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-   -   Back focus, am I soft?? (https://www.dvinfo.net/forum/sony-xdcam-ex-pro-handhelds/486334-back-focus-am-i-soft.html)

Keith Dobie October 28th, 2010 11:07 AM

1 Attachment(s)
Darren -- very good thread. l just got an EX1R recently and haven't tested back focus yet. Will be printing out a chart. Going to do some reference shots and frame grabs so I have something to compare to in the future.
The attached JPEG is the before & after shots you posted - put into a single 1920x1080 image. I desaturated it to make it a little easier to concentrate on the focus.
To me the 2nd one has a lot more contrast which might make it seem like it has better focus. When I zoom in they look pretty close to me. The candelabra and the text on the CD spine labels seem about the same.... the jaggies on the test pattern seem about the same. I didn't adjust the image in any way other than desaturating it.

Darren Ruddock October 28th, 2010 12:55 PM

Hi Keith,

Desaturating looks a good move to help test the focus. I think I have it as close as I can to being a good adjustment. What did you think of the stills? When you do get some grabs post them up, I'd love a look at what you have got.

The thing is I have nothing to really compare mine too.

Bob Hayes November 10th, 2010 01:15 PM

Darin

I am an EX1 owner of over a year, My back focus has gone out a couple of times and I have fixed it using the auto back focus adjustment successfully. One thing I notice about your environment is there is an awful lot of clutter behind your chart. I always go out of my way to do the test on a smooth white wall. I use three Fuji chart which they gave to me for free. One in the middle and two off to the sides. I tech the camera at 7' because that is an actual number on the lens.

Darren Ruddock November 12th, 2010 09:54 AM

Hi Bob,

The pictures I posted were not where I actually did the test. They were just shots to try and get an idea of the focus after the test. The procedure was carried out on a blank wall.

Got a job on next week so hoping my back focus is ok for that.

Dominik Krol November 18th, 2010 11:41 AM

I want to propose a new method.. This is for the Ex1. Not tried on any other.

All previous attempts have failed for me. They seem to work, but only with approx 90% sharpness.

First perform a test where you place your star chart (or some object) 5 feet away. Zoom all the way in. Focus. Then zoom all the way out. Now move your focus wheel up to infinite. If you experience a sharpness gain, Then your BF is not 100% in place. (this may be hard to see on the camera LCD)

Therefore I did a new attempt. And here is what I did.

Put this chart on a computer LCD monitor: http://www.bealecorner.org/red/test-...ull-600dpi.png

Make sure the lcd is located close up against a wall. Turn down the brightness so it dosnt over expose compared to the background wall.
Place your camera exactly 5 feet away, target it on the lcd, and turn your manual focus marker to 5 feet(focus ring to Full Manual setting). Zoomed in focus should be optimal.
Run the auto BF adjustment. Using an LCD as a backfocus target, seems to work perfect. Not only does the chart itself help, but so does the aliasing and CA from the monitor. You wont be in doubt when the backfocus is spot on.

How do you test?

After the auto BF adjust.. Zoom in.. Focus. Take notice of the area of confusion (the area that looks blurred in the ceter). While zooming out look on your camera lcd. The area of confusion may not change size. (meaning may not change size compared to the camera screen size, not the chart)

Then you can run another test by moving your focus ring back and forth while zoomed out.. If you end up with the sharpest image (smallest area of confusion) at 5 feet. You have a perfect backfocus.

Darren Ruddock November 18th, 2010 04:07 PM

Hi Dominik,

Sounds interesting. May give it a go.

What do the rest of you guys think??

Leonard Levy November 18th, 2010 06:52 PM

I haven't looked over this whole thread so I don't know if it was mentioned earlier but I was having trouble with the auto-back focus until someone explained to me the extremely important caveat that:

All settings on the camera must be on auto
auto focus
auto iris etc
maybe even auto white

Doesn't work otherwise - God knows why.

Lenny Levy

Dominik Krol November 19th, 2010 05:56 AM

Which infact is wrong since the camera takes control of these no matter what your settings are. Only Servo Zoom is nessessary.

Leonard Levy November 19th, 2010 09:17 PM

Dominik, were you responding to me? If so, I have no idea what you're talking about - don't understand what you mean about servo zoom.

Looking back over this thread I see that it was explained that you had to be in auto focus - missing from the Abel Cine video .

I was told by a sony repairman in LA and another tech at a shop I use that the camera had to be in all auto functions for the auto back focus to work. When I did that that the process worked fine. Don't have any idea why. It may be that only autofcus is important but why not just go full auto. I did it at 24P and it worked fine but it makes sense to go 60i as the autofunctions just work better in 60i as it samples more often.

Dominik Krol November 20th, 2010 08:35 AM

Yes Leonard I was replying to you. The servo zoom is the only switch that cant be overridden electronically (and the ND filters ofcoruse). Thats why its the only one that counts..

If you don't believe me, take your camera and perform some tests. Close down the iris, put your focus to infinite, change your shutterspeed to something rediculous, go full manual on all functions and then perform the Auto FB.

I can assure you that what instantly will happend is for the Iris to go wide open. Your focus to go macro, your shutter go to something that wont over or underexpose, and if the setting is to dim, it will add some gain. The only function that will NOT let you perform the FB is if your zoom is set to manual.

Please do not reply to this untill you have tried it out. (there is a slight chance that an older firmware requires you to go full auto, but if you have updated it to the latest, then my argument holds up).

Darren Ruddock November 20th, 2010 12:14 PM

There seems to be a lot more stipulations, with regards to completing a successful back focus adjustment, every time I read something on this thread.

Would probably help if Sony actually issued some definitive information!

Leonard Levy November 20th, 2010 07:13 PM

Dominik, Yeah you might be right. I'm not planning to try it again though as its working.

I don't remember how I was set up when the procedure didn't work but its possible that I didn't even have the focus barrel pushed into place for auto. I usually leave the servo on and the focus barrel disconnected for manual. I'm just passing on what I was told by the Sony repair department though and when I tried all Auto it worked. I'm not really sure what I changed after talking to him.

Piotr Wozniacki November 21st, 2010 08:31 AM

Dominik has it right here. The only prerequisite is sliding the zoom switch on (with it at off position, the Flange Adjust will be grayed out in the Maintenance Menu, and thus inactive).

All the other settings will be taken care of by the procedure itself.

While we're at it: does anyone know what prerequisites are necessary for the Auto Black procedure to become active?


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