Luminous Landscape Forum

Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: mdshaw55 on February 22, 2012, 01:48:43 pm

Title: Focal equivalent to stitched image
Post by: mdshaw55 on February 22, 2012, 01:48:43 pm

I'm sure there must be a simple calculator for this- if I use a Schneider 35mm lens, take an image, shift lens 10mm laterally and sandwich 2 images together... what is the equivalent focal length?

And if I did it for 10mm left + 10mm right, what then is the focal equivalent?

Matthew

Title: Re: Focal equivalent to stitched image
Post by: torger on February 22, 2012, 02:03:07 pm

You need to know what your original format size is. Say if your sensor is 44x33mm, diagonal is sqrt (44x44 + 33x33) = 55mm.

If you shift, 10mm left and 10 mm right in portrait mode and stitch you effectively increase your sensor area to (10+33+10)x44mm so you get 53x44 (almost exactly the same as fullframe 645 format) which is 69mm diagonal, so your multiplication factor becomes 69/55 = 1.25.

This means that your Schneider 35mm will give you the same field of view as an 35/1.25 = 28mm lens would have on the original 44x33mm size.

Title: Re: Focal equivalent to stitched image
Post by: Doug Peterson on February 22, 2012, 02:31:44 pm

I developed calculator like that, but have not finalized a public version. If you're a customer of ours please contact me and I'll be glad to provide you a beta version.

The math itself is not rocket science; we developed the calculator because it's much faster and less error prone than doing it by hand, especially when you want to quickly compare several options.

Example (in this case not the 35mm you asked for):
(http://www.captureintegration.com/download/FocalLengthDiagram.jpg)

Doug Peterson (e-mail Me) ([email protected])
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Title: Re: Focal equivalent to stitched image
Post by: mdshaw55 on February 22, 2012, 02:44:35 pm

It's a P45 and in landscape format.

Doug- email sent.

Matthew

Title: Re: Focal equivalent to stitched image
Post by: mjon on February 23, 2012, 01:33:06 pm

Here is another one:

http://www.alpa.ch/en/products/tools/alpa-tools/alpa-comparable-focal-length-calculator.html