Newbe lens question

[RED ROBOT]

Hello everyone.

I've been shooting short films with my T2i and 18-55 kit lens.

Recently I got 35mm prime and 50mm 1.8 prime .

I made myself a cheap camera rig as well.

But when I'm shooting with my 50mm and open my aperature to something like F1.8 I seem to get a great depth of field ,my subject seems to be perfectly focused and everything seem to be great but once I get into post production I see on my computer that 50% of the shots are just blurried and not very focused ,even though my subject seemed to be focused great on set.

Even if the aperature is set to F3 or F4 I still have problem focusing .

 

[8salacious9]

i have the t3i so it should be similar, first of all what are your camera settings, do you have an example to show us? i believe the 50mm is sharpest at f4-5 i could be wrong cant remember exactly.

when you have the lens on manual are you pressing the zoom in function to see whether or not you are in focus? the best place to focus is on the eyes, its what humans look at first and recognise people best by.

if you use magic lantern (firmware) it has focus confirm which tells you more or less when subject is in focus

 

[FernandoAndre]

my subject seems to be perfectly focused and everything seem to be great

Where? Camera lcd?
Frequently it's not reliable. Particularly when it's on a bright place. You can buy a good monitor to watch it better, or at least a lcd hood. I use one.

Another thing: is hard to shoot motion scenes with a wide open 1.8 or 1.4 lens. Is recommendable close it to get a wider depth since the actor is on moving. So you have to bring more light to compensate. This is why, among other things, the DP is so important hehe.

But maybe it's just your lens. Do you have some screens?

 

[Gonzo_Entertainment]

All lenses are softer wide open (and fully closed) than they are in the 4 to 8 sweet spot. Also, without a good external monitor and/or some kind of focus assist it's very easy to think you are in focus, but you are actually slightly out.

 

[RED ROBOT]

Well I do use Magic Lantern and I do zoom to the eyes to see if everything is focused and it seems to be but since the aperature is so open with every little movement of the actor it's just getting a bit out of focus and sometimes it stays the same for the whole clip .


But If I go to something like F4 or F5 + I'm just losing that depth of field.

But I guess I have to in order to keep my subject in focus.

 

[FernandoAndre]

You can get a GOOD monitor/hood and hire a focus guy just to monitoring and adjust the focus while the actor move. But if there is no move on the scene, orient the actor to keep the position.

If the actor really needs to move, my suggestion is to mix different takes. Make the motion with an adequate aperture, and close-ups in the middle of this with wide open lens. You bring the shallow depth inside the scene with this close shots.

 

[Zensteve]

Well I do use Magic Lantern and I do zoom to the eyes to see if everything is focused and it seems to be but since the aperature is so open with every little movement of the actor it's just getting a bit out of focus and sometimes it stays the same for the whole clip .


But If I go to something like F4 or F5 + I'm just losing that depth of field.

But I guess I have to in order to keep my subject in focus.

http://www.dofmaster.com/dofjs.html

 

[Lucky Hardwood]

Depth of field is not an all or nothing proposition. The key is to set up with the correct amount of DoF for the look desired/requirements of the scene. If you want to run razor thin DoF in a scene where anything that needs to be in focus moves, you need to block the hell out that scene and set your marks and focus points to the tee. Then, rehearse the crap out of it until everyone is hitting their marks on time, every time.

 

[knightly]

If you need to stop down to extend the focal range, you can physically move the subject and camera away from the background farther to get a blurrier background... the farther the subject is from the background, the more blur you'll see there (unless the subject is really far from the camera... if you can move them closer to the camera--or the camera to them, you'll get a bump there as well -- but a shorter DoF again with the same focussing problems).