Second Brevis DVX100 Test

[Hrafn Jónsson]

A little more footage...

Very tired so I'm not going to go any great detail. If you guys have any questions I'll be more than happy to answer them...

Anyway, Sigma 50mm f/2.8 macro. Detail level at zero. Zoom at 80 and focus at 26..

http://krummi.klaki.net/stuttmyndir/brevis2.wmv

[Steve Strickland]

I think we have a winner! That looked incredible. Really nice work, man. I can't wait to get my Brevis back.

[Moises Crespo]

Sweet! Nice colors... Nice Work!!!

[Hrafn Jónsson]

Hmm...on a completly separate note...

I tried to mount my 400mm tank of a lens on the Brevis (I think the set up is like 3 feet long) but the Brevis doesn't want to play. I get a really ridiculously bad hot spot with it. I am no scholar when it comes to optics so there's probably something really simple that I'm missing, but the lens just plain doesn't work...

It's kind of strange because when I zoom out from the GG, the image looks fine and hot spot free on the GG..but when I zoom back in the hot spot appears again..

So...no really long lenses for the Brevis?

[Rafael Lopes]

I have the exact same problem with a 28-200mm I have!

[Dennis Wood]

What speed are these lenses? In all likelihood, you need to zoom in more as a result of the small rear aperture on these lenses. Once you get below f 2.8 any adapter out there will show its limitations. In essence, unless you have very good light, the max rear aperture of an f 4.0 will vignette as you zoom in...meaning you need more light, or more zoom on the DVX. What you are seeing is not really hot-spotting, but rather vignetting. The f 2.8 lenses I've tested work perfectly at all zoom levels.

Keep in mind that the diffuser on the Brevis is a fair bit larger than an actual 35mm frame. This permits a larger frame with fast lenses, but requires more zoom in with slow lenses...and the usable image frame will shrink as you push higher f stops with slow lenses. The DVX zoom for an f 1.4 50mm would therefore change with a slower lense. This is not unique to the Brevis, and is likely much worse (if you could measure actual frame size) with other adapters out there.

[Rafael Lopes]

I do think it might be a bit of a lens quality related issue here. I have a 70-210mm at f4.5 that works beautifuly with the brevis. But my 28-200 at f3.5 shows HUGE vinagrete...ops...vignetting

[Dennis Wood]

That is definitely a factor. Also, different lense manufacturers will show variations in max rear aperture size.

[Hrafn Jónsson]

Yeah, I think we have an explanation. the 400mm monster is rated at f/5.6

[Dennis Wood]

You could still use it but you'll need to up the macro strength. You could probably try adding in a cheap 72mm +4 without a huge hit in quality...or try moving the achromat back further from the GG (extension tube or a gutted 72mm macro ring).

[Hrafn Jónsson]

yeah, I'll try that...it's not a huge deal since I really don't need to use this lense....