SGPro or Brevis 35??

Jason,
In other threads either here or on DVInfo.net we finally put that myth to rest. The 35mm screen does not expose the image , it cannot overexpose anything. I'm sorry but this one really bugs me and I have become a bit of a nut about it.
This might have turned out to be some kind of odd effect in cameras that had electronic ND filters that screwed up the picture. i don't know anything about that issue , however I can assure you that using internal ND will not leave you an overexposed image. If I have time I will find that thread on DVInfo.net.

Barry has spent a lot of energy trying to debunk this. It is ordinary exposure plain & simple - do it at HVX , do it at the 35mm lens, use ND's outside, use them inside use which ever iris you prefer- all the same. Dennis at Cinevate and Brian at Redrock have concurred.


Perhaps Tim has found that the internal ND's muddy the image with the HVX. I have not found this but perhaps if you are very critical it might be so. I would think you would see this on the bare HVX even more apparently though. I am very willing to be convinced if Tim has some screen grabs.

I know on CineAlta's some people have replaced the built in filters with higher quality HD glass because they see the effect of the filters. That is certainly possible.

Barry has mentioned that the internal 85 may raise noise since you are pushing the red channel so there is a case for an external 85. Personally I don't like any more glass in front than neccessary, but Tim may have a point.
I'd like to see the evidence in still grabs.

No one has produced any images that show that the internal ND's on an HVX will leave the 35mm adapter screen overexposed. If you have them please post them.

BTW - I'm not trying to convince people not use external ND's or matteboxes - They're on my list to buy, just want to be clearer about why & when they are important.
 
Tim is right in the sense that, if yo uwant to keep the 35 lens wide in Broad daylight, but still keep the HVX lens in the F5.6 sweet spot and avoid the possibly questionable internal ND's. then yes its a good idea.
 
Thanks for the info. Like I said, it's just what I have read... nothing I have personally noticed yet. I'm really, really new to the whole 35 adapter world :)

Maybe you are saying the same thing, but just to be clear, it's not that the image ends up overexposed, but that the image gets softened as a result of coming into the gg too hot. Again, not saying this is so, just repeating what I have read and figuring it all out now that I am actually using a 35 adapter. Now that I've got a 35 adapter, I need to test all this out anyways, and figure the best ranges for exposure for my lens and the HVX lens.

Thanks,
Jason
 
For point of clarification, there is no internal 85 filter on an HVX. The conversion between daylight balance and tungsten balance is done electronically, not optically.

The CCDs are natively optimized for tungsten light, so to adjust for daylight there's some DSP processing going on. That process may introduce a little bit of noise in the signal, which could be avoided by using an 85 filter to convert the daylight to a tungsten-balanced light.

I'll try to explore the concept of the quality of the HVX internal filters too, and post some grabs when I can.

But yes, Leonard is of course correct -- there is no such thing as "overexposing" ground glass.
 
Jason Ramsey said:
but that the image gets softened as a result of coming into the gg too hot.
Click to expand...

Nonsense. There's no such thing as "too hot for the ground glass." I've tested it by shooting a scene at proper exposure, and then at 256x the same light value (using internal ND and iris to compensate) and the sharpness was absolutely identical.
 
Ok. Good to know then. The 'too hot for the gg' was my own wording on what I read over the last several months, wherever I read it :)

Thanks for the info guys.

Jason
 
Barry_Green said:
For point of clarification, there is no internal 85 filter on an HVX. The conversion between daylight balance and tungsten balance is done electronically, not optically.

The CCDs are natively optimized for tungsten light, so to adjust for daylight there's some DSP processing going on. That process may introduce a little bit of noise in the signal, which could be avoided by using an 85 filter to convert the daylight to a tungsten-balanced light.

I'll try to explore the concept of the quality of the HVX internal filters too, and post some grabs when I can.

But yes, Leonard is of course correct -- there is no such thing as "overexposing" ground glass.
Click to expand...

I've also wondered how the image is affected by the internal ND filters, and wanted to avoid them. But, are you saying "White balancing" for daylight instead of tungsten is introducing noise? Or just using one of the internal NDs?

Sorry, not quite understanding that one.
 
" Likewise people who are choosing between f1.4 or f2 or f2.8 lenses all based on cost. Again i would maintain that the big gain in low DOF is to be using the adapter at all and f1.4 vs 2.8 doesn't make the critical difference. "
lenilanapi

Difference between 1.4 and 2.8 is big in many respects. Any DOF chart will verify that.

re: Sharpness of internal ND's. I'll get some grabs over the weekend. I never noticed this discrepancy on the camera's LCD. It's only when a client pointed it out on a large broadcast monitor that I noticed the slight degradation of the internal ND's. It was enough to make me buy glass.

re: Camera's electronic 85.
Get a glass 85. The HVX noise goes bananas with heavy blue signals. Try shooting magic hour and you'll see noise the like that'll make you wonder where the High in High Def went. The skylight is in the upper reaches of 8-10,000 kelvin. Again this is something that becomes a big deal on bigger flat screens. CRT's barely pick it up.

Back on topic. The noise of the HVX is what sold me on the clean, grainless image of the SG PRO. The last thing I need is grain in addition to noise.
 
TimurCivan said:
hehe this is gonna becme DP shootout thread....
Click to expand...

oooooooo ooooooo can i enter? :)
I'm putting 2 Brevis's to the test tomorrow in a music video for Stefani-Vara and her new hit "Lately". I'm actually going to try to get the sweet spots and all that tech stuff with the lenses since its in a studio with as much light as I want. Now all I have to remember is what the numbers are for the lenses. I should just print out this thread. ;)
 
Last edited:
Which screens are in the Brevises?

Tim , I just noticed your post on another thread about the internal ND's. Thanks for pointing this out. i'm going to test as well, but sounds convincing.

I would love to check out an SGPro. Anyone in the SF Bay area have one I can look at?
 
There will be a CF1L and a CF3 and Nikon glass. Will post a screenie or two tomorrow night if I'm still awake and they say it's ok.
 
Although I do agree with dialing in the internal NDs where required..this is only after you've used what you have externally. Having a mattebox and filters out front prevents flare, hazing, ghosting and incident reflection, throughout the optical chain. Given our climate and the type of shooting I do, water, sun and bright snow are common environments..and given the choice of mattebox and polarizer/ND filters out front, there's no question I would use them. We definitely do recommend cutting light where possible before it contacts the imaging elements in our adapter. This is not only recommended by me, but also by the optical engineer responsible for designing them.
 
You must log in or register to reply here.
Back
Top