FF is not any better for noise than crop - comments?

I had this sort of epiphany recently regarding FF vs Crop. Follow along and let me know if you agree.

1. FF does better on noise. I think it is about 1 stop better.
2. FF gives shallower DOF by about 1 stop.

So, let's say I take a photo:
40D - ISO 400, 1/125 f/2.8.

Now I want the same photo with the 5D. To get the same DOF, I have to shoot at f/4.
5D - ISO 800, 1/125 f/4


Different settings, same DOF, same SS, Same noise levels?

Yes or No?

So where's my FF advantage?

I found this to be true also, when I picked up a 5d1. I found it difficult to get the DOF I needed to keep groups of people in focus, while still having a high enough SS. Now if I want to blurr the crap out of a photo, 5d rules.

My comment is that my experience shows me your premise is totally incorrect. Full frame is MUCH better at high ISOs than 1.6X crop. So is 1.3X crop. I have never found myself in a position where I had to change the aperture from what I intended to use to get enough DOF with a full frame vs a crop.

Have had XSi and 30D and the 5DII has less noise at high ISO's. That is my experience. YMMV.

If you actually took pictures, you would see you are incorrect.

Do you really think everyone who has moved from 22x15 to 24x36 is just stupid?

A couple of things:

1) DOF difference isn't exactly 1 stop
2) ISO difference may not be either depending on exactly which bodies
3) You may not need exactly 1 stop more dof

Basically, if you need lots of DOF, FF may not have an advantage. The "advantage" is that in this scenario where you're taking away the FF advantage, the FF is still approximately equal to the crop. The rest of the time (when you're not shooting groups at birthday parties) you get to enjoy the FF advantage...mainly access to the best WA lenses, less enlargement of the image, high resolution at a given FOV, narrow dof, "natural" vignetting etc.

Of course, crops may have other advantages like "pixels on target" or apparent reach in the viewfinder and whatnot. You just have to assess what you shoot, and choose the camera that fits that the best.

When are you actually gonna take photos in that scenario???? Maybe when you're trying to replicate an image and the DOF must be identical? But then you would just use an identical camera set up.

Guys, please read my original post again. I a NOT saying that FF is worse on noise. It is clearly better.

My premise is that the reduced DOF needs to be compensated by raising the ISO, thus largely nullifying the better noise performance of the FF body.

I have no problem with people who disagree, but please make your case based on facts and on what I said, not what you misread.

But reduced DOF does not necessarily need to be compensated for, since most of us prefer less DOF. One of your premises is flawed, which makes your conclusion flawed, in my opinion.

ozziepuppy wrote in post #8565720
But reduced DOF does not necessarily need to be compensated for, since most of us prefer less DOF. One of your premises is flawed, which makes your conclusion flawed, in my opinion.

So you're saying that you don't have to get the same image and you can trade DOF for better noise performance? That is true often.

But if you can make that trade off then you can open the aperture on the APS-C setup and drop ISO. Voila, better noise performance with less DOF.

Here's another take on a similar scenario.

You're in low light and you can choose between:

a) 40D w/ 85 f/1.8 and 135L

or

b) 5D w/ 70-200 f/2.8 IS

Both are capable of producing similar results.

This is actually a side benefit that I noticed when I started using the 5DII. In some situations, I can actually use my f/2.8 zooms where I used to only use primes if I need the versatility of a zoom.

n1as wrote in post #8565746
So you're saying that you don't have to get the same image and you can trade DOF for better noise performance? That is true often.

But if you can make that trade off then you can open the aperture on the APS-C setup and drop ISO. Voila, better noise performance with less DOF.

what if you can't open it up anymore? The difference with one stop DOF is pretty insignificant in most situations given the same lens and distance to subject.

The only thing that the "FF" argument is really saying is that lower pixel density = less noise.

FF really has nothing to do with it, other than more area IMPLIES larger pixels.

So no, FF absolutely does not = lower noise.

Larger Pixels, all else being equal should = less noise.
But even that is not true as "all else is never equal"

n1as wrote in post #8565705
Guys, please read my original post again. I a NOT saying that FF is worse on noise. It is clearly better....

It really isn't any better.

There's a reason people use 35mm instead of APS-C
There's a reason people use medium format instead of 35mm.
There's a reason people use large format instead of medium format.
Larger format cameras capture more photons. More photons means more useable data equals the potential for higher quality images.

The shallower DOF inherent to larger formats can be mitigated with narrower aperture and higher ISO.

The advantages of smaller formats are size, weight and price. Maybe higher frame rates. That's all.