GG and Bokeh

[Robert Gradisen]

if you were just taling about lenses for a minute then a lense that gives you good bokeh (say a 58mm f1.4 minolta rokkor ) will generally give a less sharp image on the other hand a sharper lens has slightly poorer bokeh , however the difference is slight. This might have something to do with the fact that to get a shallow DOF and nice bokeh out of a lense you generally have to have the appeture wide open , when a lenses focal sweet spot as it were is somewhere around f5.6 . Again when taling just about a lense ( before complicating things with diffussion) there is an artistic choice between sharpness and nicer bokeh. I agree that the best focusing screen would be able to best emulate what happens on the film plane in an slr camera ( I say best because I also agree that it would be near impossible to exactly replicate what happens on film)
rob

[Andy Gordon]

I've compared my adapter footage to film shots on SLR with the same lens (50mm f1.2 Nikkor). On 100ASA and 400ASA film (surprisingly to me) the dynamic range is absolute crap by comparison, bright areas are blown out, dark areas are too dark in the same shot, bokeh is grainy and highlights have a bright edge classed as bad bokeh.

However on the adapter footage the dynamic range is good, and because the gg doesn't fully diffuse it actually softens the bokeh somewhat and the result is it looks better than actual film haha!

[Robert Gradisen]

hey andy
sorry I havent replied yet to the last email you sent me lifes a little hectic at the moment , how did you go with wax , if you are using wax ,I noticed that depending on exposure I still get slight hotspotting and occasionally the grain is evident but mostly not, haven got any decent footage to show as everything ive got has been deinterlaced and colour and gamma corrected and would probably not accurately demonstrate the ability of the adapter
rob

[Andy Gordon]

I'm oscillating 40 micron gg at the mo, wouldn't go back to wax unless you tell me bees wax can give light loss around 1-1.5 stops total loss for the system.

I always correct my footage anyway so I'd still like to see "doctored" grabs.

[Ben Winter]

This was shot on the Letus35 with a theatrical lighting gel diffuser switched out with the focusing screen. The footage is great, but there was too much grain even with the vibration. I'm sorry I can't find my sorenson serial number so I was stuck with the trial, hence the watermark. But you still get the idea.

http://www.frozenphoenixproductions....ffusertest.mov

[Francois Poitras]

Ben, the link does not work for me (Page not found).

[Ben Winter]

Sadly ever since Powweb went under new management they moved everybody to a new system and with it, new rules. You'll notice you can no longer browse my exposed directories, they're blocked. I think another dumb rule they put in is no direct file linking--which is going to be a serious problem for me since I link to files all the time. I'll see if I can fix the problem.

EDIT: problem solved. I was uploading to the old server. Link should work when the upload finishes.

[Ben Winter]

I should also mention that the R8 leica focusing screen is a fantastic gg but has a dumb split-prism in the middle. What a bummer.

[Ben Winter]

The Nikon D100 replacement screen I ordered is exactly what I hoped for. Small, but a fantastic image, very similar in construction to the Beattie Intenscreen for the Contax. It doesn't really diffuse completely to my satisfaction, but the bokeh is different than the Beattie from what I can tell, hopefully better. There's practically nil grain. I'm installing it in my Letus and I'll have test footage shortly.

[Wayne Kinney]

Ben,
Sounds great, be sure to show us some footage!

[Ben Winter]

Alright,
The D100 shows great lack of light loss, great lack of grain, and the in-focus material is the sharpest I've ever seen. But the bokeh is pretty undesirable. I'll let the results speak for themselves.

http://www.frozenphoenixproductions..../d100test1.mov
http://www.frozenphoenixproductions..../d100test2.mov
http://www.frozenphoenixproductions..../d100test3.mov

Check em out.

[Andy Gordon]

Hey Ben

You might want to try sticking two of your diffusers together face to face. You'll get the bokeh you want but possibly at the expense of sharpness and grain.

[Ben Winter]

I was going to try that--I think I'll find some less powerful diffuser gel material and glue it up against the D100 screen.

[Tim Johnson]

What about the D200s screen? lol stupid question - i dont think it will make any difference, its just the next model

[Bill Porter]

Ben, how about shooting some out-of focus-lights at night?