RED Windowed Sensor Target Area

[Andrew M.]

TJ I am not the expert but I am fast finder/reader.
See the link and the last page of the document from 2002 the references section last item.

http://www.zeiss.de/C12567A8003B8B6F/EmbedTitelIntern/DigiPrime-Artikel-KMu_SMPTE2002/$File/SMPTE2002_DigiPrime.pdf

Very good reading.
Now as it comes to the Abacus B4 mount, we should ask the question straight by e-mail to the Abacus customer service. From different sources we know that Abacus has 2 glass elements in it. I can’t imagine how you can correct chromatic focus mismatch using only two elements. IMHO, FOV correction yes but anything else no.
Now, good HD lenses will be almost impossible to use without correction of chromatic focus on the perfectly flat CMOS surface. You will buy 25K HD lenses just to perform like 3K one?

 

[tj williams]

Here is the Abakus response to the problems with their unit presented by Andrew: That second was an interesting post Andrew. (we think alike by the time I read that I'd already Emailed Abakus) So if we accept what is stated below then Digi primes are also available to RED owners who have an Abakus adapter. Getkin, Looks like good news fm Abakus that will enable those of us who already have good B4 lenses to use them. Brook guess I don't get it if Jarred says Abakus is the solution and Abakus says they have overcome the above problems, then how will you trim it in post? What will you trim in post? where will you B4 mount the RED?

Hello TJ,

Thank you for your email, I will try to answer some of your questions.

Video lenses are designed to compensate for the beamsplitter block in the camera that splits the light into red, green and blue.
When we designed our converter we re-compensated for this so that only air should be in the back focus of the lens. This is the position on super-16 and for single chip detectors.
The converter therefore DOES optically compensate for the longitudinal colour (and the spherical aberration) that would otherwise occur. It does not just magnify the image. Our website is obviously too conservative in not emphasising the point.
We did not compensate for any film curvature in the design (perhaps we should have?) since it would vary with different cameras

The design of our converter assumes that the video lens is perfectly designed and manufactured for the Sony HD block (we managed to persuade them to give us the details).
Whilst most HD lenses are fairly good they are obviously not perfect. Since the converter magnifies the image 1.32 times then the errors are also magnified. It certainly shows up any flaws in the video lens.

As far as the discussion on the effective resolution of film versus electronic detector, much has been written. Most subjective test indicate that film resolves better than it should. I suspect that this is due to the averaging effects of having a new detector every 24th of a second. Although the grain size of the film is larger than the pixel spacing on a CMOS detector and the film does not locate in exactly the same position for each frame, the human brain is very good at averaging these out and the perceived picture can be much better than achieved on present day HD cameras. This is certainly true for 35 mm and to a lesser extent for 16 mm.

Please contact me if you have any further technical questions.

regards

ken

Abakus Ltd. Registered in England, No. 2595892. - Registered Office Grange Farm, Bourne Road, Carlby, Stamford, PE9 4LU, UK

 

[Andrew M.]

TJ It is great news, I just sent the e-mail myself to Abakus, asking them how many glass elements they have in the B4 adapter, than we do some science on this info.
I would love to use B4 adapter that stretches the picture to full S35 size, maybe we can suggest to Abacus to manufacture one. The current one I believe is only stretching it to S16 size. Could you ask them this question, please? Here goes another stop of light

 

[Andrew M.]

As far as the discussion on the effective resolution of film versus electronic detector, much has been written. Most subjective test indicate that film resolves better than it should. I suspect that this is due to the averaging effects of having a new detector every 24th of a second. Although the grain size of the film is larger than the pixel spacing on a CMOS detector and the film does not locate in exactly the same position for each frame, the human brain is very good at averaging these out and the perceived picture can be much better than achieved on present day HD cameras. This is certainly true for 35 mm and to a lesser extent for 16 mm.

I will not agree with this but 4K will kill the 35mm film once and for all
He forgets that there is other part of making the movie, it is displaying it.
The same lenses and film curvature and other errors are made three times.
Once when you acquire the data, second when you process/copy/distribute, third, when you display the data (film)

In the digital world, the errors are acquired once when you record, then you mask all imperfections in the electronic massaging/editing improving the data and finally there is no errors add by watching it on large HDTV screen.
I agree, CbaleTVs companies screw the signal beyond the recognition trying to deliver it to your home but IPTV will take care of it very soon. Digital cinema will not degrade the data as much as the film projector does, if not actually improving it.

 

[tj williams]

Andrew of course there are many opinions about quality and the future. The people at the adapter company are more film centric as that has been the primary use of their product. The opinion you have comes from being more attuned to digital tech. The important thing to me is that the adapter does address the problems of HD glass since I have a very expensive piece of HD glass the opportunity to use this is phenom. for me! You do not want a 35mm size converter. They make one. It will lose 2.5 stops of LIGHT!!!! This not because of them this is the physics of any optical device!

 

[Andrew M.]

TJ, more I read and more I talk with people, more I see that we just have to try it.
Lens manufactures do not want to disclose details of the glass structure and color responses for each piece of glass in it. So it is difficult to say what will work with what.
As to magnifying 2.5 times to get B4 lenses to illuminate whole S35 I agree that we have to loose the light, but don’t we gain it back by downresing it back to 2K? Then 4 pixels are combined in to one so the signal to noise ratio goes up by 12dB?
Well the Abakus adapter is not that expensive, so if you are ready buy new one, and try it. The good thing is that you know your lenses very well so you will be able to tell right away if something is not as should be. However you will be trying it on the RED that is completely unknown to you.
What kind of HD lenses do you have now?
If your experiment will not work out good then I will rent few HD lenses and I will try it again. What I have heard, some lenses design is not lending itself for any glass between the sensor and the lenses, some lenses is very difficult to correct for chromatic focus and so on, nothing scientific and solid, just the talk. Yes, I am more science guy so numbers and data is more appealing to me but I have to take subjective opinion of practical experienced people very seriously.

 

[Michael Hastings]

Re: apparent resolution of film.

Re: apparent resolution of film.

I found the comment about film providing a "new detector" every frame very interesting. For the video guys what he is saying is that the fact that the film grains are in a slightly different position in every frame it works sort of like pixel offset on a 3 chip camera where the chips are aligned so that the pixels on one chip are aligned to the spaces of the other chips - dramatically increasing resolution of the final image - it is not double - a sony engineer explained that it is a square root factor so about a 1.4 increase. In the case of movies it is temporal - the offset occurs on the next frame but persistence of vision and the brain figure it out. It also reminds me of a software package I have seen at NAB that takes multiple frames of a video to create a much sharper still image. It doesn't work if the camera is solid on a tripod, it only works if there is some CAMERA movement so that they get more information about the scene to process. Again it doesn't work on the moving subject - it works on the change in movement of the camera (and therefore the sensor) And it definitely worked - the examples I saw took a .35 megapixel standard def video image and made what looked like a 1 or 2 megapixel still.

As far as the discussion on the effective resolution of film versus electronic detector, much has been written. Most subjective test indicate that film resolves better than it should. I suspect that this is due to the averaging effects of having a new detector every 24th of a second. Although the grain size of the film is larger than the pixel spacing on a CMOS detector and the film does not locate in exactly the same position for each frame, the human brain is very good at averaging these out and the perceived picture can be much better than achieved on present day HD cameras. This is certainly true for 35 mm and to a lesser extent for 16 mm.

Please contact me if you have any further technical questions.

regards

ken

Abakus Ltd. Registered in England, No. 2595892. - Registered Office Grange Farm, Bourne Road, Carlby, Stamford, PE9 4LU, UK

 

[Andrew M.]

I found the comment about film providing a "new detector" every frame very interesting. For the video guys what he is saying is that the fact that the film grains are in a slightly different position in every frame it works sort of like pixel offset on a 3 chip camera where the chips are aligned so that the pixels on one chip are aligned to the spaces of the other chips - dramatically increasing resolution of the final image - it is not double - a sony engineer explained that it is a square root factor so about a 1.4 increase. In the case of movies it is temporal - the offset occurs on the next frame but persistence of vision and the brain figure it out. It also reminds me of a software package I have seen at NAB that takes multiple frames of a video to create a much sharper still image. It doesn't work if the camera is solid on a tripod, it only works if there is some CAMERA movement so that they get more information about the scene to process. Again it doesn't work on the moving subject - it works on the change in movement of the camera (and therefore the sensor) And it definitely worked - the examples I saw took a .35 megapixel standard def video image and made what looked like a 1 or 2 megapixel still.

With the film though, I will not agree that brain is somehow good in averaging the picture to the benefit of higher resolution perception at 24fps.
If you look how eye is build and works, plus the persistence time of the eye sensors, picture shift averaging on the retina, will just produce more out of focus perception at low frame rate. More jitter there is at 24fps more out of focus perception of the picture will be. For 120fps (minimum 60fps) though, if film will offsets a bit up and down and left and right, it may work. It is like having not only horizontally interlaced image but vertically as well.
For the camera movement and software that squeezes out more resolution from it, I agree 100%

 

[Stephen Williams]

They make one. It will lose 2.5 stops of LIGHT!!!! This not because of them this is the physics of any optical device!

Hi TJ,

Cooke made a 16mm version of the 20-100 T3.1, I think it ended up T1.5 or 1.7.

Stephen

 

[Andrew M.]

Sent two e-mails to Abakus and no answer.
They don’t want even to confirm if it has two glass element in it.
Looks like there is a lot of misinformation out there about lenses.
Well everybody wants to sell its glass but only very few know how to make it right.

 

[Andrew M.]

TJ got the answer from Abakus, looks gooood!
Straight from the source.
====================================
Hello, I have one question:
How many glass elements Abakus 260 Converter contains?
------------------------------------
Hello Andrew,
6 elements in 3 groups.
regards

 

[tj williams]

I am more science guy so numbers and data is more appalling to me

I hope you mean appealing? I'm the opposite as numbers and data are appalling to me!

I totally don't get the counting glass elements etc. either this thing works or it doesn't and two pretty credible folks say it does?

Stephen This is not a lens adapter what your are talking about is using parts of a lens to manufacture a complete lens. I already have an HD lens and I just can't affore to have Cooke redesign and rebuild it. The deal is the larger you spread the image ie 2/3 to S 16 or 2/3 to 35mm size then in a direct relationship you will loose light. This is straightforward so about a 1/3 stop loss for S16 and a 2.5Stop loss for 35. Cooke or no one else can change that!

 

[Stephen Williams]

Stephen This is not a lens adapter what your are talking about is using parts of a lens to manufacture a complete lens.

Hi TJ,

Cooke only changed the very back of the lens, the magnification was smaller giving a brighter image. A teleconverter in reverse, not that different in principle from the adapter you are talking about IMHO.

Stephen

 

[Andrew M.]

I totally don't get the counting glass elements etc. either this thing works or it doesn't and two pretty credible folks say it does?

Yes, experience and practical knowledge is very important but thinking out of the box is also beneficial for the progress of science.

Abakus is magnifying image 1.32 times to stretch it to S16. To streach it to S35 requires magnification factor to be 2.4 or so. Yes all errors of the lenses will be magnified and we loose the light but as I mentioned before, what we loose we gain back by downresing it and it is easier to correct aberrations coming down from 4K to 2K then correcting it on the pixel per pixel basis.
Also, if Abakus will do good job on the adapter, without introducing too much of its own distortion, then good lenses versus bad ones will show right away. What I am reading here there are very few B4 ENG lenses out there of good quality.
Maybe we could pick the Graeme’s brain here on this subject:
To magnify the B4 lenses 2/3 image size to S35 and then shrink it in post back to 2K/1080 or just leave it at 2K. (you can shrink it also directly on the camera/CMOS format converter)

IMHO you can correct a lot of imperfections combining 4 pixels in to one, where once you record in one to one pixel ratio with small imperfections, then it will stay there and it is not much you can do about it.

As to the size of CMOS sensors of cameras in the future, the S35 or even 135 will be the way to go, since technology is improving and bigger the sensor is the better S/N (dynamic range) it gets. For cinematography though, I think we will stay on S35 for quite some time. Too many good lenses and accessories are out there for this format and all experience out there is based on it. Broadcast industry will move slowly to the bigger sensor size and they are the quantity users of the cameras out there so this is the force that can change a lot in this market.