k5 video and lens aperture

A quick question.
I don't use the video much but on the occasions i have done it has turned out quite good,except when i refocus if the subject moves because of light on the rear lcd it is not quite as easy to refocus and sometimes it is o-o-f.
if i use f16-f22 would that mean i would not have to refocus if the subject moves?

Theoretically you could use one of the older Pentax (K, M or A) wide angle lenses, line up all the orange numbers (aperture set to f8, focus varies between lenses but it's usually the first numbers down from infinity) and have everything in focus from infinity to a couple of metres using this hyperfocal setting, although I've yet to borrow a video-capable DSLR and try this.

Thanks Matt
I was particularly thinking of a zoom I have a pentax A smc 70-210 on the way to me

This is exactly what I have done at times. A new use for those manual lenses!
cheers
bb2

the manual lenses are the best, best feel, silent, best throw for video..
in fact I believe the mirrorless class cameras with manual lenses will be a huge seller for Pentax if they keep the k mount and copy this:
link

the manual lenses are really easy to focus smoothly even without a rig and follow-focus - I saw how shocked my boss was when he saw a section of movie from my M-135 with refocussing as it was extremely easy.
The 28 is also extremely good.
However, no, you can't always get away without refocussing.

Bret

Perhaps a rear LCD loupe would help you get that focus? Deep depth of field is a bit boring in video. You'll always struggle with a long lens anyway, even set to f16 the 70-210mm won't have a massive DOF. However, even at f4 you will see the image pop into focus quite well on a longer lens. Slowly focus past the point of best focus and then turn the focus back to the correct point using your eyes and muscle memory together.

Sometimes I wish that the centre of the Live View image was blown up to 4x for focus checking while in video shooting mode! EDIT - that Sony 'peaking mode' also looks extremely useful!

my thoughts exactly

you can set it to zoom in when focussing and then start the shot...that's why follow focuses have white skirts to mark focus points.....

Bret

Thanks Bret
I always do that it is the subsequent refocussing that is the problem.I do like the idea of the Loupe though,will try to find a decent one and give it a try,would also be useful for liveview macro focus

no, it won't, because the resolution of the rear screen becomes the limiting factor and it's only 920k dots. So that's 300k pix - meaning we're talking about 200x150 real life res. Which is pathetic.

Good loupes are expensive (see Z-Finder) or fall off regularly - the only half-decent one that's not several hundred dollars is the hoodman, IMO.

Alternative? arm and 10" TFT in native 1024x576 res (set the HDMI output in the menus to 576p).

Bret

Hmmm...
A lot to think about..
Thanks loads for your help

Maybe that's a bit over the top Brett, and the OP talked about the problem of light on the screen, not the screen's resolution being enough. I think the screen is *just* good enough to focus by, particularly with a long lens. It wouldn't be acceptable for stills, but HD video is lower resolution so focus isn't quite as critical IMO.

I disagree based on practice; focus gets far more critical with Video because you regularly shoot as wide as the lens will go, meaning you have a front of eye in focus and not the back. You also have the unfortunate problem of your viewers expecting a *lot* more from video than stills.
If you want to be able to accurately re-focus in one continuous shot then either a follow focus, monitor, or better still, both, become nearly essential. I don't like it and I didn't believe it until I saw it and experienced it in real life. Sunshades are then a necessary evil, as is a rig.

Bret

This is probably fair if you are expecting Kubrick-quality from your video shooting! However I doubt the f4 lens Roy is talking about is of such shallow DOF that you could tell whether both eyes are in focus let alone the front and back of someone's eye... The subject's face being acceptably in focus is probably going to be enough!