Help with new lens

[pgowder]

Just got my Sigma 70-200mm EX f/2.8. And I've been doing some tests shots. I'm shooting with a Maxxum 7D.

I'm a little concerned with the results. And I'm trying to figure out if the problem is with me or the lens.

I'm having trouble focusing first. But the big problem I'm having is with exposure. If I pop up the built in flash the photos are blown out, and without them, they are dark and blurred. I'm shooting in aperture priority with it set to 2.8. Shouldn't the camera adjust for the flash?

Take a look at the photos I'm posting.

Please tell me what I'm doing wrong!

Thanks!

[pgowder]

Here are the next set of photos.

[pgowder]

Here are some taken with a 28-85mm f/3.5-4.5.

http://thegowders.com/photos/display...lbum=10&pos=63
http://thegowders.com/photos/display...lbum=10&pos=27
http://thegowders.com/photos/display...lbum=10&pos=42
http://thegowders.com/photos/display...lbum=10&pos=58
http://thegowders.com/photos/display...lbum=10&pos=59

[another view]

I doubt it's a lens problem, but the best way to tell is to take some existing light shots. Flash throws all kinds of other variables into the mix, and the flash or mode that the camera's set on could be the source of the problem.

It doesn't have to be anything fancy, just take the camera outside and take a few shots. If those are accurately exposed, then the lens is OK. If they're not, try it again with that lens and one that you know works. Solving problems like this is really just a process of elimination.

[pgowder]

Ok, here is one outside. It looks correct.

So what am I doing wrong inside? Shouldn't the camera adjust for 2.8 with the flash?? Or is there a setting I'm missing?

And without the flash, what's wrong? I'm using auto ISO, but in looking at the properties of the photo, it set it at 400. Should I set it at 800 for inside?

Thanks

[pgowder]

In doing some research I think the focus problem might be the distance I'm at. I'm taking these really close for this lens.

The ones at a further distance seem to focus great.

So is it just that at close distances the depth of field is so shallow that it's hard for AF to work?

Thanks

[another view]

So is it just that at close distances the depth of field is so shallow that it's hard for AF to work?

How AF works doesn't affect DOF, and the reverse is true too. It is true, however, that with a lens like this that you can get such a small amount of DOF that focusing becomes extremely critical. Set it at 200mm, f2.8 and focus at the minimum distance. You'll see the world differently like this!

You don't necessarily need f2.8, ISO400 or even 800 with flash - it really depends on the situation. It's usually best to use the lowest ISO you can get away with because the noise will be lower. Higher ISO's get a little contrasty, and this is also true with film - but that doesn't mean that you shouldn't use them. ISO800 will be very handy indoors without a flash, but I probably wouldn't usually use it with a flash. I'd stick with 400 or lower from previous experience, and the effect I'm going for.

Flash with DSLR's is tricky, no doubt about that. Digital has much less exposure latitude than color neg film so the exposure must be correct for the best image. Two stops over with color neg film will get you a good print - not so with digital. This will take some experience to get comfortable with. On my Fuji S2 and Nikon SB28 flash, I find the best results are to use non-TTL auto mode on the flash, even though the camera is supposed to support TTL flash exposure. It does - but I get inconsistent results - a lot like what you're seeing here. Give it a try.

[pgowder]

Never thought to look, but the camera was set to fill flash not TTL. That made a huge difference!

Without the flash, I moved the ISO to 800 and the shots are great.