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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 :)

falloff?

O

Obin Olson

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Hey guys, after shooting lots on the ARRI standard lenses t2.1 I see after color grade lots of brightness falloff on the outer edges of the pictures ..is this normal? I know I am going heavy on the color at times but still ......just wondering if this is "normal" for this lens set and all lenses on the market today?
 
wide lenses?

wide lenses?

Hey Obin

What focal lengths are you talking about?

I had a real "portholing" issue on the new lightweight master zoom at the wide end - 15.5mm.

Theory has it, that it is the nature of the sensor "buckets" receiveing just a little less light as the light travels from the centre of the frame. Most evident on wide lenses.

I'll let someone more technically inclined enhance that description...but it seems to be true, from what I've seen.

Dylan Macleod
Cinematographer
Toronto, Canada
www.dylanmacleod.com
 
In some other (not RED related) Master Prime tests, we saw falloff under T2. T1.9 was pretty good but falloff increased quickly down to T1.3.
 
obin said:
Hey guys, after shooting lots on the ARRI standard lenses t2.1 I see after color grade lots of brightness falloff on the outer edges of the pictures ..is this normal? I know I am going heavy on the color at times but still ......just wondering if this is "normal" for this lens set and all lenses on the market today?
Click to expand...

Hi,

The 3 wider ones will porthole unless stopped down to T2.8. I don't know why people are paying so much for lenses that are not well suited for digital cameras. 5 years ago you could not get rid of a set for $7,500, people did not want to use them as there was better newer glass available.

Stephen
 
Obin,
This has been discussed here at great length. The issue of portholing with some cine lenses is well known but not well understood. Dylan described the leading theory of why digital sensors are more susceptible to this than film; the more off-axis you get, the more oblique the angle the photons travel to the light wells.
Lenses with tiny exit pupils (Zeiss Standards, like yours) are more susceptible to this than lenses with wider exit pupils (Zeiss Master Primes, Cooke S4s) although I will tell you that even on my 15-40 S4 I get slight portholing if the conditions are right.
Angeniuex's Optimo Rouge purports to fix this issue by making the exit pupil very large and close to the sensor (although you would think for the light to exit straighter you'd want the rear element FARTHER away), precluding its use on film cameras (it will break the spinning mirror/shutter) Personally I think they only did this to protect the cine line of Optimo lenses...
If you're doing a digital finish you can overcome this somewhat with a Power Windows dodge and burn.
Of course, in the '90s everyone was tripping over themselves darkening the corners of the frame to make it more "edgy". I think some darkening is readily accepted by the viewing public. Maybe this will even make a comeback.
Cheers,
Harry
 
Deanan said:
In some other (not RED related) Master Prime tests, we saw falloff under T2. T1.9 was pretty good but falloff increased quickly down to T1.3.
Click to expand...

I own and shoot with MP glass at T/1.3 all the time and noticed no falloff at all - none, zilch, as in zero, nada :bleh:
 
Pawel Achtel said:
I own and shoot with MP glass at T/1.3 all the time and noticed no falloff at all - none, zilch, as in zero, nada :bleh:
Click to expand...

Pawel, what S/N of the MP do you have?

I tested few of them and even at 5.6 I see 1+ stop vignetting.
At 1.3 it shows even more.
Didn't test vignetting with 8 or higher stops.

These two I am testing there were straight from the box, received this year.
Try to underexpose white surface one or two stops and measure the pixel values in the corners versus center.

Here is my test:
http://www.reduser.net/forum/showpost.php?p=219268&postcount=40

Would be good to do the same test with Cooke the same way.

I didn’t test Cooke but I did use them on some shots and I just checked some last month material and I see some artistic fall off in the corners, or it is just me. Now I can’t be sure.
Have to shoot flat surface next time I will use the Cooke. Didn’t see any vignetting on SuperSpeeds but again did shoot high contrast bright day scenes with it.
.

I think Mysterium has microlenses right above the photo-sites and that is why we see this severe vignetting. I can't take it out even in AE or PR with vignetting correction there.
It will leave ugly ring around the center of the frame when I do it.
I just leave it as it is, looks more artistic as Harry said.
I avoide to use MPs when I don't want to have this "artistic" side-effects:-)
 
hmmm good info, thanks guys

funny thing is the T2.1 lenses do it and my 11mm tokina does not do it at all....maybe because it's made for digital 2/3 system?
 
You mean digital 4/5ths?
That's likely it.
Cheers,
Harry
 
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