Chrosziel 411-53 vignettes

[joachim]

Hi,
I am using a Chrosziel 411-53 4 x 4 mattebox and only recently found out, that it vignettes at full wide.
After disassembly and re-adjustment of the rods, the vignetting was still there.
In fact it is not the mattebox that vignettes but the 72/85 mm adapter that screws on the front of the DVX. It is also funny that the vignetting is max. in the upper left corner with some in the opper right and none in the lower corners.
Any idea how to get rid of this? (maybe there is another 72/85 mm adapter out there). The vignetting is way out of the TV-safe area, but it is still annoying.

 

[Student]

Re: Chrosziel 411-53 vignettes

I have attached the the panasonic anamorphic adapter to the Chrosziel 411-53 4 x 4 mattebox but have not use the 72/85 mm adapter jet, It does look like the anamorphic adapter works better interfacing with the mattebox than the 72/85 mm adapter. The 72/85 mm adapter looks a little too deep and prevents the DVX optics from moving forward enough.
I'm no expert by any means, but that could be the problem. I guess you could trim the 72/85 mm adapter like we have to do to the anamorphic. I don't have a monitor yet, so I can't see whole frame anyway, I am glad to hear you say the vignetting is way out of the TV-safe area though. The more I use the mattebox the more I hope to learn.

 

[PrestonH]

Re: Chrosziel 411-53 vignettes

Yup, noticed the same thing here - upper corners only. It is a little annoying but the only time it will be visible is when shooting 4:3, full wide, on a PC monitor. I have a 16mm camera with a zoom lens that did that. Was never really a problem. I just wish Chrosziel would make a shorter thumb screw so that the box didn't interfere with the on-board mic. Took mine out.

 

[kai]

Re: Chrosziel 411-53 vignettes

Yeah I've noticed it. One of the downsides of having such a sweet box on the front of your rig

 

[detroitfilms]

Re: Chrosziel 411-53 vignettes

I have a related question.  What's the reason behind getting the anamorphic lens trimmed for this matte box?  And, any suggestions on where to get it trimmed or instructions on how to trim it?  Thanks.

 

[PrestonH]

Re: Chrosziel 411-53 vignettes

The hood on the adaptor needs to be trimmed back so that it will fit further into the matte box and not vignette where the filter stages are located.

16x9 and Abel Cine offer the service for $150. Another board member here did it himself successfully after taking it apart. Basically it's trimmed leaving only 1mm around the perimeter.

 

[detroitfilms]

Re: Chrosziel 411-53 vignettes

I spoke with someone at zgc about it. She said that taking it apart runs the risk of dirtying the lens. Sounds like trouble. I wonder what he used to cut the plastic?

 

[Terry_Lasater]

Re: Chrosziel 411-53 vignettes

Dremel... 8)

 

[Rush]

Re: Chrosziel 411-53 vignettes

[quote author=detroitfilms link=board=Links;num=1087849886;start=0#6 date=06/22/04 at 13:51:27]I spoke with someone at zgc about it.  She said that taking it apart runs the risk of dirtying the lens.  Sounds like trouble.  I wonder what he used to cut the plastic?[/quote]
I have had two customers' lenses rejected by 16x9 due to dirt inside the lens after customers have asked them to do the modification. They won't touch a dirty or scratched lens, for fear of being blamed for it, so if you attempt to do it yourself, but may need to have them do it in the future, for heavens sakes don't open the lens up on your dog's bed. ;D

 

[timmy]

Re: Chrosziel 411-53 vignettes

I had noticed it too, and found it was the 16x9 mask that was doing it. I machined out a 32nd and no more vignetting. You can also just take it out and it should work ok.

 

[joachim]

Re: Chrosziel 411-53 vignettes

thanks folks for all those answers.
Preston, I did the modification to the Ana-Adapter myself and it worked quite well, as Terry suggested I used a Dremel to shave off the sunshade of the adapter.
In my opinion, the discussion about dirt getting between the lens elements is a bit exagerated. Many brand new lenses are shipped with dirt particles inside.

After i did the modification, I clean the two lens elements with a lens cleaning fluid and blew all dust particles out of the housing, put the lens together and it works perfectly.