leica pradovit ca2500 vs pentacon projector

[sanjay_chaudary]

<p>Hi, I have a ca 2500 projector from leica with 90mm colorplan lens and pentacon aspectar 150 projector with 80mm meyer optik gorlitz 80mm diaplan lens.<br>

The pentacon is an east german projector from 1960s passed on to me by my uncle. The lens has a bit of fungus and projector heats up quickly and the tray can hold only two slides at a time.<br>

What I don't understand is that the pentacon images are sharper and also have higher contrast, apart from being bigger. The bulb is bigger (looks like a vacuum tube model: I could be wrong on this )<br>

Is the meyer optik lens a better lens? How is this possible?</p>

[Robin Smith]

I am prepared to bet that the image brightness is much higher on the Leica. It has 250w halogen bulb. That is worth a lot

as it makes for a more involving show. Many older projectors have great sharpness, but the brightness is poor. The Leica

has the best of both high resolution and high brightness. A brighter image increases the dynamic range.

[Robert_Lai]

<p>Keep the lens with fungus away from everything else that you own, before the other lenses become infested. You should get it attended to, if you plan to keep it.</p>

<p>The image differences may be due to the lenses being flat field or curved field lenses. Leitz Colorplan lenses came in flat field (FF) or Curved field (CF) variants. The CF lenses are marked on the identification ring. The CF lenses expected the slide to have a certain degree of curvature. These didn't look sharp until the slide heated up enough to "pop", then the image would snap into seemingly sharp focus. With the Pradovit's efficient cooling system, that could take up to a couple of minutes of continuous projection for one slide before it popped. The FF lens expects a planar slide. Popping of the slide results in the center of the slide being sharp (from the AF mechanism), but then the corners are a bit out of focus.</p>

<p>I suspect that the Pentacon projector has a curved field lens. Those old projectors typically use a 500W bulb, which will roast a slide in no time. With that furnace roaring behind the slide, it should pop very quickly into a curved shape, giving you that sharpness and contrast that you admire so much. I had a slide literally melt on me in one of these old machines, so don't project for more than about 30 seconds per slide. The intense light also tends to bleach the slides with repeated projection.</p>

[Robin Smith]

<p>Leica CF lenses were designed for Kodachromes - so if you are not shooting Kodachrome the lens will not be good - actually, in my opinion, the CFs were no good anyway even for Kodachrome - you never knew where you were with them.</p>

<p>I do agree with Robert that the cooling system is an important factor in sharp slide projection. The sharpest projector I ever used was a1962 Leitz Pradovit that had a low wattage tungsten bulb and was completely manual - but the image was very dark - you got used to it, but when I went over to a Leica CA2500 or equivalent it was a night and day difference - literally.</p>