8mm Telecine using condenser lens

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DannyQuinn
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8mm Telecine using condenser lens

Post by DannyQuinn » Mon May 09, 2011 7:10 pm

Been trying to get this working... with no luck. I've got a couple condenser lenses - one is 130mm another is 60mm. Haven't been able to get a good image and many of the tutorials online are old and missing. Any tips or links so I can figure this out?

supa8
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Re: 8mm Telecine using condenser lens

Post by supa8 » Tue May 10, 2011 10:49 am

I have one such unit that I bought from a member of this forum a few years back. It works well and was thoroughly tested by the guy.
PM me if interested
i don't need it because I have a Sniper Pro HD now, which obviously is miles away in terms of engineering and results.
You could also look into a Workprinter if your budget allows it (Moviestuff have some second hand ones they refurbish), whose results would also be better than the DIY telecine you are referring to.

granfer
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Re: 8mm Telecine using condenser lens

Post by granfer » Tue May 10, 2011 1:07 pm

The "condenser lens" method works well if you get the adjustment right; generally you need to place the lens in the same plane as a back projection screen would be for correct focus. Therefore, the image size (diagonal) needs to be rather less than the diameter of the lens you are using. Start with plain white paper to focus the correct size image on, then replace it with the lens. It's then a question of trial and error to place your camera accurately for the correct focus and image size, keeping it spot on the optical axis of the lens.
When you find the right spot, the result should be excellent, but I soon abandoned the method because of maintaining the positions accurately. I now use a smaller lamp in the projector, with the projector lens removed, and the camera pointing straight into the machine....i.e focussed on the actual film in the gate.
This requires the use of the correct choice of zoom setting on the camera coupled with the use of a supplementary lens, or, if your camera has an interchangeable lens mount, with the lens mounted on extension tubes.

DannyQuinn
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Re: 8mm Telecine using condenser lens

Post by DannyQuinn » Wed May 18, 2011 8:20 pm

Hi guys,
Thanks for the replies. I've been dealing with other issues but I'd like to give this a bump and see if i can make it happen. I want to improve the quality of my 8mm transfers - now i'm using a 'transfer box" with frosted glass and I'm not real happy with the results. I've got a number of projectors i can use Chinon, Bolex etc. which work just fine when projecting onto a screen. In trying to get the aerial image happening I've had no luck. I've got a couple condenser lenses i can use. The image from the proj. is focused more or less on the plane of the c. lens, correct? This image fits nicely in the c. lens diameter. I've tried with and without a mirror and still cannot get any kind of usable image to shoot. Is there an online tutorial anyone can point me to, to find out where I'm screwing up? I've seen where 1 guy claimed there were liability issues with c. lenses because people insist on looking at their projector thru the lens! Maybe that's why there's so little info out there.

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MovieStuff
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Re: 8mm Telecine using condenser lens

Post by MovieStuff » Wed May 18, 2011 10:10 pm

A condenser lens is essentially nothing more than a big magnifying glass. It allows a magnified view of the gate when used in conjunction with the projection lens. Typically, a 5x lens is what you need for a 22-25mm projection lens for 8mm. The condenser lens will be anywhere from about 12-16 inches from the projection lens. One thing that is essential is that you replace the bulb in your projector with a diffused light source. Many people think this simply means a bulb of lower wattage or intensity but that is not the case. What you need is a lower intensity bulb with a piece of diffusion material such as opal glass or milky plex in between the light source and the gate. If you do not have this in place, then you will see a magnified view of the gate along with the filament of the bulb behind it. This would effectively be like looking at a window of stained glass with an arc welder behind it. What you want is stained glass with a white sheet between the light source and the stained glass so you have even illumination. Forget about your camera during the initial set up. Just get down on one knee about 36-42 inches from the condenser lens and look into it with one eye. What you see is what you get.

Roger

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Re: 8mm Telecine using condenser lens

Post by john59 » Thu May 19, 2011 12:56 am

This might be of interest for you.

http://www.youtube.com/watch?v=GIPnB1GcwqU

Here it is on vimeo with full instructions.

http://www.vimeo.com/groups/84271/videos/20950590
Last edited by john59 on Thu May 19, 2011 1:21 am, edited 1 time in total.

john59
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Re: 8mm Telecine using condenser lens

Post by john59 » Thu May 19, 2011 1:00 am

http://www.vimeo.com/20900718

And here. The music to this is great.

Actually I don't think this method is what you want is it? :oops:

Bill
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Re: 8mm Telecine using condenser lens

Post by Bill » Thu May 19, 2011 1:59 am

Actually I don't think this method is what you want is it?

Well, if I could get that kind of quality, I'd be ecstatic! Thanks for those links. Just to clarify - those videos and the method Roger describes are captured directly off the gate using a diffused LED, whereas "aerial image" capture is different - projecting the image onto a condenser lens. I guess I have some more experimenting to do. i would be very happy with the results in Mr. Miller's videos.

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MovieStuff
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Re: 8mm Telecine using condenser lens

Post by MovieStuff » Thu May 19, 2011 4:21 am

Bill wrote:the method Roger describes are captured directly off the gate using a diffused LED, whereas "aerial image" capture is different - projecting the image onto a condenser lens.
No, using a condenser lens (also known as a "field lens") is an aerial image capture. Whether you use a condenser lens or a macro lens with an extension tube, you will still need a diffused light source.

Roger

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