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Alternative Imaging Methods
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Old June 24th, 2006, 02:07 PM   #16
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interlaced raw footage
Roberto Lanczos is offline   Reply With Quote
Old June 24th, 2006, 02:21 PM   #17
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Roberto.

In my post I used your name when I should have used Tom. Never mind.

Okay a few more questions :-

Is your 35mm adaptor a flip version or are you flipping the image in post?

Are you capturing a digital signal via firewire or capturing via an analog input?


If you are flipping the image after capture then this may well be where things are coming apart.

Flipping the image in post brings with it some difficulties.

Simply flipping the image in your editor may work but many editors seem to have minimal facility for manipulating or adjusting the image without introducing faults or deterioration.

I tried flipping the image from an earlier Agus35 I built. While the image flipped okay in Premiere 6, there was a softening and it was necessary to de-interlace and when exporting to "movie" which creates an .avi file the field orders I think had to be reversed. It is a long time since I messed with this issue. Adjusting the contrast and grading the colours only made it worse.

I have encountered this vertical banding on another camera after I have adjusted the image. It was of a different form to yours but it was a vertical artifact and in the colours.

Premiere 6 and some other basic editors do not permit me to apply effects and adjustments to a higher quality as After-Effects did. When you adjust a highly compressed file directly, there will be more errors than if the file is uncompressed, the adjustments applied, then recompressed again on export.

If there are already some artifacts in the image, then these may become aggravated by applying adjustments to a compressed file.

I found the only satisfactory way to flip the image and do colour, contrast correction was to take the captured file into another computer which had After-Effects and use in part the method published here at dvinfo on creating the motion signature of film.

This involved importing the file, using the interpret footage function, selecting highest quality, selecting upper field first, importing a second copy of the same file, interpreting footage, this time using the lower field first.

The method described is for blending the fields and some frames I think and reproducing as 24P. In my case, I do not change the frame rate but simply use the composition in After-Effects to flip the image, letterbox it, (shot it in widescreen on a PD150) then export back out.

I have used the 25P frame rate as this is a simple division of the 50i of PAL video.

I can't recall now whether I reversed the field order on export or not. But the result from After-Effects when exported out to Microsoft DV was heaps better than Premiere 6.

I can't recall the title of the article now but it should be findable in the resources section of this site.

There are two related articles, one on replicating the motion signature of film, the other on achieving the look of film in terms of colour and saturation. The author preferred the look of Sony HDCAM so the method yields an adjustment towards the Cinealta look.

Hopefully this gives you some sort of a lead to a solution.

A quick and dirty test would be to hold the camera and adaptor upside-down and shoot a short file and see if this can be adjusted for colour and contrast but without the flip.

The soft areas in your .jpg image do show some blotches consistent with grain seen by the camera on the groundglass. How big is the area on the groundglass you are shooting. I use a frame on the groundglass of 24mm x 18mm for the PD150 4:3 frame and about 30mm x 18mm approx for the FX1.

If you are zoomed in onto a smaller frame on the groundglass, then individual specks on the groundglass are going to be larger in respect to the size of the image and may cause greater workload for the processing in the camera.

Your groundglass?. What grade of finish do you have. ie., 300 grit, 600 grit, aluminium oxide of 5 micron grade?? Tell us a bit more about this and there may be some other clues to be had.
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Old June 27th, 2006, 11:14 AM   #18
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Quote:
Originally Posted by Bob Hart
Is your 35mm adaptor a flip version or are you flipping the image in post?
I'm using my camera upside down. The image is recorded normally.

Quote:
Originally Posted by Bob Hart
Are you capturing a digital signal via firewire or capturing via an analog input?
Firewire

Quote:
Originally Posted by Bob Hart
Your groundglass?. What grade of finish do you have. ie., 300 grit, 600 grit, aluminium oxide of 5 micron grade?
I'm using the frosted CD from the Maxell 25-pack

I'm recording a 16x10mm area. I have have to go this close, otherwise i suffer from the black corners.


Here's what i have:

Sony DCR-TRV110 ( f=3.6 - 72mm / 1:1.4 @37 )
Minolta SR-7 "50mm" ( Auto Rokkor-PF, 1:1.8, f=55mm )


My rig is very simple:

Cam --- > (0.5x Macro)1.5cm away from -----> Frosted CD -----> SLR Lens





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I tried also, a lot of DV codecs, and the only one that gived me better results, was the latest version from MainConcept.

Using Canopus DV codec + ReInterpolate411 plugin, was a lot better, with amazing quality, but the vertical banding was still there.
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Old June 28th, 2006, 07:07 AM   #19
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I'm using the frosted CD from the Maxell 25-pack. >>>>>>>>>>>>>> If you hold this up to a strongly lit scene or in front of a lamp and look through it by eye, can you see things through it?

I'm recording a 16x10mm area. I have have to go this close, otherwise i suffer from the black corners.>>>>>>>>>>>>>>> This small an image is not going to be very sharp. I am surprised a f1.8 lens vignettes or has severe edge brightness falloff as you decribe. Silly question perhpas, but is this lens aperture set to wide-open. If it is not controllable manually, there may be a small lever in back of the lens which works the aperture. If te aperture is wide-open, there should be a big window of light coming through the back of the lens whe you look at it directly from behind. If there is only a very small window, then the aperture is likely closed to whatever the smallest setting is available in this lens for exampkle someting like f11 or f16 or f22 even.

If this is what is happening then if your camera is attempting to brighten up a low light situation, then the vertical banding could be a result from that. I get vertical bands from the JVC KYF50 when the light is very low and cam is on full gain.


Here's what i have:

Sony DCR-TRV110 ( f=3.6 - 72mm / 1:1.4 @37 )
Minolta SR-7 "50mm" ( Auto Rokkor-PF, 1:1.8, f=55mm )


My rig is very simple:

Cam --- > (0.5x Macro)1.5cm away from -----> Frosted CD -----> SLR Lens





------------
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Old June 30th, 2006, 10:54 PM   #20
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The 16x10mm area being recorded is the hotspot. The vignetting is just the edge of it. I'm not a pro but this sounds like a job for a condenser lens. Good Luck.
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