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Topic: Help needed in identifying a test film

Richard Fowler
Film God

Posts: 2392
From: Ft. Lauderdale, FL, USA
Registered: Jun 2001

posted 12-27-2004 09:44 AM

The SMPTE 9KHZ is out of stock and has been for a couple of years. I have clients who still prefer to have this film as part of their kit....

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John Hawkinson
Film God

Posts: 2273
From: Cambridge, MA, USA
Registered: Feb 2002

posted 12-27-2004 11:05 AM

Sigh. I said, " I don't remember exactly how far off it was, but I seem to recall that, in comparison with a strobe, the 1k tone was off by almost 100Hz". That'll teach me to trust my memory.

Steve replied, "As to its accuracy...it was not off by 100Hz (in the batches I used). I think it came in at somewhere around 997 at its worst...and closer to 1K most of the time.."

I seem to be having trouble interpretting my fragementary notes from when I did this, but it looks like the 1k tone I had was somewher around 982Hz. Sorry for any confusion.

--jhawk

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 12-27-2004 11:13 AM

Tim almost everyone who did any large amount of alignments has been aware of the issues with the pinknoise and tone inconsistancies for a very long time long before the unamed wrote his article

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Michael Schaffer
"Where is the
Boardwalk Hotel?"

Posts: 4143
From: Boston, MA
Registered: Apr 2002

posted 12-27-2004 01:58 PM

quote: Steve Guttag
For instance...Cat. 69...no two batches have ever been the same, B&W or color....however much of the color stuff has had some significant problems (poor HF response...so-so balance on the tones)

Why is that? I understand why the absolute level can drift on both b&w and color stock and therefore affect the level setting, but isn't HF response irrespective of the level and only a matter of optical resolution? Or is that the problem, that the films are simply not printed with enough detail resolution in the HF area anymore?

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 12-27-2004 02:17 PM

quote: Michael Schaffer
Why is that? I understand why the absolute level can drift on both b&w and color stock and therefore affect the level setting, but isn't HF response irrespective of the level and only a matter of optical resolution? Or is that the problem, that the films are simply not printed with enough detail resolution in the HF area anymore?

HF response is also a function of exposure (which also affects distortion) and slippage in the printer. On a color print film, the topmost (magenta) imaging layer is the sharpest, with the middle (cyan) layer close behind. The bottom (yellow) layer is the least sharp and most grainy, and is not used for analog soundtracks. Here is the MTF curve for Kodak VISION Color Print Film 2383:

http://www.kodak.com/US/en/motion/products/print/2383.jhtml?id=0.1.4.8.4.7&lc=en

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 12-27-2004 02:19 PM

I am not familiar with Dolby's process or quality control procedures with their test films to comment on why they have poor batch to batch consistency. That is a question for them.

I can only state that they do not have good consistency and as you may have read already, we are not the only ones to have noticed and measured it.

You compare that to say 35-PA and P35-BT from SMPTE where they are camera orignal films that are measured. Note too that the cost of a Dolby test film is substantially less than either of the films from SMPTE. Even Schneider's target film is near SMPTE's price and is pretty darn consistant from batch to batch.

I have not located any test film documentation on the SMPTE P35-SL (other than catalog pages). Maybe our document master, John Pytlak has the instruction documents on P35-SL and the method of its manufacture.

As a side note, The outboard (high) "tone" on P35-BT (Buzz track) is supposed to be 1KHz.

Steve

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 12-27-2004 02:43 PM

I can not find a Recommended Practice specifying P35-SL. A sample I have has a peak-to-peak excursion of 1.50mm out of the scanned width of 2.13mm specified by SMPTE 40. The width of the clear area on the P35-SL track I have measures 1.93mm, which agrees with SMPTE 40 (D-C = 7.14-5.21 = 1.93mm)

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 12-27-2004 03:07 PM

I have often wondered why pink noise and 50% mod tone could not be recorded as a full width Mono VD track at 50% modulation and the negaive be used as the finished test film as a vd track at 50% mod should be identical to the print in density?
Being a full width mono azimuth should be mutch easier to attain as well

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