Focusing during night shoot

[markj]

Let's say you want to photograph a city skyline at night, using a 35mm 1.8 lens. What is the best way to insure accurate focusing?

 

[LizardKing]

Doing some reading and practicing... There's no shortcut to learn these things

 

[DorkSterr]

Manual.

 

[KmH]

The further from the camera the point of focus is, the deeper the total DoF becomes.

Plugging some numbers into DoFmaster.com give this information:

35 mm lens on a camera that has an APS-C size image sensor.
f/4 lens aperture
focus point 2640 feet away (1/2 mile)
The near DoF focus limit is 51.8 feet in front of the image sensor in the camera.
The far DoF limit is infinity.

Lets make just one change - move the point of focus closer, to 1320 feet away (1/4 mile)
The near DoF limit becomes 50.8 feet in front of the image sensor (1 foot closer)
The far DoF limit is still infinity.

Changing the point of focus to 660 feet awya (1/8 mile), the near DoF limit changes to 49 feet and the far limit is still infinity.

In summary, as long as you use f/4, and pick a point of focus sufficiently far from the camera (75 feet or more), the near and far limits of the DoF pretty much ensure sharp focus regarless how far from the camera your point of focus is.

Online Depth of Field Calculator

I recommend you hit the photography technical web sites and learn all you can about how DoF and focus relate.

 

[fokker]

Use a tripod and focus manually with live view. Live view is an absolutely invaluable tool when it comes to manual focus on a tripod, as you can zoom in to 10x to get the focus bang on.

 

[grantr44]

I picked up a copy of Peterson's "Understanding Exposure" and got some good tips about this subject in there. You're going to want to use a small aperture (high f-stop number) and attempt focus about a third of the way into the composition. The shot won't look completely in focus in your viewfinder, so make sure to check your LCD and adjust as necessary. As an earlier poster said, practice makes perfect and the only real way to nail it is to try a lot of different methods. Good luck!

 

[TheBiles]

I picked up a copy of Peterson's "Understanding Exposure" and got some good tips about this subject in there. You're going to want to use a small aperture (high f-stop number) and attempt focus about a third of the way into the composition. The shot won't look completely in focus in your viewfinder, so make sure to check your LCD and adjust as necessary. As an earlier poster said, practice makes perfect and the only real way to nail it is to try a lot of different methods. Good luck!

You're going to be losing sharpness after f/11 or so. I'd just stick with that and learn about hyperfocal distance and how to use the DoF preview button in live view. Google will answer all.

Sent from my Transformer Prime TF201

 

[markj]

As a matter of fact, I did check the manual, and I couldn't find anything relating to focusing to infinity with a prime lens.

 

[DanPower]

As a matter of fact, I did check the manual, and I couldn't find anything relating to focusing to infinity with a prime lens.

I think they're talking about using manual focus, not RTFM..

 

[Buckster]

Never had a cityscape I couldn't get a focus lock on just by half-pressing the shutter or using the back focus button (my preference)...

 

[DiskoJoe]

I would start at f8 and progressively use smaller apertures until you get the right depth of field. I would just use the ovf on my a200 and manually focus. My night pics always come out good.

 

[DiskoJoe]

Never had a cityscape I couldn't get a focus lock on just by half-pressing the shutter or using the back focus button (my preference)...

I used to do this too when I first started. A big wall of buildings is usually pretty easy to focus on.

 

[Buckster]

Never had a cityscape I couldn't get a focus lock on just by half-pressing the shutter or using the back focus button (my preference)...

I used to do this too when I first started. A big wall of buildings is usually pretty easy to focus on.

And you stopped doing that because... ?

 

[DiskoJoe]

Never had a cityscape I couldn't get a focus lock on just by half-pressing the shutter or using the back focus button (my preference)...

I used to do this too when I first started. A big wall of buildings is usually pretty easy to focus on.

And you stopped doing that because... ?

I kind of still do. Ill use AF the get a lock then flick my camera to manual and fine tune it a bit if needed.