Does my new 20D have a high iso problem?

TristanP

I was trying some pretty extreme exposures the other night to get a feel for what this camera is capable of. I don't like the look of the noise here at all.

50% crop


original cropped slightly to 600x400



No postprocessing done, these are straight from the camera jpegs. It's not the fact that there IS noise (it's iso3200 for crying out loud), but the regular horizontal pattern to it. I got the same thing doing some longer exposure (~8s) astrophotos earlier this month. Does the fact that the exposure is way off have anything to do with it? These shots weren't done with an accompanying RAW file, so I can't compare the two. Your thoughts?

HeldDown

The farther you push ISO, the more regular the banding will be. Also, as you mentioned, improper exposure can often make the noise even more apparent. When you're shooting that high, I'd suggest shooting raw, so you can keep final exposure control after-the-fact.
Having said that, it is MUCH nicer than the ISO3200 on the 300D, which had a noticeable GRID pattern on it.

kygarden

Try a lower ISO and a longer exposure. Works for me Just have to hope your subject doesn't move!

JimM

This example shot is out of focus, that might have some bearing on the noise, as the sensor is not sure what to capture?

wxwax

Jim, I had much the same thought. The fact that the shot's out of focus draws more attention to the noise.

TristanP

It's an undeniably bad shot. Poor lighting, couldn't focus auto or manually; it's terrible. Is this the worst I can expect, though? If so, great. I just have no experience in this territory.

wxwax

You're going to get noise at ISO3200. Why don't you try a similar shot, properly focused and properly exposed and white balanced, see what it looks like?

Steve Cavigliano

TristanP wrote:

It's an undeniably bad shot. Poor lighting, couldn't focus auto or manually; it's terrible. Is this the worst I can expect, though? If so, great. I just have no experience in this territory.

I don't see it getting worse than that. As mentioned, you will see banding at high ISOs on occassion. You will see it more in the oof and under exposed areas of the shot. You will really see it if you brighten/push these shots during post processing.

The good thing is that is usually isn't noticeable at ISO3200 (sometimes I see it at lower ISOs too). Especially with a decently lit/exposed subject

Steve

Bob&Glennie

JimM wrote:

This example shot is out of focus, that might have some bearing on the noise, as the sensor is not sure what to capture?

This was my first thought too. When it comes to noise at high ISO I don't think that digital is much different than high speed film. I remember when Tri-x was about the grainiest stuff you could get and we soon learned that sharp focus and correct exposure hid a lot of evils. In your case it's not so much that the sensor doesn't know what to capture. It will create an image of anything coming in the lens but darker (read "underexposed) and continuous tone (out of focus) areas will show more apparent noise. The noise is evenly distributed throughout the entire picture but it's more apparent where there is less detail to distract the eye.

3200 ISO is a bit of a stretch and I wouldn't ask any camera to perform well at that extreme. I have a very good DSLR which does very well at 1600 ISO but I couldn't realistically ask it for anything more. Perhaps your expectations are a bit high.

Matthew Saville

I'm looking at a CRW file from a 20D right now shot at 3200 ISO and I see no such noise line-patterns. The grain that you've got is about characteristic for 3200, but I've never seen that banding kinda stuff before...

View the un-altered JPG version of the CRW file here:

http://matthewsaville.smugmug.com/gallery/261021

And, on another note, check out my latest test comparison that has the D70 "VS" the 20D in high ISO performance here:

http://matthewsaville.smugmug.com/gallery/1223029

Here's a screenshot of my 20D CRW conversion of an ISO 1600 file:



Take care,
-Matt-

graeme_7799

i haven't recieved that much banding on my 20d when set to 3200. maybe something is wrong? or maybe i'm fortunate to have a de-effective sensor :P. anyways, photoshop always does a nice job on color noise.