Tips for manually focusing?

[yurik]

Sometimes it becomes necessary to manually focus, whether because of an uncooperative lens, bad lighting or accessories (inexpensive extension tubes).

So I've been trying to take shots by manually focusing, but I always seem to be a bit off. I get within a good range, but while it looks sharp in my small viewfinder, when I check the results on my LCD, it's blurry. I probably end up shooting 4 shots to get the last one in focus.

My question is, do any of you have any tips on how I can improve? I realize some of it probably comes with practice, but do you guys have any good tips?

[Saralonde]

First, make sure it's not camera shake. Next, you can adjust the dioptric knob for your eyesight. Check page 31 of the XTi instruction manual. I rarely use manual focus because I can't trust my eyes all the time, but I understand the situations you mentioned. Beyond that, probably practice.

[yurik]

I was going to talk about the dioptic knob and camera shake, and I'm pretty sure it's neither of those. I've been playing with it on high shutters and testing with auto focus both on and off and everything on the knob seems clear :x

Did anyone else have trouble manually focusing early on, or just me?

[inkista]

No, I had trouble, too. Too used to the old split-prism screen in my Olympus OM-10. (Mutter. Stupid matte focus screen in the XT). Part of it was indeed that the diopter dial on my viewfinder had accidentally been turned to add correction when I didn't need it. Ditto the camera shake thing--when you say "high shutter speed" are you taking focal length and magnification into account? Have you tried putting the camera on a tripod to eliminate shake as a factor altogether? If you're handholding a macro 1/focal-length or faster still might not get you through, depending on how magnified you are--it's why they sell ring flashes for macro photography--you really have to get the shutter speed up to avoid camera shake.

The third gotcha I've found is attempting to focus with the lens too close to the subject. Most lenses have a minimum focus distance; try moving back. Extension tubes make it harder, since they limit the distances at which the lens can actually focus on the object (you've lost the ability to focus to infinity for sure, no matter what lens you've put the tubes on).

[wulf]

I think a lot of modern lenses make manual focussing relatively tricky - for example, the 18-55mm that came with my D40 is excellent in most respects but there is only a small amount of play on the focus ring so it is very hard to nail the sweet spot precisely. A friend with much more camera experience has noted that older lenses often give a wider range of movement and thus allow greater precision.

So, maybe another lens that isn't all about auto-focus would help... and, otherwise, practise!

Wulf