canon d20 over exposure on slow shutter speed.

[tilos]

Have just got this camera and don't know what I'm doing! Wanted to shoot a very slow shutter speed so I could get blur effect of water. Put iso down to 50 (lowest) and aperture smallest could do but picture came out as white as over exposed. Would only do it on shutter speed of 15 which was no use. What am I doing wrong?

[Curtis N]

Shutter speed of 15?
15 seconds, or 1/15 second?

When you say aperture smallest, do you mean the smallest aperture (highest f/ number), or the smallest f/ number (largest aperture)?

[ksmattfish]

Hmmm, my 20D only goes down to ISO 100. I don't know what your lighting conditions are, but if it's fairly sunny then the correct exposure for ISO 100 film would be around 1/60th @ f/22. I've found that my 20D set on ISO 100 wants about 1.3 or 1.6 stops less exposure than my Sekonic 508 hand meter recommends. If yours is the same then 1/15th @ f/22 and ISO 100 on a sunny day could possibly be more than 3 stops overexposed. A polarizing filter will block 2+ stops, or you could use a neutral density filter, which are available in different strengths.

[CyberDyneSystems]

Sounds like you are using manual exposure and ignoring the Cameras metering?

Sure fire way to blow your exposure.. check your metering.

If you can not acheive the slow shutter you want with the light available, you may need to use some dark neutral density filters.

[Daya]

Ksmattfish,

This is exactly something I noticed with my 20D last week when I was shooting at Mt Rainier , WA...I had a CP filter on and had to underexpose atleat 2 stops to make sure I did not blow out the highlights (snow capped mountain) on a sunny day. that made it -4 stops. Could it be right ? As a result my images had a dark foreground (mostly trees)...
I could correct these to some extent because I was shooting RAW. But always wondered if it was me or the Camera ...

Daya

[lostdoggy]

Hmmm, my 20D only goes down to ISO 100.

Maybe its because he is using a D20 and not a 20D????HeHeHe.

[ksmattfish]

Ksmattfish,

This is exactly something I noticed with my 20D last week when I was shooting at Mt Rainier , WA...I had a CP filter on and had to underexpose atleat 2 stops to make sure I did not blow out the highlights (snow capped mountain) on a sunny day. that made it -4 stops. Could it be right ? As a result my images had a dark foreground (mostly trees)...
I could correct these to some extent because I was shooting RAW. But always wondered if it was me or the Camera ...

When shooting film, mostly BW, I always use my hand meter whatever camera I am using, usually incident mode, but sometimes spot with trickier lighting. With the 20D I start with center weighted averaging, but I check the histogram and fine tune from there. So far I'm following the "shoot to the right" school of thought.

I did some testing; shooting the same compositions with a 35mm camera, a 6x7cm camera, and the 20D. The film cameras were loaded with ISO 125 film, and I had the 20D on ISO 100. My correct exposure for the film was 1/8th @ f/11, while the 20D made the histogram I was looking for at 1/20th @ f/11.

Using shoot to the right and ISO 100 vs ISO 125, I would have expected the 20D to need a little more exposure than the film. I guess the real question may be does Canon call it ISO 100 because it really corresponds to ISO 100, as far as an actual exposure value, or is it just the most sensitive setting, and they wanted it to be nice and easy for the film to digital switch?

[Daya]

ksmattfish,

I noticed that my Canon Elan 7Ne was exposing the same scene a 1/2 to 1 stop less than my 20D for the same scene... I used Evaluative metering on both my cameras...

Daya

[tilos]

Thank you everyone for all your advice. So if I understand correctly if I wanted to use a very slow shutter speed and not overexpose using this camera then I could put a filter on it to stop it over exposing.


I also want to shoot a power station I have seen at night and again wanted to use a very slow shutter speed so that I would be able to get the effect of a fountain of light around it. Any advise on how I could to set it to expose properly for this?

Thanks once again for all you help and patience!

[ksmattfish]

Most filters block some light (it'll say on the package how much), as well as do other things. A polarizer reduces glare and reflections. This has the effect of increasing color saturation. It's just like polarized sunglasses for your camera.

Neutral density filters only job is to block light. You can get them in various strengths, and even split neutral density filters that you can use to reduce the exposure only in half of the photo (usually used for reducing the exposure of the sky).

[Mohawk]

Have just got this camera and don't know what I'm doing! Wanted to shoot a very slow shutter speed so I could get blur effect of water. Put iso down to 50 (lowest) and aperture smallest could do but picture came out as white as over exposed. Would only do it on shutter speed of 15 which was no use. What am I doing wrong?

Buy this book:

Understanding Exposure
Revised Edition
by Bryan Peterson

You can get it here www.amazon.com

Mike

[attu]

What mode are you shooting in ? Try using Shutter priority (TV Mode) and set the shutter speed to what you need, this will automaticly set the apature for you so the exposure is correct (subject to meetering limitations)you may also just have to much light so you could either come back at a different time of day when its not so bright or you could but a ND filter to cut some of the light coming into the lens down.
Again with your night shot,put the camera on a tripod, using TV Mode select a slowish shutter speed and shoot away, you may want to try braketing the shot so you get exposures over and under what ever youve set it to so you can see which comes out best....try try and try again, thats the beauty of digital, it doesnt cost any thing to get it wrong.