[jspi]

I have a Sigma 17-50mm f/2.8 but on many occasions it has not been wide enough. I also have a Pentax 24-70mm f/2.8 which will probably be my main lens. A 10-20mm means I expand my kit and can gift the 17-50mm to my dad.


Anyway, since I would like wider than the 17mm, I'm considering the following to use on a K3 II:
Pentax SMCP-DA 12-24mm f/4
Sigma 10-20mm f/3.5
IRIX 15mm f/2.4 Firefly
Venus Laowa 12mm f/2.8

Wants:
f4 or faster and prefer a constant aperture
Image quality
Minimal distortion (not fisheye although I expect some distortion at 10mm)

Accurate focus marks on the lens (mainly infinity is infinity)
Price - the Venus is at the top end


I found a review of the Pentax 12-24mm, Sigma 10-20mm f/4-5.6, and Tamron 10-20mm(?) which the Sigma looks like the best deal. And the review between the older and newer Sigma 10-20mm make the newer one look like a good contender.

My main hesitation on the Sigma is my other Sigma lenses focus past infinity. So when attempting to photograph stars, I have a difficult time getting focus right. I've read IRIX infinity focus is accurate but am not sure about Venus (still need to look) although price leads me towards IRIX if they're comparable. Not a deal breaker but would be nice.

I have a Rokinon 8mm which I've got precisely 0 good shots from. Someone told me they're hit & miss on quality so I may have received a bad copy. My wife has better luck with hers.

[pepperberry farm]

you may also want to consider the DA 14/2.8 - I have one and it is wondrous....

[mikeSF]

Just jumping in to share a couple cents. I would likely eliminate the 15mm from selection because for the money, you wont gain very much FOV vs the 17mm on your zoom.

I have owned a few wide lenses in that range: 10-17 FE, 8-16 Sigma, 10-20 Sigma, DA15, DA16-45...
I had the earlier version of the 10-20 and had no complaints with it's abilities. Infinity focus is not a concern wrt astro work because i am often able to accurately focus on a distant bright object on the ground(streetlight, passing car, etc) that is within the hyperfocal range at such wide focal lengths.

FWIW, here are some of my photos with the:

Sigma 8-16: Lens: Sigma 8-16mm | Flickr
Sigma 10-20(v1): Lens: Sigma 10-20 | Flickr
DA15(v1): Lens: DA15 Limited | Flickr
Pentax 15-30: Lens: DFA 15-30/2.8 | Flickr

Good luck!

[hcc]

I have the DA15mm Ltd and DA10-17mm as wide lenses, and I use APS-C (K-3, K-01, K-7). I love the DA15mm Ltd for many applications. It is definitely wide enough IMHO for outdoor landscape. (For indoor, 15mm is often too long and I tend to favor the DA10-17mm.)
Honestly, the DA15mm Ltd is a lens in its own (league). F4 is fast enough sunset and sunrise with that short focal length. (I tend to like fast lenses, but the DA15 mm is possibly the main exception.)

My 5 cents.

[clackers]

If you're shooting stars, go for the Irix.

It lets you calibrate the infinity position.

BTW, you *must* learn to manual focus for astro.

My suggestion is ignore whatever any lens says.

You need to learn to use magnified Live View, choose a star, and make its circle as small as possible - that's it! Like macro or product photography, a field monitor or a loupe can help.

[jspi]

If you're shooting stars, go for the Irix.

It lets you calibrate the infinity position.

BTW, you *must* learn to manual focus for astro.

My suggestion is ignore whatever any lens says.

You need to learn to use magnified Live View, choose a star, and make its circle as small as possible - that's it! Like macro or product photography, a field monitor or a loupe can help.

Yes, I do know how to manual focus but I'm not the best. Even with a field monitor and magnified live view, the Rokinon isn't sharp. Tried indoors with a test chart and it was still fuzzy. It's the only lens I can't get focused.

I'm getting several suggestions I'll have to review in the coming days. No rush to buy.

[Sandy Hancock]

As you already own the DFA 24~70/2.8 and like it on crop, I would suggest the DA* 11~18/2.8 to go with it. Image quality is exceptional, build quality is superb, it's weather sealed AND it shares the same filter thread.

Yes, it's more expensive than the Venus Laowa 12/2.8 Zero-D (which I also have, and it's excellent but VERY wide), but I reckon it is worth in.

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Last edited by Sandy Hancock; 06-08-2020 at 06:50 PM.

[jspi]

DA* 11-18mm? If I could find a used one that would be great. That and the 24-70mm woukd cover most everything except macro and wildlife.

I've done panoramic shots before (7 or 8 years ago). Phones make it so easy but I should check out current software. My first attempt ended up with the same ghostly figure at every stitch point. I guess she walked as fast as I panned.

And I said landscape... I know wide isn't always the way to go. We also do some historic city tours, occasional museum, and some hiking where the 17mm put me against a wall, cliff, etc. and almost got the shot. Cliffs... got to watch that last step.

[tibbitts]

DA* 11-18mm? If I could find a used one that would be great. That and the 24-70mm woukd cover most everything except macro and wildlife.

I've done panoramic shots before (7 or 8 years ago). Phones make it so easy but I should check out current software. My first attempt ended up with the same ghostly figure at every stitch point. I guess she walked as fast as I panned.

And I said landscape... I know wide isn't always the way to go. We also do some historic city tours, occasional museum, and some hiking where the 17mm put me against a wall, cliff, etc. and almost got the shot. Cliffs... got to watch that last step.

Just my opinion but historic city tours are the place for a phone or small pocketable superzoom camera and not a dslr. There just isn't enough time to take advantage of the dslr and you miss too much of the experience, plus there are usually too many other people obstructing the subject. You can sometimes go back later on your own for more extensive photography.

[jspi]

Just my opinion but historic city tours are the place for a phone or small pocketable superzoom camera and not a dslr. There just isn't enough time to take advantage of the dslr and you miss too much of the experience, plus there are usually too many other people obstructing the subject. You can sometimes go back later on your own for more extensive photography.

True. I do have a GX85 micro 4/3 which I take to some of those events (small but not a super zoom). Most are where we live (learning more about our city) so if I miss something... No big deal. We have went back and got some of those photos. It's hard to leave the Pentax at home until there's a good reason.

[clackers]

Yes, I do know how to manual focus but I'm not the best. Even with a field monitor and magnified live view, the Rokinon isn't sharp. Tried indoors with a test chart and it was still fuzzy. It's the only lens I can't get focused.

I'm getting several suggestions I'll have to review in the coming days. No rush to buy.

You may have a dud copy, Jspi.

Test it for decentreing and being able to focus to infinity, and send it back if it fails!

[Sandy Hancock]

Just my opinion but historic city tours are the place for a phone or small pocketable superzoom camera and not a dslr. There just isn't enough time to take advantage of the dslr and you miss too much of the experience, plus there are usually too many other people obstructing the subject.

That has most certainly not been my experience. Buenos Aires (twice), London (twice), Bath, Dublin, Milan, Venice, Florence, Siena, Rome, Paris, Seattle, Victoria, Canada have all been totally fine with a DSLR.

A KP and bag of Limiteds didn't cramp my style at all, or detract in any way from my enjoyment of exploring these wonderful cities. I have a bunch of shots from these trips hanging on my wall at home and I'm very glad for the extra quality from a real camera and good lenses.

[othar]

Even with a field monitor and magnified live view, the Rokinon isn't sharp. Tried indoors with a test chart and it was still fuzzy. It's the only lens I can't get focused.I'm getting several suggestions I'll have to review in the coming days. No rush to buy.

I would never use my 8mm fisheye lens wide open, but at f5.6 up to f8 (beyond that I start to see diffraction) you should get sharp images with it. What I did notice: for a final judgement of image sharpness of this lens always check on your monitor at home and not the preview of the camera, because of the way the preview image is processed in the camera the images look way softer in preview than they do on my PC (I shoot RAW not JPG).
It happens very often, especially with my 8mm and my 35mm lenses from Samyang, that I initially think all pictures are out of focus or otherwise soft when watching the preview and they turn out to be nicely sharp after importing to LR.


As others have mentioned you also have the possibility to stitch images together to get a wider field of view. (If you use Adobe CC you have a stitching software already included in LR if I am not mistaken; I use an older version of LR so I use Hugin for stitching which is a freeware, but there are many more programs you can choose from)
Especially for landscapes where in my experience tends to be not much movement stitching is a viable solution (but try to keep steel ropes or power cords in a single image of the stitch if possible, those make the most problems for the software in my experience).
For astro work stitching will be still possible but I assume it will be easier to get it right in a single shot, so you might consider a wider lens for this usage.

Here is an example for stitching (I think I stitched this from 39 single images):



and some more if you are interested:
Stitches | Flickr

[Wasp]

I have the Sigma 10-20mm f/3.5, love it.

[bdery]

Pentax SMCP-DA 12-24mm f/4
Sigma 10-20mm f/3.5
IRIX 15mm f/2.4 Firefly
Venus Laowa 12mm f/2.8

Wants:
f4 or faster and prefer a constant aperture
Image quality
Minimal distortion (not fisheye although I expect some distortion at 10mm)

Accurate focus marks on the lens (mainly infinity is infinity)
Price - the Venus is at the top end

On this list, my favourite is the Venus 12mm, mainly because of the IQ, low distortion, build quality.

See here:

Venus Optics Laowa 12mm F2.8 Zero-D Review - Introduction | PentaxForums.com Reviews

Irix 15mm F2.4 Firefly & Blackstone Review - Introduction | PentaxForums.com Reviews