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11-03-2015, 06:52 AM   #31
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Saturation point on this topic for me.

11-03-2015, 07:08 AM   #32
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And over-saturation leads to loss of detail.
11-03-2015, 07:32 AM   #33
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QuoteOriginally posted by WPRESTO Quote
Saturation point on this topic for me.
Well, thanks for your input and sticking with it this far Based on my original post, it seems I'll need to pull the lens performance data together from photozone, lenstip etc.
11-03-2015, 08:31 AM   #34
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QuoteOriginally posted by BigMackCam Quote
Well, thanks for your input and sticking with it this far Based on my original post, it seems I'll need to pull the lens performance data together from photozone, lenstip etc.
when you do I'd love to see it.

11-03-2015, 09:00 AM   #35
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I'm guessing many of you have done a similar thing, but here are my lenses with a summary of notes I've made to myself. I print this out on a halfsheet of card stock. I also include EV info where applicable. References to "Kenko" are to my Kenko 1.4x teleconverter.
LENS SUMMARY
Rokinon 8mm Fisheye
Use 5.6-8; set approx. near focal length
Sigma 10-20 f4.5-5.6
~f8-11 @10; ~6.3-11 @15mm; 5.6-9 @20mm
Pentax DAL 18-55 f3.5-5.6
Use f8-11 for best
Pentax DA 18-135
Use f5.6>8 at wide end; f8-11 at long end
Either Focal 2x (? metering) or Kenko 1.5x provides tele advantage
Pentax DA 21 f3.2 limited
f3.2 ok but improves to 5.6-8 for best
Tamron 24-135 f3.5-5.6
Use at least f5.6; better f8-11
Aetna Rokunar MC Auto 28mm f2.8 M42
Soft but ok at 2.8 < 4 < 5.6-8 > 11 > 16
Sigma Mini-Wide II 1:2.8 f=28mm Macro
Soft but ok at 2.8 < 4 < 5.6-8 ~> 11 ~> 16
EV: Dim light: -1/3; Bright: +1/3??
Vivitar 28mm f2.8
Avoid f2.8; best at f8; EV -2/3
Sigma UC 28-70mm f3.5-4.5
Meters well; fine @3.5 but better 5.6-8
Pentax DA 35 f2.4
Great at f2.4 but improvement at f3.2-8; best at f4-5.6; still good at f8
Pentax F35-70 f3.5-4.5
Fine open but use f5.6-8
Auto Chinon 45mm f2.8 Pancake
Useable @2.8 and 13; best at 5.6-9.5;
use -1 or -2/3 EV
SMC Pentax 50 f4 Macro
Can use f4 and shoot A but slightly better at 5.6-11; use -2/3 or -1 EVF
Pentax M50 f1.7
Use f2/2.8 at minimum; best at f8
Pentax A50 f1.7
Use f2/2.8 at minimum; best at f8; may need +1/3 or +2/3 EV
Pentax DA50 f1.8
Use f2.8 at minimum < 4 < 5.6-8 > 11
Super-Takumar 55mm F1.8
at least f2.8; best f5.6-8, f16ok
Pentax DAL 55-300
Best at f8/11 & even f16 @ long end for far
With Kenko 1.5x, use f11
Pentax M 75-150
Best f5.6-9.5 but f4 ok and f11-13 acceptable
EV -2/3
Tokina SZ-X 80-200 f4.5-5.6 shoot w/ A
@wide: f8 moving to f5.6 (6.3 more contrast; less CA) @200; focus up;
Focal (or Kenko) @200 @5.6
Tamron 90 f2.8
Sharp @ 2.8 < 4 < 5.6-11 > 16 > 22 > 32
S-M-C Takumar 1:3.5/135mm M42
3.5<4<5.6>8>11 but really very good at all f
Takumar 135 f2.5 Bayonet
Use f2.8 minimum; acceptable @f8; best @f11-13
Super Takumar 150mm F4 M42
Very good at f4 but does sharpen to f8 > f11
TeleTakumar 200 f5.6 M42 shoot w/ A
Use f8 at least; best @ f11
Focal 2x TC works best @ f8 or f11
SMC Pentax-M 200mm F4
f5.6 at least; best results at f8 +/-
FiveStar 500mm
Best at f11 (or 16); Kenko @f11; Viv2x @f8
11-03-2015, 09:07 AM   #36
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QuoteOriginally posted by mgvh Quote
I'm guessing many of you have done a similar thing, but here are my lenses with a summary of notes I've made to myself. I print this out on a halfsheet of card stock. I also include EV info where applicable.
This is great stuff - thanks for sharing

I'm pulling together a table for the lenses I own and I'll post it on the forum when its ready...
11-03-2015, 10:54 AM   #37
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QuoteOriginally posted by BigMackCam Quote
My subjective analysis was based on the MTF figures at Photozone for each lens... And yes, F11 shows to be worse than F5.6 on those lenses but still very good on several of them.
you can learn a lot with mtf chart test numbers, but in the end it can only tell you what the lens might do with targets that are shot at the test distance, generally ~1'-6' away from the camera.

"Focus Distance - At Lensrentals we've got targets ranging in size from 24" to 85" in diameter. But that means on the very largest targets we're testing wide angle lenses very close to the target. For example a 24mm lens is tested at about 6 feet shooting distance. A 14mm we're shooting at about 3 feet from the chart. Making the assumption that the sharpest lens at 3 feet shooting distance is the sharpest lens at infinity is, well, weak. There have been several examples where target analysis reviews say a wide-angle lens is just great, but in the field, shot at infinity, photographers unanimously say it's not that great. And now you know why I don't really trust these tests on wide-angle lenses.

The same problem comes up with macro lenses. My first Imatest results showed that the Nikon 105mm f/2.8 Micro just wasn't that great. But, guess what? Even with my smallest charts I was shooting it at an 8-foot distance. When we developed techniques using high-resolution backlit Imatest targets shot at 1 foot distances more appropriate for a macro lens, it turned out to be a great lens. I ended up writing a blog post saying, yet again, I was wrong less correct than I had hoped to be." LensRentals.com - There Is No Perfect Lens Test, Either

i bought the imatest software, printed up a nice sharp 20x30 target on the costco printers, and ran a couple of hundred images through it... i found that for mtf testing, a real-world repeatable test scene was much better... for example, look at how rishi at dpr shoots these big wide cityscapes, at all apertures:
Prepare to be impressed: Tamron 15-30 F2.8 vs. Nikon 14-24 F2.8: Digital Photography Review
Sony Zeiss Distagon T* FE 35mm F1.4 ZA samples: Digital Photography Review

online mtf chart numbers won't tell you anything about how good your particular lens is; half of all the legacy lenses that i've tested have been decentered... you can't test for that by shooting centered objects like dogs and people, it really needs to be wider long shots, of equidistant objects.
11-03-2015, 11:29 AM   #38
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@osv - thanks, that's very useful, and helpful.

I don't doubt that MTFs based on a single, close distance won't tell the whole story, and that every copy of every lens will differ slightly. However, if I compile my crib sheet as a starting point, I'll at least have narrowed down the most useful aperture ranges for each lens based on admittedly-limited tests. And that's what I'm after - a tool that gets me "in the ball-park" (without simply assuming "a couple of stops down from wide open" and "no slower than f/8"); but not a definitive reference...

Thanks again for the info - much appreciated

11-03-2015, 11:35 AM   #39
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Particularly for pre-DA Pentax lenses, I've found Takinami's lens resolution test data helpful, if it hasn't already been mentioned above - see http://www.takinami.com/yoshihiko/photo/lens_test/index.html
11-03-2015, 12:02 PM   #40
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QuoteOriginally posted by utak Quote
Particularly for pre-DA Pentax lenses, I've found Takinami's lens resolution test data helpful, if it hasn't already been mentioned above - see http://www.takinami.com/yoshihiko/photo/lens_test/index.html
Very handy. I have a few M and A lenses that I can add to my table using this data. Thank you!

Edit: I just had a quick look at his data, and it's interesting to see how the 35mm lenses seem to peak at f/8...

Last edited by BigMackCam; 11-03-2015 at 12:07 PM.
11-03-2015, 12:50 PM   #41
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The general rule is great but it indeed pay to really try and learn your lenses to understand what they do in practice and how to get the best out of them for every kind of situation.
11-03-2015, 01:08 PM   #42
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It used to be "f8 and be there". In the digital age, it is more like "f5.6 and you're square".
11-03-2015, 01:22 PM   #43
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QuoteOriginally posted by fg-one Quote
It used to be "f8 and be there". In the digital age, it is more like "f5.6 and you're square".
A depth of field tip for street shooters, right?

But there's something about IQ in that advice, too, I'm sure.
11-03-2015, 01:44 PM   #44
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QuoteOriginally posted by BigMackCam Quote
Edit: I just had a quick look at his data, and it's interesting to see how the 35mm lenses seem to peak at f/8...
an example of that would be his ff(film) test of the fa35, which peaks across the frame at f/5.6-f/8: http://www.takinami.com/yoshihiko/photo/lens_test/pentax_35.html

but if you look at the fa35 on crop(k10d), it peaks across the frame at f/4, with the center losing resolution at f/5.6, sides remain the same: Pentax SMC-FA 35mm f/2 AL - Review / Test Report - Analysis
"At f/8 there're marginal diffraction effects but the quality remains easily on an excellent level."

so per the photozone mtf numbers, the fa35 is weaker all the way across the frame at f/8 on crop, you would only want to use f/8 and beyond on crop to overcome lens aberrations like field curvature.

it backs up everything that i've been posting about diffraction losses showing up at the wider end of the crop aperture scale, because there is more dof there than with ff.

the fa35 is unusual because it's a fast lens, but at least test ff lenses, at landscape distances, you should be able to see the diffraction losses in the center by f/8.
11-03-2015, 01:58 PM   #45
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So... here's the kind of thing I was thinking of. This is a very, very rough summary of just the Limited primes, the DA35 F2.4 and DA50 1.8 - just to play with the basic layout... Data taken from Photozone reviews with the exception of the DA50 1.8 which was Lenstip. I haven't validated this yet - I may have made an error or two, but as I said, this was mainly to play with the format.

Any constructive input would be appreciated - this layout is fine for me, I think, but if I turn it into something for others to use also (and add a lot more lenses), I'd rather make it broadly appealing
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