Why does my 20D like ISO 400

[BigBlueDodge]

Okay, over the course of 4 days since I've had my 20D I've taken over 500+ pictures. Most are inside my house of my wife, kids and pets, and some taken outside in middle of day. Also I have been much about shutter speeds / aperature setting for correct exposure. As I learn more and more how the two are related, I have gone back and looked at EXIF data on my pictures to see what shutter/aperature/ISO setting the 20D chose to take the picture with, and I have seen that most (I'd estimate 80% at least) were shot using an ISO setting of 400. Being new to photography, I was under the impression that an ISO setting of 400 would be better served for low light conditions, but some of my pictures that were taken in full daylight where shot using ISO 400.

Anyway, I'm just trying to understand the logic that the 20D is using to determine optimum exposure and looking to see how the Auto setting on the 20D is working for other people. The more I read the more questions I have.

Thanks in advance.

[Wazza]

I've never used Auto apart from a couple of test shots. Just fired a couple now, and yes, also ISO400. Obviously for the beginner, Canon worked out ISO400 would give a decent enough shutter speed to avoid camera shake. And it's still very sharp, and noiseless at that point.

My tip would to be very quickly, start to learn the other modes. I shot straight on AV mode, and just researched what aperture the lens were sharpest most at. Generally I found f8 to be pretty good on all lens.
Just give it a lot of practice, and found it good.

For indoor flash photography, I just shoot Manual mode, 1/60th, and the results are always good.

[BigBlueDodge]

Thanks Wazza for the reply.

I shoot in Auto mode because I am a beginner. By taking a a picture, I can look at what the camera chose and learn from it. At some point I will move off Auto mode and hopefully get to full Manual in the near future. I've already been playing around somewhat with Av and Tv mode, but don't want to tackle another variable like ISO speed right now. I figure I'll stay busy with getting the hang of aperture / shutter speed.

At least it is comforting to see that other 20D's are exhibiting the same behavior. Thanks

[robertwgross]

Yes, you can look at the settings for Full Auto (Green Box) and Basic Zone and after a while you will see the logic of what it is trying to do. Once you switch over to Creative Zone, it expects you to set your own ISO. But that is OK, you can guess a little and that will work.

Fundamentally, I leave mine set on ISO 400 as a standard. If I have plenty of light, or if I am trying to control the Depth of Field, I may step down to ISO 200 or 100. If I don't have much light, then I will push the ISO up to 800. In a dire emergency, I will push it up to 1600. I used 3200 only for a test.

---Bob Gross---

[tim]

400's just a good compromise, it's maybe 90-95% the quality of ISO 100, and give you better shutter speeds so it's easier to hand hold. Like Bob I use ISO 400 as a default. When I turn it off I set it to ISO400, Av, F4, auto white ballance, zero EC. On ISO 400 the image quality's 95% as good as ISO 100, and with those settings i'll get a good shot if I pull the camera out and shoot in a hurry. Unlike Bob I use ISO 3200 if I need to to get the shot, but I try hard not to use it, it's pretty noisy.

[dhbailey]

I keep my camera on ISO 100 all the time, upping the ISO only when I need to to get a handheld shot without flash. I shoot in Tv mode -- for some reason I can think better in shutter speeds relative to the type of shot I want, and let the camera set the aperture. I think it's because often I am shooting motion (cars passing, people involved in various activities) and can think of what shutter speed will either capture the action in a freeze-frame or will allow blur to give the feeling of motion. I can't get my head around how aperture will affect those same things.

And of course I watch the flashing aperture indication in the viewfinder -- when that happens I simply adjust my shutter speed down until it stops flashing. If that gives me too slow a shutter speed for the shot I want, I raise the ISO until things stop flashing.

And I, too, will use ISO3200 if necessary to get the shot -- there's enough software tools to quiet the noise that I would prefer to have to do that work than to miss a great shot.

[Andy_T]

I actually use ISO 800 as 'default' on my 20D, because it gives very usable image quality and reasonable shutter speeds even in less-than-optimal lighting conditions.

If I'm outside with good light, I go to 400 or even 200, inside when it's dark I also use ISO 1600 now and then (3200 for emergencies) . For 1600 I use noiseware community edition (free), and I really like the results I get.

As a comparison - on my G2, I used ISO 50 ALWAYS -

Best regards,
Andy

[pcasciola]

On ISO 400 the image quality's 95% as good as ISO 100Tim, I'm just curious, but where did you get this info? Do you have a link?

DPReview's noise graph shows the noise levels at ISO 400 to be double that of ISO 100, so I try to stay at ISO 100 and 200 as long as it yields the shutter speeds I am looking for. I'm not saying ISO 400 is unusable, but in my opinion it's not 95% as good as ISO 100 in terms of noise.

http://www.dpreview.com/reviews/CanonEOS20D/Samples/ISO/lumi_graph.gif

[Jonny]

Hmmm... You guys have really got me thinking now.

I use ISO 100 as my default setting and generally shoot in Tv mode as most of my shots are action ones but occasionally i switch to Av when i want to control DoF.
But i find that i am always cranking the ISO up and down to achieve the desired settings in each mode.

Maybe i too should just leave it on 400 for a while and avoid that up and down ISO trouble!

[tim]

Tim, I'm just curious, but where did you get this info? Do you have a link?

No link, no numbers, it's just my opinion based on my experience of the photos i've taken and the tests i've done. I don't worry about graphs so much. I use the lowest ISO that will get me the shot, but to my eye, unless you're pixel peeping or printing huge prints, you're going to be hard pressed to tell the difference between ISO 100 and 400.

[pcasciola]

No link, no numbers, it's just my opinion based on my experience of the photos i've taken and the tests i've done. I don't worry about graphs so much. I use the lowest ISO that will get me the shot, but to my eye, unless you're pixel peeping or printing huge prints, you're going to be hard pressed to tell the difference between ISO 100 and 400.I can see the difference between ISO 100 and 400 pretty easily in most cases, even wih my glasses off. And the noise becomes amplified during post processing, especially if I apply USM, with or without Noise Ninja. Everyone is entitled to their opinions though, but the graphs don' lie. The noise levels are double from ISO 100 to ISO 400.

[tim]

I can see the difference between ISO 100 and 400 if I look for it too, especially viewing 100% crops, so yes you're quite right. When I look at a picture full screen on my 19 inch LCD I can't see much difference, which is more what I meant. You have to be looking reasonably closely to tell ISO 800 too, IMHO, you don't lose much detail but you get a bit of color noise, according to the test shots i'm looking at. Like you say, everyone's opinion will be different.

I find ISO 800 images almost always benefit from noise reduction, which is the first step in my workflow, and sometimes ISO 400 images are improved by Noise Ninja too. Since I got pro which runs inside PS CS I run a few images per batch thru and see if I prefer it before or after, and go with what I like.

[pcasciola]

When I look at a picture full screen on my 19 inch LCD I can't see much difference, which is more what I meant.This could be why you are not seeing the noise as much. I also use a 19" LCD at the moment, but I use a 17" CRT a work, and I see a lot more color problems on the CRT that go unnoticed on my LCD. I have some images that look flawless on my LCD, and on a CRT I can see all the JPEG artifcacts. I don't have a cheapo one either. It's a Viewsonic that I paid about $1000 for. LCDs just don't have the color depth that CRTs do. A lot of time I'll view some images at work that I edited at home, and they look like junk at work but look great on my LCD at home. I'm either going to try a Spyder calibration on it or just break down and get a CRT just for image editing.

[tim]

Good point - i'll do some more test shots and look at them on my work CRT and home home LCD. I need an LCD at home because of space restrictions, this one's pretty nice, but like they say you can't beat a CRT for color - i'll report back tomorrow.

Edit - will actually do it on the weekend.

[Andy_T]

... but I use a 17" CRT a work, and I see a lot more color problems on the CRT that go unnoticed on my LCD.

Phil, thanks - that's a very useful reminder for all of us.

Best regards,
Andy

[Lucky Forward]

It's interesting to read about everyone's various shooting styles. I'm actively returning to photography after a layoff of a few years (except for occasional casual shooting). I just made the switch from film to digital when I bought my 20D two months ago, and while I'm mostly happy with my results (and I'm having a good time!) I am a bit rusty on some of the technical aspects.

In the past, I've mostly done a lot of film landscape photography in manual mode, and now I favor Av mode. I used to shoot Velvia, so I've mostly been keeping the ISO at 100. The other day I was shooting my dog playing around in the water at the river's edge just before sunset. I was using ISO 100, a monopod, and the 17-85 IS lens, so I figured I was fine for the 1/60 to 1/100 shutter speed I was getting in Av mode.

What I got was lots of great shots of the river and shore in golden sunset light with my romping dog blurred in nearly every shot. D'oh! I had no camera shake, but I hadn't given a thought to the motion of my dog. Next time I won't be shy about using ISO 400 or more and a fast shutter speed when the situation calls for it.

By the way, I just love shooting digital. Shooting RAW with a 1GB card and 5fps, I'd filled up the card in no time at all. It still boggles my mind that I can see my results minutes later, at no cost. Very few were keepers on this occasion because of the shutter speed problem, but it was good that I'd learned my lesson with some casual shooting, so I'll be ready when a more rare opportunity presents itself.

[robertwgross]

... but the graphs don' lie.

Graphs probably don't lie, but they can be misleading and confusing as hell.

For example, in the graph you have above, the horizontal scale is numbered with what we assume must be ISO numbers, but the vertical scale is nothing.

---Bob Gross---

[Leorooster]

Graphs probably don't lie, but they can be misleading and confusing as hell.

For example, in the graph you have above, the horizontal scale is numbered with what we assume must be ISO numbers, but the vertical scale is nothing.

---Bob Gross---

Absolutely, consider the following graph from the luminous-landscape.com's review. The noise level at ISO 400 is apparently not much different from that of ISO 100. My point is that graphs can be manipulated to meet certain visual effect.

http://luminous-landscape.com/images-23/sn-chart.jpg

[badrotation]

I shoot 90% of the time in either 400 or 200 (if there is enough light)

I typically like to keep my shutter speeds at 1/640 or higher (I usually aim for 1/800th) while keeping the arperture around f/8-11 for most shots.

I found this is a good combo that usually gets me some very nice and sharp shots. First I try to meet the above criteria on ISO 200, if I cant I kick it up to 400.

seems to be a pretty good system for me.

I usually shoot in Tv most of the time, though I have been playing with full manual more and more.

[MarkH]

DPReview's noise graph shows the noise levels at ISO 400 to be double that of ISO 100, so I try to stay at ISO 100 and 200 as long as it yields the shutter speeds I am looking for. I'm not saying ISO 400 is unusable, but in my opinion it's not 95% as good as ISO 100 in terms of noise.

Double a very low amount that you really can't see is not necessarily a problem.

For a P&S at ISO 50 - to have noise as low as a 20D has at ISO 400 would be very good.

I alway start at ISO 100, but if the light is too low to let me have the shutter speed and aperture that I want, I'll happily bump up the ISO to 200 or 400. I will also use 800 or 1600 if I need to, the noise is still OK for web or smaller prints (6x4 or 5x7). I don't think that a well exposed shot at ISO 1600 looks noisy when printed at 6x4.

[pcasciola]

Double a very low amount that you really can't see is not necessarily a problem.I never said ISO 400 was a problem. I shoot at all ISOs regularly with my 20D (including ISO 3200) and I'm impressed with all of them. My only statement was that I don't think it is fair to say ISO 400 is 95% as clean as ISO 100, because that's just not the case from what I've seen.

Bob, sorry about posting that chart without an explaination. The vertical axis on that graph I posted above is the standard deviation of luminosity, using a color chart that DPReview uses for all the cameras they test. They have 100% crops on the link below, and the noise difference between ISO 100 and 400 is like night and day in my opinion. Again, not that ISO 400 is unusable, just not as close to ISO 100 as others have stated.

Here's the page of the DPReview site that I was quoting:
http://www.dpreview.com/reviews/CanonEOS20D/page20.asp

Now that I've reviewed the crops on DPReview's site again on my CRT at work, I want to get home as fast as possible while it is fresh in my mind, because I'm sure it will not be as noticeable on my LCD. :)

[MarkH]

I never said ISO 400 was a problem. I shoot at all ISOs regularly with my 20D (including ISO 3200) and I'm impressed with all of them. My only statement was that I don't think it is fair to say ISO 400 is 95% as clean as ISO 100, because that's just not the case from what I've seen.


Me neither. I find that ISO 100 is something like 99% noise free and that ISO 400 has twice as much noise, therefore ISO 400 is 98% noise free. In my opinion ISO 400 is better than 95% as clean as ISO 100 and with most uses of the image you don't notice that difference.

Why don't you take 2 pics of one scene, one at ISO 100 and the other at ISO 400, then have them both printed at 8 x 12. If you show the images to a dozen people, you can let us know how many noticed the higher noise on the ISO 400 pic.