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Old March 31st, 2004, 02:50 PM   #631
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<<<-- Originally posted by Gregory Joltok : hi, my result with my panasonic nvgs70 and mini35 kit.

a camcorder with a mini35 kit :)
http://www.ifrance.com/mini35/Image%20002.JPG
http://www.ifrance.com/mini35/Image%20004.JPG

a picture of my test.

http://www.ifrance.com/mini35/Comp%201%20(0-00-29-14).jpg
http://www.ifrance.com/mini35/Comp%201%20(0-00-52-00).jpg
http://www.ifrance.com/mini35/Comp%201%20(0-00-15-15).jpg

are you a sugestion ? -->>>

im not a sugestion but I did save a bunch of money on my auto insurance.

Nice pics- a condensor might be in order
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Old March 31st, 2004, 05:09 PM   #632
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usable ?

Hey you dvx100 user, do you think that somthing like that:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3807276418&category=29964


Would be of any help in our goal to make an Aldu35 for the DVX ?

Nico
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Old March 31st, 2004, 06:03 PM   #633
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yeah.... sooooo.... how does that cylindrical lens fit into the lens? before the gg??? i'm assuming your using a round one verses a rectangle one...

also, fyi, my testing with a holographic diffuser yeilded nothing promising. i had a 10 degree LSD. i had hear through an optical specialist that that would be a better version of the gg, but as someone else also reported, it doesn't work.
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Old March 31st, 2004, 09:46 PM   #634
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A 10deg holo diffuser is no good, it's surface is simply too rough. I also tried the 20 deg, it's not that bad, but the hotspot is very pronounced. The 60deg was the best with respect to smooth picture without a hotspot, but it's way too dark. The 20deg may work if you have a suitable condensor.

For those trying to make a bosscreen, you may want to look at microcrystalline wax. It has higher melting point than paraffin. I couldn't find any local suppliers, and mail-order guys sell in 10lb qty; that's a LOT of bosscreens :). As for the procedure (someone mentioned bubbles): read up on candlemaking, it's suggested to use a water bath to melt the wax, and keep it 'simmering' for 30min to get rid of the bubbles.
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Old March 31st, 2004, 10:31 PM   #635
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Thanks for the post, Roman. How did the 20 degree diffuser look as far as grain?

Also, if you don't mind, if you could post your holo diffuser results as a new thread, it would help narrow down these huge Aldu and Agus threads.
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Old April 1st, 2004, 09:35 AM   #636
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Eliminating Ground Glass althogether

Hi all,

I'm making this adapter for the HDV camera (JVC JY-HD10) and with its 1280x720 resolution, the GG grain issue becomes catastrophic.

After some experimentation with grounding of the UV filter glass, which proved still unacceptable even with the very fine grit (started with 9, finished with 25), I'm waiting on the Bosscreen material... but I don't hold my breath for it either.

So, is there positively no way to eliminate GG altogether? What if we use not 35mm SLR, but 16mm movie primes, thus making the "projected" image smaller and closer to the native size of the prosumer cams' CCD?
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Old April 1st, 2004, 11:43 AM   #637
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Rotating the GG will get rid of the grain effect, hence the eliptical(?) motion used in the real mini35.
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Old April 1st, 2004, 12:38 PM   #638
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Alex, take my opinion for what its worth (I'm no expert), but I tried in vain to take this route. I was also bothered by the visible grain - as well as the light loss, and tried taking the GG out of my adapter and simply using a relay lens. I got a great image - no question - very bright and completely grain free... but exactly the same depth of field as my video camera is used to.

I have rationalized this result to myself with the following (likely delusional) argument:

Depth of Field is determined by the relationship between the size of the hole the light enters and the size of the imaging area. The ground glass literally creates a different sized intermediate imaging area. It makes the image-making a two-step process - First an image on the ground glass - second, a different image on the CCD. Without the ground glass - there is only one imaging step... the CCD. None of the optics in between seem to comprise an 'imaging area' in my novice experimenting.

This also negates the possibility of simply using different lenses (16mm, etc.) for the same reasons. 16mm film has a significantly larger depth of field than 35mm film for exactly the same reason the video cameras have large depth of field: the relationship of the image area (a piece of 16mm film or a tiny CCD) is much much smaller than a piece of 35mm film, so the 'circle of confusion' which creates a shorter depth of field is reduced.

I realize this post is likely just 'so much mumbling' but I tried this approach and failed. However, if you're like me - you probably won't believe it until you give it a go yourself. If you succeed, let us all know!

On another note - in reference to grit size, when you say 'started with 9, finished with 25' what do you mean? I would interpret the '9' as meaning a 9-micron grit size (around 1000 grit). 25 microns would be larger than 9 - causing much more visible grain. Just confirming. From what I've heard, (but never seen) the goal is to get down to about 3 microns at the final stage.
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Old April 1st, 2004, 12:51 PM   #639
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Grit sizes: I ordered 5,9,12 and 25 from gotgrit.com. I haven't done grinding myself, rather my worker did; if I understood him correctly, 25 was the finest while 5 was the roughest. In any case, this doesn't matter much as I hated the results at every stage of the process due to the very visible grain.

I expect to get Bosscreen Friday, will report the progress with that (supposedly grainless) screen.

Would be super if Bosscreen material worked... I'd hate to have any moving parts in the adapter (the only alternative to the static screen that eliminates the visible grain)...
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Old April 3rd, 2004, 03:31 AM   #640
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upside down monitor solution

just in case you didn't check - take a look at upside down monitor solution thread. the inverting/flipping image problem is finally solved! take a look.

filip
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Old April 3rd, 2004, 07:17 AM   #641
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Filip, I intend to rather mount the camera *upside down* in front of the adapter.

This should flip the image just right, i guess.

Given that this is a custom rig anyway, I see no problem making the camera mount that allows for such 180deg. rotated positioning of the cam against the GG.
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Old April 3rd, 2004, 06:09 PM   #642
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<<<-- Originally posted by Alex Raskin : Filip, I intend to rather mount the camera *upside down* in front of the adapter.

This should flip the image just right, i guess.

Given that this is a custom rig anyway, I see no problem making the camera mount that allows for such 180deg. rotated positioning of the cam against the GG. -->>>

the intention of this idea is not to put camera upside down, which is of course always possible, but to work normaly - with the picture on the flip out monitor in proper (upside down/flipped) position. as you know - it's already discussed many times - you can easily rotate image in post, but when shooting with camera in upside-down position - it's very tricky. i tryed that, and everything is in wrong place. with this solution (just a small mecanical or magnetic surgery in your camera) you can pan and tilt normally with no stress at all.

the solution with the camera upside down is ok for NO POST. but during the filming.... hm... i will re- think that.

just a thought.

filip
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Old April 3rd, 2004, 06:27 PM   #643
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Flipping the camera around would be especially awkward when producing a video for hire. An upside down camera rigged to a tripod would not be to impressive to a client.
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Old April 7th, 2004, 12:23 PM   #644
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Chemist way

Edit : This as to be done by a Chemist, don't try this at home.

I have receive a mail from a guy's in New Zealand, and he send me a recipe to make a GG .This sound pretty hazardous to me because I have absolutely no competence in chemistry, but maybe one of you...
Maybe try this outside :~

Message:
Just I can not make any post to the h**p://www.dvinfo.net/ maybe some technical reason from over there.

Anyway I'd like to push some new idea for matting process of the Ground Glass -- chemist way:

1st recipe::: easy matt

1 part of Sulphuric Acid ---- H2So4
8 parts of potassium fluoride - KF
100 parts of Water --------------- H2O

if substitude the Sulphuric Acid - H2So4 by
-- Chloric Acid -------------------------- HCl, or by
-- Acetic Acid --------------------------- CH3COOH, than use
18 parts of potassium fluoride ---- KF

2nd recipe::: more matt

100 parts of ammonium fluoride --- NH4F
20 parts of sulphuric acid -------- H2So4
100 parts of ammonium sulphate - (NH4)2SO4
100 parts of Water --------------------- H2O

after approx 20-40 minutes just wash the glass, that's all...

Edit: Read whit attention,

From James Ball

Acid Etching
I'm a Chemist,

I believe in better living through Chemistry and offhand believe this would produce better results than a mechanical method of making gg....

BUT

Messing with fluoride can be dangerous. You'll be making hydrofluoric acid and it can not only etch glass, it can do really wicked things to your bones. HF can be absorbed through your skin to attack underlying tissues and exposure at low concentrations may not be immediately evident it may take hourse befor you notice you have a real problem. I also understand that it takes very special medical attention to treat a victim.

HF exposure can lead to a very painful death.

If I were going to do this first I'd read the Material Safety Data Sheet for HF

http://www.chem.purdue.edu/chemsafety/Equip/hfmsds.pdf


If the MSDS doesn't scare you away (it should) I'd also want a little more detailed recipe. For example, what order should you add the ingredients? Don't do it by order of occurance in the list!. You should add acid to water. Then I'd add the KF last.

I'd also want to know if there is a commercial preparations available at low concentrations instead of making your own. You probably won't save much money over making up a batch yourself. You'll have less waste, and just dumping your left over chemicals makes you a criminal in some places, not to mention stupid, irresponsible etc. Also a commercial preparation will have its own MSDS sheet and will give you a better idea of just how hazardous the preparation is at the concentration you wish to use it.


KF is chemically similar to NaF, the sodium monofluoride you'll see on your toothpast label. The NaFl you have in your toothpast is fairly dilute, here you'll be using the concentrated chemical.

So in other words, don't make your own etchant. Buy a commercial solution and carefully use it as the mfg. recommends.

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Old April 7th, 2004, 01:21 PM   #645
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I've read about acid etching, and it sounds like this could be very similar. As it ends up, acid etching (the stuff I read about) is only equivalent to 600-1000 grit. Since 3 micron is 8000 and 5 micron is 4500, the 1000 grit certainly wouldn't work for a static adapter. However, this new process could be very different chemically (even though the procedure sounds very similar) and provide better results. Either way, its certainly worth a try. Maybe 600-1000 grit was more a reference to how opaque the glass is as opposed to actual grain.
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