Originally posted by Abbazz a 55mm lens on a full frame sensor is "equivalent" to a 27.5mm lens on a M4/3 format sensor.
No, it absolutely does NOT.
No crop sensors can ever make a Lens appear to be wider then what that lens is natively.
Not even when a Focal Reducer is used.
You need to go back an redo all your maths, because you have it the wrong way around.
---------- Post added 06-07-18 at 12:41 PM ----------
Originally posted by reh321 The speedbooster does physically change the optical characteristics of the lens; light does follow a different path than it had. A 55mm lens does become a 27.5mm lens, because the path of light through it is changed.Any lens becomes wider and it delivers a higher intensity beam to the sensor. Always.
Nope.
A 55mm lens is always a 55mm lens, regardless of whether it's mounted on a FF, MF, APSc, Q or even sitting on the floor.
The lens's angle of view is always the same.
The use of a focal reducer compresses the image circle - it paints a smaller circle of the same angle of view.
Hold a lens up so the front faces an open window while standing in the door way to a darkend hallway.
Now hold a piece of paper up behind the lens and move it closer or further away until the lens is projecting a sharp image on the paper.
Note what items are in view, and the size of the circular image.
Now add your focal reducer to the back of the lens and repeat.
You will see the same items in view, but the circle will be smaller.
You only see more of the image circle on a crop sensor camera because the image circle is projected smaller.
You do not see more items projected then before.
It's simply that the camera can now see more of what the lens could already see. This is what makes people think the lens magically becomes wider, but it does not.
Use of a Focal Reducer means less of the image circle is lost.
---------- Post added 06-07-18 at 12:55 PM ----------
Originally posted by 2old4toys Forgive extreme naivety but what challenges are there to physically remove the Nikon Mount and swap in a PK Mount instead,
Originally posted by reh321 Are you suggesting that someone, some amateur here, spend $489 on one of these devices and then modify it so that provides a K-mount instead of a F-mount?
I thought about it for a long while, especially as they make C/Y to M4/3 and C/Y to E Speedboosters, as the C/Y lenses used the same FFD as K-mount and M42.
Since I made M4/3 and E mounts for my Aja Cion, I was asked by a US cinematographer if I could modify one of the PL to E speedboosters, and found it would be easier to pull the rear off the Speedbooster and manufacture a custom plate that would screw directly in to the rear flange mount, instead of using the E-mount.
Turning one of the C/Y to M4/3, E, X mounts Speedboosters in to a K-mount would be even easier, as I could pull the K-mount ring off the front of a cheap adapter, redrill the screw holes to match the Speedbooster, block the original holes if not used, and then just screw it in place.
I've been half tempted to create a range of custom fit lens flange rings, but have been busy with other needs.
Modifying the Speedbooster for a Q, to accept K-mount lenses, is basically the same, but the front ring would be much narrower, due to the longer FFD of the Nikon lenses.
The other option for K lenses on M4/3 and E mounts, is to buy one of the Kipon Focal Reducers - Kipon use the same optical supplier as Arri.
Sadly they don't make a product for the Q or Nikon 1 series.
I'd expect to see Metabones never make a K-mount version, but will probably make a version for the Nikon 1 cameras.
Having used both, the Q family are superior, even when comparing Video output.