I'm interested in a Rodenstock wide angle lens for my Arca Swiss 4x5 and want to have the angle of view roughly equivalent to a 17mm on 35mm format. I assume that to be about 107 derees in the 35mm format but which Grandagon would be equivalent in 4x5? How much exposure fall off will there be? Probably will be necessary to invest in a center filter to obtain even density on film. Thanks for any practical insight.

-- John R. (rp@asus.net), October 16, 2000

Answers

Response to 4 X 5 wide angles

17x155/43=62, so about grandagon-n 65 is ok.

-- Wisawa (wisawa@newmail.net), October 16, 2000.

Response to 4 X 5 wide angles

17x120/36=56 so the 55mm is closer to the same horizontal coverage.

-- Bill Mitchell (bmitch@home.com), October 16, 2000.

Response to 4 X 5 wide angles

Go for the 55 Apo-Grandagon, a super lens. A CF may be necessary especially for chromes.

-- Trevor Crone (tcrone@gm.dreamcast.com), October 17, 2000.

Response to 4 X 5 wide angles

i use a simple factor to determine rough equivalents for format to format comparisons. I'm interested in the long side of the format not the length of the diagonal as that seems more practical. The factor I use to compare a lens for use with 4x5 (or 6x12cm) formatcoverage to that of a standard 35mm format is 3x. so 3 x17 = 51mm. From experience I know that the Schneider 47mm XL on 4x5 film (not the image circle) has slightly greater horizontal coverage than a 15mm Nikkor, so I too think the 55mm APO Grandagon is the way to go. You probably will need a center weighted filter. If the Rodenstock looks too expensive also look at the Heliopan CWF. I haven't used this lens, but I use a Heliopan CWF with my 90mm f/4.5 Rodenstock built Caltar II with no loss of quality.

-- Ellis Vener (evphoto@heartstone.com), October 17, 2000.

Response to 4 X 5 wide angles

When calculating equivalent lenses for different formats with different aspect ratios, I like to compare diagonal of the largest 4:5 ratio that fits the format. E.g., I assume a 35mm frame is 24x30mm instead of 24x36, and thus has a diagonal of 38.4mm.

I get 72mm in 4x5 as equivalent to 17mm in 35mm.

With my method, I can use my 35mm to frame a photo and just imagine that a little of the ends of the long dimension won't be in the picture.

-- John H. Henderson (jhende03@harris.com), October 18, 2000.

Here's the formula I use in Excel.

angle =DEGREES(2 * ATAN( width /(2 * focalLength)))

For "width", I measure the dimension I'm interested in with a ruler (don't go by the specs, see how much actual film area you get an image onto). For 4 X 5 with Fuji quickload that's 96mm X 121mm. You can also do the diagonal if you like (154mm, based on the 96 X 121 mm).

-- lloyd chambers (photo@llc4.com), October 23, 2000.