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Old February 6th, 2007, 06:30 PM   #1
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HD100 back focus issues

I have an HD100 set to truecolor 3. I've gotten comments from others that the image looks softer than it should. I'd set the back focus some months ago and think I may not be doing it right.

Some questions-
1) should back focus be set with focus assist or eyeballs?
2) should the hashmark on the back focus ring and the hash mark on the macro focus ring normally be aligned?
3) should the spring loaded switch on the macro focus ring be disengaged when setting back focus? (if i do that, adjusting the backfocus independent of the macro focus seems to do nothing--the focus doesn't change.)
4) the manual says set the focus at a distance greater than three meters, is there and ideal distance?
5) any additional tips for setting back focus? I find the owner's manual consistently lacking in detail.
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Old February 6th, 2007, 07:11 PM   #2
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I don't know if this helps... but, here's my 2 and the way I know how to do it. I use a focus chart about 3 feet away. (I don't believe it should be 3 METERS or more necessarily..) I guess one can use the focus assist or eye ball it or both. Leave the macro alone and locked.

Zoom into the chart and focus, note the barrel marking, should be around 3 feet - adjust the back focus.

Zoom back all the way out and focus - play with back focus to bring it into super sharp focus.

Keep repeating until you have the back focus adjusted - both ends of the zoom range should remain in focus once the back focus is correctly set. i.e., Once you set the focus while zoomed all the way in it should remain in focus when zoomed back out to wide.
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Old February 6th, 2007, 07:22 PM   #3
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Quote:
Originally Posted by Miklos Philips
I don't know if this helps... but, here's my 2 and the way I know how to do it. I use a focus chart about 3 feet away. (I don't believe it should be 3 METERS or more necessarily..) I guess one can use the focus assist or eye ball it or both. Leave the macro alone and locked.

Zoom into the chart and focus, note the barrel marking, should be around 3 feet - adjust the back focus.

Zoom back all the way out and focus - play with back focus to bring it into super sharp focus.

Keep repeating until you have the back focus adjusted - both ends of the zoom range should remain in focus once the back focus is correctly set. i.e., Once you set the focus while zoomed all the way in it should remain in focus when zoomed back out to wide.
I'll try that thanks. Anyone know of a downloadable focus chart I can print out?
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Old February 6th, 2007, 07:51 PM   #4
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Old February 6th, 2007, 07:57 PM   #5
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http://www.rondexter.com/intermediat...us_pattern.htm

I downloaded a back focus chart from here.
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Old February 6th, 2007, 09:15 PM   #6
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Quote:
Originally Posted by Brian Luce
I'll try that thanks. Anyone know of a downloadable focus chart I can print out?
Two here:

http://www.panavision.com.au/PDFs/Ch...iemen_Star.pdf

http://www.panavision.com.au/PDFs/Ch...tars_Chart.pdf
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Old February 6th, 2007, 11:11 PM   #7
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I don't use back focus charts myself, I just use some kind of sharp edge in the distance. The depth of field is big enough on a 1/3" chip at that distance that setting the focus barrel precisely isn't as important.
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Old February 7th, 2007, 01:17 AM   #8
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Um, I adjust my back focus as I see fit for each shoot I am on.

I will change it some 5 or 6 times during the course of an evening filming a reception. I can get pretty close to someone dancing and not be happy with the focus.

Call me weird, but I could never live with a permanant setting.
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Old February 7th, 2007, 01:31 AM   #9
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Quote:
Originally Posted by Brian Luce
I have an HD100 set to truecolor 3. I've gotten comments from others that the image looks softer than it should. I'd set the back focus some months ago and think I may not be doing it right.

Some questions-
1) should back focus be set with focus assist or eyeballs?
2) should the hashmark on the back focus ring and the hash mark on the macro focus ring normally be aligned?
3) should the spring loaded switch on the macro focus ring be disengaged when setting back focus? (if i do that, adjusting the backfocus independent of the macro focus seems to do nothing--the focus doesn't change.)
4) the manual says set the focus at a distance greater than three meters, is there and ideal distance?
5) any additional tips for setting back focus? I find the owner's manual consistently lacking in detail.
1) Only do this when your camcorder is connected to a ful resolution display (lcd, ...). You'll really need this for critical back focus setting. The focus assist is way to forgiving for back focus setting...
2) Yes, when trying to set the back focus, they should be alligned. Wouldn't make a lot of sense otherwise...
3) The macro-ring will turn when you turn the backfocusring and you should see the difference.
4) In my experience with the HD101, 2,5 to 3 meters is perfect. Don't double it, don't halve it... under 2 meters is too close: you'll notice your backfocus isn't set entirely properly...
5) that's pretty much it. Make sure your light is just right to open up your iris fully and that you have a full res monitor present. Be sure to check after you re-tightened the back focus screw...
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Old February 7th, 2007, 06:17 AM   #10
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Quote:
Originally Posted by Jim Fields
Um, I adjust my back focus as I see fit for each shoot I am on.

I will change it some 5 or 6 times during the course of an evening filming a reception. I can get pretty close to someone dancing and not be happy with the focus.

Call me weird, but I could never live with a permanant setting.
You should use the macro for this.

One version of the Sony HDCam cameras are a nightmare regarding the backfocus, they need to be checked all the time because of the slightest temperature changes (even between takes in the worst instances).

However, most HD cameras only need to be backfocus checked if there's a lens or temperature change - usually once adjusted when the set & camera have warmed up it doesn't need to be touched (Camera assistants often check by eye at least once during the day). Each time you should carefully set up with a chart or a pattern that can act as a chart, it's not something that's done on the fly.

If you're losing backfocus that regularly it could be that the adjustment ring is slipping.
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Old February 7th, 2007, 06:27 AM   #11
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Or: intensive use of the macro can cause the backfocus-ring to get a little looser and shift a bit in position, thus resulting in an incorrect backfocus...

(don't ask me who uses a macro THAT often/intensively.... but you never know)
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Old February 7th, 2007, 12:19 PM   #12
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I'll jump in here too.

Not only do HDCAMs have a tempurature problem, many cameras do, as well as my HD100. Years ago I purchased one of those point and read infrared tempurature thermometers, and I check my camera body in the area near the CCC block and lens barrel close to the camera before every take. They must be tempurature stabilized (within a degree or two) or the BF will drift out. It takes about an hour or more of warm-up to stabilize, and if you put on a cold lens, you start all over again. (the lens is warmed by the camera body, and a cold lens will cool the camera body).

Unless you have the luxury of a 24" or larger monitor on set, then you must use the focus assist or peaking control to see the focus on the star chart. I printed out a small one and a larger one, and secured them side by side to a piece of foamcore; at full tele I focus on the smaller one, and at full wide I use the larger one which I can see better; they are the same distance from the lens. I printed them on photo paper, best settings. Also, you must go through the process 2-3 times; it is a dance until both full tele and wide BF are consistent.

Regarding the set screw Werner mentioned, I had much trouble working with the BF ring on the stock lens, and I also found the stock lens didn't always track focus through the zoom; I now have the 17x lens which is machined more like a high end lens, and tracking and setting the ring are no problem.

Without the large monitor on set, I pull focus on my subject at full tele, using focus assist if necessary, then widen to frame; my BF must be spot on. Occasionally I will use the stock lens with the Wide Converter, and I find it necessary to pull focus at frame, using peaking and (sometimes) a large monitor in that case.

Unless of course you are Tim Dashwood or Taylor Wigton, who have that magic touch many of us can only dream about. Maybe the fact that I'm nearly 64, and walk with a white cane has something to do with it. I also have someone steer the car while I'm driving.


Cheers,

Gary
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Old February 9th, 2007, 04:26 PM   #13
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I've found that with the stock lens, I check back focus every time I go out, and even on tape changes because it does seem to drift around a little.

use as a big monitor as you can find, but the focus assist will work if need be. its a bit unnerving to have to do this all the time, but its become habit. on my old sony cameras (327a) I checked it about once a month with constant use and it never seemed to go anywhere

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Old February 9th, 2007, 05:13 PM   #14
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Is this the case of the stock lens not performing well at all on the wide end?

I just got the HD110, and have been having similar problems with my backfocus being adjusted. I went through the Chart directions, setting the focus chart 3 meters away, zoom-in, pull focus, adjust bF, zoom out, adjust focus, repeat, etc.
It is really hard to see if the chart is in focus when I am wide, then when I do location shooting, and want a to frame a subject that is about 10 feet away, it seems like I can never get it in focus, really frustrating! I go in get my focus, pull out and the subject get more and more soft and blurry.

I do have a wide angle converter, and whenever I attach that, and adjust my bf,everything comes in focus and it works fine. Is it just the stock lens, or am I doing something wrong here?
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Old February 9th, 2007, 05:32 PM   #15
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no. I think the stock lens looks ok wide. I think its just a matter of it being very temperature sensitive. in any event, I've simply gotten into the habit of checking the B.F. everytime I load a new tape.


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