My slide projector died many years ago and I just have a basic Agfa slide viewer, so I thought I would look online at the modern versions of projectors and viewers. I spent part of the afternoon recovering some of my 35mm slide collection from long term storage, with a view to scanning some of them. Of course you can get a digital projector to do it, but you're talking about a cinema-class Barco for many tens of $k, not a powerpoint-thrower designed for office use.I am just wondering what everyone does about viewing 35mm slides (for those of you who have them) If you wanted to hack a Slide King or similar for wide angle, you could start by mounting shorter RB or RZ lenses to the front. 35mm WILL NOT cut it because the optical flux through the slide required to light up a building will melt it. I would suggest you look at getting something at least as grunty as a Goetschmann G67 (it's like a Slide King but more modern takes the 85mm mounts). They're 4-story-high images though and projected onto dull sandstone - if your building is white or concrete, you will get better brightness. There are occasional events where people project patterns on whole buildings and that particular one is done 5kW lamps shining through 5" mylar rolls that advance every two minutes I think the image is around the 5x7" size. You get the same effect from a short lens up close as a long lens further away as long as their relative aperture is the same.Īs choosing the focal length, it's a function of your slide size and how far away you want the projector. For the side of a building and decent brightness, you need a thousand watts or three. You can make one from Tyvek and screen paint, or you can paint the side of the building with either screen paint or the best white titanium paint you can find.ĭistance is irrelevant, it's magnification that matters for power/brightness, i.e. You will need an outdoor projection screen, trying to project on concrete isn't going to work very well. Your second problem is 'the side of a concrete building'. Using these with color transparency materials may be problematic as the light intensity in these things is fierce. These things normally take 3x4" (whatever the standard size) glass mounted slides. Also try A/V firms, a big one might have some available for not that much money. You might be able to get by with an auditorium projector: if you only need it for a short time, and can put an educational/arty-farty slant to your usage, you may be able to borrow a few from a local university. This would be a rather pricey rental item, try A/V rental firms. Most modern outdoor projection equipment is, of course, digital. the bottom of the image will be narrower than the top, and the sides will fan out going from bottom to top. Also, with a short lens, you'll need to have the projector closer and tilt it more to cover the same area, leading to 'keystoning' in the projected image, i.e. Usually a 90mm or longer lens works for the majority of common slide projection setups. Wide angle slide projector lenses are rare. Schneider, Zeiss, Leitz, Buhl (in the US), among others make excellent slide projector lenses. If image quality is a concern, you'd need to factor that in. Projector lenses vary widely in quality, from plastic zooms (and zooms are typically slower than fixed focal lengths) to great fixed length fast lenses with excellent glass. Both digital and slide projectors have a wide enough range of brightness that you'd have to be specific about models to get any relative brightness information, and you'd also need to be specific about the ambient light levels you're trying to overcome. With a wide lens at a short distance covering the same screen area as a long lens at a large distance, the image will be approximately the same brightness. You're concentrating the illuminating passing through the slide over a given area. It's really more a matter of how large your projected image is rather than distance.
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