Autofocus tips when lacking light?

[ChrisAdval]

Is it possible to get perfect focus with autofocus in the dark (not pitch black) but not enough for the autofocus to work perfect to get the sharpest focus? I've done a experimental shoot on this a month or two ago and didn't come out as I wanted on sharpness but I assume it was because I was at the widest aperture levels 1.8 on my 50mm and learned later if I close my aperture a bit more like 2 or 2.8 which will ten force me to shoot in a higher ISO sadly.

Besides what I've mentioned above, is there other techniques I could try and keep my ISO lowest (100 is always my goal, shooting portraiture, still not moving subject), and shoot in the dark?

Here's the series set on my flickr - http://www.flickr.com/photos/chrisad...7627536169408/


Ash Amore - "Night" 10 by Chris Adval, on Flickr

[RLucas]

Why f/2? If you are using strobes, of other off camera gear, why not stop down to an aperture that is easier to work with? You could prefocus using a flashlight/torch, or as i have seen others do, have her hold up a phone next to her face, lit screen facing you. to give enough contrast for AF to work. Since ambient doesn't play a big part of it, you could raise the flash power to suit, and/or bump up the ISO. Don't be afraid to use ISO settings. What little noise you get is easily removed in post.

[RichardTaylor]

Also keep in mind that if you are using the Canon 50mm F1.8 it is not all that sharp around wide open.

These guys use the torch technique to both illuminate the subjects for focussing and the image capture (long exposures).



Why not mount a tourch on a stand (cheap tripod?) or held by another person, and use it just for focussing.
The as soon as you get focus just shoot. The relatively small amount of light put out by the torch will not make any difference.

[ChrisAdval]

Also keep in mind that if you are using the Canon 50mm F1.8 it is not all that sharp around wide open.

These guys use the torch technique to both illuminate the subjects for focussing and the image capture (long exposures).



Why not mount a tourch on a stand (cheap tripod?) or held by another person, and use it just for focussing.
The as soon as you get focus just shoot. The relatively small amount of light put out by the torch will not make any difference.

I've heard of the technique just kinda avoided it because I didn't want to blind the model and I would need her eyes open while tourching to ensure I get her eyes tact sharp in the focus point.

[autofocus]

Obviously, when shooting wide open, or near wide open, your DOF is extremely thin. Any slight movement by you, or your subject, even if you were able to autofocus using some light source to help will result in an unacceptably focused image. I know this doesn't answer your question, but shooting with wide apertures is probably adding to your problem. How about use of an assistant? They use a flash light on the subject off to the side, you quickly autofocus, they turn off the light, and you quickly grab the shot, but it must be clear that there can be no movement by you or the subject in that brief period.