AC90: AC90 focus seems blurry matter

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dee123

Member
I really like my new AG-AC90, especially the handling and balance is very nice. better than my old Canon XH-A1.

what dazzles me is the focus. despite the small sensors, in low light (indoors) you need to watch focus carefully. now, the LCD is pretty good, but faces have no sharp lines and can be less easy to check for focus. a little digit telling the actual focus distance comes in super handy in these cases. now why do we get this abstract digit on the screen? the manual states a higher digit means focus is further away. doh! that is not helpful at all! does the camera not know how far focus is? why not tell me?
also, at some distance it shifts to "macro range". in the manual there is no indication what this means, and why it happens. it does warn you can't zoom reliably in this mode. so, it is 'dangerous' (may lose focus when zooming), but -why- does -what- happen?

it would be SO handy it this cam would have face recognition focus -without- being fully auto. just focus on faces and not adjust anything else. assignable to a user button. touch focus would be a super good addition as well (i think it has the 'intelligence' built in for it; not much different from face recognition, just connected to the touch screen).

maybe a future firmware update? could make this little cam almost perfect for ost of my jobs.

david
 
The good news is generally if you flip on the red focus assist you will see its not really hard to keep most things in focus, because of the deep depth of field this camera has. The bad news if you are looking for a shallow depth of field, you can frequently get it and thereby add to your focusing concerns.

I was just rereading Barry Green's book which would probably answer your macro question better than I will. As you can see you are alluding to a more complex problem. When I have had cameras which measured the focus distance I found they were not accurate either. On top of that unless you are measuring the distance it is not easy to judge. Then you add the impact of the zoom on the focus. That basically changes everything.

The basic steps Barry (and I) recommend for a pro in most situations (but not run and gun) is to:
1) Establish the shot how you want with auto-focus on.
2) Hit the focus button so the screen switches to MF from AF (switches to manual focus)
3) Turn on focus assist and look at the red outlines there (sometimes helpful)
4) I then like user button 2 (factory preset) with digital zoom 10x (I finely adjust then switch it off because it will record that way otherwise). Usually its still a guess because you will roll the focus ring back and forth with the best being in the middle.
5) Finally check on an external high resolution production monitor. Many of the professional monitors with their focus assist tools can take a lot more of the guesswork out.

Face detection only works in automatic mode. I commented elsewhere this can be problematic if you are shooting more than one person. The camera may decide to change from one person to another and so forth, so some of your subjects may now be in and out of focus. The bottom line is almost always you need to be manually setting focus.
 
thanks for your reply!
yes i use focus assist almost constantly. but especially for faces it not always indicates cleary, as it depends on sharp edges. if people wear glasses that makes it much easier already.. :-)
i am not looking for shallow DOF, there is not much to influence DOF with this camera as you can't add gain to influence iris. and indoors you need the lowest shutter speed already.
i know the focus procedure you describe, but many times i do the run and gun type shoot. this would make an indication in metres so handy, i can judge if the focus should be for instance roughly 1 metre, if i see 1M on the screen i can be sure instantly that focus is not on the background 6 metres away.
as for face recognition, auto-focus always takes the center as focal point, but usually it is much nicer to put heads on the third ('rule of thirds') of the screen, making the auto focus useless. and this camera can do it, but it is doing too much!! i don't want it to adjust the whole image as it does in full auto mode. of course it can be problematic with multiple faces but then i can decide to shut it off. touch focus would be perfect though..

as a positive point, when in focus, this camera is really very sharp.
 
dee123 said:
ps how can i get hold of barry green's book in europe?
david
Click to expand...
There is some talk about getting a copy of Barry's book in Europe somewhere on this forum. Maybe Barry's thread on his review. He wrote 3½ pages on focusing and its really hard to summarize it all. Also, you are mixing low light situations into the mix. There is 3 pages on low noise. I completely understand about the touch focus to help it focus on what you want, but that can again get messy. That's the fun of run and gun, no time and lots of time to make mistakes. I have shot professionally for 3 years and I have found tons of details in Barry's book which I did not understand, and quite a bit I still don't. The mechanisms vary so much from camera to camera its not easy to wrap my mind around some of it. Another tip he gives is to assign "PUSH AF" to a user button. You have to be in manual mode and manual focus, then you push and hold that User button until Autofocus locks into what you want. Then release the camera will jump back to manual (MF) and its locked. Another tip he gives is a low noise scene file setting.
 
yeah the first thing i did when i got the cam was assign the first user button to focus. but it still does focus on the center, while subjects are usually off center. so i need to move the cam for focus, not so handy..

thinking of it, why not build in a function to always focus on whatever is closest? usually you have a subject in the foreground, and a background. it very rarely happens that you want the background in focus and not anything before it. that would solve at least 95% of my focus issues automatically..

i would love to read that book, you get it free with the cam in the USA? if so they may as well make it available for download.. it would be handy as well for adjusting the user settings without having to test every single one 'randomly'. the manual is not very helpful in explaining.

david
 
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