rjschell
Established
Roger Cicala (lensrentals.com) has pointed out problems with the manufacturing tolerances of the extra interface created by adapters. Pete Myers has observed that the lens/sensor interface is unforgiving of lens aberrations, comparing it to a brick wall vs. the 30 micron thickness of film. Small sensor sizes further require more alignment accuracy than larger ones. Telecentric designs work better than symmetrical ones. What are your observations concerning combinations of lens/adapter/camera. (I saw a definite improvement in edge sharpness using a Fotodiox Pro LTM-NEX6 adapter vs. a cheaper one with adjustable set screws).
rscheffler
Well-known
My bottom line conclusion is that if you're invested in quality rangefinder glass, you'll get the best (most faithful) across frame performance with 35mm and wider, as well as some 50mm lenses, on a digital M. And of those options, the M240 is the best (if you want color).
I've shot a number of RF lenses on NEX as well as the a7 and a7R cameras. I've tried two adapters - a Novoflex and a Metabones. The Metabones had an extremely tight fit to the lens and wouldn't allow infinity focus. After realizing these two points, I stopped using it. The Novoflex seems OK, though I can't rule it out as a cause for some unevenness of sharpness across the frame with specific lenses compared to how those lenses look on a digital M.
The problem with most WA RF lenses is they have fairly short exit pupils, relative to SLR designs. This results in a more oblique angle at which light rays reach the sensor at the image periphery and are refracted through the sensor toppings in a manner that degrades image quality. The thicker the sensor toppings, the worse the degradation. Sorry if I'm repeating what you already know, but ideally you want to find a sensor with the thinnest possible toppings for WA RF lenses, especially if it's a full frame sensor. Currently, only Leica strives for this.
How bad the image degradation is perceived to be also depends significantly on the type of photography. I.e. brick walls/architecture/infinity landscapes tend to be more critical than portraits and anything else where there is great subject background separation and the subject relatively centrally positioned.
I've shot a number of RF lenses on NEX as well as the a7 and a7R cameras. I've tried two adapters - a Novoflex and a Metabones. The Metabones had an extremely tight fit to the lens and wouldn't allow infinity focus. After realizing these two points, I stopped using it. The Novoflex seems OK, though I can't rule it out as a cause for some unevenness of sharpness across the frame with specific lenses compared to how those lenses look on a digital M.
The problem with most WA RF lenses is they have fairly short exit pupils, relative to SLR designs. This results in a more oblique angle at which light rays reach the sensor at the image periphery and are refracted through the sensor toppings in a manner that degrades image quality. The thicker the sensor toppings, the worse the degradation. Sorry if I'm repeating what you already know, but ideally you want to find a sensor with the thinnest possible toppings for WA RF lenses, especially if it's a full frame sensor. Currently, only Leica strives for this.
How bad the image degradation is perceived to be also depends significantly on the type of photography. I.e. brick walls/architecture/infinity landscapes tend to be more critical than portraits and anything else where there is great subject background separation and the subject relatively centrally positioned.
Scrambler
Well-known
There is a world of difference between shooting a precise target in a lab and shooting a crowd on the street. I wouldn't fret with anything where DOF will cover any small error: even infinity landscapes won't be shot at full aperture.
The issues with degradation and colour shifts due to shallow angles of approach are the real issues (as rscheffler has pointed out), and the significance of these differ between shooters, subjects and use of colour. A quite high degree of colour shift can be tolerated if the output is B&W. As has been said, if the edges are OOF anyway, what difference a loss of sharpness?
My shooting isn't precise enough to be an issue. I'm happy adapting my Voitlander 21/4 onto my APS-C Sony, the output is better than the kit lens even at the edges. If the plane of focus isn't square with the sensor, it hasn't made a difference yet. I use a cheap adapter.
The issues with degradation and colour shifts due to shallow angles of approach are the real issues (as rscheffler has pointed out), and the significance of these differ between shooters, subjects and use of colour. A quite high degree of colour shift can be tolerated if the output is B&W. As has been said, if the edges are OOF anyway, what difference a loss of sharpness?
My shooting isn't precise enough to be an issue. I'm happy adapting my Voitlander 21/4 onto my APS-C Sony, the output is better than the kit lens even at the edges. If the plane of focus isn't square with the sensor, it hasn't made a difference yet. I use a cheap adapter.
uhoh7
Mentor
I have 10+ mount adapters. Most cost around 20usd. They work fine, except most stop past infinity.