Videospot with mini35, some problems with hotspot at

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Old April 29th, 2005, 06:54 AM   #1
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Videospot with mini35, some problems with hotspot


There was said a lot of words about a big problem of mine - I still have a hotspot inside my frame. To remember you: I have Canon GL2 > GG > ))lens > 35mm sigma lens from my nikon camera.

I recently made a videospot for my band YOGURT (we're from Slovenia), which is on our page ...please wait for some minutes, then video is loaded. I recorded most of shots with my mini35adapter, but the problem is HOTSPOT...

Have anyone some ideas how to avoid this?

Is it possible, that I grinded my GG not onough (I did it with 1000 Grit Aluminum Oxide and water for 1 hour, is it enough?)...

Must I have macro diopter for GL2? I am asking, because it can also focus on 1cm without it...

So, I really apreciate threads in this forum, I am an enthusiast and like to making videospots for my band, now I will record next one, but I have to fix problem with hotspot...


Marko from Slovenia
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Old April 29th, 2005, 03:53 PM   #2
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You need to use a condenser lens.
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Old April 30th, 2005, 06:26 AM   #3
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The area your camcorder sees on the groundglass, should be about 24mm wide x 18mm high. You may get a hotspot if the camcorder sees too much of the groundglass.

If your camcorder can not zoom close enough to frame on 24mm x 18mm, maybe you need a close-up lens. It is best if this lens is achromatic diopter. Many AGUS builders use a 7+ power close-up lens. Some people call this lens, "relay lens" "close up lens" or "macro".

I think 1000 grit should be okay for 24mm x 18mm image size on the groundglass.

Your prime lens on front is best f1.8 and a good quality lens. Best if it is a film camera lens not digital camera lens.

If money is a problem, I would buy a good achromatic diopter and good f1.8 lens before buying a condenser.

Don't take much notice of my comments. I use a PD150, not GL2 but I think the GL2 uses a similar size zoom lens and 58mm filter thread on front. Century Optics make a 58mm mount 7+ achromatic diopter. The model number is CE-AD5870. Zoom lens adjustment on the PD150 is about 70% for a 24mm x 18mm frame at 150mm distance from the camcorder.
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Old May 3rd, 2005, 05:14 AM   #4
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Ok guys, there are two ways...

Zoom to GG as close as possible to get the hotspot less visible. Usually 24x18. This is the first way, I thing not good, because you will fall into lots of problems with room. You need bigger distance between camera and thing you are recording...

Second way is to use Condenser, see this shots - its full 36x24 :

This way you get twice bigger screen ! (36x24 vs 24x18), so you are able to shoot shorter distances and get longer glass (200mm ...), get better DOF.

Condenser are usually the cheapest lens, because in the fact they are produced for distributing light.

At the beginning there was an idea, then the ambition came and the idea became to be a dream... The Satisfied Dream =>
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