[Rover]

It's a bit pointless to test, say, the big superteles - it's pretty obvious that they're perfect from the get go. The Otus types are probably the same story - but if someone offers to lend you one to test, it'd be nice to see the results (that might even be construed as "reference" in the focal length range).

 

I think that the Sigma 85mm Art could be considered a reference lens for 5DSR tests by the way. It succeeds in making most (all?) other lenses - even the brand spankin' new Canon 35mm f/1.4 II - look horrible.

[dave9t5]

Which fast 85mm APO ? The Otus ?

 

Yup.   If one is going to acquire an f/1.4 lens then presumably they are planning to use it wide open.  The pursuit of clinical resolution wide open is diminished if marred by distracting and ugly LoCA flaws.  I think to imply that it's OK on this Sigma because other lenses have it is too kind.  

 

I don't know that much about optical design and costs, but one reference comparison on the market is the Leica 50mm f/1.4 Summilux and the Leica 50mm f/2.0 Summicron APO.  The latter is a full stop slower (i.e. it's optically HALF the size) but is priced 170% higher than former.  (OK, Leica can charge whatever they want but I'm taking the pricing at face value.)

 

APO does not come easy (i.e. cheap) and that is one of the unique qualities of the Otus so I think it's not informative to lump it in with the other lenses but to add the differences of the Otus to the discussion of the SIgma.

 

[JJ_SO]

Klaus, I have a question about CA. in your report of the lens you state a CA of 0.5 pixel at f/1.4.

 

Pixelwidth means "related to sensor"? And which sensor was in use to measure that width? On the samples of DPReview were a couple of pics which had solid magenta highlights. Is that an overloaded sensor or related to the lens?

[Brightcolours]

Klaus, I have a question about CA. in your report of the lens you state a CA of 0.5 pixel at f/1.4.

 

Pixelwidth means "related to sensor"? And which sensor was in use to measure that width? On the samples of DPReview were a couple of pics which had solid magenta highlights. Is that an overloaded sensor or related to the lens?

The software measures on diagonals, so it can indeed see "half". However, it is not the most reliable measurement from the software.

The magenta you see in high lights is of the LoCA variety,, the CA from the graph is of the LaCA variety.

[Rover]

My inner editor is (slowly) getting back to life. I've found this on page 1:

easily capable to handling professional requirements

Which should be "easily capable of handling professional requirements".

[mst]

Thanks, Rover, corrected.

-- Markus

[mst]

I don't know that much about optical design and costs, but one reference comparison on the market is the Leica 50mm f/1.4 Summilux and the Leica 50mm f/2.0 Summicron APO.  The latter is a full stop slower (i.e. it's optically HALF the size) but is priced 170% higher than former.  (OK, Leica can charge whatever they want but I'm taking the pricing at face value.)

Ah, just saw that, and I just HAVE to comment... mainly because I still don't get all the hype around that 50/2.0 APO

Surprising fact about the Summilux-M 50/1.4 ASPH: it's an APO lens, too Its optical formular is very similar to that of the APO-Summicron 75/2.0, however Leica back then decided to not add APO to the product name of the Summilux... otherwise they'd probably have a hard time now selling the one stop slower lens for double the price

In general, a good APO lens doesn't necessarily need to be expensive. Very likely things get more tricky and difficult and thus expensive with faster glass, but there are relatively fast but still affordable APO lenses out there... just think of the Sigma 150/2.8 for example.

-- Markus

[davidmanze]

Ah, just saw that, and I just HAVE to comment... mainly because I still don't get all the hype around that 50/2.0 APO


Surprising fact about the Summilux-M 50/1.4 ASPH: it's an APO lens, too Its optical formular is very similar to that of the APO-Summicron 75/2.0, however Leica back then decided to not add APO to the product name of the Summilux... otherwise they'd probably have a hard time now selling the one stop slower lens for double the price


In general, a good APO lens doesn't necessarily need to be expensive. Very likely things get more tricky and difficult and thus expensive with faster glass, but there are relatively fast but still affordable APO lenses out there... just think of the Sigma 150/2.8 for example.


-- Markus

 The 150mm macro?  Yes, with APO in it's name and it's macro focal length gave it a good "hook" although it's not quite a full APO, it still bokeh fringes a tad, but only a tiny tad, let's say a tadlet (technically speaking that is!)

[wim]

The problem with many APO-lenses is that they do not correct for secondary order aberrations, which means that under certain conditions there still are some fringes to eb seen. There are only few exceptions, and those are generally rather expensive, and not easily obtainable.

 

Kind regards, Wim