Rebel XT ISO Settings

[ericgtr]

Hi all, this is a very informative site :) You will have to forgive me as I am new to all of this and recently purchased a Canon Rebel XT and am still working on learning to use it properly. When it's set to auto (the square box on the dial) the ISO speed is set to 400 and the pics seem to come out blury, mostly just still type photos, and I can't find a place to change this under that setting. It appears as if it's locked in, is that the case?

[Jwreich]

You can not change the ISO when using full auto (Green Box). When you go over to Program (P) mode you can change the setting while receiving the benefit of Auto. I would try that.

[ericgtr]

Okay, I will give that a shot, thanks. Does the stock ISO setting of 400 in that mode seem a little fast for still photos of say just animals or flowers from a relatively close distance using a tripod? I have seen some great shots at just 100 or even 200.

[formula4speed]

ISO effects how sensitive your sensor is to light, the higher numbers are more sensitive and are better for low light situations or when you need faster shutter speeds to stop action. Using 400 could be too slow if you are shooting indoors, if you are outside with good light its more than you need but the camera will compensate with faster shutter speeds so it won't hurt you other than having more noise but it shouldn't be much. Do you have any samples of the pictures that came out blurry? It could be motion blur or incorrect focusing, if you are used to point and shoot cameras you'll need to get used to the fact that you have to sharpen your pictures after you take them.

[ericgtr]

Here are a couple of examples, in this link check out the blue jay photos http://www.ericsmedia.com/showgallery.php/cat/500/ppuser/1 they were taken using a canon 75x300mm lense. I took several shots using the AF and they looked very clear when I took them. Another thing I have noticed is that when I resize them down (using 'Best' quality) that they seem to degrade. Thanks for your input on this stuff, it's appreciated :)

Edit: I should also mention that those were taken using a tripod and a wired remote.

[jmgmcg]

Does anyone know whether the ISO on the Rebel XT always stays at 400 ISO or will it vary between 100 and 400 in full auto mode? It's been a bit cloudy here so I haven't had a chance to point and shoot really bright scenes.

[robertwgross]

In my opinion, ISO 400 is a good middle-of-the-road setting for lots of stuff. You can crank it down to 100 or 200 if you have bright light, or if you want to get the aperture to open up wide for depth of field purposes. You can crank it up to 800 or more if you have dim light, or if you are trying to use a quick shutter speed, or if you have a moving subject.

ISO 400 isn't a bad place to leave it until you have a better idea.

---Bob Gross---

[Mitcon]

All the advice given already is great, do try using the camera in "P" mode as a starting point to creative shooting. I also prefer to set the focus point to center to make it easier for framing and knowing where the focus point in an image is. If your shooting moving birds with a tripod try the AI servo mode. Also with the EF 75-300 you could try stopping it down a little to f8-f11 to help make the photos a little sharper if you want.

If you do stop your lens down and/or the light is a little low don't be affraid to use iso 800, even 1,600 is useable IMO. The last issue with resizing your photos, if your shooting jpeg use the largest file size/quality and try not to compress the image any further when re-saving it after you resize it. Jpeg is a compressed image format already so when you do anything to it and save it again your compressing each time and lose more information data in the image. Try to do it only once.

[2112]

Good advice already. I will add, take your camera out of "auto" modes and pretend they never exsisted, especially if you are serious about photography. You don't have to pay for film and have an erase button so go outside and take shots at every ISO setting, ap size and shutter speed and see how that effects your photos. I would also pick up a photography book or two and practice techniques. Have fun :D

[ericgtr]

Thanks for all of the suggestions everyone. Since this post I have moved away from any of the Auto settings and have been doing a lot of reading and practice in the manual modes. The little instruction book they give you with the camera is great for understaning each of their purposes.

[dmstraton]

I've noticed my XT on Auto very rarely strays from 400 ISO, so I now use P mode most of the time instead of green box. I don't think that you need 400 on a tripod to capture flowers. In good light I can get excellent pictures at 100 handheld with my 50 1.4.