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Brevis35...pick yer diffusion.

Discussion of Beta Testing.

Brevis35...pick yer diffusion.

New postby Dennis Wood on Sun Jun 11, 2006 10:38 pm

Well guys, check this clip or http://www.savefile.com/files/4554524 (done at f2 on my f1.4 50mm) I've been doing testing all weekend..and arrived at this. I'm actually a bit shocked, as I figured specular highlights could not be done this way through a diffuser, without a growing "halo". I've figured a way to have the unit allow either "straight" brevis sharpness/light gain/diffusion, vs this look. The adapter loss is 0 f/stops with this option, and .5 stops gain in "stock" config.

If I go ahead, the user could potentially choose the diffusion level. The change would take approx 5 minutes..or less, even for a newby.

So with my f1.4 lens attached, we're looking at total "system" loss of 1 stop (diffusion cranked) or .5 stops (stock setup) total loss respectively.

Your existing setups can be mod'd for this. Factor about $100-$150 to add it. I need to do further testing with the achromat and some higher res stills before I'd make this a certainty.

Andy gets all the credit for getting me thinking on this :-)
Last edited by Dennis Wood on Mon Jun 12, 2006 7:01 am, edited 2 times in total.
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New postby Andy Gordon on Sun Jun 11, 2006 11:58 pm

Looks frikkin awesome! I want one! :D

That's the best bokeh I've seen, lots of distinct overlapping discs, that is completely film like. congratulations, you've done it again.

Are the discs solid at f1.4? For an extra .5 stops in light I can't believe anyone would choose the low diffusion. Are there any other issues such as slightly worse grain?
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New postby Hrafn Jónsson on Mon Jun 12, 2006 12:06 am

wow, I love this look. The light disks are beautiful!

This feature, if successful, will make the Brevis a very unique, very competative adapter
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New postby Dennis Wood on Mon Jun 12, 2006 12:19 am

At F1.4 the discs are mushy, pretty much as the aperture blades are not encroaching into the rear aperture. As soon as you engage them (in this case at F2.0) they show up. Quite frankly, I wasn't expecting to ever get spec. highlights looking that good :-)

As far as grain etc, I'm not seeing any...but I still have some testing to do.
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New postby Rafael Lopes on Mon Jun 12, 2006 12:49 am

Dennis, the footage looks amazing. I will need to see some more footage to come to more solid conclusions....bu I really belive you and Andy did it! This could be it! The brevis could be finaly ready for the big league, swoping the crown from all other adapters!

Could you post some full resolution "human footage". Is this a change we would be able to do our selves with your help and some components we would buy from you or would we have to ship the Brevis back to you for you to make the changes your self?
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New postby Andy Gordon on Mon Jun 12, 2006 12:55 am

I'd have to agree if the rest of the testing shows the high diffusion to be as good as the sample, this is going to be THE adapter. Even the P&S Technic focus rack on their site looks hazy.
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New postby Dennis Wood on Mon Jun 12, 2006 12:57 am

I'll see what I can do Rafael. I'd be more comfortable doing the mods here, basically to make sure everything is set up properly. However, once I've got some more confidence in this, I'll have a better idea.

The nice thing about it is the fact that the look is potentially tunable. In other words, one could likely mess with film stock emulation.
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New postby Rafael Lopes on Mon Jun 12, 2006 3:03 am

Seriously, Dennis, if this turns out to be as good as it seems you may start planning mass production, my friend.

I'm dying to see some full resolution "human footage". I'm so excited about this!

So, from what I understand we will have to ship the brevis back to you so this change can be made, right? Or will it be something like Redrocks' cinescreen, that you switch between both versions?
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New postby Dennis Wood on Mon Jun 12, 2006 6:35 am

I re-encoded the clip as there were some quality issues with respect to the avi export. I've also taken the clip somewhat "public" so the other folks could have a look. The link is the same.

http://www.cinevate.com/phpBB2/viewtopic.php?p=761#761

Rafael, I'll need to figure out whether or not to encourage the swap or not. Andy is right in that the extra .5 stops is likely not going to worry too many users. On the other hand, if they're looking for the less diffuse look, swappability would give the option. The KISS rule might suggest that the adapter be left in the more diffuse mode. There are also potentially patent issues there..meaning I'd be happier once all the legal stuff is done.
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New postby Steve Strickland on Mon Jun 12, 2006 6:46 am

Ok, Dennis, now you're making us all jealous!

The footage looks amazing. I'll be ready to mod my Brevis whenever you give the word. Great work. You've achieved a look that really mimics film, which I believe is why we all want an adapter in the first place. Is it just me, or does everyone feel like they are always sending Dennis more money? :D We're junkies!
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New postby Dennis Wood on Mon Jun 12, 2006 6:57 am

Well, let's wait and do some more testing first :-)
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New postby Rafael Lopes on Mon Jun 12, 2006 7:26 am

Dennis Wood wrote:Well, let's wait and do some more testing first :-)


Dennis is right. This inicial footage looks absolutely amazing, but it's hard to tell having seeing only this footage. I'd like to see some more, specialy in full resolution. But straight off the top it looks like the best brevis results ever! I want nothing less than what I've seen there. It's exactly what I'm looking for in an adapter. IMHO (and I'm sure most will be onboard with me), THIS should be the standard brevis. Keep drilling, Dennis! You are about to make history there.

I know it's a long long shot, but any chance you might be ready with this when the achromats are ready to ship? The reason I'm asking is just so that we don't have to pay for 2 shipments.
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New postby Dennis Wood on Mon Jun 12, 2006 7:42 am

Definitely not...however in your case, the achromat/mount shipping are on me.

One thing I'll be doing is doing a lot of testing and posting up raw avi files for you guys to pick over. Once we're all quite happy, I'll start implementing. I'll be doing some more shooting later today.

If I do post some footage at dvx and dvinfo, it will be to try and get the next production run sold. I need to pay some bills.
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New postby Rafael Lopes on Mon Jun 12, 2006 7:49 am

Dennis Wood wrote:
If I do post some footage at dvx and dvinfo, it will be to try and get the next production run sold. I need to pay some bills.


I was about to suggest you did that :D
We're all rooting for you, big D! I'm confident this new modified brevis will soon be wearing the 35mm adpter crown :wink:
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New postby Moises Crespo on Mon Jun 12, 2006 3:16 pm

See that's what I get for working hard today.I almost miss out on all the talk about the new mod's count me in all the way.Great job guys,I still want the t-shirts :lol: :lol: :lol: :lol:
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New postby Dennis Wood on Tue Jun 13, 2006 10:08 am

Well, with achromat issues sorted and construction details sorted, I will be working pretty hard to bring these improvements to market. As you may have guessed, I'm pretty commited to continuous improvement. Really having two diffusor systems makes lots of sense as you can literally please everybody this way.

The existing system will continue in it's current form as it is a very, very close film match at F4 and above...and is as sharp as I believe an adapter can be.

For those looking at the F1.4 to F4 match, and don't mind losing more light, the second option will be available. At this point, there's some serious work to do now that the proof of concept is in place.
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New postby Andy Gordon on Tue Jun 13, 2006 7:01 pm

If your objective is a film match then the next to no loss of the original set up strikes me as a moot point, I mean if you have to stop down to f4 to get it then you've got three stops more light loss over an adapter that does it at f1.4. Not to mention the difference in dof caused by both the aperture and the diffusion.

Another thing I notice on light loss - with an f1.2 lens you'd expect to gain another 0.4 stops over a 1.4, but I've found this isn't the case for 50mm lenses when I compared them. There's no visible difference in image brightness, it seems to level off at the top end, I would guess because the rear glass is nearly the full width of the gg the light is just coming staight through and the loss is going to be the same for that amount of glass no matter how big the lens is.
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New postby Dennis Wood on Tue Jun 13, 2006 11:12 pm

If you're looking to optimize image quality and maximize sharpness, you'll likely want to shoot F4 to F8 depending on the lens. For these folks the straight up Brevis is perfect as the film match (to 100 ASA anyway) is very close in this range.

Emulating film below F2.8/F4 and getting those nice specular highlights at F2, haze and ghost free, is a larger challenge and will likely bring with it a bit more softness, and potentially a bit of grain. For shooting styles like yours Andy, this will be the preferable setup. I've done another full evening of testing, and progress is good.

Having the choice, makes my job a lot easier :-)
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New postby Andy Gordon on Tue Jun 13, 2006 11:43 pm

Look forward to seeing some more footage.

I know SLR lenses are at their typically sharpest around f5.6, but can you really see that difference in sharpness in the video shot on an adapter? I would doubt it, maybe in HD but not SD?

I took some pictures with my Nikkor 50mm 1.2 on my SLR and I noticed the "bad bokeh" as defined on that website you referenced - the specular discs have a bright edge, and there was noticeable fall off towards the edge of some shots - my adapter seems to produce a better image!
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New postby Dennis Wood on Wed Jun 14, 2006 12:08 am

Way back I did some tests on the GS400 with high detail shots at f16 vs f5 (with an ND filter) and did see a difference. It wouldn't hurt to try the same with an adapter.

Did you try some 1/1000s shots with the fully open f1.2? I'm curious.

As soon as I have some post-worthy footage, I'll put it up.
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