The GetDPI Photography Forum

Great to see you here. Join our insightful photographic forum today and start tapping into a huge wealth of photographic knowledge. Completing our simple registration process will allow you to gain access to exclusive content, add your own topics and posts, share your work and connect with other members through your own private inbox! And don’t forget to say hi!

Image circle of A7R and Canon Tilt/Shift lenses compared to MFDB and shift lenses?

mbroomfield

New member
I find it better (and simpler) to just use the long width of the image size to calculate FOV ratios between lenses and formats, even when changing format ratios (ie going from 2:3 to 3:4);
1) You don't "see" a diagonal FOV, you see it by the width of your image (different landscape to portrait of course)
2) Easy enough to do in your head

So to use your example;
35mm format width = 36mm
Shifted 4:3 width = 48mm

The FOV equivalent to using a 24mm lens unshifted on FF is

24*36/48 = 18mm

If you want to know what you'd get if doing a portrait

24*24/36 = 16mm
A little different due to the change in format ratio from 2:3 to 3:4

Hope this helps


Ben,
I get the FOV equivalency by doing unsofisticated math. No scientists here.

If you’re shifting 12mm to each side, you get an image of 48X36 (4:3).
48X48= 2,304 +
36X36= 1,296 = 3600

Square root of 3600 = 60 (60mm is the image circle necessary for the capture)

We know the FF real image circle of 24X36 is 43.27

60 : 43.27 :: 24 : X
X = 17.3
17.3mm is the FOV equivalent for a 24TSmm lens when fully shifted.

If I’m mistaken, please anyone correct me asap. If there's a simpler way, I'd like to know it. Thanks.
Regards
Eduardo
 
Hi Stefan

That is awesome! Good to hear!

I will be very keen to purchase one when ready.. :)

When you refer to doing a quick 3 image stitch, I presume you mean with the camera in the "portrait" orientation? How much front rise is able to be achieved this way before the image circle/vignetting run out?

Same applies for a simpler 2 x portrait stitch? How much front rise is able to be achieved?

Ok, thanks so much, look forward to hearing some more details!
 
Top