M2 Footage looks awful

Lenilenapi said:
I assume you realize that you are crushing your blacks out there with a -10 Ped level, but again this comes down to taste and it seems like you are going for a saturated intense look.
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Yes, I count that as one of my many mistakes. And yes, I was going for the saturated, black-shadows look--typical of good golf course still photography. My plan was to stick to -7 ped level but abandoned my plan (which almost never works out for me) when i saw how good the light was...also the difference in the blacks that I saw on m LCD and what they looked like once in FCP was *huge*. I never thought it would be that different. The blacks look great on the LCD. I'll learn not to trust them...or I guess I'll learn what I'm doing wrong in FCP.
 
That's a good one, I have the AI version and the AIS 50mm 1:1.4. The AI has a longer focusing ring who is good for 35mm adapter.
 
jdorsey said:
Thanks for the links. Looks like it's the dud of the bunch. 35-70 3.3-4.5 AF pre-1989. Time for a new one. I'm looking at a used 50mm f/1.4 Manual Focus lens.
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Yes, that is the one I had.....
I had one waaaaayyyy back in 1977....

The newer AF lenses are much better.
 
With regard to setting backfocus, I've been advised to make certain the 35mm lens is set to f16, while keeping the camera iris wide-open. This allows the camera to see the most grain for backfocusing purposes. (Maybe this is obvious to you guys, but it wasn't to me.)

If the backfocus is not precise, everything else is academic.
 
Barry_Green said:
Should make absolutely no difference whatsoever. Other than the in-camera filters being more convenient and dustproof, that is.
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If your argument is correct Barry, then using inbuilt nd could potentionally be better than using external nd? If that external nd is cheap?

In the way nd filters are rated, how does the internal nd stack up? (say on the HVX)
 
Ok I read through these threads and mulled it over. My instant reaction was Barry is correct. My initial thought was this: The eye of the camera is in the CCD block anything prior to that bends and shapes the image prior to the eye (CCD) seeing it and presents a final image which is read. That made perfect sense so I turned away from that point and considered how the image was being shaped before it hit the eye (ccd). lense ---- m2 gg --- achromat --- hvx lense --- nd --- eye. Then the alternative of placing the nd on the front of the 35mm lense. ND --- lense --- m2gg --- achromat --- hvx lense --- eye. Now I have no scientific fact in front of me as proof either is better, but I hypothesis by the following:

So the lense, m2 and nd shape the image different ways until it hits the eye (ccd).

OK so Argument 1. So if we shape the image this way: First the ND shapes the image by a reduction in light. The 35 mm lense then bends this image which lands on the spinning ground glass. The achromat and HVX lense are focused on the gg which further bend the image read by the eye (ccd).

And Argument 2. The 35mm lense shapes the image etc (same as above through to HVX lense) then the ND does it part.

Thus I hypothesis that it is possible that the image being shaped by the 35mm lense and adapter will be different if the light is reduced prior to it passing through them. I also believe though that the resulting effect would be miniscule and something that unless you were an optics engineer and knew exactly what to look for then it would virtually be inconceivable. Which would support Barrys result of no visual difference. My unproven conclusion is that ND on the front would be better though by such a fraction that - whats the point?

The greatest benefit to placing the nds on the front of the lense is control.
 
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Barry, it's not detail that necessarily get's lost "overexposing" GGs. Wax for example will sometimes "haze" over in very bright light...probably from light being diffused in all directions. Perhaps flourescing would be a suitable (but obvioulsy not physically correct) analogy. This glow has been observed in several of the wax based adapters...and to some shooters might even be considered an interesting effect.

With the Brevis, the issue is the potential for image hazing in very strong light...so to be safe, we always suggest external ND filters. I have used the camera's ND filters before with the adapter, and in many cases, they work just fine. It's the situations where hazing does appear that prompt us to recommend externals which work for us in 100% of the time.

That said, I've never had my hands on any other adapters, so my testing is based on the Brevis. Our optical setup is fairly unique to any of the ones you've tested.
 
It depends on the GG but I can say from first hand experience, that the Brevis and M2 do not perform as well when using the built in ND filters to control overexposure.



ash =o)
 
THoff said:
That may well be, but the camera's ND filter simply darkens an overexposed image that has already lost some (or much) of its definition when it was projected onto the GG of the DOF adapter.

If you were to put a ND filter in front of the lens attached to the DOF adapter, you'd get a better image.
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thats not how it works. The GG is a linear trandmission medium. It doesnt have a "overexposure" threshold. Its optical, not chemichal or Photosensitive digital. Unless theres somuch light hitting it that its catching onfire, there is no reason to limit the amount of light hittitng it. Alot of times the perfomrance of the adapter system seems to go up if you stop the 35 lens down because most 35 lenses perform their best stopped own, not because the GG was "over exposed". thats a myth. maybe the Brevis is different, but its not a problem in any adapter ive ever used.
 
I don't know if the Brevis technically overexposes, but it is bright enough that you want to put ND in front of the SLR lens when shooting outside. Yes, you can stop down enough, but you don't really want your lens at f16 if it works best at f5.6.
 
but this is my point, there should be no need to cut the light reaching the GG. (unless you want a deep DOF and like closing down to F8 etc) thats the same as exposing by dimming lights in your set instead of closing down the iris to get proper exposure. Why would you ever want to starve the system of light, the one thign it needs to work properly.?
 
TimurCivan said:
thats the same as exposing by dimming lights in your set instead of closing down the iris to get proper exposure.
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huh? Not sure about you, but I tend to light the set for a specific f-stop. That is what scrims are for.

As Dennis from Cinvevate expressed, some adapters will haze when too much light hits the internal optics of the adapters (they are not all just glass you are aware, right?) Why in Gods name use a 35mm adapter, and then filter incamera? I personally like using 1.2, .9,.6 or .3. Waaay more copntrol than the 2 incamera options.
Why buy that fancy $1500 mattebox, so you can just use incamera ND:huh:
 
If the Brevis works differently and hazes because it's a wax system, well, that's different. But I can categorically reject the idea that ground glass has any problems whatsoever with the amount of light that hits it, as I've proven by photographing the same scene at variations of light intensity on the order of 256x.

Can't speak to whether wax has similar issues, although I can't really understand why it would or should, and it'd worry me if it did; I'd want to conduct thorough testing under all circumstances to know what the issues were.

But ground glass is absolutely immune to any "overexposure" effect.
 
actually your right thats a bad example. cause i light to a specific fstop too. but im referring to a purely opticall standpoint. and whether or not a gg will function with X amount of light.
 
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Well in theory I have to completely agree with Barry on this, and my very very informal tests showed no difference.

However that said, I tend to want to give some creedance to Dennis who makes the Brevis and seems to be as much of perfectionist about improving his unit as any of us are about our pictures.

Dennis says he sees a difference. I haven't seen it yet but based on his word alone I want to spend some more time and check it out more carefully.

These 35mm adapters are strange beasts and have their own peculiear properties. Why does Dennis's CF3 diffuser screen produce noticably less DOF than his #1 screen at the same 35mm lens f-stops. It does not seem to make sense to me optically. I tried simulating the greater diffusion onfthe CF-3 by holding promists over the lens with the #1 screen but while it softened in a way similar to the CF-3 it did not affect DOF. So they are new beasts and we will all need to learn their peculiarities.

Here's another one I don't get. I begin to see the grain on the Brevis or Redrock screen as soon as my f-stop goes over f4. Why ?- I would think its because the increased DOF from the higher f-stop is maybe increasing my detail on the groundglass. Yet if I instead close down the cameras iris ( which you would think would have a similar affect) it doesn't bring up the grain of the screen. Why not?

Here's another one - This one is for you Dennis. I have 6 Nikkor f1.4 . Yet on both the redrock and the Brevis I see no increase or barely any increase in exposure from f2 to f1.4. What's up with that? Showed my lens to a repair man today qnd he wondered if the Nikkor mt is maybe not allowing the iris to fully open. There is a little thingamabob on the 35mm lens that could do this. I haven't looked yet tonight.

- Lenny Levy
 
You ask some very interesing questions Lenny. DOF is a function of optics, however how it's represented essentially on a rear projection screen is very much controlled by diffusion properties of the screen. The same holds true when folks make the observation that some adapters seem to increase dynamic range. While it's impossible to change the binary nature of digital capture, you can change how the out of focus areas (bokeh) scatter light...and the effect of enhanced range is apparent. I suspect that a study of the sharply in focus area of a frame only, would show no increase in range, for any adapter :-) The Brevis, with it's quickly interchangeable imaging elements, is an interesting test bed for these experiments.

If you look at a ray diagram of a stopped down lens, vs a fully open one, you can get an idea of what's going in with respect to the changes in the lights dominant angular approach to the GG. I believe this change combined with reduced intensity has more to do with grain and grain masking (regardless of how fine the medium) than anything else. To stop done a lens on the Brevis with no grain, you must have sufficient light to actually do this without grain showing up. In other words, underexposure will generally bring up grain.
 
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From this old thread (http://www.dvxuser.com/V6/showthread.php?t=82940&page=5&highlight=brevis+overexposure) regarding "overexposure" of GG:

Dennis Wood said:
Btw, I can't speak for the Letus, or it's ground glass but if you blast the Brevis stock imaging element with too much light (call it overexposure if you like) you will definitely not get the best image. You'll still get an image that may look OK, but you will at the minimum get hazing and some resolution loss (image will look slightly washed out). I have not tested CF2 or CF3 in deliberately "overexposed" conditions, but my advice would remain the same. The best explanation I can offer is that our optical systems (CF1, CF2, CF) are definitely optimized (respectively) for increased light levels.
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My personal, lame attempt at explaining the need for ND in front of an adapter is this:

1. As stated before, you may be wanting to shoot at a desired f-stop and have to use ND to get there.

2. The GG, while perhaps not capable of overexposing is a traditional film sense, is nonetheless *not* simply a linear transmitter of light. Too much light for some can lead, as Dennis states, to a kind of hazy look. The only comparison I can think of at the moment is when you watch something on a tube TV that is out of NTSC bounds and you get that sweet bleed.

But again, I'm a user and not a constructor of adapters.

Fox
 
Lenilenapi said:
Why does Dennis's CF3 diffuser screen produce noticably less DOF than his #1 screen at the same 35mm lens f-stops. It does not seem to make sense to me optically. I tried simulating the greater diffusion onfthe CF-3 by holding promists over the lens with the #1 screen but while it softened in a way similar to the CF-3 it did not affect DOF. So they are new beasts and we will all need to learn their peculiarities.

Here's another one I don't get. I begin to see the grain on the Brevis or Redrock screen as soon as my f-stop goes over f4. Why ?- I would think its because the increased DOF from the higher f-stop is maybe increasing my detail on the groundglass. Yet if I instead close down the cameras iris ( which you would think would have a similar affect) it doesn't bring up the grain of the screen. Why not?

Here's another one - This one is for you Dennis. I have 6 Nikkor f1.4 . Yet on both the redrock and the Brevis I see no increase or barely any increase in exposure from f2 to f1.4. What's up with that? Showed my lens to a repair man today qnd he wondered if the Nikkor mt is maybe not allowing the iris to fully open. There is a little thingamabob on the 35mm lens that could do this. I haven't looked yet tonight.

- Lenny Levy
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Thats interesting. MAybe the GG is thicker, and more of the circle of confusion, is coming into the GG surface depending on where the HVX is focused on.???? Thats cool actually. :)

Also the batteries might be low on the M2 and brevis. With fresh batteries the SGpro can go down to F22 with no grain, but after an hour or two, it shows up at extreme Fstops. keep fresh batteries with you.
 
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