8x10 reducing backs

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I am considering the purchase of an 8x10 view camera, probably the Lotus or the Wisner Technical Field. I will be using it to make platinum/palladium contact prints. I also would like to use it for making silver prints in a 4x5 format (no 8x10 enlarger available). If I use a reducing back, can I use the same lens (360mm) and get good "normal view" results or do I need a smaller lens?

-- Brian Hoffman (hoffmab@gte.net), August 25, 1999


The 360mm will certainly work with the 4x5 reducing back, but if you're looking to achieve the same relative perspective that this lens gives you with 8x10, this simply won't happen. You'll need a shorter lens (probably around 180mm). A general rule of thumb for calculating the "normal" focal length for any given format is to figure out the diagonal dimension of the film format in question. For 4x5 this works out to roughly 150mm. For 8x10 it's around 300mm. When comparing 8x10 with 4x5 it's safe to just halve the 8x10 focal length to get the equivalent 4x5 focal length.

-- Robert A. Zeichner (razeichner@ameritech.net), August 25, 1999.

Actually the perspective (and size of objects on the film) will remain exactly the same. The only thing that "happens" when changing from an 8x10 to 4x5 back is cropping of the image.

I will concur, however, that a lens of half the focal length of normal on an 8x10 will be normal on a 4x5, that is, 300mm vs. 150mm. The perspective difference between these two lenses would be about the same as the perspective difference between 50mm and 25mm on a 35mm camera.

-- Chad Jarvis (cjarvis@nas.edu), August 26, 1999.

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