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next PZ Lens Test Report - Zeiss ZA T* 24mm f/2 SSM
#21
If one would rate the Canon as good as the Zeiss because of comparable performance at smaller apertures, despite the less-than-perfect performance wide open, there would not be much room for higher ratings for lenses that do better wide open. In addition, if I buy an 1.4 lens, its performance at this aperture is most important for me, and should be much heavier weighted than its performance at smaller apertures. I do not by an 1.4 lens because I have the luxury to stop it down most of the time. In daylight, ok. But 1.4 lenses are used either because one needs the bokeh or the light gathering abilities. In both cases, high MFT values are welcome. I find the current way of giving stars right.



Christian
#22
I agree with Christian - imho optical rating should represent how lens behaves wide open. After all we pay hefty premium for larger aperture, not for ability to stop down. Also I find the logic "Zeiss gives no image at all at f1.4" a bit flawed - in this case, for instance, 24mm f/2.8 shouldn't have received more than two stars, because compared to 24mm f/1.4 it can't take any pictures at f/1.4 and even at f/2, right?
#23
[quote name='Grummbeerbauer' timestamp='1292480749' post='5039']

Perhaps the rating should be transformed into an "optical quality for the primary purpose of the lens" or "relative quality to the competition". So a superzoom could receive five stars in the category of "flexible, bright-sunshine-only outdoor lenses for people that hate swapping lenses and should have bought a P&S in the first place" <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='Smile' />.

Seriously, for the purpose available-light UWA/WA (FF/APS-C) photography, the Canon is probably much better than the Zeiss.

So this is pretty much the "field quality" rating that recently appeared in some reviews. However, for many lenses, several "purposes" come into question, and the rating is often less dependent on the actual optical quality than on the general specs of the lens.



Of course we could have dedicated ratings for sharpness, optical defects (distortion, CA) etc. for those people that only look at the bottom of the last page of a PZ review, but this still leaves the question on how to judge zooms that rock at one end and and suck really hard at the other end of their range?

[/quote]



The real problem with the star ratings is not the scaling, but that many out there take them for more than they are meant to be: a final and absolute verdict, not one of many parts of the review. It's not uncommon that we are attacked because of low star ratings, especially of fast lenses (recent example: Nikkor AF-D 85/1.4 on FX), by people who haven't actually read the whole review. Or even any part of it.



I'm sure there's nothing we can do about this group of our readers. Any detailed explanation we add to the star ratings will probably be ignored just like the rest of the text. Which is a little sad, since we try to stick to rather compact review texts (2 pages, 3 when sample images are provided), so there is not really that much text to read through.



In any case, though: we're only human, of course, and that means there will always be some subjectivity in the star ratings. Not just the star ratings, in fact in the whole review.



-- Markus



P.S.: "Grummbeere" sounds local. Pälzer?
Editor
opticallimits.com

#24
[quote name='Lomskij' timestamp='1292491625' post='5044']

I agree with Christian - imho optical rating should represent how lens behaves wide open. After all we pay hefty premium for larger aperture, not for ability to stop down. Also I find the logic "Zeiss gives no image at all at f1.4" a bit flawed - in this case, for instance, 24mm f/2.8 shouldn't have received more than two stars, because compared to 24mm f/1.4 it can't take any pictures at f/1.4 and even at f/2, right?

[/quote]



The "Zeiss gives no image at all at f1.4" comment was of course meant "tongue-in-cheek". <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' />
#25
[quote name='mst' timestamp='1292494993' post='5045']

The real problem with the star ratings is not the scaling, but that many out there take them for more than they are meant to be: a final and absolute verdict, not one of many parts of the review. It's not uncommon that we are attacked because of low star ratings, especially of fast lenses (recent example: Nikkor AF-D 85/1.4 on FX), by people who haven't actually read the whole review. Or even any part of it.

[/quote]



I just compared the Nikkor AF-D 85/1.4 with the Canon 85 1.2 II review, and here I can see the different ratings justified. The Canon is one third of a stop faster, and is still better at 1.2 than the Nikkor at 1.4, as it has about the same center resolution, but worse borders (but slightly better vignetting, but this is at f1.4...). Further, the Nikkor has more CA over the entire aperture range. I even agree with the 3.5 stars rating of the lowly EF 85 1.8 (which I have, BTW, so I might be a bit biased here... <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='Smile' />), as it has much better corners at its wide open setting than the 85 1.2 or 1.4 have at f2.0.



So, I agree that the star ratings are of course in part based on personal opinion of the tester and "gut feeling", and in case of the 85mms, our gut feelings match. <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' />



BTW: Speaking about 85mm primes, is there a review of the new Sigma 85 1.4 on the horizon yet?



[quote name='mst' timestamp='1292494993' post='5045']

I'm sure there's nothing we can do about this group of our readers. Any detailed explanation we add to the star ratings will probably be ignored just like the rest of the text. Which is a little sad, since we try to stick to rather compact review texts (2 pages, 3 when sample images are provided), so there is not really that much text to read through.



In any case, though: we're only human, of course, and that means there will always be some subjectivity in the star ratings. Not just the star ratings, in fact in the whole review.

[/quote]



It seems that many people are lazy and want the ratings to be reduced to one or a few simple numbers so that they don't have to think at all about their purchases. This also explains why so many computer magazines produce numerical ratings, have some kind of "test winner" award for manufacturers to put on the case etc.

More serious magazines ("c't" comes to mind) only give individual ratings in different categories and leave it to the reader to make an informed choice based on which rating categories are most important to them. I clearly favor the later approach, but since your tests have all the important measurements published, it is no problem for the interested reader to create his own "internal star rating" for vignetting, resolution etc., so no loss here. <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' />





[quote name='mst' timestamp='1292494993' post='5045']

P.S.: "Grummbeere" sounds local. Pälzer?

[/quote]



Exactly. <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='Big Grin' />

Though currently actually more like a "Pälzer in exile" living in a different Bundesland.
#26
[quote name='Grummbeerbauer' timestamp='1292480749' post='5039']

While this might be true when shooting brick walls and test charts, it is of course not so much of a problem in real world shooting, especially at wide apertures.

[/quote]

Which is also my point... who's going to put anything in to that little triangularish corner bits of a frame (as shown in my illustration) ever, especially at f/1.4 or something?





[quote name='Grummbeerbauer' timestamp='1292480749' post='5039']

However, even while being aware of this fact, I can't help but admit that still a lens with soft corners puts me off a bit.

[/quote]

That's because we've been listening to too many people who don't know how to interpret data for far too long <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Big Grin' />







[quote name='Grummbeerbauer' timestamp='1292480749' post='5039']

but this still leaves the question on how to judge zooms that rock at one end and and suck really hard at the other end of their range?

[/quote]

I think if Klaus simply renames the Analysis section to "Conclusions" and gets rid of the star rating... this will solve all these problems <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='Smile' />



GTW
#27
[quote name='Klaus' timestamp='1292394472' post='4993']

[url="http://www.opticallimits.com/sonyalphaff/568-zeiss24f2ff"]http://www.opticallimits.com/sonyalphaff/568-zeiss24f2ff[/url]



Still very impressive compared to its Nikon and Canon counterparts.

[/quote]



I had the lens for about half a year and I love it.

Most of the frame is sharp wide open and AF is fast & quiet. I can't compare to the Canon & Nikon counterparts but I'd say it's a very good lens.

What I don't appreciate so much is the plastic hood and size/weight seem a bit large for a F/2.0 lens.



You can see some sample shots on my flickr page:

http://www.flickr.com/photos/ephankim/tags/sal24f20z/



The photo on the Zeiss page is also of me <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' />

http://lenses.zeiss.com/photo/en_DE/prod...usage.html
#28
[quote name='youpii' timestamp='1305712745' post='8487']

The photo on the Zeiss page is also of me <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' />

http://lenses.zeiss.com/photo/en_DE/prod...usage.html

[/quote]



Wow, congrats!



-- Markus
Editor
opticallimits.com

#29
Do you work for zeiss ?



[quote name='youpii' timestamp='1305712745' post='8487']

I had the lens for about half a year and I love it.



The photo on the Zeiss page is also of me <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' />

http://lenses.zeiss.com/photo/en_DE/prod...usage.html

[/quote]
#30
[quote name='you2' timestamp='1305720987' post='8498']

Do you work for zeiss ?

[/quote]



Nope. They picked the photo from my Flickr page and contacted me.
  


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