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B&W Neg. vs Reversal


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#1 Ray Friera

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Posted 14 June 2008 - 08:14 PM

What are the advantages in shooting Plus-X negative film vs the reversal film other than the neg. got more latitude? I read somewhere that Plus-X 7265 reversal film has finer grains compared to Plus-X 7231 negative film. Is this true, or this is just in theory? Should anyone have any experience using these films, pls. help clarify.
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#2 Satsuki Murashige

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Posted 15 June 2008 - 02:41 AM

Hi Ray,

You've got it right - Plus-X reversal (7265) is much finer grained than Plus-X negative (7231). The reason is that the reversal stocks (Plus-X and Tri-X) are modern emulsions that have been updated only several years ago, so there is less silver in them and thus less visible grain. They do render a different look than the negative, so you should test them both to see which look you prefer. Also, the process by which reversal film is developed helps to lessen the amount of visible grain compared to negative film. Plus-X and Double-X negative emulsions have not really changed since about the 1950s, so they do not incorporate the technological advances that are in Kodak's more modern filmstocks.

I can however think of one advantage that negative has over reversal - assuming that you will be projecting your footage, you would be making a workprint from your negative and projecting that. Thus, your camera original is safe from further damage. With reversal, you would be projecting your camera original (unless you made a workprint, which is more difficult and expensive with reversal). The reversal stock is quite a bit stronger than negative stock but you can still scratch it or tear it up if you're not careful.

Edited by Satsuki Murashige, 15 June 2008 - 02:42 AM.

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#3 Ray Friera

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Posted 15 June 2008 - 11:15 PM

Hey Satsuki,

What is the ASA rating for Pus-X reversal when processed as negative? How much latitude gained? What about the grain structure,
is it comparable to 7231 Plus-X negative film?
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#4 Satsuki Murashige

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Posted 16 June 2008 - 01:41 AM

I have no idea, never even thought about doing that before! After you test it, please let me know the answers. :)
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#5 Brian Pritchard

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Posted 01 July 2008 - 03:48 PM

Hey Satsuki,

What is the ASA rating for Pus-X reversal when processed as negative? How much latitude gained? What about the grain structure,
is it comparable to 7231 Plus-X negative film?

The Kodak Booklet om B/W Processing states ' Reversal films lose 2/3 stop when processed as negative.' It recommends overexposing by 1 stop but says you can use the latitude of the film and overexpose by 2 stops but you might have to adjust the processing.

Hope this helps
Brian
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#6 Jim Carlile

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Posted 10 July 2008 - 01:42 AM

Of course you can also process any negative B/W stock as reversal, too, but it's way off by a couple stops and the contrast is off as well. But it will work with some tweaking.

You can also shoot positive B/W print stock in the camera to save money but the ASA is way down low. But it has been done successfully and this used to be a standard practice years ago, as was "reversing" negative for amateur use.

The thing to do is get the double perf 2000 foot core from Kodak and then spool down to smaller camera loads. The double perf allows you to obtain the correct camera wind merely by spooling it around in the proper direction.

This can be a very cheap and effective alternative for gonzo or low budget B/W productions.
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#7 Robert Houllahan

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Posted 10 July 2008 - 02:44 AM

Of course you can also process any negative B/W stock as reversal, too, but it's way off by a couple stops and the contrast is off as well. But it will work with some tweaking.



X-Process of negative to reversal does tend to get muddy and a bit grainy, but X-Process Reversal to negative is really nice, retains all of the qualities of reversal stock but is a negative. I shot a 360 fps shot for a short I am neg cutting and answer printing right now, used Tri-X rated it a 160iso and carefully measured fc. We X-processed it and I could not be happier with the shot which cuts from 7231 to tri-x at 360fps and back to 7231..

-Rob-
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#8 Ira Ratner

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Posted 20 July 2008 - 09:39 AM

I shot a 360 fps shot for a short I am neg cutting and answer printing right now...

-Rob-


Can I ask an amateur question? A really stupid one?

Shooting so many fps gives you better quality, correct? So is it resolved in your answer print? Or when you Telecine?

See--I told you it was going to be stupid.

Edited by Ira Ratner, 20 July 2008 - 09:40 AM.

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#9 Damien Bhatti

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Posted 24 July 2008 - 02:59 PM

I have bought some plus x and 7222 off of ebay and when I was comparing how much money i saved on a shop website in the UK, they state that with 7222 it virtually has no latitude and should be basically treated like a reversal stock; having the exposure spot on. Is this correct? I thought that negative by default has more latitude than reversal? Thanks,
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#10 K Borowski

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Posted 26 July 2008 - 03:54 PM

Can I ask an amateur question? A really stupid one?

Shooting so many fps gives you better quality, correct? So is it resolved in your answer print? Or when you Telecine?

See--I told you it was going to be stupid.


Well it could be better quality, if there were some way of projecting it at 360 fps available to the masses, but no I think Rob was probably just going for a high degree of slow motion.

It works like this: the higher the frame per second count over 24 (or 25 in Europe or 30 if you're shooting 30fps for specialized TV commercial work), the slower the footage moves when played back in comparison to it's actual real-life speed.

48 fps (with 24 fps projection) would render the motion of the subjects or objects in frame as playing back with half of their normal speed.

Conversely, any frame rate lower than 24, 25, or 30 will appear to move faster. A classic example is the timelapse footage you'll see of streaking car taillights at night or a plant growing at a highly accelerated rate, where they're only shooting one frame every couple minutes or hours.

So 12 fps would render the motion of the subject as twice as fast as in real life. You can also vary the actual exposure time of the frame by varying the f/stop, shutteer angle in some cameras (like shutter speed with still cameras), and in time exposure actually just stopping the shutter and exposing the film for very long lenghts of time. Remember the first photograph took nine hours of continuous exposure!


Hope this helps!

~KB
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#11 K Borowski

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Posted 26 July 2008 - 03:59 PM

I have bought some plus x and 7222 off of ebay and when I was comparing how much money i saved on a shop website in the UK, they state that with 7222 it virtually has no latitude and should be basically treated like a reversal stock; having the exposure spot on. Is this correct? I thought that negative by default has more latitude than reversal? Thanks,


No, I think that is incorrect. Plus-X won't have as much latitude as Double-X probably, as it is a slower film, but it'll have more than even Tri-X reversal, and you'll be able to do a greater degree of pushing, pulling, and pulling information out in digital or optical post, so negative is all-around more versatile than negative film at the expense of slightly coarser grain (though not much with Plus-x negative) and a greater degree of post work in the printing stage.

B&W Reversal's original design was for the allure of being able to pull the film out of the processor, maybe still wet, after you'd hurriedly driven back to the TV station and thrown it into the machine, to get it onto the 10 o'clock news that night. No printing, sound-striping, or post work necessary except for maybe a few cuts and splices with a pair of scissors and some splice tape!
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#12 Brian Pritchard

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Posted 28 July 2008 - 02:53 AM

The latitude of a film depends on the length of the straight line portion of the characteristic curve, the contrast of the film and the brightness ratio of your subject. Kodak Plus-X negative and Kodak Double-X negative have very similar characteristic curves as far as length is concerned. They will accommodate an exposure range of roughly 1 to 100. If the brightness range of your subject is 100 to 1 then there will only be one correct exposure and no latitude; if the brightness range is 1 to 10 then you will have a wide latitude of exposure. Changing the development time will change the contrast of the film and will change the latitude. As the contrast goes up the latitude goes down. Black and white reversal films are processed to give a projection contrast result and are therefore much higher contrast than a negative film and will have less exposure latitude.


Brian
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#13 Leo Anthony Vale

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Posted 28 July 2008 - 03:31 PM

B&W Reversal's original design was for the allure of being able to pull the film out of the processor, maybe still wet, after you'd hurriedly driven back to the TV station and thrown it into the machine, to get it onto the 10 o'clock news that night. No printing, sound-striping, or post work necessary except for maybe a few cuts and splices with a pair of scissors and some splice tape!


The original design back in the 20s was for the allure of home movies.

TV news came much later. & some stations shot on negative and reversed the polarity of the image during broadcast.
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