Having "too much grain" issues? at DVinfo.net

Ben Winter · July 22nd, 2006, 07:55 PM

http://www.frozenphoenixproductions....vibrations.jpg

The analogy that comes to mind is the "rocket strapped to a station wagon" scenario.

Once I build a case this puppy will be ready to rock.

Andy Gordon · July 22nd, 2006, 09:18 PM

haha don't put your best GG in there the first time you switch it on!

Stick some poc 20 in there, if you get eliminate the grain on that stuff you will have awesome bokeh.

Actually, just a thought - I think the that amount of vibration will cause you serious problems with tripod, cam etc etc vibrating in sympathy, unless you have a counterbalance. I have enough trouble with the coin vibrators causing image wobble due to vibration.

Ben Winter · July 22nd, 2006, 09:36 PM

Quote:

Originally Posted by Andy Gordon

Stick some poc 20 in there

haha...funny thing about what's already in there...edmund optics 20 degree holo diffuser...

Quote:

Originally Posted by Andy Gordon

Actually, just a thought - I think the that amount of vibration will cause you serious problems with tripod, cam etc etc vibrating in sympathy, unless you have a counterbalance. I have enough trouble with the coin vibrators causing image wobble due to vibration.

I'm going to experiment with that, and leave no stone unturned. If there's a way to get around the issues associated with that level of vibration, I hope to find it.

I already have a preliminary case ready, I just have to shape it the right way. My main concern is light getting in, and the massive vibration unhooking the sticks from their seating. Hot glue should solve the latter, hard work and time the former...

Bob Hart · July 22nd, 2006, 11:35 PM

That is a really aggressive eccentric mass. I don't think I would care to go there but don't let my opinion put you off the direction of your experiment.

To fix some optical issues related to vibration on the tripod, the centre point of the mass you are using will have to be directly over the centre pivot of the tripod you use, which is likely to make the tripod balance rear heavy.

With anything more than say a 28mm SLR lens, you will likely get an interlace artifact which will look like every second or fourth line actually reproducing the image. Keeping the moving mass over the tripod centre will lessen anything the tripod may cause.

Depending upon how flexible the whole assembly (SLR lens / mount >> GG enclosure >> relay optics >> camcorder) is, you will likely get some interlace artifacting anyway.

Converting your interlace footage to progressive will help with interlace artifacts but then there may also appear a periodic weaving effect in any direction, even circular, depending on how close to the frame rate of your camera the vibration period is.

Fixing some static mass firmly to the housing you put the adaptor in may help but artifacts introduced by flexing of the whole structure can only be fixed by stiffening the whole structure up.

This unfortunately is going then to transfer unwanted vibration to the camcorder lens servo-system, the cassette load - unload system and the SLR lens itself.

I think you would do well to follow Quyens lead, lighter eccentric mass, faster RPM, smaller excursions of the GG.

Frank Hool · July 24th, 2006, 02:24 AM

Quote:

Originally Posted by Ben Winter

I'm going to experiment with that, and leave no stone unturned.

Ben, whats Your target? Getting grainless picture at small iris sizes?

Ben Winter · July 24th, 2006, 11:14 AM

Haha. I really don't know what my target is. That would be nice though wouldn't it?

I think Bob is right. This was mostly a joke anyway.

David Delaney · July 24th, 2006, 01:45 PM

What GG are you using? Is it homemade because it looks like it comes in a ring like a UV filter, which is a nice touch.

Ben Winter · July 24th, 2006, 05:04 PM

it's a 20 degree holographic diffuser from edmund optics. Diffuses nicely, wayyy too much grain. Thus the need for a lot of movement.

July 22nd, 2006, 07:55 PM	#1
Ben Winter Trustee Join Date: Jun 2005 Location: Hollywood, CA Posts: 1,675 Images: 1	Having "too much grain" issues? http://www.frozenphoenixproductions....vibrations.jpg The analogy that comes to mind is the "rocket strapped to a station wagon" scenario. Once I build a case this puppy will be ready to rock.

July 22nd, 2006, 09:18 PM	#2
Andy Gordon Regular Crew Join Date: Mar 2005 Location: Perth WA Posts: 103	haha don't put your best GG in there the first time you switch it on! Stick some poc 20 in there, if you get eliminate the grain on that stuff you will have awesome bokeh. Actually, just a thought - I think the that amount of vibration will cause you serious problems with tripod, cam etc etc vibrating in sympathy, unless you have a counterbalance. I have enough trouble with the coin vibrators causing image wobble due to vibration.

July 22nd, 2006, 11:35 PM	#4
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	That is a really aggressive eccentric mass. I don't think I would care to go there but don't let my opinion put you off the direction of your experiment. To fix some optical issues related to vibration on the tripod, the centre point of the mass you are using will have to be directly over the centre pivot of the tripod you use, which is likely to make the tripod balance rear heavy. With anything more than say a 28mm SLR lens, you will likely get an interlace artifact which will look like every second or fourth line actually reproducing the image. Keeping the moving mass over the tripod centre will lessen anything the tripod may cause. Depending upon how flexible the whole assembly (SLR lens / mount >> GG enclosure >> relay optics >> camcorder) is, you will likely get some interlace artifacting anyway. Converting your interlace footage to progressive will help with interlace artifacts but then there may also appear a periodic weaving effect in any direction, even circular, depending on how close to the frame rate of your camera the vibration period is. Fixing some static mass firmly to the housing you put the adaptor in may help but artifacts introduced by flexing of the whole structure can only be fixed by stiffening the whole structure up. This unfortunately is going then to transfer unwanted vibration to the camcorder lens servo-system, the cassette load - unload system and the SLR lens itself. I think you would do well to follow Quyens lead, lighter eccentric mass, faster RPM, smaller excursions of the GG.

July 24th, 2006, 11:14 AM	#6
Ben Winter Trustee Join Date: Jun 2005 Location: Hollywood, CA Posts: 1,675 Images: 1	Haha. I really don't know what my target is. That would be nice though wouldn't it? I think Bob is right. This was mostly a joke anyway.

July 24th, 2006, 01:45 PM	#7
David Delaney Trustee Join Date: Feb 2006 Location: Niagara Ontario Canada Posts: 1,121	What GG are you using? Is it homemade because it looks like it comes in a ring like a UV filter, which is a nice touch.

July 24th, 2006, 05:04 PM	#8
Ben Winter Trustee Join Date: Jun 2005 Location: Hollywood, CA Posts: 1,675 Images: 1	it's a 20 degree holographic diffuser from edmund optics. Diffuses nicely, wayyy too much grain. Thus the need for a lot of movement.