SGpro doubts

The machine has little to do with one's ability to pull focus.
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I disagree. I recently shot a short with the SGpro under some pretty tough lighting conditions due to limited equipment and we were forced to shoot at f/1.4 which made the focus pulls near impossible with the amount of time we had to rehearse. If I had been using the Brevis I would have been able to shoot all the way down to f/4.0 with similar light loss to the SGpro (since light loss on the Brevis is the same from f/1.4-f/4.0), and mind you that in terms of perceived depth of field, f/4.0 on the Brevis looks like f/8.0 on the SGpro/LetusEX.

The circumstances of the shoot were some that I will try to avoid in the future because I hate working like that, but I'm just trying to point out a situation where the Brevis would have made things easier.


Marco
 
I can do a HVX Brevis vs. SgPro rev.3 soon if you guys want that.... My bud just got his HVX and new brevis so it would not be a problem.


Jon
 
if you can try to check out the Brevis flip on the SGPro Rev 3.
I'm doing that on a Rev2 but I don't know if the fit is the same. It would be good to compare notes.

Marco, Very good points. There are pros and cons to all of these adapters and situations that suit them each best.


Lenny Levy
 
my productions will always be small low budget things and though i hope to buy proper lighting in the next year i don't currently own any and i'm about to relocate from Japan to Canada anyways. I'd like to get an adapter soon and shoot some nice footage while i'm still here so that having been said, low light and ease of use probably reign supreme.

If this is the case, people would recommend the Brevis, right? I like the SGpros ability to stop down in bright conditions but honestly thinking i'll probably be in lowlight more often then too much light situations.
 
this F1.4-4.0 losing the same light buisiness sounds fishy to me..... also if its "apparent" DOF is deeper that just means something is wrong.....

the SG looks like what a film camera would show. linear stops, linear increases in DOF. i can pull focus with a tape measure, and use a DOF calculator, and its all accurate. ITs a pro tool.
 
Timur:

I love the Brevis and I love the SGpro. They each have different advantages.

I never use a DOF calculator, or a light meter, or a tape measure for that matter, but that's just me. My footage is always in sharp focus and properly exposed because I have other methods (zebras, waveforms, using an HD monitor to set marks, etc.) So I don't see your points as a disadvantage for the Brevis. If a person is a film veteran that doesn't want to change habits then yeah, maybe the Brevis will seem odd.

But the fact remains that since digital camcorders are not yet very light sensitive (HVX at 320 ISO minus the light loss from the adapter) it can be invaluable to have a tool such as the Brevis that treats light and depth of field in a quite nontraditional way to let you work better in difficult scenarios.


Marco
 
Tim, if you just phrase it the other way - the SG's "apparent DOF "is shallower does that sound fishy? Apparent DOF varies with the amount of diffusion. If anything I suspect the SG is decreasing the technically accurate DOF, and the Redrock even more so.

All these affects are just the optics of adapters in the real world and they've been well documented. There's nothing "fishy" or "non-pro" about the Brevis or the SG. I had hoped these arguments had died down and we just accepted how these tools work. BTW the SG is my favorite looking adapter and I generally prefer it when its appropriate.

Have you really found the SG's DOF to be accurate with a DOF calculator? That's interesting to me as I've wondered whetehr they really applied. What calculator do you use and what size circle of confusion? And then how large a video screen do you use to determine whether it was accurate?

I might be worng about this but my understanding of DOF is that to some extent its arbitrary where you set the circle of confusion that determines when something is out of focus, and that depends on what the expected viewing conditions are. As I recall in the ASC handbook, 35mm has a larger circle of confusion than 16mm for example. That makes me think that video is even more arbitrary. How big is the monitor? Is it for projection, Blow-up, etc.? But I'm not too clear about that issue and maybe there is a more precise meaning. I might be completely off base.

Lenny Levy
 
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TimurCivan said:
this F1.4-4.0 losing the same light buisiness sounds fishy to me..... also if its "apparent" DOF is deeper that just means something is wrong.....

the SG looks like what a film camera would show. linear stops, linear increases in DOF. i can pull focus with a tape measure, and use a DOF calculator, and its all accurate. ITs a pro tool.
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I'm glad I'm not the only one that finds the light business fishy. You can cheat death, but you usually lose an arm or a leg in the process.
 
Can anyone else other than the manufacturer verify the 1.4 to 4.0 "no change" on light loss theory? I saw the the link. Not that I don't trust Dennis but it's always good to hear an unbiased report. In a weird way it makes sense but I really want to hear from other Brevis owners who've tested this phenomenon.

Also, regarding the light loss of the SG, it's something you need to test or know (in ASA terms) before bringing in the whole shoot party. For large night exteriors if you want to shoot above a 2.0 at 1/48th, 24fps you'll need 2.5k HMI's or above. 1.2k's wil force you into 1/24th or wide open - neither of which I find worthwhile. For interiors, I find myself using 1k baby's to backlight where I'd use an inky.

So yes, it does take a little more firepower. But I'm one of those veterans who started with black and white reversal plus X (see wikipedia), so lighting for the SG is not traumatic - just more juice.

The thing you have to balance is at what point does my lighting package equal or surpass renting a better camera/adaptor (ie. Varicam/PS tech)? So in short, I see these adaptors ideally for small productions. And in some cases (large night exteriors or day interiors) the SG may prove too expensive to light.

It makes a great case for owning two. One will eventually go down (happened to me three times already with both brands). So get one for speed and one for high fstops/shutter and bokeh.

If I could only afford one, it'd be a coin toss. If I was doing primarily run/gun, no decent lighting budget, I'd lean towards the Brevis.
 
I'm glad I'm not the only one that finds the light business fishy. You can cheat death, but you usually lose an arm or a leg in the process.
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What is that supposed to mean, that there must be a catch? I've used the Brevis extensively and there has never been any drawback to the way it handles light and diffusion. The only thing I dislike about the Brevis is a problem that plagues all vibrating adapters: that you can't stop down all the way.


Marco
 
I completely agree with Tim about the value of owning two for exactly those reasons. If you only can afford one like most normal people then you need to make your choices.

Tim alot of people chimed in to verify the light loss thing on that long testy and difficult thread a short time ago. I haven't looked at f4 but I am certain about 2.8. Not a single Brevis user said it wasn't true and not single one reported any bizarre light affects. Marco is typical of them. I hope to finally post some grabs within the week to lay it all to rest.

Lenny Levy
 
marco0782 said:
What is that supposed to mean, that there must be a catch? I've used the Brevis extensively and there has never been any drawback to the way it handles light and diffusion. The only thing I dislike about the Brevis is a problem that plagues all vibrating adapters: that you can't stop down all the way.


Marco
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It's not defying physics, there's a reason it happens and when someone finally shows what's going wrong with the image everyone's gonna go "Oh. Now I see it."

You can't possibly expect the image to not be suffering in some way from it. You may not SEE it, initially, but there's something wrong.

Edit-- But then again it's like Audiophile's say (And MacGregor at one point): If you can't hear it/see it, it really doesn't matter which one you choose.
 
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I believe it exists - not in a Santa like way. I just would love to understand how it exists. I don't even need to hear from unbiased folks. Just want an explanation. Something tells me it has something to do with not using the entire field a 35mm still lens is capable of. But who knows. Perhaps the inventor can explain it.

Maybe it's just a run of the mill miracle. You know, Shroud of Turin stuff.
 
It's not defying physics, there's a reason it happens and when someone finally shows what's going wrong with the image everyone's gonna go "Oh. Now I see it."
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Physics doesn't state that there is only one good way for light to be captured.

You can't possibly expect the image to not be suffering in some way from it. You may not SEE it, initially, but there's something wrong.
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What makes you think that there's something wrong? It doesn't sound like you have any good reason except that you can't comprehend the existence of something that is different. Remember, NONE of these 35mm adapters treat light the same way as film. NONE of them have the same exact response to light or the same exact depth of field characteristics. The Brevis is the one that's the most far out there, but even a P+S Technik still isn't exactly like film because film and ground glasses are completely different and affected by different variables.

Edit-- But then again it's like Audiophile's say (And MacGregor at one point): If you can't hear it/see it, it really doesn't matter which one you choose.
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That doesn't even make sense. Maybe if you were talking about 4:2:0 vs 4:2:2 or MP3 vs WAV. It's pretty pointless for you to keep speculating that there must be some kind of catch to the Brevis' unique advantages. If you haven't used it and you're going to ignore people that claim they have significant experience with it and other adapters, then that's your loss I guess.


Marco
 
Tim if you read through that long thread there were a couple of good possible explanations offered. if I can find mine I'll email you , but i don't want to redo the whoile thing again.

One person who posted there observed that if you have a 35mm SLR look through the viewfinder as you close down an f1.4 lens and you may see that the first few f-stops don't seem to show the expected full stop of light change each. Gradually the difference per stop becomes more noticeable. I believe this is the same phenomena, but it may vary depending on the GG of your still camera. If you exposed film in that camera you would get an absolutely predictable full stop though.

Lenny
 
Exactly Lenny, and also the reason why in a film camera you can't trust the ground glass to show if the image is in focus; you HAVE to use a tape measure.


Marco
 
marco0782 said:
Physics doesn't state that there is only one good way for light to be captured.



What makes you think that there's something wrong? It doesn't sound like you have any good reason except that you can't comprehend the existence of something that is different. Remember, NONE of these 35mm adapters treat light the same way as film. NONE of them have the same exact response to light or the same exact depth of field characteristics. The Brevis is the one that's the most far out there, but even a P+S Technik still isn't exactly like film because film and ground glasses are completely different and affected by different variables.



That doesn't even make sense. Maybe if you were talking about 4:2:0 vs 4:2:2 or MP3 vs WAV. It's pretty pointless for you to keep speculating that there must be some kind of catch to the Brevis' unique advantages. If you haven't used it and you're going to ignore people that claim they have significant experience with it and other adapters, then that's your loss I guess.


Marco
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This has nothing to do with film: It has to do with manufacturing and engineering. We can go 'round about it, but until someone with an objective opinion on the subject gets a Brevis and shows exactly what it's doing, saying that it's some sort of advantage is improper and misleading.

The closest explanation that I can see making sense is the ground glass properties being too transparent. Yeah, if that's the case, then stopping down the lens won't really matter too much because the image is ghosting on the HVX lens. Your colors, contrast, etc are dripping right onto the glass behind the ground glass and you're losing what makes the image an image.

Change the screen in your Brevis, as an experiment, and tell me if your contrast, highlights and color look a bit more pleasing.

You have a movie projector? A screen? Trade your screen out for a white sheet and project your favorite movie. Tell me how washed out and flat it looks. Then stand up and go and look behind the screen to see where the rest of your image is going: to the wall.

Now put your screen back up and see all of your image properties being netted by an adequate screen. That's not exactly apples-to-apples, but the same principal applies in that you need something to net the image to be displayed properly. With the ground glass it can only be so transparent before you start losing the guts.
 
#1 - I consider myself objective. Far more than you seem to be on this issue because i have actually studied it extensively. I reported on it because I noticed it and it was unusual. You just call us all not objective because you don't like what has been reported by me and every other user of the Brevis.

#2 -
"your colors, contrast, etc are dripping right onto the glass behind the ground glass and you're losing what makes the image an image."

This is complete nonsense Kholi. No one would use it if this were true. People are shooting features on this . Are they blind? Are their clients Blind? Are mine? I get fired for crappy pictures. I shot a short on this that I get compliments on all the time for its rich saturated color. Everyone must be blind. No one seemed to notice that the right side of the image was out of focus either.

I have changed the screen on the Brevis and studied the difference - the phenomena departs as the screens become more dense and diffuse. #2 show less of it & by #3 you are in similar exposure properties as the SG or the Letus, and a similar amount of general diffusion.

#3 - Many of these adapters display artifacting under some circumstances especially overexposure. I suggest you look at your own adapter (s) carefully for artifacting or displeasing affects. I have not seen them in particular on the Brevis CF1, but there may be some. I didn't like the CF2 - I found it less pleasing even though it doesn't have the exposure issues we are arguing about. (Haven't looked at the CF2LE) There are things in the Letus I don't find pleasing and I found the Redrock too diffuse for many applications.

There are reasons to prefer the more diffuse Redrock, SG or Letus and reasons to prefer the Brevis image for different purposes. Please drop the issue until you can prove this horrible problem you hypothesize about.

This is a great forum. Lets talk about issues that are real instead of wasting our time on this .


Lenny Levy
 
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