FrankS
Registered User
I am currently waiting on a Nikon slr-Fuji X adaptor for my XE-2.
I already have Leica M and ltm adaptors. (Thank you Joe!)
I'm thinking about how much closer RF wide angle lenses are to the film/sensor, the spread of light rays, and how they fall in the pixel pots.
Wide slr lenses are designed to clear the reflex mirror and are farther away from the film/sensor plane, with less of a spread of rays.
Might this mean that adapted wide SLR lenses would perform better?
I already have Leica M and ltm adaptors. (Thank you Joe!)
I'm thinking about how much closer RF wide angle lenses are to the film/sensor, the spread of light rays, and how they fall in the pixel pots.
Wide slr lenses are designed to clear the reflex mirror and are farther away from the film/sensor plane, with less of a spread of rays.
Might this mean that adapted wide SLR lenses would perform better?
typically yes.
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I don't see the point of using wide angle manual focus lenses on a crop sensor digital camera. I too have an XE2. My widest slr lens is an 18mm f3.5, a focal length which is covered nicely by my Fuji 18-55mm zoom. The use of macro and telephoto slr lenses on crop sensor digital cameras is where the advantages lie.
FrankS
Registered User
I agree. In my case though the 2 Fuji X lenses I have lack an aperture ring. (27 and 16-50) Since I'm older and less flexible, I like the feel and control of an aperture ring concentric to the lens alongside of a mechanical focusing ring.
I will also use longer lenses but this thread was about the difference in performance of 2 styles of wide lenses where the difference in design would have the largest effect on performance, and might be noticeable.
Rob-F
Likes Leicas
I like an aperture ring on the lens myself. As to the angle of incidence at the sensor, the SLR lens definitely has some advantage over the RF lens. However, it seems to me that the closeness of the RF lens' principal plane to the sensor is somewhat offset, or mitigated, by the smaller sensor size. The most severely grazing light rays from the RF lens will be outside the image area, and therefore won't be used. So the two factors might cancel each other out.
Axel
singleshooter
I think that it makes no difference Frank. The angle of hitting the sensorpixels should be the same in both cases.
If not you would have a different field of view because of more or less light from the optics edge areas.
If not you would have a different field of view because of more or less light from the optics edge areas.
Alfonso B
Established
I haven't noticed any edge performance loss even with Heliar 15/4.5 II on X-PRO1. That's my only RF lens that's actually wide on aps-c. Maybe I need to pixel peep more 
Yet if I had some money to spend, I'd get the 10-whatever native zoom and forget the Heliar.
Yet if I had some money to spend, I'd get the 10-whatever native zoom and forget the Heliar.ruby.monkey
Mentor
The rear elements of SLR lenses typically sit further from the sensor than do R/F lenses (made for film cameras anyway), so light hits the edges of the sensor at a less extreme angle and so causes less light fall-off.
Wide-angle R/F lenses can show less distortion that do equivalent SLR lenses so they do have their uses.
willie_901
Mentor
Yeah.
The angle is extremely important.
With film the light angle has a trivial impact. The photosensitive particles are essentially randomly distributed in a three-dimesional space. So Gauss designs and retrofocus designs are angle insensitive except for ultra-wide angle lenses where the latter typically has less vignetting.
Digital cameras are very sensitive to light angle. A photosite can only respond to light at a limited range of angles. On-sensor microlenses and other advances minimize this limitation to some degree. Fujinon XF lenses are just one example of many optical designs that attempt to optimize the light angles over the entire sensor surface.