Small and lightweight, but not amazing

iudex · Jan 22, 2015

After switching from 17-50mm to 18-35mm I felt the need for something wider. My Sigma 18-35mm Art is optically perfect, however with 18mm (27mm eq) beginning it´s not really wideangle and shooting landscapes or interiors was not ideal, since a lot did not fit in the frame. So I searched for wideangle lens, either zoom or a prime lens. As regards the zoom the Sigma 10-20mm appealed to me, the reviews were OK, but I wasn´t sure I want to carry another big zoom lens; my Sigma with it´s 810g is really heavy and I didn´t want any other bulk to carry. So I chose a prime lens and the choice was easy there: Pentax 14mm/2,8 or Pentax 15mm/4. Again the wider 14mm lens was not that light, plus it was fairly expensive, so the choice was the 15mm f4.

Pros: I really love the small size and weight of this prime. You almost don´t feel it on the camera body, it´s so light. Ideal for ling hikes or as a second lens you can carry in your pocket without the need to take the camera bag. The build quality is superb, too. All-metal body (including metal cap!), precise build that leaves good feel of quality, plus smart feature like the built-in lens hood. Optically positive is that there is almost no distortion, typical for UWA lenses (I think because it is not that wide), so shooting architecture is not a problem. HD coating really works and the lens is really flare resistant, shooting directly into the sun is not a problem.

However there are downsides, too. The sharpness is not great, I have expected better results. Maybe I am spoilt by superb Sigma Art, however I would expect a prime lens to perform at least on equal level as zoom lens, if not better. Also from famous Limited badge you may expect anything but perfect outcome. But this lens does not deliver it. I do not say the lens is not sharp, it is, but not razor sharp and even stopping down does not help much. Plus from lens this slow (f4) you would expect decent sharpness even at f4. So landscape photographers who search for ultimate sharpness will not be completely satisfied.

Then there is the speed issue. Of course if you buy an f4 lens you must be aware that it will be no low-light king. Anyhow the behavior in interiors is worse than I expected, tha camera with this lens on has troubles focusing, something I didn´t encounter with f2,8 lenses. So this lens is only usable indoors with a flash (but when using a flash check that your flashgun supports this wide angle).

So owerall: I got what I expected: small, portable wideangle lens with perfect build quality, but with only sub-par low-light capability. The sharpness results were a small let-down, in general it is nothing to complain about, but from a prime lens with Limited badge I expected something more. However I am not a pro, do not pixel-peep my pictures so despite this small downsides I am going to keep this lens.

kh1234567890 · Jan 23, 2015

KL Matt said:
This lens has excessive field curvature, which is why you're seeing mushy edges on the horizons of your landscape. Stop down to f/8 and try to focus slightly beyond infinity to enhance your corners if the lens will allow (but obviously not so much that your image is no longer sharp in the center.) Or alternatively use live view to focus midway between center and the edge of the frame. This may be the best compromise focal point along the very drastically curved plane of focus.

In my experience that is rubbish. The DA15 is basically soft outside the frame centre when wider than some f/8, no matter where you focus it at. Field curvature is not that bad.

Cynog ap Brychan · Jan 23, 2015

While I can, to some extent, understand the preoccupation (one might say "obsession") with sharpness in these digital days when one can check images at a pixel level, it should be remembered that some of the greatest photographs ever taken are not "sharp" by modern standards. I guess I'm trying to say that sharpness isn't everything, especially when other factors such as colour and rendition are compromised. But, it is one thing about a lens that can be measured reasonably objectively, so it gets much attention.

Cane · Jan 23, 2015

asp1880 said:
Sharpness is certainly not a DA15 forte. Everyone agrees with that. But it's a tradeoff that yields unique qualities in high contrast and backlit situations where the lens just delivers punch and colour like nothing else. It's a lens built for sunshine and I use mine a lot.

Regards,

--Anders.

Sharpness isn't everything. Why is it always everything?

Gary Martin · Jan 23, 2015

In regards to sharpness, tests at Photozone and other sites show that the DA15 has very comparable performance to most compact wide-angle lenses: “excellent” in the center, and only “good” to “very good” in the corners when stopped down to f8 or so. As has been pointed out elsewhere, field curvature is a common occurrence in compact designs and the DA15 is no exception. I get excellent results shooting at f9.5, which is a good balance between getting good depth-of-field and avoiding too much diffraction. But proper focus technique is still essential. When framing a scene with a wide angle, it’s going to be rare that everything in the frame is at the same distance; there could be a subject as close as a few feet away and other objects extending all the way to a distant horizon. Even though hyperfocal scales show a wide range of sharpness when stopped down, in my experience they are overly generous; *critical* sharpness covers a much narrower range than these scales indicate. So again, proper focus is key to getting good results from the DA15, DA21 and any other wide lens with significant field curvature.

As for the DA15 not being a good low-light lens, the f4 aperture should be your first clue that it’s not the best tool for that sort of thing. All lenses are designed with compromises, and a 15mm lens that would be fast and have minimal field curvature would have to be a much larger, bulkier lens for a K-mount camera. I'm sure when Sigma releases its rumored 24/1.4, it will be a big, heavy beast like their other Art lenses. The sharpest wide-angle lens I've seen is the Nikon 14-24, and that lens is freakin' huge (and a flare-monster as well).

SlamDesi · Jan 23, 2015

iudex: If you're looking for "wide" I might suggest you look at the Tokina 11-16mm f/2.8. My sone is a real estate photographer and had this lens recommended to him by a peer. There's another individual that I stumbled upon online who uses this with a Canon T3i and gets "amazing" results with a variety of subject matter: http://www.digitalrev.com/album?id=2122916

hans_ch · Jan 23, 2015

I agree that the DA 15 mm may not be the best lens regarding corner sharpness but it's definitely a nice lens and a joy to use. I like the colours that it produces. Below a few examples, taken at various light conditions. The DA 15mm is one of my favorite lenses.

The polarizer filter used here was a bit too much ..

Cheers, Hans

--
www.hrfisch.com

prime instinct · Jan 23, 2015

Cynog ap Brychan said:
While I can, to some extent, understand the preoccupation (one might say "obsession") with sharpness in these digital days when one can check images at a pixel level, it should be remembered that some of the greatest photographs ever taken are not "sharp" by modern standards. I guess I'm trying to say that sharpness isn't everything, especially when other factors such as colour and rendition are compromised. But, it is one thing about a lens that can be measured reasonably objectively, so it gets much attention.

iudex · Jan 23, 2015

I agree with you. Small size and low weight was the main attraction and slow speed was a downside I was aware of and accepted. As I wrote, for low light situations I have the Sigma with f1,8. And maybe this small complaint about the speed was only because of the winter period with long nights and not many opportunities to shoot daytime landscapes, I believe in spring/summer I will use this lens for what it is made for: outside sunny-day shots. I can´t wait to take it for my next sightseeing trip to some european city and I am sure it will do it´s job well.

SBS · Jan 23, 2015

I'm going to assume that all the comments about the 15mm not being that sharp are not referring to center sharpness. It is very sharp in the center, but unfortunately gets soft pretty quickly away from that point.

BobORama · Jan 23, 2015

Cynog ap Brychan said:
I guess I'm trying to say that sharpness isn't everything, especially when other factors such as colour and rendition are compromised.

Let me prefix this by saying that its not a bad lens, but it embodies some fairly large compromises in design.

It has high levels of coma and astigmatism which account for a lot of the edge softness, and higher than average levels of CA, also leading to softness. Any lens can be sharp when you stop down a little or a lot. In comparing two lenses, the better lens won't force you to accommodate its failings as much. On the plus side, it is a light weight, small lens which is very sharp centrally, and has good field flatness.

I could see ones disappointment if edge to edge IQ is the goal.

But to your piont, heck, my Sigma 10mm/2.8 fisheye has higher central resolution than most lenses, but again, its a fish eye, and the sharpness at the edge is, uh, "special."

-- Bob
http://bob-o-rama.smugmug.com -- Photos
http://www.vimeo.com/boborama/videos -- Videos
http://blog.trafficshaper.com -- Blog

stanic042 · Jun 23, 2015

asp1880 said:
Sharpness is certainly not a DA15 forte. Everyone agrees with that.

Regards,

--Anders.

I do not agree

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Small and lightweight, but not amazing

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