[Bertrand3000]

Hi,

My LBA needs another lens. I would like a lens with the following qualities :
- Wide prime or normal zoom with wide end (17 or less)
- 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?

I read the reviews of course. Unfortunately coma is very rarely tested. Body is K-S2.

My options :
- DA 15
- DA 21
- Sigma 17-50 2.8
- Tamron 17-50 2.8
- Sigma 17-70 2.8-4 C
- Something else?

Thanks for your advice.

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Last edited by Bertrand3000; 01-31-2020 at 12:17 PM.

[aslyfox]

have you considered the HD Pentax-DA 16-85mm F3.5-5.6 ED DC WR or the HD Pentax-DA* 11-18mm F2.8 ED DC AW

[FozzFoster]

I'd love to see how the DA* 11-18mm f/2.8 performs in terms of coma ...

[luftfluss]

Lenstip tests for coma.

[FozzFoster]

Lenstip tests for coma.

I do not believe they have tested the DA* 11-18...

[pepperberry farm]

why do people forget about the DA14/2.8?

[Bertrand3000]

have you considered the HD Pentax-DA 16-85mm F3.5-5.6 ED DC WR or the HD Pentax-DA* 11-18mm F2.8 ED DC AW

Way out of budget for those two, unfortunately.

Lenstip tests for coma.

Thanks, I didn't know this.

why do people forget about the DA14/2.8?

I knew about this one, but I left it out because it is unavailable, and more importantly, this lens seems to be somewhat subpar when it comes to sharpness according to reviews.

[luftfluss]

Lenstip's review of the Tokina 12-24 (Pentax DA 12-24 twin): Tokina AT-X 124 PRO DX II AF 12-24 mm f/4 review - Introduction - LensTip.com

They feel that the DA 15/4 has "really huge" coma wide open.

[stevebrot]

- No coma at wide end and wide open (for stars shooting)

How important is this? I suspect you won't find satisfactory performance center+corners with any wide zoom and with primes only with careful shopping and $$$.

Taking that out of the equation, I have been quite happy with my Sigma 17-70/2.8-4.0 | C.


Steve

[Qman]

I think the DA14 2.8 is a fantastic lens, and the sharpness of mine is very good, but it does suffer from coma. Rokinon makes some fine astro lenses with no coma, but of course they are not autofocus.

[Wingincamera]

I have the Sigma 10-20mm F/3.5 EX DC HM and of course can recommend it. I still keep my DA 15 because of the size difference.
And the Sigma is on sale right now at B&H. Sigma 10-20mm f/3.5 EX DC HSM Lens for Pentax K 202109 B&H Photo

[ChristianRock]

Usually for astro, the Rokinon 14mm f/2.8 and 16mm f2 are the ones people talk about. The 14mm is wider but the 16mm is faster, and both are well corrected for coma (as far as wide angles go). Too bad they don't meet your requirement for autofocus...

[aslyfox]

I have the Sigma 10-20mm F/3.5 EX DC HM and of course can recommend it. I still keep my DA 15 because of the size difference.
And the Sigma is on sale right now at B&H. Sigma 10-20mm f/3.5 EX DC HSM Lens for Pentax K 202109 B&H Photo

another vote for that lens

if it is within budget of course

[Kevin B123]

Usually for astro, the Rokinon 14mm f/2.8 and 16mm f2 are the ones people talk about. The 14mm is wider but the 16mm is faster, and both are well corrected for coma (as far as wide angles go). Too bad they don't meet your requirement for autofocus...

This.
What body are you using too?
You won't really need autofocus on wide anyway since the DOF is massive after 6 feet.

[Bertrand3000]

I have the Sigma 10-20mm F/3.5 EX DC HM and of course can recommend it.

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.

Usually for astro, the Rokinon 14mm f/2.8 and 16mm f2 are the ones people talk about. The 14mm is wider but the 16mm is faster, and both are well corrected for coma (as far as wide angles go). Too bad they don't meet your requirement for autofocus...

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.