Just a thought about 35mm adapters and ISO ratings

PaPa said:
how many zones do you alocate for video work? I know film its 0-10 5 being medium grey, but what aboud video for lack of latitude?
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The zone system is always 0-10. In video there always can be white with no detail, and black with no detail, therefore the zones should always be there. What you seem to be referring to is latitude.

Latitude is measured in stops and refers to how many stops it takes to go from zone 0 to zone 10.

And you are correct, film almost always has more latitude (although all film stocks are different) than video. It most definitely has more dynamic range.

The weakness video has is in the upper zones where the latitude seems to quickly rush to zone 10.
 
Papa,

It depends on the end result. Some people shoot their video flat, but add contrast in post (changing how it looks), thus reducing their range further. This is why people need to be a bit more detailed when planning out a video shoot.

Test Test Test!

I don't use zones personally, I just figure out the brightest highlight with detail, the darkest shadow with detail and then middle gray pegged around 50 IRE. You can get more detailed if you want. By the way, a "Zone" is simply an f/stop. Its just a catchy title really. 10 Zones = 10 stops. Get it?

To me, planning is a lost art in the world of digital cinema, at least in the lower budget indi world.
 
cardmaverick said:
You can get more detailed if you want. By the way, a "Zone" is simply an f/stop. Its just a catchy title really. 10 Zones = 10 stops. Get it?
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hmmmm that's not my take on the subject. That is how I think about zones with film, but not video.

Zone 0 is always no detail black and Zone 10 is always no detail blown out white.

I have shot video with both no detail black and blown out whites, which I know for a fact was not capable of a 10 stop latitude. Yes?


Everything has the potential to have all 10 zones but video cameras with limited latitude just accelerate through them faster.
 
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cardmaverick said:
To me, planning is a lost art in the world of digital cinema, at least in the lower budget indi world.
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You mean in regards to people who shoot or what? I'll be damned if I get called out for not planning ahead enough ;) Come on Chris! You need to get with the program here! heh
 
=Prodigy= said:
The weakness video has is in the upper zones where the latitude seems to quickly rush to zone 10.
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That "rush" you describe is a result of the signal processing in the camera (its a combo of how the gamma is handled, white balance, bit depth, etc..). Thats the beauty of newer cams like Red, you can determine the ultimate display curve yourself with greater flexibility.
 
Charlie Anderson said:
You mean in regards to people who shoot or what? I'll be damned if I get called out for not planning ahead enough ;) Come on Chris! You need to get with the program here! heh
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Hey Charlie!

I'm referring mostly to DPs and their cameras, but hey, it could apply elsewhere. I'm not pointing fingers at any one person LOL. I've meet some pretty plan heavy low budget production people around the DC/Baltimore area :)
 
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So what is accurate is that if you are shooting on a 10 stop latitude film stock or video camera then each zone does = a stop.

Yes?

Except not many video cameras with particular gamma settings can achieve a 10 stop latitude. HVX Cinelike D approaches the maximum the camera can pull.
 
=Prodigy= said:
hmmmm that's not my take on the subject. That is how I think about zones with film, but not video.

Zone 0-1 is always no detail black and Zone 10 is always no detail blown out white.

I have shot video with both no detail black and blown out whites, which I know for a fact was not capable of a 10 stop latitude. Yes?
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All I'm saying is 10 zones for 10 stops, when your shooting with a 10 stop camera that is. Sorry for the confusion.

Again, Zone System in video should be custom made. Lets say you have a setup that gives you 5 usable stops with detail, 7 stops when you include the black and highlight clip. Your complete custom zone system would be a 7 zone system. Make sense? I just don't always sit down and peg each zone on its own one at a time, I find the barriers, which actually do reveal the number of zones I have, because I can literally count how many stops fall between those two points.

This seems to another point of confusion with light metering for video, the whole approach needs to be adjusted and modified.
 
Yep you're definitely right. I was just trying to clear some confusion between what you and I were saying. I see that we were talking the same language the whole time.

:)
 
Not sure if I should dive into this yet, but....

When you start messing with cameras that shoot linear footage, you have several curves to take into account.

My camera has a good 9.5 stops linearly (or zones if you like). But I treat it as a 7.5 or so stop camera because of how my curves are set up to roll into the highlights and shadows.
 
i understand completely about there still being 10 zones, but im trying to configure something more specific to digital video capabilities. Yes you can still have 10 zones, but as you said, i would like to maintain the ratio of 1 zone = 1 stop, and since video does not have 10 stops, probably around 7. is it safe to say that there are 0-7 zones, 0 being black,

so zones:

0(black) - 1 - 2 - 3 - 4/neutralgrey - 5 - 6 - 7 - 8 (blowout)
 
Thats right, your still using one zone for each stop, but again, it depends on your camera settings/post corrections.
 
Well folks I looked at this thread as much as could digest and if you guys want to make custom charts for every gamma and figure different ISO's for them be my guest. I do suggest that you check the monitor before shooting though because you might just be off a bit.

Looks like a lot of work for my world and it doesn't fit any experience I have with professional video production methods.

On a normal set, you look at a shot you have lit pretty well then you paint the camera - adjust the gamma, knee, black level, black stretch, color sat etc, to optimize the picture - so you've just thrown your chart out the window.

I used to work with a film DP shooting video who lit the whole set like film with a meter with an aproximate ISO then at the end he looked at the monitor and made corrections and painted if neccessary. That makes sense.

NOTE * With 35mm adapters the exposure results are not linear as you change the 35mm lens f-stops. A stop is no longer a stop - forget everything you learned in film school. That's critical, light meter readings will be completely worthless at least with some of the adapters - certainly with a Brevis - they will absolutely completely worthless for setting exposure.

- Lenny Levy
 
i agree with everything you are saying completely, however if i were to use a light meter, as i stated before, it would only be to check my ratios and keep things within the digital range ( without using a monitor ) or having any camera on set to begin with.

i ran some tests on the XH A1 with an adapter, and it seems as though there are a solid 8 stops from black to pure white, therefor it would be 0 - 7 . 7 being pure white, and medium grey being at zone 4, so its not exactly in the middle. There is less room when you get into the high's, obviously, but this was a nice way to really see it for myself.
 
Lenilenapi said:
NOTE * With 35mm adapters the exposure results are not linear as you change the 35mm lens f-stops. A stop is no longer a stop - forget everything you learned in film school. That's critical, light meter readings will be completely worthless at least with some of the adapters - certainly with a Brevis - they will absolutely completely worthless for setting exposure.
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http://www.dvxuser.com/V6/showpost.php?p=1058387&postcount=12

http://www.dvxuser.com/V6/showpost.php?p=1058449&postcount=16

I haven't done extensive work with adapters, so I can't say too much about them ISO wise, but from those posts, I take it that this only applies to the host camera aperture....

IF thats correct, then by leaving the host camera aperture locked off, and only changing the SLR lens aperture, you should be able to use a light meter perfectly fine. Dennis, care to chime in here? Until I can try this myself, I'm purely speculating.

As for using a meter to determine ratios without bothering to figure out what your curve looks like, I'm a bit perplexed.

A three stop difference reflectively will produce different results depending on your curve.
 
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You know, I just did some more thinking, if the GG does in fact cause issues with the f/stop on the SLR lens, then maybe the best approach is to simply pick an f/stop on the SLR lens and only use that one f/stop. Many DP's shoot whole films at only one f/stop, so this isn't uncommon.

All exposure adjustments (including initial ISO rating) would then be made using the camera aperture instead. If you want to use different f/stops on the SLR lens, then you could just create a small list of f/stops and their ISO ratings, not too unreasonable.

Sometimes you just gotta think outside the box!

I'm very interested in testing that approach, I bet it would work out just fine too.
 
Lenilenapi said:
NOTE * With 35mm adapters the exposure results are not linear as you change the 35mm lens f-stops. A stop is no longer a stop - forget everything you learned in film school. That's critical, light meter readings will be completely worthless at least with some of the adapters - certainly with a Brevis - they will absolutely completely worthless for setting exposure.

- Lenny Levy
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Are you telling me that Nikon marked their lenses wrong? I think you are misinformed. Last time I checked professional photographers demanded their professional equipment be marked correctly. If a nikon lens says f2 and you dial it to f2.8 you better believe it's half the amount of light.

I know the lenses are not in T-Stops but they are accurate enough. Unless I have been sorely mistaken I think that comment is completely inaccurate.

And about the GG... does it matter what the GG does? It is after the light has passed though the lens. Think of it (the GG) like a rear projected movie screen. The native camera will record the screen at the same f-stop as long as the native camera aperture is not changed. Therefore if you are projecting a film onto a screen twice as bright it will show up twice as bright. If you stop down it will appear half as bright.

As long as the HVX aperature does not change, the light hitting the ground glass movie screen will be accurately doubled or cut in half depending on if you close down or open up. That is pretty linear.

I may have missed some crazy variable in physics, but I doubt it.

F-stops should remain 1/2 or 2x the amount of light (depending on if you are opening up or closing down)
 
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=Prodigy= said:
Are you telling me that Nikon marked their lenses wrong? I think you are misinformed. Last time I checked professional photographers demanded their professional equipment be marked correctly. If a nikon lens says f2 and you dial it to f2.8 you better believe it's half the amount of light.

Unless I have been sorely mistaken I think that comment is completely inaccurate.
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He's referring to the effect of the GG transmission, and its a perfectly valid point, but if you read my last post, that should, in *theory* solve the issue with using a light meter with an adapter. Perhaps Dennis could confirm this, as I don't have quick access to any adapters.
 
No - Please listen to what I'm telling you - I am being extremely clear but you do not believe me because you have not experienced it so you'll just believe what you want until you see it - however I have tested this many many times. I have been shooting for over 25 years - Panavision, Arri you name it.
For reasons I can only surmise have to do with the optics of looking at an image on a diffusing screen from a distance away, these 35mm adapters do not always respond to f stop changes on the 35mm lens in a linear way. They all vary in their own particular way and some are more linear than others. A Brevis for example will show NO CHANGE FROM f1.4 to f2.8 - no exposure change - no DOF change - at least on an HVX.
After that the f stops as I recall show more exposure change until they exceed 1 stop each .

Don't believe me if you don't want to, but i am tired of repeating myself so i'm signing off this thread.

Lenny Levy
 
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cardmaverick said:
I haven't done extensive work with adapters, so I can't say too much about them ISO wise, but from those posts, I take it that this only applies to the host camera aperture....

IF thats correct, then by leaving the host camera aperture locked off, and only changing the SLR lens aperture, you should be able to use a light meter perfectly fine. Dennis, care to chime in here? Until I can try this myself, I'm purely speculating.
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I'm with cardmaverick on this one.

I've shot many films with the HVX and M2 combo. The only thing I have witnessed even close to what you are describing is that I sometimes when stopping down from a f/1.4 to a f/2.8 I don't see a change large enough then what I expected, But I never chalked that up to the gg interfering with the lens. But I always assume I just over estimate the effect of a two stop difference.

And this is also the first time I have ever heard anyone mention this.

Edit: I do see a difference between a 1.4 to a 2.8... just sometimes not as much as I would have thought. I'm not sure that means the GG is causing this overestimation.
 
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