Sigma 10-20mm f/3.5 and Shooting in the Dark

[Overstanding]

I have two questions for you guys.

Question 1: What do you guys think of the Sigma 10-20mm f/3.5? Do you think it's worth it or is the Sigma 10-20mm f/4 a better bang for the buck?

Question 2: How do you guys auto focus in the dark? I did a Winter Formal shoot a week ago and auto focusing in the dark was quite a challenge. I had to get my buddy to shine a flash light on the subjects. I didn't feel very professional shining a flash light at people. Is there a product out there that can help me out?

Thanks for any info.

- Derrick

 

[goodoneian]

I don't know much about the f/3.5, but aside from price the major deal breaker for me between that and the f/4-5.6 was the filter mount. All my filters are already 77mm and i didn't want to have to replace them with 82mm ones.

Hmm, I would assume in a place where a winter formal would be held would be illuminated decently, but I've never shot one. But in tricky dark situations with people I usually let my camera auto focus first then just manually correct it with my 50mm. I don't really have any specific tactic.

 

[Overstanding]

I forgot to mention that it was at someone's house. They had all the photos taken in the back yard. Mabe I should practice manually focusing. I'm not really good at that.

 

[goodoneian]

Ah well that could make a pretty big difference then. Does your camera have an AF assist light? That has always seemed to help me out pretty good.

 

[Overstanding]

That would be on the built in flash? The light flickers so you can auto focus? Yea I have that. I shoot with a Canon Rebel XT, but when I'm doing night photography I use the cactus v4's and a couple flashs.

 

[RyanLilly]

The IR assist light on canon speedlites works well if you set the only the IR focus assist to fire but not the flash. Some third party flashes also have this. However, you would need to either then connect your cactus transmitter, via the sync port on your camera(does an XT have one?) or via the sync connector on speedlight if it has one.

 

[epp_b]

When shooting in the dark, choose an AF sensor explicitly (don't let the camera choose it for you), and place the selected AF sensor on a point of contrast.

 

[Overstanding]

RyanLily - Thanks for the info. I looked at the XT, and I don't see a sync port on it. It has three ports one for video output, remote for the shutter button, and one digital port to connect to the computer. There is a sync port on my 580EX II though. I'll have to look into this IR stuff.

epp b - I try this when I'm in a dark situation but for this shoot it didn't work. Thanks for the tip though. I was more wondering if anyone knew of a battery charged continuous light I could shine on the subjects or any other ideas about using auto focus in the dark.