Another underscan question

F

fritz

Well-known member
I just bought the 4x4 Chrosziel 440-03 mattebox and found that it vignettes slightly (in the top and bottom corners on the left side only) when I view my footage in underscan. If I zoom in to about Z10, it seems ok.

Do I need to only shoot from Z10 onwards, or is this not really crucial? I've read posts which say that people watching on tv sets will never see the underscan area, but does this hold for LCD tvs as well as CRT sets? Does it only apply to footage screened from VHS tape or DVD? What if the footage was broadcast by a tv station? (Probably getting ideas above my station there, but we all can dream...!)
 
if you see stuff in underscan, it may be an issue if your video is projected or if you encode it for web distribution or if somebody watches your dvd on a pc.

personally i would try to get rid of it. if the problems are just on the corners, it could be enough to letterbox it sligthly on top and bottom. if you letterbox still staying out of the tv margin area, it won't affect the tv displaying and will cover the vignetting in critical situations.

Andrea
 
Thanks Baluardo. It sounds like I should be ok if my product is going to television and not being projected or placed on the web.

Do you know if LCD tvs show underscanned images? I read somewhere that HDTVs do, but what about just normal standard def LCDs?
 
fritz said:
Do you know if LCD tvs show underscanned images? I read somewhere that HDTVs do, but what about just normal standard def LCDs?
Click to expand...
Im not really familiar with that, but from what i see in media stores all TVs display (CRT, LCD, etc) roughly the same amount of frame. so no underscan, at least by default. But i can't deny some may have that as an option, even if i doubt it.
I'm sure somebody has a sure answer around here.

:)Andrea
 
Thanks again Andrea! I can't believe I never even thought of that - I should go to a department store and check out their tvs and compare CRT to LCD for how much image they display. Thanks for the tip!!
 
Isn't the -03 for the JVC?

Anyway, if not, or if it doesn't matter...spending that much on something, it had better work without vignetting.

Check your mounting. :)
 
This is the one I have: http://www.evsonline.com/merchant2/...003DVXK1&Category_Code=2A3D1&Product_Count=34

It seems to indicate pretty clearly it's for the DVX.

My mounting is fine - there's only one way to do it. You screw in the step-down ring and then clamp the mattebox onto it. I've actually noticed it vignettes before the mattebox goes on - it seems to be the screw-in step-down ring which you can see in the left top and bottom corners. And yes, I've screwed it in as far as it will go.
 
fritz said:
This is the one I have: http://www.evsonline.com/merchant2/merchant.mvc?Screen=PROD&Product_Code=44003DVXK1&Category_Code=2A3D1&Product_Count=34

It seems to indicate pretty clearly it's for the DVX.

My mounting is fine - there's only one way to do it. You screw in the step-down ring and then clamp the mattebox onto it. I've actually noticed it vignettes before the mattebox goes on - it seems to be the screw-in step-down ring which you can see in the left top and bottom corners. And yes, I've screwed it in as far as it will go.
Click to expand...

It can't be right that it vignettes. It seems that this particular mattebox (440-03) requires two step down rings ie 104 to 85mm, and 85mm to 72mm. The extra depth may be the problem. IF you can get a single step down ring from 104 to 72mm, that might be a solution, although you might have to use a different make as I don't think Chrosziel do one.

I'm not sure that this model 440-03 of mattebox was designed specifically for the DVX100, unlike the more expensive rod mounted 411-53P, so with the extra wide stock lens of the DVX100, you may just have to live with a little vignetting or zooming in slightly. Personally I don't like to leave things that might appear in shot on underscan.

I would query it with the retailer you bought it from or directly with Chrosziel. If it's sold as suitable for the DVX100, then don't think it should vignette! Maybe they have a single 104 to 72mm step down ring they should GIVE you. It's also possible your matte box may be slightly out of spec or warped (as it only vignettes on one side) - is it still under quarantee?

Looking at http://www.chrosziel.com/ACPL09_03.pdf, page 37, the 440-03 isn't listed, but the 440-01 is. Maybe that's the clamp-on mattebox that should be used?
 
I was a bit worried about the vignetting being only on the left side, but then I did some searching on here and found other people mentioning their cameras vignetting (with various other matteboxes) on the left side also. I can't explain why it would be like that, but it doesn't seem to be uncommon.

I don't think the mattebox is warped because I think the vignetting is coming from the step down ring. If someone can tell me how to post a still photo, I'll let you guys see what I'm seeing in the underscanned frame.
 
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