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Old July 4th, 2005, 11:25 AM   #451
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Bill,
ANY GG/diffusing material will vignette. ANY Fresnel focusing screen (if placed at the "right" distance to camcorder's lens combined with a "certain zoom-in") will NOT vignette, thus having a bigger usable frame size.
Subject to: 1)focal length of SLR lens, 2)max aperture of SLR lens, 3)distance to camcorder's lens and 4) the amount of "zoom-in" combined with MOD of camcorder's lens. A nightmare but:
Any camcorder WILL have a "sweet spot" where you can zoom-in AND focus on a Fresnel screen. That is why all contraptions having a GG (static or spinning) have to use an achromatic and zoom-in as much as possible to get away with vigneting. Vigneting IS THERE when shooting FILM!!! ALL THE TIME!!!!!! But FILM has 12 STOPS of latitude and it does not SHOW ALL THAT BAD. Now.... if you capture the same image with CCD/CMOS, the available range is 5?stops?
The effect is the subject of this morning's discussion.
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Old July 5th, 2005, 05:02 AM   #452
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The difference between the image on the FILM and on the GG is night and day, in terms of vigneting. And the difference is not the latitude, but the way the image is formed.
As far as I know, there's the usual vigneting that you get because of the lens - this will affect film and GG as well - and there's the extra vigneting you only get on the GG, that is generated by the GG itself and the way it works. Light that passes through the GG (coming from the lens) will be scattered in some proportion, but part of it will follow its straight path, thus, the light in the middle of the GG will go straight to the camcorder's lens, but the light on the outside will miss the camcorder's lens... So, on the midle of the image you have scattered light plus direct light, while on the margins you only get the scattered light.
If you have a very dense GG, more light will be scattered and less light will go straight (less vigneting). In turn, you'll loose some BIG steps there... If you have a thinner GG, as you approach clear glass, more light will get thru the GG (brighter image), but this also means that more light will follow its straight path - more vigneting. You can work this out using a condenser. (have you ever heard of a condenser used when working with film?!)

BTW: "condenser" means TWO plan-convex lens. (it is an system, not just ONE lens).


After I finish my morning coffee, I might change my mind to the above.... :)
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Old July 5th, 2005, 05:26 AM   #453
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Quote:
Originally Posted by Cosmin Rotaru
the difference is not ,,,,,,,,,,the latitude, but the way the image is formed
You missed the word <<only>>>! now put it back where it belongs before I have my coffe and change my mind too (;-)< and...the rest is true.... however,.... what was a conderser again?....
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Old July 5th, 2005, 05:58 AM   #454
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"only" - I agree (this is half coffee later :) ).

And I don't know what a "conderser" is! :)
A condenser is a... "system" is not the word? My english is not that good... :(
I mean where you have two or more lens, not just one...
A plan-convex lens is.. just a plan-convex lens. And you can find it shaped on a fresnel, of course. But you need two of them before you can say you have a condenser. And this could actualy be an uncorrected condenser (not corrected for color and spherical aberrations). While a fresnel is good for focusing on a SLR (or large format photography) I don't know if it's enough for a mini35 addapter. I tried it. Granted, I didn't have a beatty or whatever $$. I mean GG.
"Any camcorder WILL have a "sweet spot" where you can zoom-in AND focus on a Fresnel screen"
But a two lens condenser can help here. You can move one of the plan-convex lens to "tune" the condenser. Don't ask me which one - I don't know. Try it! :)
The thing is, condenser have their focal length. That's where the eye should be. The "sweet spot". What should be in the focal point Dan? The CCD or the lens? Or what? I don't really understand.

Anyway, right or not, I've tried with one and then added the 2nd plan-convex. It is way better with 2 lens.
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Old July 5th, 2005, 10:58 AM   #455
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Hey all,

why not put that trial and error empirical approach behind you and use a tool for the job - Optical design software - everything you need to get that computer to optimise your design for perfect results.

After all you wouldnt edit your video with your eyes shut would you?

http://www.zemax.com/zemax/index.html

its expensive but there is time limited demo for free here

http://www.zemax.com/demo_z.html

you will learn a LOT about optics from this

EOT
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Old July 5th, 2005, 12:48 PM   #456
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Cosmin Rotaru<<<<<<A condenser is a... "system">>>>>>>>>>>
Noooooooo,..... that can't be..... another "system?".....
<<<<<I mean where you have two or more lens, not just one...>>>>>>>>>
Would they be looking like this?:
http://dandiaconu.com/gallery/album28
<<<<But a two lens condenser can help here.>>>>>
Dam' bad condensers! Didn't want to help here!
<<<<What should be in the focal point Dan? The CCD or the lens? >>>>>
Which one was first? The chicken or the egg? White spot knows better...lol.
John, the program is sweet. Too bad they do not have lenses by brands (Canon 20X, or 16X, or Z1's zoom....) so you can test different combinations to a "given lens"....
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Old July 5th, 2005, 02:54 PM   #457
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Just Curious

Dan,
A quote from the first page of this thread...

[QUOTE
However, I can assure you that if anyone will be on the market with a lesser quality and a higher price than what
our world film community desrves, I will be there to make sure
ANYONE who can afford to buy an HD Sony (or whatever brand of prosummer HD) will access CONFORTABLY one of this adapters.
My aim is to open the "inner circle" to many.
QUOTE]

From what I've read, the device is $8,000, or $450/day to rent.
Is this correct? If so, do you consider your goal ("aim") met?
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Old July 6th, 2005, 01:32 AM   #458
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No, I did not meet my goal and I am not happy at all I still have to machine all parts. If it was done industrial, the price could go down to $2500 or even less (I guess) but as long as I make the parts measuring a hundred times (instead of CNC-ing them).... what can I do? I posted twice a request for anyone interested in production to contact me. I would rather share real revenue with someone, than keep all I can do by myself. I got carried away with other "toys" (of no lesser value), but still someone should organize the production (only not me). Too many temptations..... and I am weak and fall for anything that crosses my mind. I am neither “business oriented” nor money making inclined. I used to, but business is dirty. Imagine this:
http://dandiaconu.com/gallery/album04/IMGA0879
selling for US $300. It has too many features to publish here and I would rather hold till I can look after manufacturing (hmmm... again...) A whole new concept. Is it patentable? You bet. More "toys"? You can bet on that too. The Oct "feature" I have in development will "require" nothing less than what I think I "need" for a good image. Wireless pan-tilt head on a motorized dolly (wireless controlled as well) anamorphic on MPIC and a lot more... Now... how can I organize production under these circumstances? MPIC is not "new" anymore, I made it and I am done with it. (I had a bit of "excitement" with the solar panels though) From now on, all that's left is production and that is not fun. That is work. I will make an effort though and thank you for the reminder! Honestly!
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Old July 6th, 2005, 06:55 AM   #459
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Hey! Speak for yourself! Production engineering methodology is fun for some of us! :)
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Old July 6th, 2005, 07:18 AM   #460
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I bet it is Bill and I am lucky not to know. I could get carried away just as well...
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Old July 6th, 2005, 07:41 AM   #461
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Quote
"I will make an effort though and thank you for the reminder! Honestly!"

Dan,
Thanks for the reply. Your device is very well designed and built. I certainly understand the challanges of scaling-up to production quantities.
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Old July 23rd, 2005, 01:59 PM   #462
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I have added a new album (under brightness comparison)
http://dandiaconu.com/gallery/album31?page=1
while I am having parts manufactured to lower the price. A few versions of the same movement might be available. I know the most sensitive issue here is PRICE (son of a..b-udget) but good news are on the way.
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Old July 24th, 2005, 01:33 AM   #463
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Further testing:
http://dandiaconu.com/gallery/album32
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Old July 24th, 2005, 11:55 AM   #464
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Quote:
Originally Posted by Dan Diaconu
I have added a new album (under brightness comparison)
http://dandiaconu.com/gallery/album31?page=1
while I am having parts manufactured to lower the price. A few versions of the same movement might be available. I know the most sensitive issue here is PRICE (son of a..b-udget) but good news are on the way.
That is indeed good news!
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Old August 3rd, 2005, 02:26 AM   #465
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Quote:
Originally Posted by Dan Diaconu
but good news are on the way.
So Whats up ? Hmm... manufacturing cheaper parts, thats good. Also solar power sounds great... Do not be quiet and tell us news !
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