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Arriglow vs. the Ground Glass


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#1 Jme Segschneider

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Posted 22 September 2005 - 08:05 PM

when the arriglow markings are a hair to the left and down from the ground glass markings, what is the cause and which is safer to go by?? I told my DP that the ground glass is safer, but now he is concerned because for the first half of the day he was framing for the arriglow... we probably should have stuck with that and shot a framing chart for the arri glow markings, huh? what do you all think? thanks
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#2 Jme Segschneider

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Posted 22 September 2005 - 08:14 PM

btw, this was on an arri 435... is there a way to adjust the alignment of the arriglow to the ground glass?
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#3 Dimitrios Koukas

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Posted 23 September 2005 - 02:57 AM

btw, this was on an arri 435... is there a way to adjust the alignment of the arriglow to the ground glass?

<{POST_SNAPBACK}>


First of all don't panic.
435 Arri gives you (as u allready know) the possibility to change ground glass, but also it has some short of masks for the Arri glow feature.
Wich means if you have changed the ground glass then u have to change the Arri glow mask too.
It's located somewhere in the top left of the cameras door.
Regards
Dimitrios Koukas
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#4 Dimitrios Koukas

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Posted 23 September 2005 - 08:41 AM

It's located somewhere in the top left of the cameras door.
Regards
Dimitrios Koukas

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I meant inside the camera.
Dim
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#5 Stephen Williams

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Posted 24 September 2005 - 04:17 AM

when the arriglow markings are a hair to the left and down from the ground glass markings, what is the cause and which is safer to go by??  I told my DP that the ground glass is safer, but now he is concerned because for the first half of the day he was framing for the arriglow... we probably should have stuck with that and shot a framing chart for the arri glow markings, huh?  what do you all think?  thanks

<{POST_SNAPBACK}>



Hi,

The ground glass will be checked by the rental house and should be very accurate. The Arriglow must me lined up to the ground glass.

Its always a good idear to shoot a framing chart, then any telecined dalies will be correctly framed. If the film is only going to be scanned or telecined then you can re-frame at the transfer stage. A very slight possitioning error is rarely a problem.

Stephen
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#6 Dimitrios Koukas

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Posted 24 September 2005 - 06:43 AM

Hi,

The ground glass will be checked by the rental house and should be very accurate. The Arriglow must me lined up to the ground glass.

Its always a good idear to shoot a framing chart, then any telecined dalies will be correctly framed. If the film is only going to be scanned or telecined then you can re-frame at the transfer stage. A very slight possitioning error is rarely a problem.

Stephen

<{POST_SNAPBACK}>


My first AC or me usually changing the ground glass with the appropriate glow mask for it.It is different for different ground glasses.
Dimitrios Koukas
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#7 Stephen Williams

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Posted 24 September 2005 - 10:16 AM

My first AC or me usually changing the ground glass with the appropriate glow mask for it.It is different for different ground glasses.
Dimitrios Koukas

<{POST_SNAPBACK}>


Hi,

The rental house will check that the ground glass collimation is correct. Just sliding in a new ground glass should be fine, but always check that the infinity mark of lens looks good. I once had an assistant put in a glass upside down!

Stephen
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#8 Dimitrios Koukas

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Posted 24 September 2005 - 03:57 PM

Hi,

The rental house will check that the ground glass collimation is correct. Just sliding in a new ground glass should be fine, but always check that the infinity mark of  lens looks good. I once had an assistant put in a glass upside down!

Stephen

<{POST_SNAPBACK}>


Not a big deal, once my first AC didn't mount the lens at all (a bayonet mount ),
and was hanging half out the whole scene.
I have used 1/2 promist and a twelve mm lens, so I was looking thru the viewfinder this blurred misty image that I ve thought in the begginning it was the filtering+ the lenses wide open F/stop. ofcourse I have reshoot this after I ve found out what he have done!
Funny thing was that' it was invissible from operator's point of view, cause the sunshade and mattebox have covered it!
Anyway
That's for the history of bad 1st AC's
Dimitrios
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#9 Matt Petrosky

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Posted 25 September 2005 - 01:04 AM

when the arriglow markings are a hair to the left and down from the ground glass markings, what is the cause and which is safer to go by??  I told my DP that the ground glass is safer, but now he is concerned because for the first half of the day he was framing for the arriglow... we probably should have stuck with that and shot a framing chart for the arri glow markings, huh?  what do you all think?  thanks

<{POST_SNAPBACK}>



The ground glass is almost certainly more accurate, especially if it it an ARRI-made (and not a hand-drawn) ground glass. The adjustment and positioning of the ground glass relative to the film plane is limited to very small adjustment amounts because the tolerances are so critical. Why would one need to move the ground glass further away or to the left by 2mm? The Arriglow glow-mask is another story. It is easily moved and adjusted in very large/coarse increments. Assuming that you have matching formats on both the ground glass and glow mask I would wager that the ground glass is much more accurate and the glow mask is off. BTW it is very easy to adjust the glow mask in the field. Similar to alining the video tap.

Hope this helps,
Matt


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Los Angeles, CA
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#10 Jme Segschneider

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Posted 27 September 2005 - 12:35 PM

First of all, thank you all for the replies and advice....
Secondly...


"Wich means if you have changed the ground glass then u have to change the Arri glow mask too"

I was aware of this, and our ground glass and ArriGlow mask were both S35 Full Frame, I even unscrewed and pulled the ArriGlow mask but it seemed like there was no way to adjust it... the mask was glued into place and the only way I was able to make any adjustment was to screw the door back on tighter, but it really didn't help much... i had been wondering if there were some dial or something to adjust it... but mechanically it doesn't seem possible.... I'm guessing that CSC just glued it in a little askew?

"Its always a good idear to shoot a framing chart, then any telecined dalies will be correctly framed."

We did shoot a framing chart, but it was for the ground glass, not the arriglow mask (which he had framed for during the first part of the shoot).

"The rental house will check that the ground glass collimation is correct. Just sliding in a new ground glass should be fine"

I checked the ground glass, it was in properly... if it weren't the letters on it would have been backwards or the eye to tape focus would be off and it wasn't...

"BTW it is very easy to adjust the glow mask in the field. Similar to alining the video tap. "

it is? i unscrwed it, but could not find a way to adjust... how?

again thank you all... the dp is seeing dailies later today so i'll know for sure how bad it is very soon. I'm sure it's just going to need minor frame adjustment during telecine.
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#11 Stephen Williams

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Posted 27 September 2005 - 12:53 PM

  I'm sure it's just going to need minor frame adjustment during telecine.

<{POST_SNAPBACK}>


Hi,

What you saw will be on the film in any case!

Stephen
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