How to focus when the stage is dark

[pele2010]

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Hey , 

 

Any advice on this? 
i was taking pictures in a dark room with an installation of light. 
the autofocus did not pick up the subject and with the manual focus it was also quite hard to find the focus. And when I got it the autofocus kicked in and made the picture unshared again. 
 

sl2s 

35 mm Sigma 2,0 DG DN 

Kind regards 

peter 

[Photoworks]

did you try enhance live view?

do you have the focus assist light on?

[LocalHero1953]

In that situation I would set it to MF and use back-button (joystick) auto focusing. It won't necessarily make it any easier to focus, but it will stop the AF messing up your manual focusing.

A couple of weeks ago I was using the SL2S for theatrical rehearsals in a normal room (not a theatre) as it got dark in the evening. Towards the end I was shooting at ISO 25,000 and getting the occasional missed focus, but I thought it performed well, and I was getting far better exposed shots than I could see with my naked eye. There were no bright lights - perhaps your light installation makes it difficult to focus on shaded/dark objects.

[BernardC]

One trick for focusing in the dark is to find a small specular reflection, or light source, within the scene. Use manual focus to make the reflection as small as possible, indicating the proper point of focus.

[beewee]

If you have the luxury of measuring the distance between your vantage point and the target ahead of time, you can use MF and the top display and dial in precise distance for focal plane, front/back focus.

Otherwise, picking out a specular highlight is your best bet if you’re shooting at wide apertures. If having shallow DOF is not your end goal, then bumping up the ISO and shooting hyper focal is probably the most reliable.

[Tailwagger]

Which focus mode/settings were you using ?

Beyond the other advice here and while perhaps obvious, it's worth remembering that CD systems rely on points of contrast which typically means that you should be finding/aiming at edges or areas with sharp contrast, such as the highlights mentioned above.  If you try to focus the camera on a blank wall (pretty much any AF camera), it will hunt forever until it just gives up as it can not find anything to lock onto.  Better results in difficult lighting (and in general) means ensuring that the thing you're focusing on contains contrast the algorithm can actually detect.  I'd add that in lower light I tend to switch to from field to spot focus mode as I find it to be more reliable when seeking such locations out.