GH3 crop factor question

S

stefanocps

Well-known member
hello, rteyng to undesrtanbd better the equivalence of vintage ff lens when used in mft
i have tried in a lunix native lens to shot a 50mm (the lens is a 45-175)
then i shot with md rokkor minolta at 50mm (th elens is the 35-70)
and the pics are the same
so i should thing that even when talkinb about native lense in mft we are thinking at x2 when compared to fullframe
a 50 on a mft, both nativ elumix or vintage ff will be both similar to a 100mm on a ff?
thanks for helping clarify
 
stefanocps said:
update: i have tried a prime rokkor 50 md and it is a bit different form the 50 of 35-70. why??
Click to expand...

A lens marked 50mm will give the same FOV regardless of it's being a native m4/3 lens or any other, with maybe a +/- 10% variation from marked FL. This is what you are probably seeing.

Have you tried the excellent "Extended Teleconversion" video feature on your GH3? This converts the full frame width FOV to a central crop of 1920X1080 pixels, giving a 2.3X mag. factor while keeping the same aperture setting. Your 50mm/1.4 lens becomes a 115mm /1.4 lens (230mm FF equivalence rather than 100mm.

Pete
 
never tried...is it really useful anothe magnification?WITH MFT WHAT is more required often is to have a wide rather than tele
this magnification is digiatl or analogical?i mean is there any loss of quality?
 
In terms of DOF equivalence a Micro 4/3 camera with 25mm f/1.4 lens produces the same image as a Full Frame camera with a 50mm f/2.8 lens. ( so 2x the focal length and 2 F-stops higher when going from Micro 4/3 to FF )
 
stefanocps said:
never tried...is it really useful anothe magnification?WITH MFT WHAT is more required often is to have a wide rather than tele
this magnification is digiatl or analogical?i mean is there any loss of quality?
Click to expand...

This is still full res 1080HD - just a central 1080x1920 px crop of the sensor rather than the full width sensor reduced to that by line-skipping and pixel binning. The resolution in ETC mode is actually improved a bit as you're shooting with a small but "native" 1:1 pixel ratio segment. I would expect moire to be less also. The one downside is that higher ISO shooting will resort in more noise at equivalent lens settings. But practically speaking, since your aperture remains the same, it's unlikely you would have a lens as fast near the 115mm/1.4 that your 50mm/1.4 becomes in ETC mode.

For performances, I use my native m4/3 12-35/2.8 for wider shots, and closer, my Nikkor 50/1.4 and 85mm(195mm ETC)/1.8, for head shots.

For GH4 4K shooters, the 2X dig. zoom gives very smooth FHD-res footage, upsampled on the fly to 4K dimensions.

Pete
 
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