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05-21-2013, 09:27 AM   #1
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Interesting Observation - Pentax vs "other" lenses

Over the last year, I've converted most of my lens kit from Sigma EX lenses to Pentax F/FA, a DA* and a couple DA ltd.

One observation that's become apparent is that the "Add Hue/Saturation layer" action I've created in PS has been archaic.

In the past it was required to bump up Saturation by +10 to +15 to get a decent look in my images. Now the layer just isn't needed.

Anyone else have similar observations or experiences?

05-21-2013, 09:41 AM   #2
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Oh yeah, Pentax lenses are pretty special in the way they render, especially warm colours. I don't have any measurements to back this claim up, but different brands have different characteristics. Pentax has some unique optical formulas and SMC.
05-21-2013, 09:56 AM   #3
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I agree with your assessment. I've shot primarily Pentax glass, but have tried a couple from Sigma. I did have to work at the Sigma images a bit to get them to what I am used to with the rendering of the Pentax glass. Because of this, I am 100% Pentax lenses now except for the Bigma which I use for the 500mm reach.
05-21-2013, 10:38 AM   #4
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Pentax multi-coatings are excellent. But since color is so easily tweaked in PP, is color saturation level all that important a lens attribute? Unless I intend to use a lens wide open for bokeh quality, my lens priorities are resolution, resolution, and resolution.

05-21-2013, 12:56 PM   #5
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I've had the reverse. With my Sigma 10-20 (the cheaper one) I have found I do not need to tweak the contrast or the color as much as my Pentax 18-135. But then again, the 18-135 is not a limited.
05-21-2013, 01:49 PM   #6
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QuoteOriginally posted by nomadkng Quote
Over the last year, I've converted most of my lens kit from Sigma EX lenses to Pentax F/FA, a DA* and a couple DA ltd.

One observation that's become apparent is that the "Add Hue/Saturation layer" action I've created in PS has been archaic.
I'm a big fan of Sigma lenses, but I haven't used many Pentax lenses since I have judged most of them to be either too expensive, or too unreliable, or (all too often) some combination thereof.

I did have a Pentax M 50mm 1.7 and then an F version of the same lens, and I did think they had very nice contrast, color, and bokeh. I'm not sure that I noticed any more saturation though. My experience has been that saturation is very dependent on the lighting. Whether using my Pentax or Sigma lenses, I still find myself occasionally dialing back the saturation a bit in certain lighting conditions. But again, I don't have extensive experience with Pentax glass, and that's a situation not likely to change anytime soon based on what I'm seeing from Pentax.

Just out of curiosity, what is the advantage of adjusting hue/saturation via a layer, instead of just using the sliders in Adobe Camera Raw when opening the RAW file?
05-21-2013, 01:51 PM   #7
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Isn't SMC co develop with carl zeiss MRC at the time?
05-21-2013, 02:20 PM   #8
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QuoteOriginally posted by Timd Quote
I've had the reverse. With my Sigma 10-20 (the cheaper one) I have found I do not need to tweak the contrast or the color as much as my Pentax 18-135. But then again, the 18-135 is not a limited.
I've noticed the same thing with both those lenses, but the only other Sigma lens I have is the 105 macro, which isn't overly colourful. The 10-20 (mine's a 3.5) is a cracker though.

05-21-2013, 02:53 PM   #9
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QuoteOriginally posted by RobA_Oz Quote
I've noticed the same thing with both those lenses, but the only other Sigma lens I have is the 105 macro, which isn't overly colourful. The 10-20 (mine's a 3.5) is a cracker though.
I've got the 4-5.6 Sigma 10 20, and it is great. Plenty of color, and with the Lightroom correction profile, very little distortion.
05-21-2013, 06:32 PM   #10
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QuoteOriginally posted by Anvh Quote
sn't SMC co develop with carl zeiss MRC at the time?
you mean T* lens coatings? - yes they were.

It is a known fact amongst lens aficionados that different lens makers produces lenses with slightly different colour casts to them. It is difficult to make borosilicate glass of varying refractive indexes perfectly neutral - this is further complicated when ED, Flourite and other exotic glass types are used in a lens design.
05-22-2013, 11:57 AM   #11
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QuoteOriginally posted by Edgar_in_Indy Quote
Just out of curiosity, what is the advantage of adjusting hue/saturation via a layer, instead of just using the sliders in Adobe Camera Raw when opening the RAW file?
Maybe it's because I learned PS in the 90's before digital photography even existed in my world.

One reason I can think of off hand, is that as a layer, if I don't like the result, or I want to change the result, I don't have to start over again.
On occasion, other adjustments in PS could change the image, such as level adjustments.

But honestly, it's probably a workflow process that evolved with ACR coming last in my learning curve.

I do use ACR to adjust highlights and shadows, defringe a little, tweak WB, blacks and recovery/fill, but everything else I do in PS like contrast curves, levels etc
05-22-2013, 02:28 PM   #12
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Now I know why i am using 85-90% saturation in UFRaw to get "normal" colour!
(with DA* 55mm f/1.4)
(Or I do not like to surfeit colours...)
05-22-2013, 03:08 PM   #13
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Color rendition is an interesting (if complex) subject. IMO it is mainly affected by three factors:
1. Transmission, or rather the variation thereof across the visible spectrum.
2. Contrast.
3. Exposure.

#1 is a function of glass and coatings. Unfortunately, with AWB in play, it is not easy to judge the effect of a certain observed tint by eye, though I suspect brownish tint might be more critical than greenish tint. (AWB can only shift the levels of the red, green and blue channels as a whole. It cannot compensate for any variation / tilt within the respective wavelength ranges. The sensor has already "binned" these with its primary color filters.)
I do know that my Sigma 70-300 DG OS (moderate brownish cast) takes its toll on blues, with the sky always looking a little muted. By contrast, the Pentax 55-300 (slight cast only, and very clear for a complex lens like this) seems to produce beautiful colors.
Oh, and there is a point beyond which AWB will refuse to fully correct a lens tint even in broad daylight, probably as a safety measure. I have at least one lens that you can identify by the slight greenish tint on pictures (old Tokina AT-X 28-85) - it does exhibit a rather heavy one when looking through!
Usually primes are a safer bet here, as in general there's simply less glass in them (along with fewer surfaces).

#2 is influenced by many things. Lens configuration, coatings and which ones are used where, internal blackening, aperture surface, use of a hood. (The hood comes into play when there is a tendency towards veiling flare and you've got a nice and bright blue sky.) It's not necessarily predictable. I've had a nominally single-coated lens whose contrast proved just fine, and a nominally multicoated one that struggled even on my indoor test target. (That one has the last few elements single-coated in amber, which is not a good combination with a DSLR sensor. By contrast, magenta single-coating seems to be uncritical.) There apparently is one uncoated element lurking in the cheapo Sigma 55-200 (a typical cost-cutting measure seen in inexpensive '90s/2000s zooms), but its contrast struck me as good.
BTW, contrast does not necessarily always differ between lenses - once it comfortably exceeds either the dynamics of the scene or the camera's capabilities, they will generally produce equivalent results.

#3 comes into play because of the camera's internal gradation curve, which is nonlinear. Simply put, a mere difference in exposure (due to inaccurate aperture calibration or whatnot) may yield a difference in contrast in the resulting image. Tweaking contrast by varying exposure should actually be familiar to seasoned film shooters. If, however, you're aiming to compare lenses fairly by image results, it means you won't get around shooting RAW and matching exposure very accurately afterwards (sub-1/6 EV if need be). Suffice to say, it's a PITA when you have basically well-performing lenses. A truly "bad apple" will be obvious without going to such extremes, but often it's subtleties that are harder to track down.

Fun, eh?

But it's true, Pentax lenses can be very good performers when it comes to transmission and contrast. Before I'd seen the 55-300, I had already been quite impressed by the old M 80-200, which does really well in transmission for such a complex old zoom (12 groups!). SMC sure was something special in those days. Well-performing coatings are much more generally available nowadays though. The issue with (some) Sigma lenses may simply be one of price pressure, as several of their models are essentially better-value alternatives - I'm thinking telezooms in particular (50/55-200/4-5.6, 70-300/4-5.6 et.al.). They have to cut corners somewhere.
05-22-2013, 03:23 PM   #14
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I guess for FYI sake, here are the lenses in question.

sigma ex 10-20 and 12-24 - replaced by DA15, FA20-35 - not only do I get much better color at f11 the sigmas start really suffering from diffraction whereas the pentax lenses keep chugging along great at f16 and even f22 -

sigma 24-70 ex dg macro replaced by DA 40 and DA*50-135 - same issues as above, this lens really bit the dust at f13 but was great to about f10, it just had very muted colors, at times I was up to +25 on the saturation

I also compared sigma's 70mm macro with the FA50 and FA100 macros. pentax won that battle too

this was all started when I began collecting FA lenses, the 28/35/50. I was actually DE-saturating in PS first couple times because the images didn't look "normal"
05-22-2013, 04:38 PM   #15
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QuoteOriginally posted by Digitalis Quote
you mean T* lens coatings? - yes they were.
Yes good very well be, thanks for the correction.
I hear it meantion somewhere but forgot the precies details.
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