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10-22-2013, 05:55 AM   #1
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was it a dream??

I have quite a few lenses and while I've come to learn some of their sweet spots I'm interested in skirting the process a little and get to the goodies.

Is it my imagination or did somewhere along the way in researching lenses I thought I chanced upon unbiased and thoroughly technical lens performance charts that depict info/details about how effective/sharp the lens is at various settings?

I'm really interested in finding (and using as much as possible) the sweet spot of each of my lenses. Lately I was pretty disappointed with the 1.4 of my Pentax-A 50mm. Coincidentally, the -A50/1.4 does better at 1.7. I did try it at 5.6 (I'll try and share a sample) and was a bit horrified. So I'd also like to know which settings to avoid. The18mm of my Tamron 18-250mm is also pretty bad. I know you can get some of this info from reviews but I wonder if it's more neatly compiled somewhere to reference?
I almost want to grease pen ideal settings on the lens caps or somewhere though with use I'm certain I wouldn't need to do this.

THanks for listening


Last edited by Iksobarg; 10-22-2013 at 06:48 AM. Reason: expand on question
10-22-2013, 06:16 AM   #2
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Guess I found something close:
Camera Lens Ratings - DxOMark
but I'll keep looking.
10-22-2013, 06:28 AM   #3
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You can also have a look at photozone.de database, they do a lot of sharpness test at various focal and aperture, but be sure to not compare results between different bodies :
Pentax K Lens Tests

And yes, the A/F/FA 50mm f/1.4 are known to lack contrast at f/1.4, even compared to others, but I find a bit of post-processing can restore it, when I even want it (may be nice for portraits).
10-22-2013, 06:32 AM   #4
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QuoteOriginally posted by Iksobarg Quote
Guess I found something close:
Camera Lens Ratings - DxOMark
but I'll keep looking.
Yeah I would rather carry on looking than take seriously any details from this biased ratings . There you have a best example - did you know that the very first Pentax lens that made it from top is at 594 place !!

Pentax smc DA Star 55mm F1.4 SDM
Pentax K-50
59423
f=55mm & f/2

With mere 23 DxOMark Score - which places it basically just above Poor or in the middle of chart in Average area.

Seriously !? So now we see that Pentax hasn't got *any* lens above that - according to DxOMark of course..

To me - that is *very* unreliable and childish - they made it really over the top with some of the lenses that are according to them actually higher marked.

--manntax

10-22-2013, 06:46 AM   #5
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Okay, getting closer. I'm on about MFT res. at various at apertures.
I don't know why I haven't visited the One-Stop Pentax thread already. I forgot all about it. (looking).
Thanks for quick feedback so far, gents!
10-22-2013, 07:49 AM   #6
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QuoteOriginally posted by Iksobarg Quote
Okay, getting closer. I'm on about MFT res. at various at apertures.
I don't know why I haven't visited the One-Stop Pentax thread already. I forgot all about it. (looking).
Thanks for quick feedback so far, gents!
Photozone posted above is the best when it comes to that I think. Dxomark averages the lens' values and I think Pentax doesnt have that many lens that performs well at all settings and focusing distances, often it is optimized for a certain use (so that when it is doing what it's designed to, it really delivers)

Usually 2 stops down from its max aperture is the lens' optimum performance.

When you have a blurry background, the center is the only important part though, so just keep that in mind.
10-22-2013, 08:01 AM   #7
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QuoteOriginally posted by manntax Quote
Yeah I would rather carry on looking than take seriously any details from this biased ratings . There you have a best example - did you know that the very first Pentax lens that made it from top is at 594 place !!

Pentax smc DA Star 55mm F1.4 SDM
Pentax K-50
59423
f=55mm & f/2

With mere 23 DxOMark Score - which places it basically just above Poor or in the middle of chart in Average area.

Seriously !? So now we see that Pentax hasn't got *any* lens above that - according to DxOMark of course..

To me - that is *very* unreliable and childish - they made it really over the top with some of the lenses that are according to them actually higher marked.

--manntax
You're not supposed to directly compare test results taken with different cameras.

If the highest score on a Pentax camera is from the DA* 55/1.4, then that's the best Pentax lens that they've tested.
10-22-2013, 08:07 AM   #8
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If you're looking for resolution information of older Pentax lenses at various apertures checkout Yoshihiko Takinami website at...

http://www.takinami.com/yoshihiko/photo/lens_test/index.html

10-22-2013, 08:35 AM   #9
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QuoteOriginally posted by iisrmm Quote
If you're looking for resolution information of older Pentax lenses at various apertures checkout Yoshihiko Takinami website at...

http://www.takinami.com/yoshihiko/photo/lens_test/index.html
That site needs to be used with care.

For example, it makes the FA*24/2 look too good,
and the M100/2.8 too bad.

The reason is that it just measures perceived "resolution",
which also factors in contrast.
This made sense on slide film,
but is not particularly relevant on digital.
10-22-2013, 09:50 AM   #10
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Digital photography makes personal evaluation of lenses both inexpensive and . . . well, personal.

Just go systematically shoot the type subjects you're interested in with typical setting in the typical lighting you use and record, and thoughtfully analyze, the results. Like with people, try to find the 'sweet spot' in every lens . . . and you will. With the wide choices in ISO we have today it's not too hard to find optimal 'sweet spots' and functional roles for any lens.

If you're not experienced with long focal lengths or apertures faster than f 2.8 don't jump to conclusions as to lens quality -- there's a lot of technique and understanding of how the camera deals with sharp focal planes and 'bokeh' at wide apertures involved. Some things you may consider "not good" are simply natural characteristics and/or the "personality" of wide apertures or the lens itself. It's much less expensive to acquire experience than to find the 'perfect' lens according to other folks' opinion.

I've always considered the fastest aperture available in any lens to be a convenience for 'brightening' the view finder and a competitive marketing factor rather than a particularly useful f-stop and never been disappointed in my expectations.

H2
10-22-2013, 11:07 AM   #11
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pacerr said "If you're not experienced with long focal lengths or apertures faster than f 2.8 don't jump to conclusions as to lens quality -- there's a lot of technique and understanding of how the camera deals with sharp focal planes and 'bokeh' at wide apertures involved. Some things you may consider "not good" are simply natural characteristics and/or the "personality" of wide apertures or the lens itself. It's much less expensive to acquire experience than to find the 'perfect' lens according to other folks' opinion."

-to that I say Amen

I shoot exclusively at higher aperture speeds to capture my children and lower light settings in the house. While on vacation last week and analyzing my A50/1.4 pics I realized I was sometimes AF'ing(autfocusing) twice on a single shot, as I noticed more and more that the AF would adjust again when I AF'd the second time. I was not certain each time if the image was better on the second AF but it turned out that only some of the pics came out OUTSTANDING, while the majority of the others came out OK (I was shooting exclusively at 1.7, in dusk with moving children and some stationary parents).

Anywho, I feel I'm ranting a little but that's because I've loosened the lid, so to speak, on my thoughts. Really, I've had very little time to think as much as I'd like to about my photo-taking life, RL has me by the cojones most of the time.

Back to the quote, I have a lot to learn, yes, and I might sound like a real amateur when I start into a small rant about how I do not understand why at least Pentax doesn't make the sweet spot at or close enough to maximize performance of the 1.4 end of the A50mm but I digress.
Characteristics I have seen a fair share of by now, particularly with the A50/1.4 as I find myself avoiding flash for natural lighting, of course only when possible. I'm looking for a Sigma50/1.4 because I cannot bring myself to fully appreciate the f1.4 results of the A50/1.4 but I'll keep one of them, as I own two, until I'm happier with the Sigma.

Last edited by Iksobarg; 10-22-2013 at 11:29 AM.
10-22-2013, 12:13 PM   #12
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Regarding ISO: I try to keep it below 800, anything above is most of my cases gets too chunky.

About aperture: My Tamron 17-50/2.8 is sooo sharp wide open.
I agree with one of you about Photozone but then "your results may vary" is always possible.

I appreciate the feedback from you guys. I'll just keep snapping away, optimize as I go and find some time to re-research perceived sweet spots of all my lenses.

So I did some homework and am just throwing this out there:
My lineup/sweetspot status

DA 10-17/3.5 (5.6@10mm-8@17mm)
http://www.photozone.de/pentax/132-pentax-smc-da-10-17mm-f35-45-edif-fisheye...report?start=1

Tamron 17-50/2.8 (f5.6)*sourced result
http://www.photozone.de/reviews/289-tamron-af-17-50mm-f28-sp-xr-di-ii-ld-asp...review?start=1

Pentax 50/1.4 (f1.7-2)*sourced result and subjectively confirmed
http://www.photozone.de/pentax/126-pentax-smc-fa-50mm-f14-review--lab-test-report?start=1

Pentax-A 50/2 (?)

DA* 50-135 (5.6)
http://www.photozone.de/pentax/137-pentax-smc-da-50-135mm-f28-ed-if-sdm-revi...report?start=1

SMC Pentax FA 100mm f/2.8 Macro
http://www.photozone.de/pentax/130-pentax-smc-fa-100mm-f28-macro-review--lab...report?start=1

FA 80-320mm 4.5
http://stans-photography.info/BriefComments.html#80-320%20mm%20f/4.5-5.6%20FA

Last edited by Iksobarg; 10-22-2013 at 12:47 PM.
10-22-2013, 12:17 PM   #13
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QuoteOriginally posted by Iksobarg Quote
I do not understand why at least Pentax doesn't make the sweet spot at or close enough to maximize performance of the 1.4 end of the A50mm.
The 50/1.4 was a "standard" lens,
intended to do a lot of different jobs.
A gentle portrait lens open wider,
but a sharp recorder of detail when stopped down.
10-24-2013, 05:06 AM   #14
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I know I've looked at all of the limiteds however believe the Sigma 50/1.4 (big & heavy, I know) will probably do the trick.

Thanks to everyone and Pacerr for the extra insight.
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