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Old February 11th, 2006, 04:25 PM   #61
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Steev, now that you've played with the MPIC a bunch, how would you characterize light loss with your assorted primes? We're seeing close to 0 apparent light loss with the beattie (50mm F1.4)...just curious if you're seeing the same.
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Old February 11th, 2006, 05:34 PM   #62
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It's a few stops. I don't think there's any way around losing some light, even with a Beattie. At least this is the case with the HVX200 now.
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Old February 11th, 2006, 06:31 PM   #63
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Right, even a lens has light loss (5-7% even, for uncoated glass).

Denis have you seen my light loss tests? I would be curious to see if someone with a beattie can do a light loss test (as outlined in the alternative screen materials thread) in comparison to a GG, thin-film, wax, etc.
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Old February 12th, 2006, 10:38 AM   #64
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Alain, somewhere in these threads another user had reported near zero loss with a beattie. What we have realized is that test conditions vary with the cam on a chart almost always showing less light loss than in the field. So 0 f/stop loss under an ISO chart test might turn up to be 1 or 2 when less than ideal conditions are faced.

Dan had reported the MPIC at 0 light loss, and under some conditions, I believe this to be true. Yes, light is lost at a minimum of 7% for any uncoated glass surface. Let's not forget though that we are videotaping a projected image. It's entirely possible for that image to be concentrated in one area, then captured by another optical system to represent a gain over what the cam would choose without the adapter.

With Steve reporting 1 or 2 stops and Ben reporting similar, I suspect that under test conditions (shooting a chart) the MPIC may very well show no relative loss of light with an F/1.2 or F/1.4. From these reports, one might theorize that under normal shoot conditions (and with an F1.4 lens) 1 f/stop loss might be more accurate. Obviously, most longer primes are at the F2.8 or above range...therefore another stop or two for MPIC and the host of adapters to follow using a Beattie.
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Old February 12th, 2006, 01:14 PM   #65
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Denis, you are correct. But as you mention all the assesements are subjective. I really don't know what exactly "near zero light loss" means. It could be 1% or it could be 12%. (0.01 and 0.12 can be considered near zero quantities)

That's why I have proposed more objective methods for testing in the Alternative Screens thread.

There is no way around light loss, it's just physical reality. Photons will scatter, reflect and not get to the CCDs. You can only minimize your losses. Lighting conditions do not affect this, light will get lost at the same rate independent of how much light you have on the set.

Saying that some adapter loses a given number of stops has, up to this point, been done very subjectively to the best ability of the users. A test that does not depend so much on our perception would be far more precise.

This is why I am waiting for someone to do a lightloss test with a beattie using my procedure (or something like that). I offered the testing software for free and I am even offering to do the analysis for anyone that can take a picture of a Beattie against a computer monitor :)

All the details are here:

http://www.dvinfo.net/conf/showthrea...824#post429824
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Old February 12th, 2006, 01:23 PM   #66
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Alain,
I love the work your doing in this area, I really do. Creating a standard method of testing is whats needed, taking away subjective opinions from users perceptions making their way into the final results of the tests.
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Old February 12th, 2006, 01:27 PM   #67
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Quote:
Originally Posted by Wayne Kinney
Alain,
I love the work your doing in this area, I really do. Creating a standard method of testing is whats needed, taking away subjective opinions from users perceptions making their way into the final results of the tests.
Wayne, thank you for the vote of confidence :)

We really need to do this. And unless we do, we will just keep making guesses.


PS. When was the last time you bought a memory card that instead of saying 1Gb, it just said "Pretty big memory card" ?
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Old February 12th, 2006, 01:36 PM   #68
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Quote:
Originally Posted by Alain Bellon
...it just said "Pretty big memory card" ?
Costco was having a sale on those. I think the tag said something like "pretty expensive."

I have to adjust the position of the GG on my unit, so I'll be taking the Beattie out anyway, and I might be able to do one of your tests. The only thing is, I can't take it out of the slide thing (it's glued in well and I can't risk tussling with it) so there's about a half-inch border around the screen, so you won't be able to take samples directly next to one another. The monitor should be pretty uniform however.

What's this 180RGB you speak of? How do I create it?

Another note to consider: the placement of the camera will change how much light hits it. The fresnel lens on the Beattie makes the viewing angle very directional. So I wouldn't trust these results too much.

Also, a quick question: If my image reaches infinity focus before I reach the infinity marking on the SLR lens, which way do I need to move my GG?
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Old February 12th, 2006, 02:23 PM   #69
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Please can we get back on topic, or split off?

Thanks,

steev
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Old February 12th, 2006, 06:10 PM   #70
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So Steev, what's the topic? Our friend Dan has been suspended for more than a month. His own message board is down and and he doesn't seem to receive my emails. Wonder when things will come back to normal...
So how about the MPIC 35mm imager? Is it that good? Better? Can you shoot a side by side by side by side by side to compare with the other adapters? (or should I post that question on the ultimate 35mm adapter thread.)
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Old February 12th, 2006, 06:28 PM   #71
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I was just curious myself about the light loss of the Beattie, which I thought is what the MPIC uses anyway.

I think, and Steev knows this too, that a moving focusing screen like the Beattie is leaps and bounds ahead of any other focusing screen in terms of usability. The sharpness and light loss allows for more shooting conditions and personally I encounter no issues when combining both adapter and non-adapter footage.

And that, I think, is my summary of the beattie which will hopefully lead us back "on topic." :)
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Old February 13th, 2006, 01:15 AM   #72
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Quote:
Originally Posted by Oscar Spier
So Steev, what's the topic?
The topic is Dan's MPIC 35mm Imager. If we are to discuss the light loss characteristics of the Beattie screen, I'd think the topic would be "Light loss of Beattie screen". And I was thrown off by the comment about memory cards, but I see now it was a point of comparison.

Quote:
Originally Posted by Oscar Spier
Our friend Dan has been suspended for more than a month. His own message board is down and and he doesn't seem to receive my emails. Wonder when things will come back to normal...
I can't comment on any of that there, but if you email Dan with interest in his products, I would assume he would email you back.

Quote:
Originally Posted by Oscar Spier
So how about the MPIC 35mm imager? Is it that good? Better? Can you shoot a side by side by side by side by side to compare with the other adapters? (or should I post that question on the ultimate 35mm adapter thread.)
I think the MPIC is built really well, professional fit and finish, and has low light loss (I don't techinically know how much), and has a very crisp image, with no visible grain on DV, and very little visible grain on HD. You can see a little bit of grain on very bright lights every once in awhile, but to me it's not a big deal. It's a big improvement over my static Beattie adapter I made. It's also a more pro solution with the Nikon mount, plate, rails, gears and follow focus. Very well done.

I would like to get an M2 by Red Rock and contrast and compare, since I've been impressed by the images I've seen. I'd like to test how the M2 handles stopping down of lenses. I'd also like to try the production G35 unit once it ships. The Letus flip has me cautiously intrigued as well. If I did get a chance to try all of them, I would anticipate reporting how all of them yield an awesome image, and I would not be aiming to come up with a winner or defining one as being the best. I have a massive respect for the work that has gone into these things. I'd hate to fall into the trap I've seen elsewhere with camera wars.

Quote:
Originally Posted by Ben Winter
I was just curious myself about the light loss of the Beattie, which I thought is what the MPIC uses anyway. A moving focusing screen like the Beattie is leaps and bounds ahead of any other focusing screen in terms of usability. The sharpness and light loss allows for more shooting conditions and personally I encounter no issues when combining both adapter and non-adapter footage.
Agreed. ;)
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Old February 13th, 2006, 08:05 AM   #73
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Bokeh

A Beattie may be great in terms of sharpness and light loss, but the fact of the matter is it doesn't diffuse enough. A point source of light should become a distinct disc in the shape of the lens aperture when it's out of focus.

With the Beattie, as I found in my own experimenting and as evidenced in Steev's footage, the streetlights (for example) have a hazy halo. Personally, the discs of light from a properly diffused bokeh are my favourite thing about shallow DOF, and Beattie, Nikon D, Optosigma 1500 or other finely ground GG just don't diffuse enough for that, and the bokeh becomes a hazy mush (regardless of whether it's static vs moving).

Then again it's a trade off against light loss and comes down to personal taste at the end of the day. Unless you can find the right brand of plastic bag. :)

To illustrate what I'm talking about, here's some grabs from my own oscillating adapter which I'm still messing with.

Beattie bokeh example:
http://imagedump.filefactory.com/full.php?id=2514

Approximately the same shot with two face to face Optosigma 1500 GGs showing increase in light loss but properly diffused boken and "discs of light" (static, no condensors):
http://imagedump.filefactory.com/full.php?id=2515

Same shot oscillating (the two GGs are too heavy and don't oscillate enough so there's still some grain):
http://imagedump.filefactory.com/full.php?id=2516

Last edited by Andy Gordon; February 13th, 2006 at 08:53 AM.
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Old February 13th, 2006, 10:37 AM   #74
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From what I've seen so far substances like the POC LSD20 appear to diffuse too much. Specular highlights are thus "mush" when you rack through them. I think the mush effect may be the result of diffusion that is actually too effective...but I'm no expert.

In my less diffuse GG's, the same highlights are growing "balls of haze" with a definite second halo that grows as you rack through them.

My theory here (soon to be tested out btw) is that the halo is coming from secondary reflection compliments of the GG polished face.

So back to the MPIC topic. Steve, could you post a focus rack through a point source of light? A light reflection off a wine glass at 1 foot to infinity? Humour the tech heads out here....
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Old February 17th, 2006, 04:25 PM   #75
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demo

Steve,

Can you post some clips shot on MPIC & HVX200?

Thank you,
Hari
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