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06-16-2012, 01:14 PM   #76
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QuoteOriginally posted by normhead Quote
You can buy a DA*16-50 for about the same money you can buy an FA 31. You still need the 21 and and a 50 as a bare minimum.
The FA 31 is a very expensive lens, but yeah, if you bought it you'd have a good lens that's faster and much smaller for 31mm. You don't NEED anything else, that's the point. You might want to go wider or longer, but even then the package is smaller than using an f/2.8 zoom.

But seriously, just buy a damn DA 15. You're over-thinking this far too much. You can sell it if you hate it. Stop worrying about CA and MTF and distortion, buy a lens and use it. I'd recommend the DA 15 first as it's desirable and tiny, so it'll sell on easily afterwards and it's very easy to carry around. It'll NEVER be redundant unless a new lens came along that offered the same quality in a smaller package. My DA 35 f/2.4 is not redundant because I got a DA* 16-50. My Miranda 28mm is not redundant either, because they're tiny, and for entirely different things. I don't want to carry a huge lens around all the time, hence why my 50-135 sees so little non-work use. And I'd happily say my 16-50 beats both in terms of IQ. Distortions and CA be damned. I prefer how images look from the 16-50.

Any of the lenses you're thinking about will be good enough, go out and buy one. Most likely you won't like it because of the corner sharpness or something, or you'll wonder whether the Sigma would have been better. You've already pretty much ruined your experience of your new lens by agonising over every little detail of it already. Almost any contemporary lens is good enough for the job.

06-16-2012, 02:12 PM   #77
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I'm not ready to buy a lens yet, I'm just working up to it. I'm just making sure that next time a grand comes my way, I'm ready to blow it on something. I just love throwing things out there and seeing what people do with them. I always think, there must be somebody out there who knows more than I do about this stuff. I don't know, now I'm starting to think maybe I'm wrong. Maybe it's just us... and we know nuttink. Scary thought.

There really is no one lurking in the shadows who's developed a formula to predict pixie dust. The universe is full of endless and infinite possibilities which the lens makers make more infinite every year. ( Ya I know, infinite cannot be modified by the word "more", you know what I mean. ) How do the Canon and Nikon guys deal with it?

Last edited by normhead; 06-16-2012 at 02:22 PM.
06-16-2012, 02:38 PM   #78
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QuoteOriginally posted by Marc Sabatella Quote
Either you got a defective copy,
There is always that possibility. However, the only issue I saw mentioned was decentering - what I see in the DA 15 is lack of microcontrast - I doubt that the lens was damaged or badly assembled, but just a tiny bit, to make it mediocre without giving it any other serious effects.

QuoteOriginally posted by Marc Sabatella Quote
or your testing was perhaps not sufficiently well controlled,
No testing. Just plain use. But I plan to use it on my E-PL2 now that I got a DA adapter, so I will be able to see better if the problem is sharpness of just the fact that AF is unreliable on the Pentax bodies (I cannot MF this lens with the OVF).

QuoteOriginally posted by Marc Sabatella Quote
or perhaps you jus just have unreasonable expectations for what is possible for an ultra-wide lens
QuoteOriginally posted by Marc Sabatella Quote
But compared to other ultra wides, it is objectively speaking the sharpest lens available for Pentax
From the samples and reviews that I saw, the Samyang 14/2.8 may be the sharpest wide lens available for Pentax. My DA 15 is not as sharp as the Samyang samples I saw around.

Have a look at the border performance of the Samyang in the bottom left sample image on the photozone review using 5D Mark II (the people in the church plaza). That is the kind of performance I am looking for in a wide angle lens. If everyone's DA 15 produces similar performance, then perhaps my lens is a dud.
06-16-2012, 02:56 PM   #79
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QuoteQuote:
From the samples and reviews that I saw, the Samyang 14/2.8 may be the sharpest wide lens available for Pentax. My DA 15 is not as sharp as the Samyang samples I saw around.
But out of this world barrel distortion. Samyang obviously didn't understand the concept of Aspherical. This should be labelled a fisheye.

06-16-2012, 08:20 PM   #80
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QuoteOriginally posted by normhead Quote
Anyone have an example of a zoom that out performs a prime at a given focal length and F-stop or even somewhere in it's range of F-stops.?
If you mean MTF numbers, check 16-45 results at Photozone.
Sharper borders than DA 15mm below f/8 (my 16-45 has sharper corners than my DA 15 at f/8 too).
Sharper across the frame that FA 20mm @ any aperture (interpolated)
Sharper across the frame than DA 21 @ f/4, equal at 5.6, and the zoom has lower distortion (interpolated)
Sharper center than FA*24mm at f/4, sharper borders @ any aperture, zoom has lower distortion

I only have the DA 15mm and 16-45 of the above lenses. The prime beats the zoom for contrast, flare, and CA, probably the other primes do too. The 16-45 is pretty good for vignetting.

Last edited by audiobomber; 06-16-2012 at 08:29 PM.
06-16-2012, 08:45 PM   #81
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QuoteOriginally posted by normhead Quote
But out of this world barrel distortion. Samyang obviously didn't understand the concept of Aspherical. This should be labelled a fisheye.
"Aspherical" normally describes the form of certain individual glass (or hybrid) elements making up a lens,
not the geometric distortion visible in the actual image.
06-16-2012, 08:51 PM   #82
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QuoteOriginally posted by normhead Quote
Anyone have an example of a zoom that out performs a prime at a given focal length and F-stop or even somewhere in it's range of F-stops.?
I have a Tamron 17-50/2.8 A16P.
At 24mm, its edge resolution is higher than my K24/2.8 and ZK 25/2.8 primes.
The primes have (mild) barrel distortion,
while the zoom is virtually free of geometric distortion at that focal length.
Of course, the primes have their own individual advantages and uses.
06-17-2012, 08:24 AM   #83
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QuoteQuote:
Of course, the primes have their own individual advantages and uses.
Like centre sharpness?

Comparing the 16-45 @ and 15 ltd , as I said, most zooms don't control CA very well.



Maybe this will show you how I'm thinking.

Which lens gets you the best image with the best edge sharpness?

The 15ltd @ F8 gives you excellent edge sharpness. Not many zooms can do that, not many primes can do that. Most at best fall into the "very good" range.
If you want a centre sharp image where the edge is going to be bokeh, the F 15 still gives you the absolute best image @5.6

Once you go over F8 you're getting into an image degraded by diffraction, there's really no point in thinking about maximum sharpness at that point.

Then look at the CA. The CAs on the 16-45 are 3 times what they are on the 15. SO bad photo zone actually put in an image as a warning. If any lens will give me a chance on the test shot I posted, it will be the 15, not the 16-45. If I can take that shot at F-8 with the 15 ltd, I should get the best shot that can be taken with any of the lenses mentioned. That's what I'm going for. Not the best shot @ F11, 16, 2.8,4. The best shot period, in absolute terms. That's what I want from a prime. You have to get something for giving up the flexibility of a zoom. As I said, I will do whatever it takes to maximize the image.


Last edited by normhead; 06-17-2012 at 08:37 AM.
06-17-2012, 08:43 AM   #84
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QuoteOriginally posted by Mareket Quote
I'd disagree. The difference between contemporary zooms and primes is minimal, both will give fantastic shots. You buy primes because they're smaller, faster and cheaper for a specific focal length.

In general.
Agreed, except you might want to amend the "and" in "smaller, faster, and cheaper" to say "or", since except in a few cases (eg, fast 50's), it's usually at most two of the three.
06-17-2012, 09:34 AM   #85
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QuoteOriginally posted by normhead Quote
The 15ltd @ F8 gives you excellent edge sharpness. Not many zooms can do that, not many primes can do that. Most at best fall into the "very good" range.
If you want a centre sharp image where the edge is going to be bokeh, the F 15 still gives you the absolute best image @5.6
There's basically no difference in centre sharpness between the two, and the 16-45 comes out better because of it's superior edge sharpness at f/5 and f/5.6. And the DA* 16-50 is plagued by the worst CA I've ever seen in a lens, but I love it and it doesn't bug me because it can be corrected in a single click.

Think less about IQ. Both of these lenses will have fantastic IQ, as will the Sigma 8-16 or the 10/12-24 zooms or whatever. Think about utility. The zooms will give you more chance to get closer or wider if you really need to, but the DA 15 is so small you'd be hard pressed to find a reason not to take it with you. If you don't have the lens with you, it's not going to get you a good image no matter how good the IQ is.

That said, without the zooms, you won't have the option of 8mm or 45mm either, and those could be choices that get you a shot where the DA 15 just couldn't.

Sharpness, distortion and CA are all unimportant if you don't like the lens enough to use it anyway. Maybe it's too big, too heavy, too small, plasticky, sloppily built, too expensive, has slow AF, looks weird, feels weird or just doesn't make you want to use it. These are all far more important when thinking about modern lenses, because IQ wise, they're all top-notch.
06-17-2012, 10:03 AM   #86
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As I said. when we have a choice between the $1700 DA*60-250 and the $450 Tamron 90.. we use both, but the Tammy images are noticeably better if we've both taken the same image. I'm not buying the "these day it's all the same" Argument. About any two lenses, forget about a zoom and a prime. You can postulate all you want. We can see the difference. Sure we like the range of the 60-250. But compared to the one prime we haven ti's range. We can see a difference. As long as that's true, we're always going to make the effort to get the better image. The 60-250 can gets us it's great images from 60-80 and 100-250. In the case of a pancake lens like the 15 ltd, the only excuse for not bringing it would be you're too weak to carry and extra half pound. We carry the 21, 35 and 50 1.8 and 90, 10-17 , 18-135 and 60-250 all the time. The 15 will hardly be noticed in the camera bags, until it gets us a saleable shot we wouldn't have otherwise. If we sell 4 images from it it will have paid for itself. I like it's chances. Just based on what we shoot.

Hey, I'm not a picky person, and the Tamorn 90 is my wife's favourite lens. If I was able to make a case, I would have found a way to convince myself the DA*60-250 was in some way better. I wasn't an easy convert here. I used to think like the above. In the end, the images did the talking. The 35 2.4 and 50 1.8 have been the same way BTW. Faster than a zoom, and better. The 21 you have to love for other reasons. It's great lens because of it's treatment of out of focus areas, and how that blends with it's soft focus. But that it also worthwhile. If it's sharp, I want razor sharp, if it's soft, the image has to look like a watercolour painting.
06-17-2012, 10:48 AM   #87
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The Tamron is better for IQ, but the DA* is more than good enough, and has a bunch of other stuff going for it too. If IQ is really the big thing you love about a lens then yeah, my views aren't very helpful. It just irks me when people spend ages poring over every minute scrap of detail they can find before a purchase. I can see why they do it, it is enjoyable in a weird way, but it still annoys me.

If you're looking to sell images then yeah, I can see why you want the best IQ but for general photography? My kit lens has all the IQ I need for most situations, I just prefer using the DA* because it's faster and feels much nicer. Plus it doubles as a work lens when I have something that needs to be done.

And how dramatic is the difference between the Tamron and the 60-250? I apologise if I'm too aggressive about all this. We're two totally different photographers and I should stop assuming everyone works the way I do. I've never sold landscape shots, so I've no idea what you look for in a lens for that purpose.

But I will reiterate: Buy a DA 15 (when you have the money). You seem to love it based on what you've read, and as you say there's no reason not to take it with you, whereas a zoom is big enough that you might reconsider.

I guess all this boils down the fact that photography is far more enjoyable when you aren't doing it for money, when you can just buy the lens you want and not worry about whether going wider, faster or sharper will give you a better shot. But the DA 15 is a good lens that will probably satisfy you artistically as well as financially when you get rolling with it.

Last edited by Mareket; 06-17-2012 at 11:13 AM.
06-17-2012, 05:25 PM   #88
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There's a great thread on the Sigma 8-16. I'm looking forward to giving it a test drive. Due diligence and all.

https://www.pentaxforums.com/forums/lens-clubs/107938-sigma-8-16mm-club-20.html\


You end up asking yourself... do any bad photographers ever buy this lens?

Last edited by normhead; 06-17-2012 at 05:35 PM.
06-17-2012, 05:35 PM   #89
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QuoteOriginally posted by normhead Quote
There's a great thread on the Sigma 8-16.
Seriously, the 8-16mm is a no brainer. It was a choice of sit around and wait for Pentax to produce a FF, or go wider than even my SIgma 14 FF would go on FF. As also go for the :bigthumbsup: from Photozone.

BTW, I posted the last two shots on that thread, if you want to see a test shot in full resolution here of the 8-16 @ 8mm look here: https://public.sn2.livefilestore.com/y1p9WHlDs2ltwHGppm0aRLCnq8fmQU7mpqv7Bu3...eet.jpg?psid=1

Another point in favour of the 8-16, at the long end, it is FF compatible.
06-17-2012, 07:39 PM   #90
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QuoteOriginally posted by Laurentiu Cristofor Quote
No testing. Just plain use. But I plan to use it on my E-PL2 now that I got a DA adapter, so I will be able to see better if the problem is sharpness of just the fact that AF is unreliable on the Pentax bodies (I cannot MF this lens with the OVF).
Well, I just used the DA 15 on my E-PL2 today and I now changed my mind about it. I mounted it on the K-7 again and I tried some side by side shots too, to see if I get results as good, and I did. Nothing scientific, just trying to nail focus and checking results afterwards. My use scenarios were close up details, my daughter playing in a park, etc, but *not* landscaping, so I did not examine focusing close to infinity. Here are my new observations:

- The DA 15 is indeed very sharp if focused correctly (being a wide lens, it might sound like focus shouldn't matter that much, but at close distances it does, even at f/8)
- Even wide open at f/4, focusing towards the borders, sharpness is very good. (I didn't focus on a flat surface so I couldn't check the field curvature)
- The E-PL2 makes it easier for me to manually focus accurately - this was something I was struggling with on the K-7. With the Pen, even if I don't take an image, I can see the sharpness of the lens while focusing it in LiveView, by watching how details pop out in focus.
- My K-7 might backfocus a bit with this lens, but I will have to look more into this. To get over any issues, I shot a page at an angle, so that I could have something in-focus anyway - the in-focus area of the K-7 came out very well.

So the DA 15 is indeed a sharp lens and my different impression seems to be caused mainly by focusing issues. I don't know if it is sharper than the Samyang 14, but it passes my sharpness bar even on the higher density E-PL2 sensor.

I'll edit my recent posts on this topic, to add a link to these observations.
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