Any tricks to getting a nice focus?

[Karen Love 0]

Hey guys, when I set my variable focus lens on three different cameras and the adgust the focus, it seems to be super sensitive. I mean you have al this "travel" of blurr and then Bam! it's focused, so you let go but it moves just a tiny tiny bit and it's slightly out of focus. Or you spend the time moving the lever or wheel within it's miniscule focus range to get it perfect but then when you tighten the lock it's slightly "not perfect". I know trial and error but the reason I start playing with the focus is because over time the pictures seem to be slightly out.

Any thoughts or is the answer...trial and error and be careful when you tighten the lock

[Scruit 0]

I'm not a professional, just a home user.

 

I have a 7" LCD screen that I carry with me when I adjust camera aim. I use this for initial focus adjustment.

 

For precise focus adjustment, I hook up the camera to a portable TV that I take outside with me. It's a PITA, especially in the sun, but gives a better result. I also put something in shot at the distance I want to focus on. An old license plate sometimes works but can be a little small. This gives me a better idea of when I'm at best focus.

[marzsit 0]

i use a portable totevision 4" monitor when i'm up in the air on the scissorlift adjusting cameras solo, it actually has pretty decent resolution for doing final focusing as long as the backround lighting isn't high.. otherwise we do it by cell phone, with me adjusting the camera taking orders from whomever is down by the monitors at the time.

 

 

from your description of the problem you're having, i'm guessing that you need to reduce the focal length of your lenses so that you can maintain focus at and beyond infinity, so that your focus won't have to be so precise and sensitive. there may be a more technical description for it, but for now it's just my observation

[Splat 0]

Don't drink caffeinated beverages before focusing cameras. I used to think up new curse words when focusing cameras... got it right and then sure enough while tightening those tiny set screws it would move a hair and be off.

[kensplace 0]

You should focus the cams in low-light (or use a neutral density filter to simulate it, or on manual iris lenses, close the iris enough to simulate low light) as depth of field alters according to light level. Focusing low light means your pictures wont 'drift' out of focus when its brighter.

[kao 0]

When doing the initial walk-thru, I note the distances of where each camera is supposed to focus.

 

When the cameras arrive, I try to pre-focus them in the shop by pointing them at something at the same distance in the building or out the window.

 

As far as the sensitivity goes, once you have your zoom locked down and are fine tuning the focus, screw the focus down so that its not quite tight, but takes some effort to move...this allows you to not overshoot the sweet spot for focusing.

I have worked with lenses that offer resistance when focusing them - which is a nice feature, but their lens quality wasnt very good and now I pretty much just stick with fujinon.

[BKerlin 0]

A hand held spot monitor is a god send for focusing cameras. Aside from that, always try to focus the camera as best you can *before* you are up on a lift/ladder.

[survtech 0]

One trick is to get the zoom and focus close to optimum; then tighten the lock screw enough to still allow movement but have some resistance; then finish the zoom or focus.

 

On some varifocal lenses, zoom is less critical than focus so we adjust them both for the appropriate field of view and nearly the best focus, lock the focus ring and complete the focus adjustment with the zoom.

 

The neutral density filter is a must with auto-iris lenses and in changing lighting environments. One trick there is to get #5 or #6 welding glass from a welding supply store. It tends to shade the color slightly but is cheaper than filters and works nearly as well.