Using a 1.4 50mm

minky_monkey · 20 Aug 2010

Hmm, I know the DoF is tiny, but in low light I find that I'm missing the focal point I want. Sometimes I find that the hair infront of the face is in focus, but the eyes aren't.

I noticed this with shots of my friends kids, so not the easiest models to work with!

Any pointers? Good focussing techniques that I may have overlooked? What realistically would you use as a comfortable apperture setting?

trevorbray · 20 Aug 2010

On a 7D with subject 5 feet away DOF is just 2 inches. Half of that is in front of the focus point. As you say, it's all about good technique. With kids you're up against it. Even at f2.8 DOF is only 4inches. Keep trying, it'll be worth it when you get it right.

tikkathreebarrel · 20 Aug 2010

Manual focus? I find maximum sharpness on my copy is around 1.8 btw.

onform · 20 Aug 2010

With that lens at f1.4 try not to hesitate after focussing and keep the shutter speed up! See the shot focus on the eyes bang all in a split second, job done.

minky_monkey · 20 Aug 2010

Very helpful stuff as ever, I'm determined to get the measure of this lens. It's the one that I bin more shots than anything else in my bag. And yet when you do nail the shot they're so much better than any of the others.

Trevor, thanks for the idea of just how narrow it is, I've always been a trial and error person rather than knowing the specific distances (probably where I'm going wrong TBH) That's really helpful, thank you!

trencheel303 · 20 Aug 2010

The Canon 50 doesn't always focus so well in low light, which may be why you are noticing some duff shots. I wouldn't even try using f/1.4 in close quarters, especially in low light. Just stop it down a bit, you'll get more sharpness and more DOF. Unfortunately if one wants a properly usable lens wide open you usually have to pay more - like the canon 50mm f/1.2!

paulcamcas · 22 Aug 2010

Another thing to be wary of with the 1.4 wide open is focus and recompose. The DoF is so small that this very often leads to missed focus.

philthejuggler · 23 Aug 2010

trencheel303 said:
The Canon 50 doesn't always focus so well in low light, which may be why you are noticing some duff shots. I wouldn't even try using f/1.4 in close quarters, especially in low light. Just stop it down a bit, you'll get more sharpness and more DOF. Unfortunately if one wants a properly usable lens wide open you usually have to pay more - like the canon 50mm f/1.2!

Unfortunately the 50mm f/1.2 exhibits focus shift between about f/1.8 - f/3.5 at closer focussing distances. It focusses perfectly and then the plane of focus shifts when the aperture stops down on shutter press.

I had it for a week using it for portraits and got countless ears in focus when I had very carefully focussed the eyes!

I actually think you are better (light allowing) to use f4-5.6 for headshots - the f2.0 aperture shots work better with full body portraits to make the subject pop from the background.

Phil

mastertrinity · 23 Aug 2010

tbh i would autofocus on the eye and then switch to manual to proper adjust and compensate for any shift. I think it's normally recommended to manual focus on lenses when using a very wide f1.8/1.4/1.2 aperture.

Dman · 24 Aug 2010

mastertrinity said:
tbh i would autofocus on the eye and then switch to manual to proper adjust and compensate for any shift. I think it's normally recommended to manual focus on lenses when using a very wide f1.8/1.4/1.2 aperture.

Good luck with that when shooting kids!

Shooting wide open is hard but keep going and practise really does make perfect. I now get a very high success rate when shooting wide open, if you have kids of your own it's a LOT easier to keep trying, but when you nail it, the rewards are very evident.

boyfalldown · 24 Aug 2010

mastertrinity said:
tbh i would autofocus on the eye and then switch to manual to proper adjust and compensate for any shift. I think it's normally recommended to manual focus on lenses when using a very wide f1.8/1.4/1.2 aperture.

no its not, your AF can still do as good a job as you can at very wide apertures

Dman said:
Good luck with that when shooting kids!

Shooting wide open is hard but keep going and practise really does make perfect. I now get a very high success rate when shooting wide open, if you have kids of your own it's a LOT easier to keep trying, but when you nail it, the rewards are very evident.

+1.