Thu May 17, 2018 3:57 pm
Yes, forget about crop factors, this was a marketing term used to get 135mm film photographers to use the new APS-C digital cameras, by comparing the angle of view between full frame 135mm and the smaller digital sensor, and only adds confusion if you were not a 135mm film photographer. It (crop fsctor) has nothing to do with actual focal length of a lens, which does Not change when you use a given focal length lens, like 12mm, on a MFT size sensor or a larger sensor camera.
So your 12-40mm lens on the new Pocket camera will have a slightly wider angle of view than it would on the smaller MFT sensor in the Panasonic GH4/5, which has a smaller sensor than the GH5S or new BM Pocket camera 4K.
A good starting point is to know what focal,length is a “normal” AOV (45-degree) lens, and on the MFT format this is 25-30mm, based on the diagonal of the sensor area in native 4:3 format. The diagonal does not change on the new Pocket 4K, and remains the same at 16:9 or 17:9 aspect ratios (unlike the GH4/5 which gets a smaller shooting area in 16:9). So from 25mm, going to 12 or 15mm is a wide angle and going to 35-40 and up is a long or tele lens focal length.
I find the 12-40 a nice focal length range for the MFT format, giving a nice wide to reasonable long shot.
The Oly 12-40 f/2.8 Pro Zoom is a very nice lens. Also the Panasonic Leica 12-60 makes a good video Zoom, as it is parfocal, has steppless iris control, and very quick and quiet zoom/iris motors. It’s only drawback is it changes thr max f/stop from f/2.8 to f/4 as you zoom out to the 60mm end (known as reaping): But if you are shooting at f/4 to 5.6 this is not an issue. Still cameras use auto shutter or ISO to compensate the ramping, the BM Micro and new Pocket Camera 4K can set auto shutter angle to compensate the f/stop change.
Hope this helps.
Cheers
Denny Smith
SHA Productions