Trouble focusing in low light...using tighter aperture?

[Neiby]

I've had widely varying levels of success shooting in very low light. The biggest problem I have is focusing, but I think I just need a little practice. If there is a light source anywhere, I can focus in on that, but if there are no good clear light sources, that makes it more difficult.

Is the trick to use a really tight aperture to get a better acceptable near and far limit of sharpness? That seems to be the case, but that means much longer shutter times and I don't have a remote shutter yet and am limited to 30 seconds. I think the "magic" trick to this is to focus as best I can manually, then use a very tight aperture and a long exposure time at the lowest reasonable ISO, all while on a tripod using mirror lock and a two-second delay.

Am I on the right track?

Thanks!
John

EDIT: Sorry, I'm being a knucklehead and left out a very important piece of information. I was shooting a pond that was probably a couple of hundred feet across and had some houses on the far side. At various locations, the near side of the pond had plants, a dock and some canoes that I wanted to be in focus while keeping the pond and the houses on the far side in focus, as well.

 

[bennielou]

Can you post a few photos that didn't work out so well? Also, we need more info.....settings and soforth.

 

[Neiby]

Can you post a few photos that didn't work out so well? Also, we need more info.....settings and soforth.

I'm at work, so pics will have to wait until tonight. I didn't post any yesterday because I just wasn't pleased with how they turned out. I was using 30 second exposures at ISO 800, mostly, but I tried bumping it up to 1000 and even 1600 once just to see if I could pull it off, but the noise level was completely unacceptable. I was trying apertures around f/7.1 to f/11, but most of my pictures were too dark unless I raised the ISO.

I think I really need to get a remote shutter control so I can get the exposure time up to 60-90 seconds. Then I can really tighten the aperture and keep the ISO low.

EDIT: Forgot to add that I was using a tripod and I had mirror lock enabled with a two-second shutter delay.

 

[Big Mike]

Yes, you can use a smaller aperture to get a deep DOF (Depth of Field)...and that will likely make easier to get your subject into focus...but that's not really the best solution to your problem. You should choose a DOF that appropriate to your shot, as long as it can allow you to use the shutter speed and ISO that you want to use. For more info, look up 'Hyperfocal Distance'.

The problem is that you can't focus because of the low light levels....so one solution would be to add light. At close range, your camera and/or flash will probably have an AF assist light (check your manual). Also, you could add light in other ways. You could use a flashlight, video light or maybe even a laser pointer to put some light onto your subject, allowing the camera to focus on it.

 

[bennielou]

Whoa, that is really high aps for shooting low light. Really high.

Are you shooting manual?

 

[Neiby]

Yes, you can use a smaller aperture to get a deep DOF (Depth of Field)...and that will likely make easier to get your subject into focus...but that's not really the best solution to your problem. You should choose a DOF that appropriate to your shot, as long as it can allow you to use the shutter speed and ISO that you want to use. For more info, look up 'Hyperfocal Distance'.

The problem is that you can't focus because of the low light levels....so one solution would be to add light. At close range, your camera and/or flash will probably have an AF assist light (check your manual). Also, you could add light in other ways. You could use a flashlight, video light or maybe even a laser pointer to put some light onto your subject, allowing the camera to focus on it.

Sorry, I'm being a knucklehead and left out a very important piece of information. I was shooting a pond that was probably a couple of hundred feet across and had some houses on the far side. At various locations, the near side of the pond had plants, a dock and some canoes that I wanted to be in focus while keeping the pond and the houses on the far side in focus, as well.

My apologies for not including that in the first post. I'm sleep deprived.

 

[bennielou]

Big Mike posted after me, and he had some great suggestions.

 

[Neiby]

Whoa, that is really high aps for shooting low light. Really high.

Are you shooting manual?

Yes, it was manual. I totally forgot to mention what it was I was actually shooting! It was a pond with items both near and far that I wanted to get into focus.

 

[Neiby]

As a reference, had my shot worked as intended, it might have looked something like this:

Nighttime lake:

http://2.bp.blogspot.com/_VEUL9uubN...v60/s1600/Legend+Lake+Night+082810-8-Edit.jpg


EDIT: Removed inline image link and replaced with standard link

 

[TheBiles]

Google "hyperfocal distance" and learn how to use it for awesome landscapes.

 

[Neiby]

Google "hyperfocal distance" and learn how to use it for awesome landscapes.

Awesome, thanks! I hadn't heard of that term until this thread, so I'll check it out.

 

[KmH]

As a reference, had my shot worked as intended, it might have looked something like this:

Nighttime lake:

Be careful! Forum rules don't allow us to post photos that aren't ours. Photography Forum & Digital Photography Forum FAQ

It is OK to post a link to someone elses photos.

 

[Neiby]

As a reference, had my shot worked as intended, it might have looked something like this:

Nighttime lake:

Be careful! Forum rules don't allow us to post photos that aren't ours. Photography Forum & Digital Photography Forum FAQ

It is OK to post a link to someone elses photos.

That was a link. The forum software just displays the linked image inline, but it's still just a link. I read the FAQ and it doesn't make a clear distinction. Under the hood, it's still just link that is being treated in a special way by the forum software. After re-reading the rules, it seems to me that uploading a picture that isn't mine would not be allowed, which makes perfect sense. But in cases where it's just a link, it's less clear if a distinction is made between inline posting and other types of links. I definitely don't want to break the rules, though. I should PM a mod and see if they can clarify this.

 

[Neiby]

Just for grins, I just read up on the copyright issues associated with various types of linking. Despite the fact that a link is a link, from a technical perspective, it does appear that the copyright issues are less clear in cases when images are displayed inline versus just posting the link itself. So, based on that, it makes sense not to post inline images to images we don't own. I'll change the link in this thread to a regular link.

 

[Neiby]

I found an online depth of field calculator:

Online Depth of Field Calculator

According to that, if I used my 18-200mm lens and kept it at 18mm at f/16, assuming I could have gotten my exposure time to be long enough, I would have been able to get the entire field of view into focus, pretty much. If I understand that page correctly (big assumption!) I could have used a flashlight to manually focus on something about four feet away. At 18mm and f/16, that should mean everything I wanted to be in focus last night would have been in focus. I'll need to re-read that information to make sure I understand it, though.

Thanks for the help!