[Spindrift]

Hi,

I have a K-50 which I use almost exclusively for astrophotography, which I took up recently. I am mostly using the kit 18-55 lens but have been advised that the Samyang 14 mm F2.8 Manual Focus Lens is ideal for astro work.

However, I have also seen the Pentax 10-17mm f3.5-4.5 DA Fisheye Lens. I'm just wondering if anyone has any experience of this lens, especially for astro? Both are in a similar price bracket, so that is not an issue. If anything the Pentax is slightly cheaper. But... is it any good?

Any answers would be appreciated.

Thanks.

[jatrax]

This article might offer some insight: Lonely Speck’s Ultimate List of Best Astrophotography Lenses – Lonely Speck

I do not think either the 18-55 or 10-17 would be particularly good for astro but I've not tried the 10-17 myself so I could be wrong. Several people I trust have stated the Rokinon / Samyang 24mm f/1.4 is the best astro lens but I'm sure others here with more experience will chime in.

[DWS1]

I have the Samyang/Rokinon 14mm. It's biggest advantage is the field of view and f:2.8 aperture, and it works good overall on a K50 and K70. Lately I've been using the DA 16-85mm for astrophotography and like it better. It is 1/2 stop slower but still fast enough, has better image quality, and has many more uses than the 14mm and the DA18-55. The kit lens will do a very satisfactory job. Astrophotography is so much more about knowledge, technique, and post processing than equipment. However, the built-in astrotracer (with the optional OPS-1 GPS unit) and the intervalometer on the K50, K70, and other models is very useful for astro work.

My biggest problem is finding somewhere dark enough.

[Kozlok]

The 10-17 for Astro depends on what you want for Astro. If you want to add some fun fishy horizons, it's great. If you want accurate astronomy, not so useful.

[johngs]

I only tried night sky astro photography a few times with my K-50.

The lens I used was a Sigma 10-20mm f4-5.6 EX DC
I got the best results with the lens at 10mm, using ISO 1600 and f4 and 30 seconds exposure.
My Milky Way shots with this set up were pretty good for a beginner like me!

[johngs]

I only tried night sky astro photography a few times with my K-50.

The lens I used was a Sigma 10-20mm f4-5.6 EX DC
I got the best results with the lens at 10mm, using ISO 1600 and f4 and 30 seconds exposure.
My Milky Way shots with this set up were pretty good for a beginner like me!
I'll try to attach one of my shots taken with the above setup and settings ...

[Papa_Joe]

I would not use a fish-eye for night-sky photography, as often landscape is included and koszlok showed the point.
To be honest I wouldn't buy a fish-eye for anything else then fish-eye photography.

The two main requirements for a night sky lens are a fast aperture, to get as much light as you can during exposure time and sharpness over the whole frame. The Samyang 14 / 2.8 is a excellent choice in both categories and thus is often recommended for night photography, although it has some flaws during daytime. The IRIX lenses are comparable. And both Samyang and IRIX do not cost you an arm and a leg.

I started some weeks ago with my Tamron 2.8 / 17-50 mm, which is fast and has quite a good performance over the frame as well. If I can master the post processing I might look for a shorter focal length.

Don't you have any other lenses with a short focal length?

@johngs : Nice picture!

[MossyRocks]

The Samyangs are generally considered to be excellent lenses for astro if you can get a good copy. I had been considering getting a good ultrawide for astro for a while and ended up getting the Laowa 12mm f/2.8. I've only had the lens out once for astro since getting it to put it through it's paces and learn how to run it before I go out and use it for capturing quality pictures.

What I learned from that outing is:
It is actually good and sharp wide open but does have some coma that if stitching a panorama image I wouldn't worry about
To clean up the coma you have to stop it down to f/4
With ultrawides like this you can really push the astro recommendations, however the old rule of 500 is still BS because digital doesn't have reciprocity failure like film does. Stick with 200/(focal length) is your max exposure time in seconds and you will be good
Images taken with this lens stack very cleanly

The Laowa is a much more expensive lens but I don't regret purchasing it as it will solve the problem I want it to solve. I haven't had it long enough to get a real good feel for it yet so haven't written a review as I want to take it out in a couple weeks when I can get some good milky way shots first.

I started doing astro with the 18-55 kit lens before that got broken and while it is doable don't expect great results but you will still learn from using it. Also don't try astro with the old 17mm f/4 fisheye, it is awful for astro so you don't need to repeat my mistake. If you want a narrower view that works good for constellations you can fit all of Orion in the view of a 50mm. I use my S-M-C 50/1.4 and will run it at f/2.4 and my SMC A 50/1.2 at f/1.8 with good results. The 50/1.4 can be picked up pretty cheap and there are a lot of things you can snap with it. If you want to dip your feet into deep sky object photography (DSOs) consider getting the super/S-M-C 200/4 takumar, or the P, M, or A version of it as they are basically the same. They are all cheap but very good lenses for starting astro. Do not use the 100/2.8 macro it is awful for astro. If you want longer than 200mm you will want glass that was designed more recently as it took longer for those long lenses to become solved problems but things designed in the mid 80s can be absolutely phenomenal (looking at you SMC A* 400/2.8). For ultrawides you really do need something modern and new as they only really started to become good for astro since digital really took off.

[disasterfilm]

On crop sensors, I've found the Samyang/Rokinon 16mm f/2 to be vastly superior to the 14mm f/2.8 for most of the Milky Way season in North America.

When the Milky Way is tilted away from vertical, there is plenty of space in the frame to arrange foreground elements and secure the most interesting visual parts of the galactic core in the frame. Shooting wider only extends to include the lesser-interesting parts of the Milky Way, at the cost of de-emphasizing the spectacular galactic core.

Also, if you're using an O-GPS1 module, the wider you shoot, the less effective the O-GPS1 will be... particularly in the outer thirds of the image frame.

Add in the extra stop of light from f/2 rather than f/2.8, and the fact that the 16mm receives 77mm filters (allowing you to mount a red enhancer/noise pollution filter), and the results you get between 2 similar lenses will be day-and-night different.

[Snapppy]

I own the 14mm f/2.8 Rokinon and will never sell it. I find it fantastically sharp wide open for milkyway stuff, and also great for daytime landscapes on APS-C. Like others have mentioned, there's a reason this one gets mentioned everywhere. It's not that just for the price it's very good, it's also just very good.

On crop sensors, I've found the Samyang/Rokinon 16mm f/2 to be vastly superior to the 14mm f/2.8 for most of the Milky Way season in North America.
...
Add in the extra stop of light from f/2 rather than f/2.8, and the fact that the 16mm receives 77mm filters (allowing you to mount a red enhancer/noise pollution filter), and the results you get between 2 similar lenses will be day-and-night different.

This is a compelling option, and what sounds like an amazing review from @disasterfilm. If I had stayed with APS-C for astro stuff I would definitely have tried this out already, exactly for the mentioned reasons. New, the prices of these two lenses are similar with the 16mm being more in the places I saw. In my experience it is easier to find the 14mm used for a good price than the 16mm, though that is just my personal experience. So, cost may be the deciding factor here for you depending on budget. Reminding me of this makes me want to pick one up again...

For what it's worth, for full-frame I tried the Rokinon 24mm 1.4, and while it was also very good and allowed me extra light, I ended up back on the 14mm because of the wider angle and I found it sharper at infinity.

[Pizza]

This is Andromeda with an old vivitar 70-210mm F2.8-4 lens @ 210mm on my K1-ii, but cropped a bit more than ASP-C (so probably similar to something between K-50 and a K-5). I took I think 5 stacked photos with astrotracer with about 20 second exposures, no dark frames. You would be able to get something similar with 20-30 stacked exposures of about 1.5-2 seconds each without an astrotracer module. With a K-50, taking dark frames would probably be beneficial to help with noise. (sorry, I don't have much experience with dark frames yet.)

Edit: I know your post mentioned wide angle, but thought I would give some info on a longer lens that wouldn't break the bank if you find a used one.

[Spindrift]

Thank you all for the great responses and for the guidance. Your comments are more useful than you could know and have helped me narrow down the choice, which if I'm honest is now going to come down to a simple coin toss and what I can find online.

Thanks, too, for sharing the incredible images. I can only aspire to that!

I'll let you know what lens I end up with. Thanks again.

[kypfer]

This is Andromeda with an old vivitar 70-210mm F2.8-4 lens @ 210mm on my K1-ii, but cropped a bit more than ASP-C (so probably similar to something between K-50 and a K-5). I took I think 5 stacked photos with astrotracer with about 20 second exposures, no dark frames. You would be able to get something similar with 20-30 stacked exposures of about 1.5-2 seconds each without an astrotracer module. With a K-50, taking dark frames would probably be beneficial to help with noise. (sorry, I don't have much experience with dark frames yet.)

Edit: I know your post mentioned wide angle, but thought I would give some info on a longer lens that wouldn't break the bank if you find a used one.

Excellent!
It's results like this that encouraged me to buy an O-GPS1 for my K-70.
Limited success as yet, but still waiting for that clear moonless windless night

[Spindrift]

OK, so I went for the Samyang 16mm f2, guided I admit by the fact that I found one online at a significant discount. However, the feedback I got from my original post was pretty influential! The lens is being shipped from the US (even with the import duties it was cheaper than I could get it here), so it won't arrive much before early July. All I have to hope then is that the fickle British summer weather doesn't revert to normality!

Thank you again for the advice and pictures, all hugely appreciated. BTW Pizza, I'm definitely going to try longer lenses. I've just bought a t-ring and tube to fit the camera to my telescope. I hope 700mm is long enough!

---------- Post added 06-22-20 at 02:51 PM ----------



---------- Post added 06-22-20 at 02:54 PM ----------

This is Andromeda with an old vivitar 70-210mm F2.8-4 lens @ 210mm on my K1-ii, but cropped a bit more than ASP-C (so probably similar to something between K-50 and a K-5). I took I think 5 stacked photos with astrotracer with about 20 second exposures, no dark frames. You would be able to get something similar with 20-30 stacked exposures of about 1.5-2 seconds each without an astrotracer module. With a K-50, taking dark frames would probably be beneficial to help with noise. (sorry, I don't have much experience with dark frames yet.)

Edit: I know your post mentioned wide angle, but thought I would give some info on a longer lens that wouldn't break the bank if you find a used one.

This is inspiring, I'll definitely be trying longer lenses. Clearly, I need an Astrtotracer, too!

[VILLAINofOZ]

I had had some good success with the DA10-17 fisheye between 15 and 17mm.
I much prefer my Sigma 10-20.
I think once you get your astrotracer then even the 18-55 kit lens works well enough.