Brevis35 - Optional GG Footage
 

Here are some quick shots using the first in our collection of optional GG release candidates. Swapping from the standard diffuser element to this one using our interchangeable system takes less then 5 minutes...and there are no setup changes. This GG setup takes us much closer to a film match from f1 to f2.8 where the standard diffuser is a very good match from f2.8/4 to f16. The shots are all done using a 50mm f1.4 using the GS400 in pro-cinema mode...nothing done in post except the flip and some slow mo.

Fast Link

Slow Link

What kind of gg is this? Is it better material?

Not better, just different. Early in testing it became obvious (and more so now) that every shooter has different expectations with respect to bokeh. Just as directors of photography choose primes and apertures for a specific look using film, it was obvious that some choice in the diffuser would offer similar options. I've done extensive testing comparing actual film bokeh taken with a 35mm SLR to the adapter footage. This is the first result.

You know, about 4 months ago (right after I got my letus35a) I kicked about the idea of controlling the look of your footage through different GGs. Something like the RMS ratings on film. You want a dark gritty look use ground glass A. You want a sharp clear picture use ground glass B.

Personally I think this a real solid idea. I'm already sold on the combination of HD and a 35mm adapter, but with the ablity to have additional control over the look is pretty friggin nice.

Plus, I fully expect rapid advances in the GG and can't justify buying a whole new adapter just to get a better GG.

I agree this is a good idea. Its been something I have wanted to implement into the SGpro for a long time, but due to the nature of its design, it has been difficult to make it user changeable.

I think you have done a great job, Dennis. What are the main optical differences between the 2 GG's? Level of diffusion/diffusion angle??

It looks very soft, maybe because the GS400, but I'm pretty sure I have seen sharper footage from the brevis. The bokeh looks nice. I wonder if it isn't possible to get both, a sharp image and a nice bokeh together.

Jim, I'm not sure there will be tremendous advances in GG's simply because physics gets in the way of a diffuser trying to be film :-) The fact that the diffusers can be swapped out though makes good sense in a number of ways and certainly opens up other GG options.

Wayne, the option could be visually quantified as providing more diffusion.

Michael, the interesting thing about your comment is that some folks think the footage is sharp, some think it's soft, and some think it's a bit noisy. The noise is the GS400, however the other two criteria are pretty subjective, particularly as I've provided no baseline reference. It is true though that because the DOF is shallower, less of the frame is actually in focus. Having alternatives makes sure that the ultimate authority, the shooter, get's to choose their look :-) What I'm pretty excited about is that when compared to my extensive test shoots with the standard diffuser, this stuff looks just as sharp. The penalty is another .5 stops of light loss.

I have invested a great deal in some pretty cool stuff, so this is just the start with respect to diffuser options. Now if I could just recover costs on the failed trials...

Thanks for your feedback gentlemen.

Soft? Noisy? I wonder if they also complained about the small amount of gg seen in the left edge of the picture? I found the footage as sharp as it should be and the new GG seemed to perform great also. It's amazing how fast these adapters are developing.

Yep, there's some GG there. It would be nice if the LCD/viewfinder didn't have the overscan issue. I get caught all the time by this. Thanks for your feedback Mikko.

I'm comparing it to SD footage from the Mini35 and Movietube and also SGPro and M2. Now none of them were with a camera as low end as a GS400 I have to admit. That may be the difference. They were mainly DVX, XL or PD.


I was, naturally, talking about the parts that are in focus. They look soft to my eyes.



Yes, this is a great idea and a great feature you are offering.


0.5 loss is nothing if the bokeh is better, but I really can’t see it being as sharp as the older tests. Maybe it’s just me.

hmm
 

sorry but its really sharper than previous tests, you have something with eyes :))

When I get some time, I'll post up comparative footage to end that debate :-) With camera differences, camera aperture, backfocus accuracy, achromat type, 35mm lens and aperture used, GG used, and 35mm lens focus accuracy, there are way too many variables that potentially will make even my own footage suspect. I really need to post up the comparisons (film, bare cam, stock and optional diffusers) under very controlled conditions, with uncompressed DV, to allow folks to judge the relative differences.

Could someone please explain what "bokeh" is. Thanks

Thankyou Theo, I had no Idea such a word existed until I kept reading and seeing it on here.

Steve, based on your posts of late, you'll become intimately familiar with the term bokeh in very short order. You'd be surprised at how many folks in the industry haven't heard that term before. It's a bit of an obsession in the 35mm adapter world :-)

Hey Dennis,
My wife is working on her PHD and I can't wait to use this word in front of her.

I have also become very familiar with the GS400 footage from your adapter and I like what I see. I will very much consider purchasing your adapter in the future, but it seems like the intitiation into the adapter world is to build your own first. I'm gonna try the rotating CD(GG) first so I can say "been there done that". What is your favorite 35mm lens to use with your Brevis35 adapter and GS400 combo?

bokeh
 

Steve, here's my earlier post about bokeh with link to best explanation imo.

I built a few spinners first too....pmail if you need some stuff. You can likely build yourself a very good adapter providing you're willing to play a bit :-)

If you are looking for lenses, a 50mm f1.4 or f1.2 should be your first. I also frequently use an f2.8 28-70 zoom. A stable of primes would be better, but the f2.8 zoom is very versatile. Light loss, a spinner, and the GS400 will predicate the fastest lenses you can find.

Thanks Dennis. I pretty much have what I need for the spinner(I think), except the Lens itself. Did you use a "macro" with your spinner or just let the GS400 do its own macro thing?

Frank Hool, Thankyou for the link to your explanation post.

Steve, if you're going for a standard spinner you'll need a condenser and an achromat. If you search here for the terms, you'll find plenty of info on what works, and where to get them. I've yet to see a spinner that did not require an achromat to properly frame the GG. With the Brevis design, no achromat is required for smaller cams like the GS400, due to the adapter's large usable frame size.

The GS400 macro is useless to you as it will force 12X zoom, allowing you to focus on objects ~3 feet or more away..but no closer.

Still learning
 

Hey Dennis,
The condenser that you mentioned above for the spinners......is this something that go's between the camcorder and the adapter, or between the 35mm lens and the adapter?

Also, I have bid on a 35mm canon FD 1.4 SSC manual lens on Ebay. If I win it will be about $20 with the shipping. Anyhow, I wasn't sure what the S.S.C. stood for and was looking for a little help here also.

Thanks for everything.

Steve, there's setups with before, after and both. You need to experiment a bit with your setup.

Hey Dennis,
I've read on these Condensers (plano-convex type) for cd blank spinning adapters. Are there lenses like this that come with the "threads" (like filters, attachments, etc)that we can use with our camcorders and lenses? My searches on this are only coming up with a lense with no rim or threads. Just a piece of glass/plastic. If this is what everyone is using...how do you attatch it to your assembly?

Can anyone help? Thanks.

just for your info.
i purchased recently a letus35a for some test.
i took it from the "Handyman corner" so price is lower.
the goal is to test all the ways it could be enhanced in order to get a really good picture for a FX1, without the hassle of dealing with basic mechanic.
I will remove all useless glass (front window), widen the gg window, change the lenses, build a better GG.
For the GG glass , i selected ultra thin glass (0.2mm and .5mm thick) from Schott glass.
I will use 1500 grit al. oxyde as per my previous static GG.
They sell the glass (AF45 quality, the best for optical use) in set of 3 sheets of 100 by 100 mm for about 130$.
since it is a lot more than i need, if somebody is interested, i hope to be able to cute more than one GG.
obviously it is for use on vibrating gg, not rotating.

Ok, here's some of that famous garden footage done at dusk with the Brevis optional diffuser. This version is the production element. It's shot with a Minolta Rokkor 50mm f1.4, set at f2.8. A little GS400 shooting 16:9 procinema (frame mode) was perched at the other end. I had the rig on a stabilizer, but obviously need more practice...a lot more. Check the crispy bokeh at time 1:20.

43MB WMV, Fast
43MB WMV, Alternate

Looks great. Any difference in light loss between the two diffusers, Dennis?

Jim, I haven't properly quantified it yet, however the value will be close to .4 stops or so. The adapter "total system loss" with a 50mm f1.4 attached and using the diffusor option will be just under 1 stop...or basically the light loss attributable to the 35mm lens. My holy grail, other than keeping light loss low, and visible grain 0, is to get proper rendition of specular highlights in out of focus areas, that are free of halation during focus racks. This is as close to perfect film emulation as I can imagine. This GG also has a usable "grain free" f range well into the f4 area.

I have two other diffusion options on tap, but these have too much grain, (I'm pretty sure anyway) to work well with our incoming OCT19 cinema lenses.

Giroud,

Let me know how the Letus35A mod turns out, I might want to try that as well.

How did you get on with the mod?