Backfocus problems

Michael Mann · January 6th, 2008, 01:22 PM

Can anyone please give a brief explanation/guess what the camera does when it performs this backfocus adjustment procedure?

Graeme Fullick · January 6th, 2008, 03:14 PM

Just confirming that I did use an A4 sized back focus chart.

This one

http://www.rondexter.com/professiona...us_pattern.htm

for those that want to find it. I printed it out on a high quality printer to get as sharp as possible (although I doubt that this made any difference).

As Eric has described it is amazingly simple and totally automated - sure beats the old manual method. I did my adjustment on a white wall with only the chart in centre view at a distance of about 3.5 meters.

Bill Heslip · January 6th, 2008, 06:25 PM

OK, I ran the backfocus routine with no issues, however, my problem was not resolved. Again, manual focus mode, iris wide open, zoom into a distant object, focus, zoom out wide, the entire image is still very soft, progressively softer the wider I zoom. Something else is going on here.

If you have an early camera like mine (#12), I suggest you check this out if you haven't already (especially if you are in the US with a 90 day warranty). I never noticed until I tested by lowering the f-stop to wide open. It's difficult to spot at any other stop.

Another odd thing is that when focus is set all the way to the stop at the infinity side while zoomed wide, I must pull focus back just inside the ∞ symbol to around the 8 meter mark for proper infinity focus. If I zoom in to a distant object, focus, and then zoom wide, I must roll focus all the way to the .8 meter mark for sharp infinity focus. I hope this makes sense.

One more thing. The focus ring actually travels beyond the midpoint of the ∞ symbol to the outside right edge of it. Is this normal? If I remember correctly, pro lenses always stopped in the middle of the symbol.

I've got to ship the camera back anyway for minor vignetting, so hopefully they can address these other problems at the same time.

Mooho Bae · January 6th, 2008, 09:14 PM

Quote:

Originally Posted by Bill Heslip

OK, I ran the backfocus routine with no issues, however, my problem was not resolved. Again, manual focus mode, iris wide open, zoom into a distant object, focus, zoom out wide, the entire image is still very soft, progressively softer the wider I zoom. Something else is going on here.

If you have an early camera like mine (#12), I suggest you check this out if you haven't already (especially if you are in the US with a 90 day warranty). I never noticed until I tested by lowering the f-stop to wide open. It's difficult to spot at any other stop.

Another odd thing is that when focus is set all the way to the stop at the infinity side while zoomed wide, I must pull focus back just inside the ∞ symbol to around the 8 meter mark for proper infinity focus. If I zoom in to a distant object, focus, and then zoom wide, I must roll focus all the way to the .8 meter mark for sharp infinity focus. I hope this makes sense.

One more thing. The focus ring actually travels beyond the midpoint of the ∞ symbol to the outside right edge of it. Is this normal? If I remember correctly, pro lenses always stopped in the middle of the symbol.

I've got to ship the camera back anyway for minor vignetting, so hopefully they can address these other problems at the same time.

Bill, I have exactly the same problem with you, and I tried the backfocus adjustment, and nothing changed at first time. But I tried several times again with various distance to the chart, and I forgot what's the best distance, but finally it fixed. Was I just lucky?

Bill Heslip · January 6th, 2008, 11:31 PM

Good hear you were able to correct it, Mooho. I'm wondering if 12 meters would be a more appropriate distance to perform the FB routine instead of 12 feet. May need a larger chart than A4 size, though.

Mooho Bae · January 7th, 2008, 01:21 AM

Quote:

Originally Posted by Bill Heslip

Good hear you were able to correct it, Mooho. I'm wondering if 12 meters would be a more appropriate distance to perform the FB routine instead of 12 feet. May need a larger chart than A4 size, though.

Bill, I once tried the adjustment to the scenary out of the window (100 feet or so), and the result was much worse than original. (of course..) I'm not sure the distance of my final adjustment but maybe it was about 5m.. Although I just use A4 size chart, the result was quite obvious. I can show you the image befor-and-after when I return to home. The image softness of full-wide, full-open case was really a headache for me, and I guessed it was the limitation of the lens performance.. Frustrated.. But after the adjustment, I'm really happy. Crystal clear through All the aperture size, All the zoom range. Great!!

Nick Wilson · January 7th, 2008, 04:12 AM

Quote:

Originally Posted by Bill Heslip

Another odd thing is that when focus is set all the way to the stop at the infinity side while zoomed wide, I must pull focus back just inside the ∞ symbol to around the 8 meter mark for proper infinity focus. If I zoom in to a distant object, focus, and then zoom wide, I must roll focus all the way to the .8 meter mark for sharp infinity focus. I hope this makes sense.

One more thing. The focus ring actually travels beyond the midpoint of the ∞ symbol to the outside right edge of it. Is this normal? If I remember correctly, pro lenses always stopped in the middle of the symbol.

Page 47 of the camera manual says "The infinity position has some margin to compensate for focus changes caused by variation in ambient temperature. When shooting an image at infinity in MF or Full MF mode, adjust the focus whilst observing the image on the LCD monitor/EVF screen." So the focus markings have some lattitude - it will be interesting to see whether your replacement/repaired camera has tighter tolerances.

Nick

Michael Mann · January 7th, 2008, 04:14 AM

I am beginning to doubt the quality control of Sony's prosumer units. (Never heard/read about backfocus problems of Sony/Canon consumer HDV camcorders before.)

Mooho Bae · January 7th, 2008, 07:42 AM

Please see these images:

http://www.moohobae.com/mine/test/EX...Adj/after2.bmp

http://www.moohobae.com/mine/test/EX...dj/before2.bmp

The conditions of the two images are not the same because of the different day, different time, etc.., but I tried my best to match.

Frame grab : original MP4 --> MXF by using clip browser 1.1 --> .AVI by using NeoHD --> .BMP by using Premiere Pro 2.0.

Eric Pascarelli · January 7th, 2008, 08:26 AM

Mohoo,

What were the f/stops for each of those? The sunny one seems to exhibit some diffraction softening (rather than or perhaps in addition to backfocus softening) which becomes quite obvious on the EX1 at f/11 and above.

Mooho Bae · January 7th, 2008, 08:33 AM

Quote:

Originally Posted by Eric Pascarelli

Mohoo,

What were the f/stops for each of those? The sunny one seems to exhibit some diffraction softening (rather than or perhaps in addition to backfocus softening) which becomes quite obvious on the EX1 at f/11 and above.

Eric, I see what you mean. But these two images were shot with the iris opened(=f/1.9),( as we discussed in this thread) and with ND2 filter.

Edit: if you used about f/3 or smaller aperture, maybe you cannot see any differences between the images before and after.

Eric Pascarelli · January 7th, 2008, 08:37 AM

Fair enough.

Looks like a definite improvement in sharpness.

Mooho Bae · January 7th, 2008, 09:47 AM

I found a clip which can show a really fair comparison. But it's not befor and after comparison. It just shows the simtom before the adjustment. You can see the problem by these images. I found this simptom just before when I shot this clip(2007-12-20 morning). This problem is now fixed for myself, because it was Christmas season, so I don't loose my important shooting chance. Maybe Bill experenced the same thing, I guess.

Please see these frame graps form a single clip.

focla length of 0.8m:

http://www.moohobae.com/mine/test/EX...#37;3d0.8m.bmp

focal length of 40m (This should be the best)

http://www.moohobae.com/mine/test/EX...ocus%3d40m.bmp

Bill Heslip · January 7th, 2008, 10:35 AM

Mooho, thanks for posting the comparison images. Your back-focus issue was much more subtle than what I am experiencing at f 1.9 (imagine 180º out), leading me to believe that my issue won't be resolved so easily. I may execute another FB from a different distance, but I am not optimistic.

Bill Heslip · January 22nd, 2008, 10:57 PM

Well, I've been without my EX1 for two weeks, as it has been enjoying a holiday at the San Jose repair center. Today, I was able to get a few answers.

The good news is that they have been able to replicate the focus problem. The bad news is they are in correspondence with Japan attempting to determine what is causing it. I was told to call back at the end of the week and maybe they could tell me more. After protesting, I received a call back from the product manager who promised to call me tomorrow upon speaking with the technician. I don't expect there is much more he will be able to tell me until they hear back from Japan.

In spite of their seemingly sincere efforts to find a solution, it is apparent that it may be a while, if ever, before they will be able to repair the defective unit. I've already turned down a nice gig this week and this delay is really putting me in a bind.

My questions are, at what point should I expect Sony to step up and simply replace it with a new one? And whom might I contact at Sony that would have the authority to make such a decision? Given their uncertainty of the what what the fix might be and no estimate of when I might expect to have it back, sending me a replacement unit right away seems reasonable. Agree?

January 6th, 2008, 01:22 PM	#16
Michael Mann Major Player Join Date: Dec 2005 Location: Kelkheim, Germany Posts: 375	Can anyone please give a brief explanation/guess what the camera does when it performs this backfocus adjustment procedure? __________________ Michael

January 6th, 2008, 03:14 PM	#17
Graeme Fullick Major Player Join Date: Mar 2005 Location: Newcastle, Australia Posts: 337	Just confirming that I did use an A4 sized back focus chart. This one http://www.rondexter.com/professiona...us_pattern.htm for those that want to find it. I printed it out on a high quality printer to get as sharp as possible (although I doubt that this made any difference). As Eric has described it is amazingly simple and totally automated - sure beats the old manual method. I did my adjustment on a white wall with only the chart in centre view at a distance of about 3.5 meters. __________________ Graeme

January 6th, 2008, 06:25 PM	#18
Bill Heslip Regular Crew Join Date: Feb 2007 Location: Southeast USA Posts: 129	Update OK, I ran the backfocus routine with no issues, however, my problem was not resolved. Again, manual focus mode, iris wide open, zoom into a distant object, focus, zoom out wide, the entire image is still very soft, progressively softer the wider I zoom. Something else is going on here. If you have an early camera like mine (#12), I suggest you check this out if you haven't already (especially if you are in the US with a 90 day warranty). I never noticed until I tested by lowering the f-stop to wide open. It's difficult to spot at any other stop. Another odd thing is that when focus is set all the way to the stop at the infinity side while zoomed wide, I must pull focus back just inside the ∞ symbol to around the 8 meter mark for proper infinity focus. If I zoom in to a distant object, focus, and then zoom wide, I must roll focus all the way to the .8 meter mark for sharp infinity focus. I hope this makes sense. One more thing. The focus ring actually travels beyond the midpoint of the ∞ symbol to the outside right edge of it. Is this normal? If I remember correctly, pro lenses always stopped in the middle of the symbol. I've got to ship the camera back anyway for minor vignetting, so hopefully they can address these other problems at the same time.

January 7th, 2008, 04:14 AM	#23
Michael Mann Major Player Join Date: Dec 2005 Location: Kelkheim, Germany Posts: 375	I am beginning to doubt the quality control of Sony's prosumer units. (Never heard/read about backfocus problems of Sony/Canon consumer HDV camcorders before.) __________________ Michael

January 7th, 2008, 09:47 AM	#28
Mooho Bae Regular Crew Join Date: Jan 2005 Location: Korea Posts: 52	I found a clip which can show a really fair comparison. But it's not befor and after comparison. It just shows the simtom before the adjustment. You can see the problem by these images. I found this simptom just before when I shot this clip(2007-12-20 morning). This problem is now fixed for myself, because it was Christmas season, so I don't loose my important shooting chance. Maybe Bill experenced the same thing, I guess. Please see these frame graps form a single clip. focla length of 0.8m: http://www.moohobae.com/mine/test/EX...#37;3d0.8m.bmp focal length of 40m (This should be the best) http://www.moohobae.com/mine/test/EX...ocus%3d40m.bmp Last edited by Mooho Bae; January 7th, 2008 at 10:18 AM.

January 6th, 2008, 11:31 PM	#20
Bill Heslip Regular Crew Join Date: Feb 2007 Location: Southeast USA Posts: 129	Good hear you were able to correct it, Mooho. I'm wondering if 12 meters would be a more appropriate distance to perform the FB routine instead of 12 feet. May need a larger chart than A4 size, though.

January 7th, 2008, 07:42 AM	#24
Mooho Bae Regular Crew Join Date: Jan 2005 Location: Korea Posts: 52	Please see these images: http://www.moohobae.com/mine/test/EX...Adj/after2.bmp http://www.moohobae.com/mine/test/EX...dj/before2.bmp The conditions of the two images are not the same because of the different day, different time, etc.., but I tried my best to match. Frame grab : original MP4 --> MXF by using clip browser 1.1 --> .AVI by using NeoHD --> .BMP by using Premiere Pro 2.0.

January 7th, 2008, 08:26 AM	#25
Eric Pascarelli Major Player Join Date: Nov 2007 Location: Los Angeles, CA Posts: 498	Mohoo, What were the f/stops for each of those? The sunny one seems to exhibit some diffraction softening (rather than or perhaps in addition to backfocus softening) which becomes quite obvious on the EX1 at f/11 and above.

January 7th, 2008, 08:37 AM	#27
Eric Pascarelli Major Player Join Date: Nov 2007 Location: Los Angeles, CA Posts: 498	Fair enough. Looks like a definite improvement in sharpness.

January 7th, 2008, 10:35 AM	#29
Bill Heslip Regular Crew Join Date: Feb 2007 Location: Southeast USA Posts: 129	Mooho, thanks for posting the comparison images. Your back-focus issue was much more subtle than what I am experiencing at f 1.9 (imagine 180º out), leading me to believe that my issue won't be resolved so easily. I may execute another FB from a different distance, but I am not optimistic.

January 22nd, 2008, 10:57 PM	#30
Bill Heslip Regular Crew Join Date: Feb 2007 Location: Southeast USA Posts: 129	Update Well, I've been without my EX1 for two weeks, as it has been enjoying a holiday at the San Jose repair center. Today, I was able to get a few answers. The good news is that they have been able to replicate the focus problem. The bad news is they are in correspondence with Japan attempting to determine what is causing it. I was told to call back at the end of the week and maybe they could tell me more. After protesting, I received a call back from the product manager who promised to call me tomorrow upon speaking with the technician. I don't expect there is much more he will be able to tell me until they hear back from Japan. In spite of their seemingly sincere efforts to find a solution, it is apparent that it may be a while, if ever, before they will be able to repair the defective unit. I've already turned down a nice gig this week and this delay is really putting me in a bind. My questions are, at what point should I expect Sony to step up and simply replace it with a new one? And whom might I contact at Sony that would have the authority to make such a decision? Given their uncertainty of the what what the fix might be and no estimate of when I might expect to have it back, sending me a replacement unit right away seems reasonable. Agree?