposed and sharp! ISO3200 will give great results if you expose right and clean it with with Neat Image or Noise Ninja or the like...

To the OP, the brightness difference is pretty much evident from what the cow posted but you also have to ask yourself if you want the extra "artistic" fluff that 2.8 will give you...

look at a any picture indoors in a room that isn't lit very well and then imagine it being completely black=D Ok, maybe slightly exagerated, but not by much

Mr. Clean wrote in post #2271561
What noise software do you use? That shot is very good, well exposed and sharp! ISO3200 will give great results if you expose right and clean it with with Neat Image or Noise Ninja or the like...

I used no noise removal software. I simply shoot 1/3 stop over exposed at ISO3200 and I never have major noise.

Wayne MG wrote in post #2269194
length, and factored for being on a 1.6 crop camera.

Don't factor in for 1.6 crop - it doesn't make a difference.

For me, the biggest real world difference is the ability to isolate (blur) the background a little better with lenses that open to 2.8 but overall there are at least five potential differences.

- Depth of field (described above)
- faster shutter speeds
- brighter viewfinder
- more accurate focus with some body/lens combos
- brighter background potential with flash photos

rabidcow wrote in post #2271913
I used no noise removal software. I simply shoot 1/3 stop over exposed at ISO3200 and I never have major noise.

....damn....

NOTED!

lakiluno wrote in post #2271946
Don't factor in for 1.6 crop - it doesn't make a difference.

Hello, but are sure that it doesn't make a difference. I'd appreciate any documentation or sources you could provide, because I've heard otherwise. Cheers.

Wayne MG wrote in post #2272070
Hello, but are sure that it doesn't make a difference. I'd appreciate any documentation or sources you could provide, because I've heard otherwise. Cheers.

Focal length is focal length. An 85mm 1.8 has a focal length of 85mm on a 30D or a 1D or a 1DIIN. Field of view is different though, at which point you would add the appropriate "crop factor" to the 85mm to get the relative FOV.

Thanks Mr. Clean, I understand that. However, my question was about whether the guideline for handholdable shutter speed for, say a 100mm lens on a 5D would be 1/100 sec whereas on a 30D it would instead be around 1/160 sec. That's what I actually meant about 'factoring'. Cheers.

Wayne MG wrote in post #2273823
Thanks Mr. Clean, I understand that. However, my question was about whether the guideline for handholdable shutter speed for, say a 100mm lens on a 5D would be 1/100 sec whereas on a 30D it would instead be around 1/160 sec. That's what I actually meant about 'factoring'. Cheers.

Gotcha, I still think the same applies. I say "think" because while I don't have anything to reference, I know that I can handhold my 70-200 @ 1/200 and still have sharp pics instead of having to up it to 1/250 or 1/320. And I'm not the steadiest of shooters by any stretch of the imagination. The 1:1 shutter speed to FL rule is still "focal length" not field of view.