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08-23-2014, 11:52 AM   #91
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QuoteOriginally posted by Nicolas06 Quote
Objectively, many sigma lenses are exactly that, bulky, heavy to have an impressive spec sheet in term of chart tests and wide appertures.
So, to possess any shred of truthiness your premise needs to apply to any brand. So for clarity you believe that lenses with a fast aperture that are "bulky, heavy" and generally quite similar to something offered by Pentax are designed with the intention of impressing someone who reads a spec sheet, say a reviewer, or someone who doesn't get away from the computer very often. Correct?

Please help me do a reality check on my assumptions here: Tokina has sold several sister versions of lenses branded by Pentax. For example, the 12-24mm f4 weighs 431 grams as a Pentax lens and 540 grams as a Tokina lens. Or the 35mm 2.8 Macro in K mount is about 217 grams vs. 340 grams in the Tokina EOS offering. And the excellent DA* 50-135mm f2.8 is 686 grams for Pentax and 845 grams branded Tokina (including the built-in tripod foot).
My assumption is that you believe that all of these Tokina lenses were bulked up just to impress someone, rather than reflecting a brand-specific design value? Or is Tokina exempt from your Sigma rule?

Thanks
M

08-23-2014, 12:20 PM   #92
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QuoteOriginally posted by Nicolas06 Quote
You speak of sigma 50mm lenses, let's see the tendancy...

Pentax
FA43 f/1.9 : 2,7cm x 6.3cm, 168g
FA50 f/1.4 : 3.7cm x 6.5cm, 220g
DA50 f/1.8 : 3.8cm x 6.3cm, 122g
DFA50 macro f/2.8 : 7cm x 6.7cm, 265g
DA*55 : 7cm x 6.6cm, 375g

Sigma
50mm f/2.8 macro : 7.1cm x 6.4cm, 315g.
50mm EX f/1.4 : 8.4cm x 6.8cm, 505g
50mm Art f/1.4 : 9.9cm x 8.5cm, 815g
That's an interesting table, and it helps to illustrate that Pentax does tend to focus on making lenses smaller and lighter. That seems to be Pentax's niche (even if all of their lenses do not fit that mold). I think what Sigma tries to do, in many cases, is to find niche's where they can offer something unique and different from the first party lenses.

In the case of 50mm lenses, I would say that each of the camera makers already have the "nifty fifty" market pretty much sewn-up with inexpensive, lightweight, 50mm lenses that have reasonable image quality, even if they do make a few compromises in maximum aperture and wide-open image quality. So Sigma comes along and offers something for somebody who wants a better and very usable f1.4, even if the lens is bigger and/or costs more.

As has been said by Nicolas and others, it's good to have choice. That's why I hope SIgma keeps supporting the K-mount.
08-23-2014, 01:48 PM   #93
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QuoteOriginally posted by Miguel Quote
So, to possess any shred of truthiness your premise needs to apply to any brand. So for clarity you believe that lenses with a fast aperture that are "bulky, heavy" and generally quite similar to something offered by Pentax are designed with the intention of impressing someone who reads a spec sheet, say a reviewer, or someone who doesn't get away from the computer very often. Correct?
I think you are mistaken in what I was trying to explain. I says that to get good reviews lens maker will want ultimate sharpness and very wide apperture. And both if possible. The latest in this direction is DxO score that factor exactly and directly that in the lens review and nothing else.

If you go far in that direction, you need bigger and also heavier lenses. This is because we don't know how to do better. At some point you start to get heavy and bulky lenses as a result.

As for Tokina, they sell their lenses cheaper than Pentax. Maybe being lightweigh and small is not and objective for them and it allow to cut costs. Who really care?

As client you care of the result. If it doesn't fit your needs, you don't buy.

---------- Post added 08-23-14 at 10:50 PM ----------

QuoteOriginally posted by Edgar_in_Indy Quote
That's an interesting table, and it helps to illustrate that Pentax does tend to focus on making lenses smaller and lighter. That seems to be Pentax's niche (even if all of their lenses do not fit that mold). I think what Sigma tries to do, in many cases, is to find niche's where they can offer something unique and different from the first party lenses.

[...]

As has been said by Nicolas and others, it's good to have choice. That's why I hope SIgma keeps supporting the K-mount.
Exactly. Everybody choose a compromize of price/weight/size/max apperture/sharpness.

Last edited by Nicolas06; 08-23-2014 at 01:54 PM.
08-25-2014, 12:43 PM   #94
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QuoteOriginally posted by Edgar_in_Indy Quote
Personally, I don't know what you're talking about the color cast. I never see it mentioned on professional review sites that review all brands of lenses.
Digitalis testified to such a cast with the Sigma 8-16: "...the Sigma 8-16mm f/4.5-5.6 has the pronounced yellow/green cast followed closely by the Sigma 18-35mm f/1.8." The fact that no professional review sites mention this is irrelevant. Professional review sites tend to be dominated by numbers-orientated gearheads who don't care about color rendition.

QuoteOriginally posted by Edgar_in_Indy Quote
And even if it were true that Sigma lenses all somehow manage to have some kind of unusual color cast, is that even an issue if you shoot RAW?
Yes, it can be. Color changing controls in PP software are rather crude. You can target large groups of color and make broad changes, but if you have a very specific tone of color in mind (a very specific hue of green or blue, for instance) achieving that in post can be very difficult. You can't necessarily achieve that tone merely by shifting the hue controls targeted at all green or all blue tones. The most powerful color changing control in PP software tends to be white balance; that's the most effective way of correcting color casts from lenses. The problem is, if a lens is producing yellowish-green foliage, and you use the white balance sliders to correct it, it will throw all the other colors off.

QuoteOriginally posted by Edgar_in_Indy Quote
So Pentax lenses all have the same exact perfect color cast, even though they are designed variously by Pentax, Tokina and Tamron?
I'm not sure any lens has an "exact perfect color cast," but some lenses seem to render colors in a way that's more pleasing to some of us. These differences are subtle, but so are differences in sharpness, bokeh, color fringing, and other lens' characteristics that people endless fuss over. I happen to be acutely sensitive to color, so these differences are important to me. Other photographers who are less sensitive to color differences or whose style of photography is less concerned with color may not care.

The fact that some Pentax lenses were designed by Tamron and Tokina is largely irrelevant to color rendition, since coatings play a big role in color rendering, and all the non-Pentax designed Pentax lenses feature Pentax's SMC coatings. The Olympus M. Zukio 75 f1.8 is (supposedly) a Sigma designed lens; but it renders colors, not like other Sigma lenses, but like other Olympus' lenses, because Olympus used their own coatings on a Sigma design.

QuoteOriginally posted by Edgar_in_Indy Quote
I think there's a lot of people who reflexively don't want to give too much credit to a non-Pentax lens, and to sometimes attribute undue virtue to anything with "Pentax" on it. Somewhat conveniently, Pentax seems to excel at everything that can't be measured.
Some Pentax lenses (the limiteds for example) are designed with a greater emphasis on non-measurable qualities than qualitative specs. So it shouldn't be surprising that you would find, in a pentax forum, people who are sympathetic to Pentax's lens design philosophy, who care more about what images from a specific lens look like to human perception, rather than how that lens performs on so-called "objective" tests.

QuoteOriginally posted by Edgar_in_Indy Quote
And if a particular Pentax lens is sharp, the sharpness is mentioned and praised on here endlessly. But when Sigma lenses are sharp, it's because they're one-dimensional spec-whores.
There are a lot of people who will praise any lens they like as being "sharp" because they believe (falsely) that sharpness largely determines a len's IQ.

Not all of us who like Pentax glass because of its unique characteristics or color rendition or the design philosophy behind the limiteds are Pentax fanboys who like anything with a Pentax label on it. I'm not a fan, for instance, of the DA 18-55; I think it's over-rated even as a kit lens. Nor am I a fan of Pentax's flashes (I prefer Metz). I think both Canon and Nikon produce better high end cameras than Pentax. This is not a fanboy issue, but an issue regarding how best to evaluate lenses. Can comparable Sigma lenses be regarded as good (or better) than Pentax lenses merely because the Sigma glass scores as well (or better) on numerical tests? Since photography is essentially an aesthetic discipline, geared to the aesthetics of human perception, I say No, numerical specs are over-rated. That does not, however, mean that I regard Sigma lenses as "one-dimensional spec-whores." The issue really has far more to do with questions over how lenses should be evaluated than questions about Sigma vs Pentax. What I object to is not that someone happens to prefer (or regards as a better value) Sigma glass. That's a personal decision based on preference. What I object to is when people try to justify this preference on the basis of numerical specs, which I regard as a mistaken approach.

08-25-2014, 12:45 PM   #95
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QuoteOriginally posted by northcoastgreg Quote
Color changing controls in PP software are rather crude. You can target large groups of color and make broad changes, but if you have a very specific tone of color in mind (a very specific hue of green or blue, for instance) achieving that in post can be very difficult.
I thought it was just me.

I've never been able to change colors very well.
08-25-2014, 01:56 PM   #96
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QuoteOriginally posted by northcoastgreg Quote
What I object to is not that someone happens to prefer (or regards as a better value) Sigma glass. That's a personal decision based on preference. What I object to is when people try to justify this preference on the basis of numerical specs, which I regard as a mistaken approach.
It's funny you should make that complaint in a response to one of my posts. I think that I, more than most other people on here, consistently post samples of my own images when I'm talking about lenses. And I always include a link to a full-size pic. If you go back just a page or two you'll see where I posted pics. And I think I've managed to change some people's minds, or at least encourage them to be open to some non-Pentax lenses.

And I don't think I mentioned any numerical specs, other than to observe out that some Pentax lens fans point to the specs of Sigma lenses as some kind of indictment against them.

And in regards to color casts of Sigma lenses, the thing that I've mostly heard is that Sigma lenses render in a warmer tone than Pentax lenses, and this, of course, is a bad thing. But when Digitalis was posting comparisons last week from his Sigma 18-35mm vs Pentax 31mm, I noticed that the 31mm pictures were a bit warmer (more yellow?), and he also confirmed this. So...

Anyway, I'll just keep enjoying my yellow/green Sigma lenses, and I'll keep encouraging others to do the same.

BTW, I just went to Photozone.de, and they conveniently have a review of both the Pentax 31mm and the K-mount of the Sigma 30mm 1.4, and both reviews feature of a lot foliage and greenery in the sample pics. Looking back and forth at the pictures from the two lenses, I must say I was completely underwhelmed at any differences in color rendition. Might we be making a mountain out of a molehill?

QuoteOriginally posted by northcoastgreg Quote
I'm not sure any lens has an "exact perfect color cast," but some lenses seem to render colors in a way that's more pleasing to some of us.
Is there no such thing as measuring color accuracy? Does anybody ever do this for lenses? It seems like it's done for everything else (cameras, monitors, printers, etc.) Just curious, because I can't say I've ever seen mention of any such tests for lenses. And I'm also not saying that the "most-accurate" lenses would be the "best" or most desirable lens. I'm just curious.

Last edited by Edgar_in_Indy; 08-25-2014 at 02:07 PM.
08-25-2014, 03:27 PM   #97
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QuoteOriginally posted by Nicolas06 Quote
if one want to argue that sigma have small lenses like pentax this is plain wrong
Nobody said that.


Steve

---------- Post added 08-25-14 at 03:30 PM ----------

QuoteOriginally posted by Nicolas06 Quote
If you go far in that direction, you need bigger and also heavier lenses.
Interesting, but unsubstantiated, assumption. References please.


Steve

Last edited by stevebrot; 08-25-2014 at 03:33 PM.
08-25-2014, 03:48 PM   #98
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QuoteOriginally posted by Edgar_in_Indy Quote
Is there no such thing as measuring color accuracy? Does anybody ever do this for lenses? It seems like it's done for everything else (cameras, monitors, printers, etc.) Just curious, because I can't say I've ever seen mention of any such tests for lenses. And I'm also not saying that the "most-accurate" lenses would be the "best" or most desirable lens. I'm just curious.
Of course! Nothing is perfect, but this is one of the current standards:



08-25-2014, 04:00 PM   #99
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To get back on topic, has anyone been to Sigmaphoto.com recently? The sky is falling for more than just Pentax:
  • 50/2.8 EX DG Macro Discontinued in Canon, Pentax and SIGMA. Still available in Nikon and Sony
  • 70/2.8 EX DG Macro Discontinued in Canon (only). Still available in Nikon, Pentax, Sigma, and Sony.
The is an update from last week when both lenses were still listed as available in all mounts. The current OS versions of the longer Sigma macro lenses have never been available for Pentax.

So, back to the 70mm macro. After all this discussion, are we sure it is discontinued? Both the 50mm and 70mm are still available for sale in Pentax mount at B&H. Adorama, on the other hand only has the 50mm in Nikon and the 70mm in Sony and Sigma mount.

From all appearances Sigma is reordering their ranks across brands.


Steve
08-25-2014, 04:03 PM   #100
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QuoteOriginally posted by Edgar_in_Indy Quote
BTW, I just went to Photozone.de, and they conveniently have a review of both the Pentax 31mm and the K-mount of the Sigma 30mm 1.4, and both reviews feature of a lot foliage and greenery in the sample pics. Looking back and forth at the pictures from the two lenses, I must say I was completely underwhelmed at any differences in color rendition. Might we be making a mountain out of a molehill?
I would not speak against or for sigma, but just speaking of a good lense:

Having just tryed the FA77, i will comment my impressions: The picture this lens take are just fantastic. The color are perfect out of the box. Constrast is great. Bokeh is really smooth and transisions are subtle and nicely done. Many lenses benefit of post processing. This one just doesn't really need it. There no much to improve.

For sure I prefer the rendering compared to FA50 & DA50-135. Both lens that I own already and that are very well seen by many as already great lenses.

This FAltd is still really supperior - at least to me -.

FA31 is the same kind of lenses as FA77, maybe even better bokeh and rendering. That just how it is.


At least thoses characteristics are visible at normal viewing size of a picture. Wider apperture that thoses lens miss too, I would agree.

Absolute sharpness is just irrelevant as not really visible in most conditions. Still thoses FA ltd have it anyway.

Last edited by Nicolas06; 08-25-2014 at 04:10 PM.
08-25-2014, 09:11 PM   #101
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QuoteOriginally posted by Nicolas06 Quote
FA31 is the same kind of lenses as FA77, maybe even better bokeh and rendering. That just how it is.
Has anybody else looked at the Photozone sample images from the Sigma 30mm and Pentax 31mm? Even on my calibrated Dell U3011 monitor I'm not seeing any clear advantage in colors or contrast for the 31mm. To me, the images both look pretty darn good. With the way people talk on here, I would expect the differences to slap me in the face.

If anything, I prefer the colors from the Sigma. They look absolutely beautiful from what I'm seeing. Whereas the green color of the leaves doesn't look quite right on the church picture or the statue picture for the 31mm. Also, comparing the similar pics of the 4-wheel bicycle-thing picture (31mm) vs the picture of the press thing (Sigma 30mm), it seems like the 31mm pic is unnaturally warm/yellow.

Last edited by Edgar_in_Indy; 08-25-2014 at 09:45 PM.
08-25-2014, 09:19 PM   #102
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QuoteOriginally posted by stevebrot Quote

BTW...the 50/2.8 Macro does have a warm color cast, though I would hesitate to label it as yellow or greenish.
The Sigma 50mm macro has beautiful colour rendition, unlike the Tamron 90mm.
08-25-2014, 11:33 PM   #103
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QuoteOriginally posted by Edgar_in_Indy Quote
Has anybody else looked at the Photozone sample images from the Sigma 30mm and Pentax 31mm? Even on my calibrated Dell U3011 monitor I'm not seeing any clear advantage in colors or contrast for the 31mm. To me, the images both look pretty darn good. With the way people talk on here, I would expect the differences to slap me in the face.

If anything, I prefer the colors from the Sigma. They look absolutely beautiful from what I'm seeing. Whereas the green color of the leaves doesn't look quite right on the church picture or the statue picture for the 31mm. Also, comparing the similar pics of the 4-wheel bicycle-thing picture (31mm) vs the picture of the press thing (Sigma 30mm), it seems like the 31mm pic is unnaturally warm/yellow.
There threads FA31 vs sigma 30 I think somewhere here. I remember looking at it. It was like picture of some plant or something in the foreground and a building out of focus in the background.

The difference is rendering for out of focus area was quite different:
- FA31 was smoother bokeh overall
- FA31 was more colorfull (maybe warmer).
- FA31 did have colors aberations in the bokeh with greens visible in out of focus areas.

For sure the result was clearly different. After that, peak what you prefer ! if you are really interrested, look for the thread and maybe respond there? Maybe I didn't respond to it as I didn't manage to find it again.
08-26-2014, 05:03 AM   #104
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Please understand, my point isn't that there is anything wrong with the 31mm. My point is that people make absolute statements that Pentax lenses have better colors and contrast, particularly the Limited, and particularly the 31/77 lenses, but here we have a chance to directly compare the 31mm to the Sigma 30mm (a lens that is frequently held in low-regard around here), and the much-vaunted advantages in color and contrast of the 31mm Limited seem to be non-existent, at best.

The picture subjects are similar, taken in the same place at the same time of year (within days of each other, from the EXIF), with similar sunny lighting, so comparisons can be drawn. And to me, at least, the colors on the Sigma actually look better, with a clarity that the 31mm seems to lack.

Not to say that the 31mm doesn't have some things going for it. Bokeh is probably a bit smoother, although I think the 30mm still looks fine in that regard in these pics. And the 31mm is sharper at the edges, although the 30mm still looks fine to me at the edges stopped down.

But sharpness isn't that important anyway, right? So the edge sharpness advantage of the 31mm should not be considered, and the center sharpness of the 30mm should also not be considered.

To me, it's kind of like judging a beauty contest between a gorgeous blonde and a stunning brunette. Some will prefer the blonde, and others the brunette, while some will prefer whichever happens to be standing in front of them at the time. (The part where the analogy breaks down is that the 31mm costs 3x more than the Sigma.)

Last edited by Edgar_in_Indy; 08-26-2014 at 05:21 AM.
08-26-2014, 05:14 AM   #105
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QuoteOriginally posted by Edgar_in_Indy Quote
(...)

To me, it's kind of like judging a beauty contest between a gorgeous blonde and a stunning brunette. Some will prefer the blonde, and others the brunette, while some will prefer whichever happens to be standing in front of them at the time. (The part where the analogy breaks down is that the 31mm costs 3x more than the Sigma.)
Which one costs three times more than the other one? The gorgeous blonde or the stunning brunette?
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