New moving ground glass mechanism

[Brett Erskine]

Everything that has been mentioned before about the positives and negatives of using MF lenses is true but I can add two more positives that led me to make my adapter use both MF and 35mm lenses. By far the weakest point in the optical system of a DOF adapter is the ground glass. Thankfully MF ground glass is much larger so the clarity you can achieve from it will be greater than that of 35mm. Also the moving "grain" from the ground glass becomes even more subtle (almost like using 100 speed film instead of 800 speed). I would say run a test and see if you are losing any resolution after shooting thru your ground glass at a resolution chart. Dont forget that a HDV or HD camera might be in your near future so make sure your GG isnt robing your new HD camera's resolution. If you dont see ANY resolution loss between shooting with your adapter or without your adapter when using 35mm lenses and 35mm GG then your fine. Just use 35mm GG. BUT I personally haven't found that to be true. HD shooters have even complained about the P+S Pro35 and its inability to resolve FULL HD clarity. Now some people like the softness (as I do) but how much is the question. Does i My thoughts are why not make it with MF ground glass and you can always use 35mm lenses with it too.

A second reason why I went with MF is that for MY particular video camera I wasnt able to zoom in and focus on a 35mm sized piece of GG without the aid of some type of close up lens. I found that unless I paid big bucks for top quality glass, like the Century close up diopter, I was losing a lot of quality in my image. Now you my have a camera that CAN zoom in and focus full frame on a piece of 35mm GG (a lot of smaller/non-professional cameras can do this) so in this case you can go without a diopter and thus MF gg is not as important.

Anyways run tests.

[Frank Vrionis]

The way I see it is the a 35mini/micro device is good for medium/close-up talking head shots. This way the shallow DOF isolates the subject from the background. plus the resolution loss on HD is welcome when you have medium/close-ups on people. Last thing I want to see is blackhead blemishes.

For the wider establishing shot the more detail the better. So no GG for those. Plus I for one want a deep depth of field for those shots because in normal eyesight in long 'shots' (or views) aren't as focus dependent. So seeing the whole scene in focus is cool by me...generally...of course there's moments in the story where you will need to think about controlling your depth of focus field.

[Leo Mandy]

Brett, my camera is like that too - I cannot zoom in close enough to the GG withou some sort of Macro or Dioptre to fix this problem. What did you do to fix this?

[Brett Erskine]

You can read the details above. Of coarse if you want to do 35mm lenses we have no choice but to use a high quality diopter

[Leo Mandy]

I went through the post Brett, but I guess I am missing something. What does the MF stand for? Manual focus? I am not sure I am following you on this one. I have a panasonic dv-pv852 and I cannot get near the GG without it going out of focus (at least while maintaining the 18X24 ration. Kind of sucks because I am still waiting around for an achromatic dioptre that I can find that is cheap enough for me to test. So if you have a work around, I would love to hear about it!!

[Dan Diaconu]

zoom out Leo (till you can focus) and get closer to GG till you fill the frame.
what gg do you have?

[Leo Mandy]

I am using a spinning CD with mylar. It is really nice as far as the picture without any spinning striations. Problem is light loss which is a bit heavier than I would want, but that is the trade off.

If I get really close to the GG, I will see the black vignetting as well as the image in the GG. That is why I wanted to get a proper and strong Achromatic Dioptre (which seems to be out of my price range).

[Dan Diaconu]

I did not mean that close to get vigneting, just a touch closer. If it does not work, $219 to Century and it will work.
How is it possible for GS200 to play back 24P footage from DVX100A?

[Leo Mandy]

Yes the problem is that I cannot find that middle ground. I cannot get close enough without vignetting or far enough that it does not focus. It is a crappy deal even though the camera is great. The dioptre sounds great, but again too much money - I already spent $85.00 on a macro lens that I problaby will never use, so I am trying to tone down my spending on anything else - if possible. Any surplus places sell Achromatic dioptres?

[Brett Erskine]

Mandy-
Been down that road...many times. Trust me. I've been fine tuning this project for a long time, even longer than Dan, and I can tell you that your going to save yourself a lot of headached, time and perhaps even money in the end if you just get yourself a Century Optics. I never have been able to find a proper surplus lens that will be nearly the quality of the Century. Or you can use MF lenses and MF ground glass only and you wont need to buy any diopter.

MF= Medium Format

Dan-
"How is it possible for GS200 to play back 24P footage from DVX100A?"

Pulldown. The same thing happens when you professionally telecine 24fps film to tape. You can read about it in detail on Panasonics site (Google 2:3 pulldown).

[Leo Mandy]

Thanks for the info. I have never heard of Medium Format lens, so I will have to do some research. Yeah, I am still going to try and find a surplus one for cheap, just to make sure it works, then I probably will go with a Century or something along those lines.

[Dan Diaconu]

Brett,
I have heard of pulldown. My question was how come a few $ hundred camera has the feature built in.
You mean to say also that original 30P or 60i footage could be converted and played back as 24P right (from whatever NLE)?

[Oscar Spierenburg]

Leo, make a test with your camera and see if it gets a 6 x 6 cm image (so about 2,4 ") in focus. There are professional camera's that use such big negatives (is this MF?), with expensive lenses. But you could find second hand Rolleiflex or Rolleicord camera with a non detachable lens a lot cheaper.
Those are camera's with two lenses like this:
http://www.classiccamera.org/rolleif...d%20v%20rt.jpg

A good thing about this is you probably have even more DOF that 35mm and some have a nice sort of rack focus. It would also be easy to put a GG on it because it's just a box. Disadvantage is you have just one lens.

(I bought an old one called Lubitel2 for about $5, but a Rollei could be more than $ 40.)

EDIT:
It is probably best suited (because of it's size) to use with either a static GG or a oscillated one, hum...which brings back the subject of this thread.)

[Leo Mandy]

Dan,

The challenge with pulldown is that it doesn't exactly look like film, but it doesn't look like video either - it is a beast all its own.

[Brett Erskine]

Dan-
Send me your email and I can send you detailed info about the pulldown issue. I dont want to talk of subject in your thread.
berskine@mail.com