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Thank you Bart....What I wrote earlier was indeed a mistake :loco:, so thank you for spotting it :thumbup: ...The dangers of starting to write this on one day and finishing up at 4:30am BST the next day...I guess :facesmack:That's an extensive table, Barry. But why is '1.5 times the "True" focal length' not good enough ?
Thank you K-H, yes I have "not" made it at all clear, that I was referring to a crop made within the A7R4 camera settings at a typical Landscape 3:2 ratio taken from the Sony Specification sheet https://www.sony.co.uk/electronics/interchangeable-lens-cameras/ilce-7rm4/specifications ...I have just Edited it to hopefully make it more clearer for everybodyThanks Barry.
Of course, your analysis applies for using entire images, as in landscape photography, comparing Fields or Angles of View.
For birding and such one is more interested in the linear resolution one can achieve with a particular setup. When comparing two different camera formats (mMF, FF, APS-C, MFT) and high resolution lenses the question becomes which system results in finer resolution, i.e. more detail captured. That’s easy to figure out by multiplying the ratio of the lens focal lengths FL involved by the inverse of the ratio of the sensor pixel pitches PP.
So R = (FL1/FL2) * (PP2/PP1)
If R = 1 then resolution is the same.
If R > 1 system 1 wins.
If R < 1 system 2 wins.
Well anyway that’s how I think about it.
So instead of 1,5 the "actual" factor is 1,523076923076923 times.Thank you Bart....What I wrote earlier was indeed a mistake :loco:, so thank you for spotting it :thumbup: ...The dangers of starting to write this on one day and finishing up at 4:30am BST the next day...I guess :facesmack:
"I know it's easier just to say 1.5 times the "True" focal length and be done with it...but I have tried to be a little more accurate than that"
has now been changed to...
"I know it's easier just to say 1.5 times is the focal length and be done with it...but I have tried to be a little more accurate than that"
The "True in camera crop size" (6240 x 4160) that I used was taken from the Sony Specification sheet https://www.sony.co.uk/electronics/interchangeable-lens-cameras/ilce-7rm4/specifications
See below
Image Size (pixels) [3:2] ....35mm full frame L: 9504 x 6336 (60M), M: 6240 x 4160 (26M), S: 4752 x 3168 (15M) APS-C L: 6240 x 4160 (26M), M: 4752 x 3168 (15M), S: 3120 x 2080 (6.5M)
I am sure that using the 1.5 times rule is more than good enough for most people...I was just trying to write lets say a more accurate guide so people had the answers quickly at their fingertips when comparing one lens against another
For instance the CV65mm lens x 1.5 (rule) = 97.5mm when in fact it's the "equivalent in focal length" of a 99mm lens in camera cropped mode (not much difference I would agree...but none the less it's incorrect).
Cheers Barry
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Thank you K-H, yes I have "not" made it at all clear, that I was referring to a crop made within the A7R4 camera settings at a typical Landscape 3:2 ratio taken from the Sony Specification sheet https://www.sony.co.uk/electronics/interchangeable-lens-cameras/ilce-7rm4/specifications ...I have just Edited it to hopefully make it more clearer for everybody
What you say is equally true when comparing one camera system against another's...There is more to resolution than meets the eye when comparing different camera format sensors with their different pixel pitches and pixel sizes etc...you were right to point that out...Thanks :thumbup:
Cheers Barry
The Sony A7R2 didn't adhere to your Japanese calculator either (built in 1.500000000000 Factor).So instead of 1,5 the "actual" factor is 1,523076923076923 times.
F.i. 1,523076923076923 x 600mm = 913,846153846153834
For a 1,5 factor Sony should have cropped to a 26,763264 MB (6336 x 4224) file according to my Japanese calculator that is.
What could have possibly gone wrong ?