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Old July 8th, 2008, 05:15 PM   #1
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Soft Focus With Stopped Down Aperture...Help!

Hello,
Since May 5th, I've been down in the Caribbean shooting a documentary feature. I purchased the EX-1 especially for this project, and have been shooting every day for the past 75 days.

For the most part, I am very happy with the camera, besides the issue I'm about to describe, my only gripes are the paint on the top handle is flaking off (lots of hand-held, outside, hot sun) and some ergonomics/menu issues.

Now on to my problem...

When the camera is on a wide lens and the aperture is closed down (F16 to F8 range) the image is soft. When I open the aperture (F5.6 to F1.9) and cut the light with ND or shutter the image is sharp. Because I can not send this camera in to Sony for repair because of my remote location and I can not stop shooting the film, I have taught myself to shoot with a more open aperture. But sometimes with "run-and-gun" shooting it becomes challenging.

Has anyone else seen this issue? Is there a fix for non Sony techs "at-home"?

200 hours shot, and still going!

Cheers,
Jason
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Old July 8th, 2008, 05:22 PM   #2
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It's diffraction softening. Avoid using the camera above f/8 and you'll be fine.

This is a phenomenon of physics and happens with any small chip camera at small apertures.

http://www.cambridgeincolour.com/tut...otography.htm#
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Old July 9th, 2008, 07:21 AM   #3
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So this is common with this camera? If so, I'm a little shocked. It's the first time I have ever seen this characteristic in a "handycam" sized video camera, and I have been shooting for 15 years.

Thanks,
JA
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Old July 9th, 2008, 07:28 AM   #4
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Eric is correct.
I never stop down more than f/8 due to diffraction.


Like Eric mentioned, this is not uncommon for smaller chipped cameras. My JVC HD100 is no different - actually a bit worse.
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Old July 9th, 2008, 07:39 AM   #5
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Quote:
Originally Posted by Eric Pascarelli View Post
It's diffraction softening. Avoid using the camera above f/8 and you'll be fine.

This is a phenomenon of physics and happens with any small chip camera at small apertures.

http://www.cambridgeincolour.com/tut...otography.htm#
... and with any photographic camera. Back in the days of chemical films, it was well known for photographers that closing the iris too much softened a little bit the entire image, so they avoided the smaller apertures unless they had to widen the DOF to the maximum. Of course, the smaller the film size, the more visible this was for a given aperture, and the limiting aperture varied, this was about f11 for 35mm, f16 to f22 for medium format (6 cm wide film) and f32 for large format studio cameras (from 4x5 to 8x10 inches film). Digital SLRs haven't shown it until they reached the 10 Mpixel barrier.

But for SD video, the resolution was just not enough to show this effect, so videographers have never cared of this... until now, when true HD cameras like the EX1 have made it visible.
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Old July 9th, 2008, 07:47 AM   #6
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Diffraction effects are stronger the smaller the diameter of the physical aperture, and since that diameter is determined by the f/stop and lens focal length (which in turn is related to the size of the sensor), diffraction is far worse for cameras with smaller sensors than for the EX1. However since the resolution of this camera is excellent you may well notice softness that escaped notice with your other cameras. On the Z1 diffraction started to degrade the image for f/stops greater than f/2.8 (i.e. f/4, f/8 etc). You have experimentally proved the relationship.
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Old July 9th, 2008, 08:08 AM   #7
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I have a matte box with an ND6 filter permanently on the camera so that I can always shoot at around F4 to 5.6. I add camera NDs where needed.

You can get a screw on filter to keep size down.
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Old July 9th, 2008, 01:32 PM   #8
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Originally Posted by David Lorente View Post
But for SD video, the resolution was just not enough to show this effect, so videographers have never cared of this... until now, when true HD cameras like the EX1 have made it visible.

This was clearly visible on my old PD150 as well so I don't think it is something that you need HD to see.
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Old July 9th, 2008, 01:41 PM   #9
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I only noticed it recently and never observed it with my HVX200, but maybe i just never looked for it. It is very striking though. They really ought to have an iris that just doesn't close that much.

Lenny
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Old July 10th, 2008, 06:21 AM   #10
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This was clearly visible on my old PD150 as well so I don't think it is something that you need HD to see.
Yes, I was thinking only in professional cameras. With 1/2" or 2/3" sensors, the effect is not noticeable at SD resolutions.

Leonard, knowing that the HVX200 sensors have 1/4 the resolution of the EX1 ones, it's not surprising that the effect is also invisible. And the iris must close down to f16 because sometimes you can need a great range of iris, or to widen DOF. When my father worked as photographer in a museum, he used an old Nikon F2 with a 55mm macro lens that could stop down to f32. Even if the sharpness was not the same, the extra DOF was a must when photographing small pieces that where not much larger than the film frame.
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Old July 10th, 2008, 07:07 AM   #11
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I must admit the EX1 gets really soft at F8 and tighter. This has been quite a surprise to me when switching from the V1E, which was OK up to F8 even though its imagers are only half the nominal size of EX1's.
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