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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Rectangle 'flare' with LLO OLPF

Lee Kelly

Lee Kelly

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I would assume this may have been spoken about earlier but I never have time/luck to deal with search function on here.

I was shooting a film recently and had a set that was gorgeous and lit from top with nice diffused light, as well as a big soft source behind camera. I noticed a strange 'flare' if some of that top light hit my lens at a particular angle. The thing is, it wasnt an optical flare like you would normally like or try and cut, it was a perfect rectangle, sensor shaped block.

My Dragon is one of the last sent out by Red, before they dropped that upgrade path getting ready for Weapon.
I have LLO filter in place. (factory installed) I was shooting with some gorgeous old Mamiya medium format lenses wide open at 2.8 and maybe 4 sometimes but never anything past that! Had screw on Firecrest NDs (single, not stacked)

Thankfully this 'flare' did not cause me any actual problems as i was able to notice it on my monitor and adjust my angle to avoid it, however, it was a little worrying that if I am not using a mattebox, some light angle can produce this sensor flare.

Is this a common issue with Dragon or is it something that LLO is mainly dealing with?

I dont think I ever shot any frames of this to post but hoping its either a common thing and something to work around or a fault with my particular camera/filter and can be repaired by Red.
 
I dont have access to the rushes right now to sift through and see if I shot a frame or not. Ill have to have a look when I get the chance.

It was completely different to your flare, which was more of a pleasing conventional flare. Mine was a perfect rectangle and felt internal, as opposed to something hitting the various elements in the lens. It was the sensor. Not a reflection and not those red orbs that some people experienced.

Ill find it and show it and see if this is something I should make Red aware of before it causes me more issues. Might be a repair needed...
 
It is hard to see in this image, but there is a line you can see in the dark timber above his head, where it goes lighter. This is a straight line and is actually the top section of the rectangle 'flare' or reflection or whatever it is. Its very hard to see but its there.
 

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I'm having trouble seeing what you mention in your picture, but that looks like a situation where CMOS smear might show up, which is a perfectly horizontal light purple 'flair' that shows up in contrasty situations like that on Epic / Scarlet cameras.
 
CMOS smear, yeah that sounds about right.
This was very hard for me to show in a single frame when it seemed I could only upload a tiny file size, and that compression made what I am talking about disappear pretty much damn it.
I guess the lesson is to cut the lens as often as you can unless you have a sharp optical lens flare you want to keep. I dont think my Epic ever had this issue though?
Pretty bad that this kind of thing can happen though.
 
Lee,

I think it's the gate shadow issue, not CMOS smear.

The new swappable OLPFs solve this issue (in their latest version, improved holder).

Hope it helps!
 
It's not fixed with the swappable OLPFs. It's still there. And if you look back at the video that Patrick posted and go through slowly, you'll see a hard vertical gate shadow cutting off the more organic optical flare. Which is what is problematic. Both on the way toward the light source and the when panning away from it. What you're describing sounds like some form of this issue. And if it's what's shown in the picture you posted, then yes, it's definitely gate shadow.
 
Doesn't weapon use the same OLPFs? If so, I would assume that it would cause the same issue. I have no idea though. Only speculating.
 
The problem comes from the OLPF holder, not the OLPF itself!

And apparently V2 of removable system (for Dragon, not Weapon) solves this issue.

On Weapon it's completely gone since they could implement the new mods from the beginning.
 
Definitely still present with the swappable OLPFs. You can make it happen by framing up the sun and then tilting down.

I'm interested to know if this serious issue (unique to Dragon) has been resolved with Weapon and Raven. It seems the CMOS smear has been cleared up on the newer cameras. It's an expensive fix, though.

Tommaso Alvisi said:
Lee,

I think it's the gate shadow issue, not CMOS smear.

The new swappable OLPFs solve this issue (in their latest version, improved holder).

Hope it helps!
Click to expand...
 
Tommaso Alvisi said:
Guys, read carefully...
Click to expand...

I have no idea what you're referring to. The "DSMC Standard OLPF" is the newest one from Red, that one? Both the Skin Tone Highlight OLPF and the Low Light Optimized OLPF produce pronounced gate shadow in many common shooting situations.
 
Here is the stand as of today for CMOS smear wich has nothing to do with the gate flair wich can also be produced by the OLPF mount and optical path :

full size here

1441999508.jpg


Pat
 
I think it has something to do with the Bellows and its generation/model v. The OLPF for the Scarlet has thicker bellows and a thicker "plate" I think Bjorn is correct. But in seeing your post....the standard seems a more even keel. It's the Skin Ton and LLO that pronounce it more.
The best boy in me would say don't point it at pure white, the DP in me says i love the flare, the director in me says, why is there a flare, the EIC in me says, how much does it cost to fix. I'd be interested in seeing if we have a technical answer for this. Keep us updated please.
Edit: You can actually see the definite halation in the Dragon Sensor v Weapon. I think it's kinda nice but i understand you want to get rid of the streaking across your image.
-E
 
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