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Old October 22nd, 2007, 08:39 PM   #1
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Adaptor + A1 (or any fixed lens camera) question

Has anyone found a particularly good way to keep focus on an image adaptor's ground glass specifically in relation to a fixed lens camera, ala Canon A1?

The reason I ask is that in the past I used the LETUS with a XL2 and it was great b/c the adaptor fit to the camera body and there was no need to keep focus on the ground glass. Now, I use the Brevis with the A1 and really love the image qulity but just can't stand the darn focus ring. There have been time when I have a perfect focus on the ground glass and then in moving the camera I bump the damn focus ring and everything grinds to a halt as I fix it. Ug.

Anyway, is there some easy fix I am missing to make my life with the adaptor easier? LOL. Thanks for any fun, creative insight.
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Old October 22nd, 2007, 08:53 PM   #2
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I've always thought a large wide rubber band or rubber strap would work really well in this situation but I've never been able to find something of the right size. I think I'm going to buy a long rubber strap about 2 inches wide and then sew it to fit snugly around the focus ring, thus covering it and holding it in the right position.
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Old October 22nd, 2007, 09:07 PM   #3
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The great thing about the A1 are the focus/zoom presets. Once you've got the proper zoom and focus, set both the focus/zoom preset. If you bump anything, just hit the presets and you're good to go. We hit the preset everytime we start to record.

Since the A1 lens is fully electronic, it would be nice if the camera had a zoom/focus lock.
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Old October 22nd, 2007, 09:12 PM   #4
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Gaffer Tape

Use Gaffer tape to tape across the focus and zoom rings once everything is set. Works like a charm.
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Old October 22nd, 2007, 10:35 PM   #5
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Like the idea of the focus and zoom auto set - should've thought about that feature.

I tried the gaffer tape a number of times, but the problem is that once you achieve good critical focus on the ground glass just the action of applying the gaffer tape almost always knocks it off slightly.

I guess I will just get accustom to setting the above mentioned feature. Does it always return to EXACTLY the set focus and zoom?
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Old October 22nd, 2007, 11:00 PM   #6
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Quote:
Originally Posted by Devon Lyon View Post
Does it always return to EXACTLY the set focus and zoom?
Since the lens is fully electronic, it does return to the exact position, and retains the settings between power cycles.
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Old October 23rd, 2007, 09:52 PM   #7
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As long as your SLR lens image is already sharply focussed on something, the autofocus in your camcorder can be used for quick trimming if you bump the focus ring accidentally.

I also prefer to tape the focus and zoom rings separately, each with a bit of gaffer tape with a fold on it so I can pull it off quickly if need be.

My personal preference with the Sony cams is to use a short burst of autofocus with each shot to make sure nothing has moved. With practice it becomes quick and easy. It also means you don't have to shut down the groundglass motor.

With the short excursion groundglass movements like Mini35-400, Letus35 and I think Brevis, the motion stops almost immediately. A disk movement takes longer to spool down and time is wasted.

The autofocus may do just as good a job as you can and may just get that little sweet bit inside the groundglass texture where the relayed image is sharpest.

The caveat is in setting up a shot which has a lot of soft areas in it or pulling focus with the SLR lens. In this situation the autfocus may go hunting to find the next best sharpest thing which will be specks of dust on the camcorder lens. I call this a focus crash.

If your aufofocus has a choice of "infinity"-"manual"-"auto" like the Sony family, then the relay focus can be quickly recovered from a crash by switching to infinity. I then switch back to autofocus and switch to manual to halt it when the image sharpens, then trim the SLR lens focus to sharpest to give the autfocus a sharp target on the groundglass, then give the autofocus a short burst for final trim.

I find it a quick process once practiced and wastes little time versus a fully manual re-adjustment where you may do this several times due to difficult vision in the LCD or viewfinder. The zoom ring is always taped.

Find a good Siemens pattern and test your camcorder's autofocus versus yourself on it in a variety of under and over-exposure conditions. You may be surprised just how good it is.

Last edited by Bob Hart; October 23rd, 2007 at 10:03 PM. Reason: error
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Old October 26th, 2007, 10:52 AM   #8
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Devon your A1 has focus and zoom presets. What we do here is carefully set both after the adapter is mounted (every time we attach the adapter) using peaking/focus assist to both frame the GG properly and set the back focus. Every time I move the camera where there' s a risk that zoom/focus has been altered, I just engage the focus/zoom presets to guarantee both settins are correct. If you can set these with the cam outputting to a true 1080P panel, you'll be assured of great image quality.

The focus/zoom presets switch is a great feature for adapter use. I likely used them 5 or six times to get this footage from the XHA1, and you can tell the focus is pretty much perfect.
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