Steve's Digicams Forums

Steve's Digicams Forums (
-   Canon (
-   -   [Recovered Thread: 43065] (

Bill_CA Dec 30, 2004 5:21 PM

I am wondering if anyone has tested out the Auto ISO feature vs manual ISO setting in the P, Av, Tv modes with no flash? It seems the Auto ISO only gives equivalent of ISO 50. I called Canon and they said the auto ISO can only range from ISO 50 to 200, but not 400.

What I did was set the camera to any of the above mentioned mode, with the ISO set to Auto. Next I move the camera from a dark area gradually to a light area. When the camera shutter/appature shows green, then I freeze the camera at that spot. Next I switch to the various manual ISO settings (50, 100, 200, 400) and take another reading for each. What I find is that I get the equivalent of only ISO 50 and not the other three.

Canon is looking into this. I wonder if anyone else has this same problem.



Nicolas Dec 30, 2004 8:46 PM

I did not noticed this before since I never use Auto ISO, but in my very small test it did show that Auto ISO was using ISO 50 in dark environnement.

I took 5 pictures of the same thing, without flash, the settings were the same, except for the ISO. As you can guess, ISO 400 is much clearer than ISO50. ISO50 shows the exact same light as in Auto ISO.

pulp Dec 31, 2004 1:22 AM

So... what you guys are saying is that AUTO mode is basically shot to h*ll. We will be getting dark/noisy shots in low light because ASO is stuck at 50? I hope a firmware upgrade can fix this... money back if not?

Bill_CA Dec 31, 2004 4:25 AM

I called Canon and they said the auto function is supposed to go from ISO 50 to ISO 200, but not ISO 400 because of the grain (although nowhere did the manual say this). In any case, I was not able to get more than ISO 50 and Nicolas' quick check seems to confirm thisproblem.

style="BACKGROUND-COLOR: #000000"If more members respond with the same situation, then I would say this is a firmware problem and not just our two cameras.

style="BACKGROUND-COLOR: #000000"Canon said they will check into this and get back to me. I will post their answer when I get it.

If does not make sense to have an auto setting if all I am getting is just ISO 50. I need the ISO 200 or 400 for some indoor shots without flash. I can set it manually to the other ISO settings, but then why pay for this feature if it does not work?

Nicolas Dec 31, 2004 9:54 AM

Seeing how this was still up, I another very small test. And Canon is right.

It just depends on the mode you use. In P mode, the Auto ISO is set to 50, that is why tests from yesterday were like that, I only shoot in P mode...

So, today I tried to set the Camera in Auto Mode and the ISO is automatically set at Auto ISO, I checked the settings, reproduced them in Manual mode and tried with ISO 50, 100, 200 and 400. In Auto mode, the ISO is set between 50 and 200, tho I did not see it go any below ISO 200, I presume it did. Anyway, I did my test shots and compared and it turned out Auto ISO(in auto mode) was the same exposure as ISO 200.

So its just Auto ISO from P mode that doesn't leave ISO 50. That doesn't really bother me since I always shoot at ISO 50 orI set the higher ISO manually, but I understand how it could bother someone else.

JimC Dec 31, 2004 10:29 AM

Bill_CA wrote:

If does not make sense to have an auto setting if all I am getting is just ISO 50. I need the ISO 200 or 400 for some indoor shots without flash. I can set it manually to the other ISO settings, but then why pay for this feature if it does not work?

Bill, chances are the way it works was deliberate. Keep in mind that ISO 400 is going to have a lot of noise (whichusers may find objectionable).

ISO 200 is not really fast enough to allow indoor photos without a flash or tripod in most lighting with a compact model -- even if your subject was not moving (otherwise, you'd get motion blur from camera shake from shutter speeds that are too slow). Even ISO 400 would be borderline (even if it was noise free) from a f/2.8-4.9 lens --- unless you were shooting at full wide angle, being careful to hold the camera steady.

Keep in mind that typical indoor lighting has an EV (Exposure Value, which is how light is measured) of around 6. So, even at full wide angle, you'd only get shutter speeds of around 1/15 second in typical indoor lighting with an aperture of f/2.8. This is less than half of the speed you'd want to prevent blur from camera shake (the rule of thumb to prevent motion blur from camera shake is 1/focal length).

So, with flash off, you'd want to use a tripod anyway indoors, keeping ISO speed set to it's lowest value for the least noise.

Ifyou want totake photos at higher ISO speeds in marginal lighting without flash, you can simply set the ISO speed manually (keeping in mind that you will probably want to use noise reduction tools later, and that shutter speeds may still not be fast enough to prevent motion blur in typical indoor lighting if your subject is not stationary and/or you try to use any zoom).

BTW, I've got a little Konica KD-510z that works the same way. If you force flash off in lighting that would have shutter speeds below the 1/focal length rule of thumb - even if ISO speed was increased was increased to 200-- the camera automatically sets the ISO speed at 50with Auto ISO (the programmers probably assumed that anyone taking photos in lighting that would normally require a flash to prevent motion blur from camera shake would want to use a tripod).

pulp Dec 31, 2004 11:18 AM

1 Attachment(s)
Okay, how about this example guys. I set my A95 to SNOW scene. The shots came out dark and I used the software to whiten them up. The ISO was at 50 I presume. Should I go to Manual on cloudy days and bring the ISO up to 100 or 200? This shot is original, not software enhanced.

spark Dec 31, 2004 12:07 PM

If Canon is claiming ISO 50 to ISO 200 usability in Auto mode and it doesn't work as such Canon needs to correct this via a firmware update or revision in their marketing. My personal judgment is that anything over ISO 100 in the Powershot A series is ONLY there for marketing anyways. If the choice is between using a tripod (and lower ISO), using flash, or trying to take noisy semi-focused indoor/low light photos I'll take the first 2.

Pulp- I never liked the special scene mode - as for your shot it's difficult to tell but was it sunny? If it wasn't there really isn't any need to use "snow" mode - my guess would be it wasn't particularly sunny that's why the picture came out a bit on the dark side. Taking photos with cloudy lighting does take some experimentation. Your shutter, aperture and ISO settings are going to depend on what you're taking a picture of and how much ambient lighting is available. If your subject is stationary I would use the lowest ISO setting with an aperture that matches the depth of field you want and adjust your shutter speed to achieve proper exposure (also a tripod is a must). If you don't have a tripod or your subject is moving sometimes you're forced to use a higher ISO than you want - good thing we have "Noiseware", ect. I'm a bit of a newbie myself so take my advice as such.


pulp Dec 31, 2004 12:15 PM

1 Attachment(s)
TX spark! So, even at Auto the ISO will be stuck at 50 in low light. Hmmm... guess I will have to manually take low light shots.

You are correct, was cloudy day. The following pic had same darkness to it as previous picture but I enhanced it. Was hoping the camera could do it on it's own in Auto or Snow. Is the blurryness in both pix typical of cloudy day shots or just my reliance on snow scene and/or Auto with the ASO problem?

spark Dec 31, 2004 12:35 PM

When shooting reflective surfaces (snow, ice, ect) and it's an overcast day definitely stay away from "snow" mode. "Snow" mode is designed for use with reflective surfaces and bright light that would otherwise create an overexposed picture in Auto mode. I would guess the blur you have in both pictures is the result of "shaky hands". This was probably compounded by the use of "snow" mode which basically notched down your exposure when you wanted it higher for a cloudy day shot. Before you try using the "manual" mode I would suggest using the "Av" and "Tv" modes first. Using these 2 will help you see the relationship that shutter speed and aperture have for a properly exposed picture. If your subject is moving then use "Tv" mode to choose how much relative motion you want to capture, if stationary use "Av" to experiment on depth of field and to reduce problems with high contrast compositions that might create purple fringing. Which ever mode you use remember to look at what the camera thinks the correct aperture (when using "Tv") and shutter speed (when using "Av") is needed for correct exposure, this will help you when you want to fiddle with both in manual mode yourself.


Oh ya if you want better pictures with the same type of shooting conditions try these:
1) use tripod
2) use flash
3) before you take your real pictures take test shots with various ISO settings and EV + or - settings.
4) remember what might look ok on the small camera lcd might look blurry and noise printed or on your computer monitor. Be on the safe side.

All times are GMT -5. The time now is 5:06 PM.