Here is the link to nikon APS-C:
http://www.dxomark.com/index.php/en/Lens...ric-Scores. I have particular trouble with T-stop. I read the explanation and I understand the concept, but I still do not understand the mechanics how the number is derived and whether higher number is better than lower number or the reverse. Similarly with CA, I understand what CA is, but the usual explanation (the diameter of the purple/green halo) does not seem to fit. Thanks
P
Hmmm - 28 views and no takers?
I viewed. But I don't speak klingon,
It is a bit above me Pavel.
I'd tell you if I understood it....really!
Pavel, you made it much farther into the explanations than I did: I hit that massive graph with so many close little marks and shut down. I'll have another go at it when I have more time - i.e., tomorrow at work - but it seems like a wall of noise so far.
Pavel, I read your post yesterday, saw the graphics and I didn't understand anything. I thought tomorrow with fresh head...Today in the morning, I did it again, and I don't really know what all this is about... sorry....
There's a famous saying that states "There are lies, damn lies, and statistics"...
In photography, there are lies, damn lies, and DXO...
While I actually think their testing is valid and the results useful in the hands of a small number of
people who know what they are doing, the number of conflicting and wrong conclusions that many people (ie trolls and DPReview users
) draw from DXO data is astounding. A person could pick just about any combination of cameras and find DXO data that "proves" both cameras are better than each other.
I'm not having a go at you Pavel - I don't consider you a troll (or a DPReview user!). Just saying the data is very easy to misinterpret.
As for your question though... sorry but the link didn't work for me. It returned a "Module Not Found" error page.
Thank you guys- now I do not feel so bad. I have been reading technical materials not necessarily in my field and I am generally good with technical plots, but this really eluded me (and still does). If I ever find a decent explanation foir this, I will post here.
So, Pavel, now you know. Or, not really.
I was incensed enough to write to DXO.
Haha... Ich spreche kein Deutsch...
My interpretation of the T-stop is that they're just measuring light transmission and testing whether the manufacturer's claimed f-stop / aperture is really what it is. i.e. the canon 85mm f/1.8 is supposed to be f/1.8 but their measured "T-stop" is actually more like 2.2
http://www.dxomark.com/index.php/en/Lens...amera)/483 (click on the transmission tab)
The 2nd graph shows the difference between the claimed f-stop and their measured "t-stop". In this case, there's a difference of "0.4".
It would stand to reason that you would want the 2nd number to be as low as possible.
Hope that helps...
This is very helpful Julian. The difference between stated max aperture and t-stop is the amount of light lost due to scattered light (flare). Thus the flare is presumably 0.4 f-stop at maximum aperture. The smaller the number the less flair tendency there is. I think you pretty much got it Julian. Real good.
Pavel
NP Pavel - happy to help!