Indoor photography with available light

[yangsimo]

I haven't been able to wrap my head around this problem. I use a relatively fast prime to shoot indoors (35mm f/1.8 on a DX) because I generally don't like to use flash. I understand that getting an even faster prime (say f/1.4) will give me another stop.

However, isn't the DOF offered by a f/1.4 too shallow to use? Say I want to capture a quick group shot indoors, I find it impossible to keep everyone in focus with the lens wide open.

Any tips re: focusing that can help this? I have gone up with the ISO but sometimes there's just not enough light at smaller apertures.

Thanks!

[sk66]

1.4 would be more like a 1/2 stop gain. The DOF will not be that much shallower at 1.4 than 1.8, but it IS shallow enough to cause problems either way.

You are at the end, about the only thiing you could do is step up to a camera with better high ISO ability or add light.

[zona5101]

Your usable depth of field will depend on your f-stop, your focal length and your subject distance.
For example a 35mm lens at f1.8 subject at 10 feet will have a front to back focus depth of 1.77 feet. Move the focus distance to 20 feet and that range increase to 7.28 feet. Similarly a 20mm lens f1.8 at 10' = 5.82' ; 105mm f1.8@10' =0.19'

[Doug Pardee]

Originally Posted by yangsimo

I have gone up with the ISO but sometimes there's just not enough light

If there's not enough light and you've run out of ISO, you're stuck.

There are photos that can't be gotten. Photography is the recording of light. If there's not enough light, there's nothing to be done about it except to add light or walk away.

[teaking]

Why not combine your flash with the natural light? you can get some pretty good results.

Heres a link to a tutorial on mixing natural light with interior light it may not be what you want to do but its an interesting read: The Ultimate Guide to Working with Interior Light: Part 2 | Phototuts+

[yangsimo]

Thank you everyone for your advice, particularly the bit about focal length and DOF. I think I will stick with my f/1.8 prime and maximize exposure elsewhere. And TEAKING, that guide is awesome, got a lot to learn.

[zona5101]

Originally Posted by yangsimo

Thank you everyone for your advice, particularly the bit about focal length and DOF. I think I will stick with my f/1.8 prime and maximize exposure elsewhere. And TEAKING, that guide is awesome, got a lot to learn.

Check out this on-line depth of field calculator, play with it a bit and some of the pieces will come together...
Online Depth of Field Calculator