[ChristianRock]

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Well, in that case, how about a Samyang 14mm for astro, and then switching your Sigma 10-20 for a Pentax 12-24mm f4? The old 12-24 might not be as good as the 11-18mm, but it's a fine lens...

I'm not a dedicated landscape shooter, but in terms of a zoom that gives you great results even wide open at f4, but especially at f8, there's the old DA 16-45mm f4.... not very popular these days, as it's now an old discontinued lens, but whenever I compare pictures from it, with pictures from the DA*16-50, and the Sigma and Tamron 17-50mm lenses, and especially the Sigma 17-70mm, I always stick with my 16-45mm... wobble and all... the colors and contrast are just wonderful in my opinion - not the most realistic, but wonderful. And it's plenty sharp, even at the edges. A zoom with character.

[Sidney Porter]

I have the sigma 17-50 f/2.8. it is a great lens.

If I need to go wider I have the Rokinon 8mm f/3.5 fisheye. With framing and some work in post I came eliminate most of the fishiness. It is manual focus but being so wide just about everything is in focus

[yucatanPentax]

I agree that the Pentax 12-24mm is a fine lens. Use it often.
A separate lens for astro would also be my choice, simply because the characteristics for astro in a zoom aren't readily available at lower cost.

To save on buying two rather than one, you might consider the Pentax Forums Marketplace where well-treated lenses come up often.

[krazykat]

The Sigma 8-16 has pretty good coma performance and is usually sharper than the 10-20's (depending on the copy of course).

Even though I shoot full-frame it and the DA15 are the two APS-C lenses I keep because they're so good and there's no FF equivalent for them.

[DWS1]

I had the same dilemma as the OP. I ended up purchasing the Rokinon (Samyang) 14mm f2.8 specifically for astro. I may try to find some other uses for it. However, because of the low price, I consider it a one purpose lens. I shoot a lot of landscapes and don't really like wide angle single shots, unless there is a strong and close foreground element in it. I prefer longer focal lengths and stitching. When I do want a wide angle view, I really like to use the DA 16-45mm. It is a very good lens when stopped down to f:8 or so, and kept in the zoom range of about 18-35mm.

[MaineNative]

The only lens I have found that comes close to the Samyang 14/f2.8 for Astro is the Pentax DFA 15-30. It has comparable coma control but also has the same distortion in the corners with Astrotracer as the Samyang on FF shots. Besides the price, the DFA 15-30 is also a very heavy lens. So like others, I have the Samyang for astro shooting only. I bought an FA 20 for FF wide angle with auto focus during the day.

[Bertrand3000]

Hmm. So maybe the lens is the Samyang 14 F2.8? Its abilities when it comes to astro are well-known, but for landscapes, how it fares compared to the Sigma 10-20 F3.5? After all, I could try without autofocus thanks to the short focal length and small aperture setting by setting the lens to hyperfocal. I've read about bad resilience against flare, which is bad, few chromatic aberrations (which is good, my DA 10-17 is plagued with them), and what about sharpness and color rendition?

PS: I didn't think about the DA 12-24, but cost in my country is prohibitive (1000 €).

[texandrews]

Another vote for the Sigma 17-50. I had that lens for my Oly cameras before 2010, and used it on an E-3 (lovely camera). Was very fond of it, especially for portraits. Had a warmer color cast, less clinical.

[Biff]

A used Pentax DA 12-24 is a great quality/price proposition.

[5r82]

You can't go better and cheaper than Sigma 10-20mm f3.5 currently on sale. Fantastic lens. I have slower version. Very good lens and I used it so much.

[angerdan]

- Fast aperture (at wide end)
- No coma at wide end and wide open (for stars shooting)
- Autofocus (required)
- Very sharp at wide end
- Reasonable price

The perfect lens! Does it exists?

You want the perfect lens but are not willing to pay the neccesary price, even if it is only 100 bucks more?
pentax da 11 18 | eBay

[Bertrand3000]

You want the perfect lens but are not willing to pay the neccesary price, even if it is only 100 bucks more?
pentax da 11 18 | eBay

Thank you for the link, but my budget is only around 300 €. 1100 $ is way too much.

It seems that the Sigma 17-50 F2.8 is rather praised. If it is really good for wide angle and is better than DA-L 18-50 at all foccal length, that could be a good choice.

[Bertrand3000]

What about the older lens, the Pentax DA 16-45 F4? Is it still worth something on a modern K-S2 compared to a DAL 18-50 WR RE Kit and a Tamron 18-250 superzoom? I don't have interest in WR, but I do have interest in both wider angle of view and sharpness.

[mikesbike]

Thank you for the link, but my budget is only around 300 €. 1100 $ is way too much.

It seems that the Sigma 17-50 F2.8 is rather praised. If it is really good for wide angle and is better than DA-L 18-50 at all foccal length, that could be a good choice.

Definitely better than the DA-L 18-50mm. I have both. The very small Pentax lens is great as an all-around zoom lens when needing to go as small as possible. The Sigma 17-50mm f/2.8 EX DC HSM is seriously a pro-style constant-aperture lens, very sharp, and very good for low light use, as well as fast action. It also has a handy AF/MF switch on the lens in a good location.

---------- Post added 02-03-20 at 06:18 PM ----------

I already have this lens. This is my best for astro, currently. I noticed coma on the edge, though, and I wondered if any prime or fast quality zoom would have been better and in budget. Apparently, it's not really the case.




Yes, I am aware about the excellent coma performance of Samyang 14 F2.8. I didn't know about the 16 F2, though, and I agree that autofocus has no value when it comes to astro. But I hoped that I could buy another lens, more versatile (hence autofocus and perhaps zoom range, that could do astro AND daylight photo, especially razor-sharp landscape, something I cannot get with the Sigma 10-20, nor the DA 10-17 Fisheye.


I was almost convinced by the Sigma 17-70 F2.8-4 C, until I read the user reviews, most complaining about IQ being rather average at the wide end. That's a pity since it will be probably my most used focal length.

I realize that my prerequisite are too contradictory, that such a lens maybe do not exist (except perhaps with DA* 11-18, but it's too costly).

If the Sigma 10-20 F3.5 is already rather good in that category (astro), then maybe I should drop the coma prerequisite and only look for a razor-sharp wide-angle capable lens for landscapes.

I am quite surprised you have difficulty getting sharp landscape shots with your Sigma 10-20mm f/3.5 EX DC HSM. I have both it and the Pentax 12-24mm f/4, and I find both are similar in their sharpness capabilities, both highly-rated in lab tests. Only the corners of the frame lag behind with the Sigma lens, and this only at 10mm. If you are using very small apertures for maximum DOF in landscape shots, like above f/11, there can be a reduction in quality due to the onset of diffraction.

[pinholecam]

The Perfect UWA costs big money.
That said, the Samyang 14/2.8 is really proven.
If its for astro and landscapes, you just need to mark off the infinity point on the copy of the lens that you have. (the factory marking on the lens is not accurate)