EF-M 55mm f/1.3 Coming in 2013? [CR1]

[drjlo]

I'm really hoping for EF 55m f/1.3 (why not 1.2?).  Call it L and charge $2000 if you want.  As long as it's a bit sharper with a bit faster AF, I would buy it. 

[TrumpetPower!]

So the noise from a EOS D30 (2001) is one stop behind the 1D X?

No, of course not. Don't be silly.

Forget digital for the moment and think of film.

Your favorite film has an effective one-stop ISO advantage with each increase in format size.

If you're happy with the grain you get from an 8" x 10" print from APS-C with ISO 50 Velveeta, you'll be equally happy with an 8" x 10" print from 135 format with ISO 100 Velveeta and with an 8" x 10" print from 645 format with ISO 200 Velveeta. Couple all those film and camera choices with a 50mm @ f/1.4, an 85mm @ f/2, and a 135mm @ f/2.8 respectively, adjusting shutter speed (but not composition / distance / framing / etc.) as needed, and you'll wind up with very closely comparable images from all three, with the only variable remaining being resolution.

Obviously, you can shoot your medium format camera with a 135mm f/1.4 lens and ISO 50 Velveeta and get an image that's comparable to what you'd get with an APS-C camera with a 50mm f/0.5 lens and ISO 12 Velveeta...which would be quite the trick!

Comparing a D30 with a 1DX is as silly as comparing Velveeta with Cojack; make the comparison instead between an EOS-M and a 6D.

Cheers,

b&

[Stone]

Considering the constant f1.3, I would think of this as a low light lens suitable for indoor use, but 55mm on an APS-C sensor is going to give a field of view equivalent to 88mm on a 35mm sensor.  A bit too long for indoor shooting in all but the biggest rooms IMO and forget about full body portraits unless you've got quite a bit of distance from your subject available.  I would have expected something in the 28-30 mm range first for the EOS-M mount, I think it would have been quite a bit more useful.

[RLPhoto]

Now this would be a cool lens. 

[KyleSTL]

Comparing a D30 with a 1DX is as silly as comparing Velveeta with Cojack.

In your hypothetical world, yes, I think your assertion is correct that a frame with a crop factor of 1.4x would have 1 stop worse noise (and 2x would be 2 stops, 0.7x would have a 1 stop advantage, etc).  However we don't live in the world of film anymore and not all sensors are created equal at the pixel level and simply scale by overal size of the sensor.

But facedodge's statement is still true that the exposure triangle remains unchanged (f/2.8, ISO 400, 1/250 is the same no matter what format the camera is in) is still completely valid.  I understand people pointing out the DOF different in formats in terms of equivalence, but I think stating the same thing in ISO would only serve to confuse less informed people attempting to understand the fundamentals of photography and the differences in formats.

[TrumpetPower!]

I think stating the same thing in ISO would only serve to confuse less informed people attempting to understand the fundamentals of photography and the differences in formats.

Quite the contrary.

Image quality and noise / grain is very closely tied to the degree of absolute enlargement, which is itself very closely tied to the format.

ISO is determined in no small part by the noise / grain threshold...but that very threshold in the practical real world is dependent upon image quality, thus enlargement, thus format.

In a very real sense, one that you see hold up as a rule when comparing cameras from the same generation of technology, each larger format has roughly a one-stop ISO advantage. If you need to shoot at least at ISO 200 on a 135 format camera to get noise to levels you find acceptable, then you need to shoot at at least ISO 100 on APS-C, but you can get away with ISO 400 on medium format.

(And, yes, it doesn't scale linearly -- despite their size advantage, many medium format cameras have lousy extreme-high-ISO performance. This is partly due to there not being much demand for low-light utility in the medium format world, and the manufacturers putting their efforts into improving low-ISO performance instead. The fact that it's a much smaller market also plays a role.)

Understanding why this is so is a very basic part of photography, and essential to understanding why the different formats exist in the first place and one of the reasons why you would choose the one over the other.

b&

[louislbnc]

I think stating the same thing in ISO would only serve to confuse less informed people attempting to understand the fundamentals of photography and the differences in formats.

Quite the contrary.

Image quality and noise / grain is very closely tied to the degree of absolute enlargement, which is itself very closely tied to the format.

ISO is determined in no small part by the noise / grain threshold...but that very threshold in the practical real world is dependent upon image quality, thus enlargement, thus format.

In a very real sense, one that you see hold up as a rule when comparing cameras from the same generation of technology, each larger format has roughly a one-stop ISO advantage. If you need to shoot at least at ISO 200 on a 135 format camera to get noise to levels you find acceptable, then you need to shoot at at least ISO 100 on APS-C, but you can get away with ISO 400 on medium format.

(And, yes, it doesn't scale linearly -- despite their size advantage, many medium format cameras have lousy extreme-high-ISO performance. This is partly due to there not being much demand for low-light utility in the medium format world, and the manufacturers putting their efforts into improving low-ISO performance instead. The fact that it's a much smaller market also plays a role.)

Understanding why this is so is a very basic part of photography, and essential to understanding why the different formats exist in the first place and one of the reasons why you would choose the one over the other.

b&

While I do agree with your statement, I find your way of putting it a bit weird (at least to me). One of the primary thing that determines the noise level is the pixel size. It's the reason why some high-speed cameras (say a vision research v1210) can have no apparent noise at it's native ISO40000 (yes, 4 zeros). Thought it sacrifices resolution to get there, it only has 1MPx on a full frame sensor.

So if you compare an APS-C and a full frame sensor with both the same number of pixels with the same die technology, the full frame has a larger pixel size.  This means that the full frame receives more light per pixels meaning that it needs less gain to bring it to a comparable ISO to a APS-C sensor. Bottom line, the full frame will always have a better signal/noise ratio. Usually, the APS-C sensors don't have much less pixels than the full frames so this is probably a better way to look at it (7d's 18 MPx vs 5d mkII's 21.1 MPx) so it does have a smaller pixel size.

The other way to look at it, if sensors had an equal pixel size. Kind of like putting the same ISO 200 film on a medium format camera and a FF camera. The FF sensor has less MPx or resolution in film terms. Where as the medium format camera has an increased resolution but the same signal/noise ratio. Once you blow them up to large print size, you're blowing the details up as much as the noise. Bottom line, you're getting worse signal/noise ratio on the full frame and the noise will be more apparent when blowing up the image to a comparable size.

When comparing camera formats, I think one should separate field of view, image quality (and noise) and depth of field as they all differ in different ways... though I do agree with you that it's important to consider all of it. Another thing to consider as that lenses usually aren't as sharp on corners as they are in the center so lenses might seem sharper on an APS-C sensor as you're only looking at it's best portion.

[TrumpetPower!]

One of the primary thing that determines the noise level is the pixel size.

Actually, pixel size in and of itself has no bearing whatsoever on noise. Once again, it's entirely a question of (absolute) enlargement.

The only reason pixel size appears to relate to noise is that people like to compare noise at a 100% pixel view. But, right there, you're now comparing different enlargements. A 36 megapickle full-frame camera has twice the linear resolution as a 9 megapickle full-frame camera. To compare the noise, you'd need to either show the one at a 50% view (turning the noisy small pixels into unnoticeable fine-grained smoothness) or the other at 200% view (thus making the noise in those big pixels much nastier and blotchier). Or, much better, by actually making prints and comparing the prints. But, then again, your 24" x 36" print (or whatever) is going to be done at 300 ppi by the one camera and only 150 ppi by the other.

The short version is that there will be the exact same S/N ratio (all else being equal) between the two; you just get to pick between more fine-grained noise or less large-grained noise. If it helps, imagine scanning film at different resolutions; the grain is still there no matter what, and all you get to do is decide how faithfully you want to render the grain.

And, of course, the usual engineering caveats apply. Newer cameras are made with more megapickles and thus smaller pixels, yes, but also with newer and better and more efficient electronics that's therefore less prone to noise. And there may well be engineering matters that make it easier to design bigger circuitry and so forth.

Cheers,

b&