30d Exposure Problem?

Jon Harris

Hey there... I've been lurking behind the scenes for quite awhile. Never really thought I had any photos quite up to snuff but I got a 30d the other day and hopefully I'll be getting some pictures up here soon. But to my problem.

As I said I got a 30d the other day... when taking pictures with it in AV or TV mode it wants to do insane aperatures or shutter speeds that aren't really necessary. I took some pictures to show you examples... I'm hoping that I may just have a setting wrong on the camera that I haven't seen before.

All pictures taken with a 50mm 1.8, and a 430ex.


This picture was taken in TV mode at a shutter speed of 1/100, Aperature of 1.8 and a ISO of 100.


This picture I took in AV mode... still at an Aperature of 1.8, however it chose a shutter speed of 1/4th. ISO 100.


This one also was taken in AV mode with an Aperature of 1.8, however I bumped it to 1600 ISO causing a shutter speed of 1/40th.

Guess I'm really just trying to figure out why it isn't choosing a different shutter speed with such a low aperature. Anyone have any ideas? The actual shot in real life looks identical to the first picture.

Thanks and I'm looking forward to become more active in the future,

Jon

erich6

Jon,

Welcome to Dgrin! And congratulations for de-lurking!

The way the camera exposure with flash works is different between Tv mode and Av mode. In Av mode you set the aperture and the camera will find the right shutter speed to get a good exposure somewhat independent of what the flash will do. The flash will only fire and provide enough light to give you fill flash. Shoot the same scene without flash in Av mode and you will see the two shots look very similar.

When you shoot in Tv mode you set the shutter and the flash will fire enough light to give you a good exposure, particularly if you've reached your max aperture. You're shot is actually a bit underexposed in Tv mode. That's because the majority of your scene is fairly bright and the camera is trying to make it a medium gray. Use exposure compensation in Tv mode about +1 stop and you will get more flash output.

The best mode to shoot with flash is manual mode. You set the aperture to what you want for depth of field and the shutter speed to what you think you can handhold and the flash will automatically fire enough light to get a good exposure. It works phenomenally well with 50mm on my 20D and 420ex so I expect the 30D/430ex works the same....

I don't think you have an exposure problem with your camera from what you've posted here. 1/4th of a second at ISO 100 for indoor lighting like you have here is reasonable....

Erich

kini62

Yeah, what he said

When I first got my 30d and 580ex, I set it to Av mode and was shocked that the shutter speed was so slow!

I was used to my Oly E-300 that would set the shutter speed according to the lens, ie on my 50 macro it would always set the shutter speed to 1/100 no matter what the aperture.

So after a little fiddling and rereading the manual I found that in Av mode the camera sets the exposure the same with flash as without so that you get the most ambient light.

In Sv mode it holds the aperture wide open (at least from what I've seen so far, indoor use only) to again allow for as much ambient light as possible.

So yes manual is the best mode and with Canon's E-ttl it's also very easy and gives great results.

Also try bumping the ISO up to 400 or so. It gives the flash more range, lets more ambient light in and the flash uses less power and recycles faster.

Gene

Trasmc

Jon,

Erich is exactly right. Use M mode, set the aperture to correct for whatever DOF you would like. If you don't really know, set it somewhere in the 7.1 range, and shutter speed for 1/60. This is good for starters, and you can adjust from there.

Have fun - using an external flash makes a HUGE difference. Make sure you are trying to bounce the flash as well - I usually use my 430 pointed straight up at the ceiling (or if farther from the subject almost straight up with a slight angle towards the subject) in normal indoor rooms - this gives a much more natural light.

Experiment - you will be very happy with the results.

Scott

Jon Harris

Thanks for the tips guys, I've been messing around with it a bit more since and I'm getting a bit better with it. Appreciate all the feedback.

Jon