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tzhang4284 wrote:
DXO is hard data and lots of other sites measure MTF data as well. Is there room for error, limitations and flaws? Yes, but that's true with everything including lens rental data. I'm not sure what data you have to backup the statement that "all other testing sites are collecting mostly meaningless numbers."
they do not measure MTFs, they use imatest to measure something approximating MTF that is camera specific based off the data from the camera sensor and does not allow meaningful comparisons across cameras. They also typically measure from single samples of lens only and only at one focus distance (usually pretty close). lens rentals is starting to compare lenses using an optical bench that produces data that can be compared across lenses since the data is collected without a camera and is looking at MTFs at infinity as well as measuring field curvature and other meaningful aspects of lens performance and is using many samples of a lens so that results aren't dominated by outliers and consumers can gage the range of performance one could expect for a given lens. even lens rentals doesn't produce any useful data for me to choose a lens, but they at least have interesting info i can mostly trust for my lens geekery.
tzhang4284 wrote:
The statement I was responding to was: "Let's say the RX-1 delivers 100% concerning sharpness, rendering, bokeh and overall image impression, the king in the field. How much "worse" would a A7RII with the 35mm f2.8 perform vs. the RX-1?"
You can answer this question with hard data based on DXO, Lens Rental and other sources that indicate the corners are a little weaker on the 35mm f2.8 but it's on par with the RX1 lens in the center. You can also verify this by taking a look at the multitude of crops out there on the internet to decide whether that extra performance is worth the $2000 premium over the 35mm f2.8. Maybe a $40 lens might be the highest ROI, but that's not what we're talking about here and it probably does not offer a minimally acceptable level of performance that the 35mm f2.8 does meet....Show more →
first, it's a really silly question. second, you absolutely cannot answer that question with the "hard data" provided by dxo because the data from the 24mp and 42mp (or 36mp) sensors is not compatible. dxo tries to provide sensible multipliers to make the data vaguely comparable, but even they give a disclaimer that it's not comparable (or at least they used to). finally, i actually prefer the $40 35/2.8 to the FE 35/2.8 in most areas.
tzhang4284 wrote:
The other option is to say the "RX1's lens has a magical special rendering to me that's worth every cent and is how I see the world. The bokeh is pleasing and I love the way it draws" But I can say that about the $40 lens too and it is just as true.
yes, but only if it's true for you, and that is how this thread started. the OP said basically: i have the rx1 and have tried a bunch of other 35mm lenses on an a7, but none compare. does anybody else have suggestions for what might do the trick given the aspects that i'm looking for and what i like about the rx1? you can say the reason people prefer the rx1 is nonsense, but that's not really helpful. you can also say you prefer lens B and that's perfectly valid, but again not terribly helpful.
if i show you the same photo taken with 10 different 35mm lenses and ask which you like best and why, i bet you'd be able to answer the question. if the reason why isn't an imatest MTF50 value does that make it nonsense?
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The size difference is hard to appreciate from the photos, sub par shooting experience. 
