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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 :)

Resolution, softness and back focus...

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and then there is the softness for the still lovely, yet aging actresses ...

14. Vasoline, hairspray, black netting, etc.
 
Jannard said:
Passion begets passion.

Jim
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Now would ya just look at the all the crazy passion your Passion begets ...

Jim Jannard, THE BEGETTER OF RED (a very noble title indeed), you have every reason to be proud!!

Thank you and Merry Christmas.:biggrin:
 
ibloom said:
13. Ratio of compression.

IBloom
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yes, it might be interesting as some people have suggested multiple times that it could be possible for the RED to have selective amount of compression available, so if you are doing a very detail oriented image where storage is not a problem you could select a lesser compression

here is an image of how jpg2000 reacts to differents amount of compression

251_1177422924.jpg
 
Jim , do you check back focus on camera like a film camera? With a Flange depth tool? Any issues scratching the sensor with the feeler?

Marry Christmas!
 
richcam1 said:
...do you check back focus on camera like a film camera? With a Flange depth tool? Any issues scratching the sensor with the feeler?
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You can't set FFD with a depth tool as the imager plane is considerably behind the physical surface of the OLPF/IR filter assembly (2mm in the earlier design, 8mm in the later one).

For digital cameras, there are several methods that can be used, however all involve optical targets not mechanical means.

We have been developing a system to go along with the various mounts for the RED that we have developed. The best method involves a laser drilled aperture and a high intensity coherent illumination source.
 
khmuse said:
We have been developing a system to go along with the various mounts for the RED that we have developed. The best method involves a laser drilled aperture and a high intensity coherent illumination source.
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Is this 2 light targets that converge to a point on the sensor at the correct distance, a kind of optical depth gauge?

I've been trying to figure out how one could set the depth on a EC camera - at least beyond the resolution of the sensor which you could get with a tape measure, trusted lens and chart.

Matt Uhry
www.mattuhry.com
 
Actually no. What you are describing would be a methodology to calibrate using the focus distance marks. This makes the assumption that the marks are correct in the first place. Rather than make that assumption, our approach allows for a very quick method of finding the absolute FFD (or 'back focus') and makes no reliance on the accuracy of the lens barrel markings.
 
khmuse said:
Actually no. What you are describing would be a methodology to calibrate using the focus distance marks. This makes the assumption that the marks are correct in the first place. Rather than make that assumption, our approach allows for a very quick method of finding the absolute FFD (or 'back focus') and makes no reliance on the accuracy of the lens barrel markings.
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We are talking about the same thing, I did not write it out very clearly.

Is this a product or service that you plan to offer ?

Matt Uhry
www.mattuhry.com
 
For testing lens mount depth something like a collimator works well, Zeiss(sharpmax) and Century make such devices for checking backfocus on HD cameras. This is basically a collimator that is calibrated to infinity. Place the lens focus to infinity and the view the pattern in the viewfinder or on a large monitor. Also if the camera has a way to check sharpness of the image like Panasonics where you null out the noise of a pattern, that can be just sharp blocks of black against white since you are looking at the contrast in the transition. More contrast more sharpness. There are machines called MTF machines which do a similar thing to quantify sharpness over the optical range of the lens.

When I worked as an assistant many years ago I made my own sharpness charts and test charts to check lenses and distance scales on lenses. I worked at a studio that had a set of Zeiss primes that were marked in meters so I remarked them with feet and had to recheck them often during a show, tedious but worth the effort to ensure my dailies looked good as far as focus. To get the best performance out of any camera you really have to know a lot of technical stuff as a starting point, a set of rules so to speak, which after you learn them you can then break to your advantage. Otherwise it's all hit or miss.
 
RCFisher said:
For testing lens mount depth something like a collimator works well, Zeiss(sharpmax) and Century make such devices for checking backfocus on HD cameras. This is basically a collimator that is calibrated to infinity.
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This depends on the lens being set correctly in the first place and you are limited to the max resolution of the cameras output - neither are huge problems and you can get it reasonably close. Probably could record a few second and look at it in RedCine and see how well you hit infinity or your known distance

In a perfect world you would have something much more accurate to work with. Hopefully that's what Kevin is working on.

Matt Uhry
www.mattuhry.com
 
BASSAM MSSALATIE said:
Kevin :shifty:
Is Laser thing helping things to be much accurate ?or what ? will you explain a bit please ?:innocent:
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Well I don't know how Khmuse is doing it. But if you laser cut a flat piece that fit into your PL mount, with two tiny slits and a light source with a very thin spectrum such as an LED, it would create an interference pattern on the sensor. The pattern would vary as the depth was modified and could be used to measure distance. Gotta work out the details.... Hope that helps.

http://en.wikipedia.org/wiki/Double-slit_experiment (this contains a broad explanaition of how an interferometer is used, which includes the relationship of the interferometer to distance, and then a bunch of other stuff about physics that don't apply here.)

IBloom
 
Why use a small spectrum light like an LED when you can go for the gold. Lasers. Also makes focusing that much easier and the interference pattern that much clearer.
 
Jim Arthurs said:
If the goal of RED footage is always a 3K or 2K or HD final, won't the simple act of downsampling be enough to provide natural sharpening?

Of course experimentation with the various downsampling methods is important, but all things being equal, I can't see adding anything in addition to the act of scaling... That's what I love about having the RED have NO in camera sharpening and a generous 4K sampling container to work with in the first place...

Now windowed 2K is a horse of another color and needs help to look sharp, of course...
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Jim, this what what I was wondering as well, and since no one from RED has disputed what you said I assume it to be true.
 
Matt Uhry said:
We are talking about the same thing, I did not write it out very clearly.

Is this a product or service that you plan to offer ?

Matt Uhry
www.mattuhry.com
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We will test it out in the next week or so and if it works out well, it might become a product (at a minimum, I want one). I won't say much more until I have a chance to test it out. Its a somewhat different approach than the assumptions being made here, and as such, has to be confirmed to be a viable and quick to use device before I am comfortable sharing more.
 
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