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08-30-2012, 04:52 AM   #1
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How wide is this?

A question for the clever ones amongst us.

I was describing my occasional method of landscape photography where I've used a tripod mounted Pentax Shift 28mm F3.5 lens fully shifted (11mm) to the left for shot 1. Then only the lens rotated 180 degrees horizontally, hence now fully shifted right for shot two, then stitch both together in Photoshop.

I was asked what equivalent wide angle does that make the final image look like? I haven't a clue or indeed knowledge of how to work that out, it's just for fun, no prizes anyone care to have a go?

I realise there will be at least two correct answers, FF and APS-C.


Last edited by Kerrowdown; 08-30-2012 at 05:10 AM.
08-30-2012, 05:09 AM   #2
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Used a what?
08-30-2012, 05:13 AM   #3
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QuoteOriginally posted by Docrwm Quote
Used a what?
Apologies got called away to phone while mid edit.
08-30-2012, 05:28 AM   #4
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Short answer is that you efectively get 28mm focal length on a sensor of 45.6mm by 15.7mm. Now this gives you horizontal field of view just a bit shorter than 89 79 degrees (provided that you do it on digital APS-C size camera).

If you would put a lens on APS sensor to give you similar horizontal field of view, you would need a lens of about 14.5 mm in focal length.

Since you are shifting 11mm I assume that you do it in horizontal direction, since if you wold do that in vertical direction, there would be no overlap to stich panorama right?

Well, I counted it here to be just a bit shorter than 79 degrees, but I wrote 89. Well the correct answer is just a bit less then 79


Last edited by stanislav; 08-30-2012 at 08:01 AM.
08-30-2012, 07:51 AM   #5
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There are a whole lot of possible answers here. There is a web site that does provide a calculator for this, at...Horizontal Shift
  • So in the landscape orientation, as you described - 78 x 31 degrees
  • In the portrait orientation - 68 x 45 degrees
Vertical Shift
  • So in the landscape orientation, as you described - 45 x 68 degrees
  • In the portrait orientation - 31 x 78 degrees
Also as stanislav pointed out, in the horizontal shift you will need to take a third image with the lens centered (not shifted) in order to have a continuous image.
There is also yet another possibility. And that is shooting an image in the center (unshifted), then shift, and shooting an image at each clock position. This would result in an image of about 78 x 68 degrees (and note the corners would not be covered of the largest rectangle, so you would need to crop a bit smaller). This process would take 13 images, but the result is extremely large - providing about 3 times the original coverage.

08-31-2012, 12:54 AM   #6
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There is a calculator for your question:
Using Tilt-Shift Lenses to Control Perspective

On full frame 35mm: focal equivalent = 17.4mm
On 1.5 crop sensor: focal equivalent = 14.5mm
02-23-2013, 11:10 AM   #7
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Hey big apologies to everyone who replied to this thread, I thought I had already said thanks but can't see it here.

I'm not a rude man by nature, so forgive me, better late I guess than never.
02-23-2013, 02:23 PM   #8
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QuoteOriginally posted by kerrowdown Quote
better late I guess than never.
With the Samyang 24/3.5 T/S due in a couple of months,
your thread revival is quite timely.

It has a 12mm shift off-axis,
and a shorter focal length,
so will be wider than the shifty K.

02-24-2013, 01:40 AM   #9
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QuoteOriginally posted by lytrytyr Quote
so will be wider than the shifty K.
Aye your right, according to the calculator link given in the thread, for FF the Samyang 24/3.5 T/S will have an Angle of View ( Horizontal x Vertical ) 102.7 x 53.1 and Focal Length if Single Photograph of 14.4 as opposed to 92 x 46.4 and 17.4 for the Pentax Shift 28mm F3.5.

The calculator also shows a couple of crop sensor variants as well, if your interested.
02-24-2013, 01:58 AM   #10
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QuoteOriginally posted by kerrowdown Quote
The calculator also shows a couple of crop sensor variants as well, if your interested.
Yes, for Pentax APS-C, the Samyang 24/3.5 T/S will effectively become a 12mm rectilinear lens. Very nice!
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