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02-19-2021, 12:04 AM - 1 Like   #1
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K70 or K1II for Astro (Milky Way Landscapes)

Somewhat of a deceptive title. But, I have a friend who has been shooting his K70 for 2 years now and is thinking hard about upgrading to a K1II. Prior to this he only shot with a smart phone. He has an excellent eye for composition. Here are some examples from his InstaGram page.A little backstory. We met out in the field shooting the Milky Way. He had just had his K70 for a couple of weeks and just had an old 28/f2.8. So, I pulled my GPS and 18-30 lens, set up his body, calibrated and shot the Milky Way. The image came up and he was very happy. I stood there with my jaw on the ground - because, the Milky Way color was as good as my K1 and 15-30/2.8. This K70 is absolutely excellent for wide field astro and night landscapes.

My reasoning is that the K70 with the Acceleration Chip has a 1.5 stop boost starting at ISO 630. This just happens to match the K1, the K70's Acceleration Chip essentially making up for the difference in sensor size.The K1II also using the Acceleration Chip is another 1.5 stop boost again starting around ISO 630. Also, the closest I can get to comparing dark current on the cameras is hereI tossed in the Canon 6D as a baseline comparison because Rodger Clark a PhD Astronomer notes that it has the best dark current read available. The K1, K1II and the K70 show well here. The K1II and K70 compare very well up through ISO 1600-2000.

He has been using his K70 with a Sigma 18-30/f1.8 and has been getting extraordinary excellent images. I've packaged up a number of my raw images for him to process and compare. He has been looking at the two sets, and finding little difference between them - which I would expect.

So, over the last week he has been looking at the K1II again with probably the Rokinon 24/f1.4. The K1II should yield a 1 to 1.5 stop advantage over the K70. The 24/1.4 should also provide an additional 1.5 stops beyond what the 18-30/f1.8 is providing at 18mm. The 24mm field of view should be pretty similar to 18mm on the crop sensor. The new combination should provide about a 3 stop advantage over his current equipment. That's about the most he can expect.

A year ago, I suggested that he just stay with the K70. Now, his images are so good, that another 3 stops of light he can really put to use.

Any additional suggestions?



02-19-2021, 12:38 AM   #2
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If this move is all about that one lens, then review it very deeply. I read somewhere that it was a heart breaker, and poor until stopped down some, defeating the point of it.

He is getting great results from his current kit, stay with it I think.

Edit: This isn't the review I was thinking of, but is largely positive:
https://www.lonelyspeck.com/rokinon-24mm-f1-4-ed-as-umc-review/#more-3156

Last edited by Kevin B123; 02-19-2021 at 06:56 AM. Reason: Link added
02-19-2021, 08:04 AM   #3
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:P my two cents say keep the K-70 and buy a 11-18mm f/2.8.

Sure, you lose some stoppage, but you will still get incredibly great images.
You can get incredibly great images with a darn kit lens!
You definitely don't "need" f/1.8 or 1.4 to take a good image.

Sure, you could stitch to get the same field of view, but then you are taking SO many images to not only cover the same field of view, but then the multiple exposures for each stitched shot. I would rather have the wider field of view with the 11-18mm and stack those images rather than stitch together narrower images.
02-19-2021, 09:42 AM   #4
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All, Thanks for the comments and suggestions...
QuoteOriginally posted by Kevin B123 Quote
If this move is all about that one lens, then review it very deeply. I read somewhere that it was a heart breaker, and poor until stopped down some, defeating the point of it.

He is getting great results from his current kit, stay with it I think.

Edit: This isn't the review I was thinking of, but is largely positive:
Rokinon 24mm f/1.4 ED AS UMC Review Lonely Speck
He does want to be able to get better images - and at this point, it's all about the light. There are a number of lenses available. There is some subjectivity in the way folks evaluate them. The bottom line is that it does come down to a few to select from.

If you go wider that say 20mm, the physical area of the aperture decreases, essentially diminishing the amount of light going through the lens. The longer the focal length the larger the physical aperture, but you still want a reasonable wide field of view - hence the sweet spot becomes 20mm to around 35mm - which is getting somewhat narrow. Also, all the lenses have their own strength and weaknesses - varying amounts of coma, vignetting, color fringing and de-centering problems. Yes, with each lens you can stop down to clear up the problems, and with each lens the amount you stop down varies.
  • Rokinon / Samyang 24/f1.4 - mainly decentering with a bit of coma. Reading reviews stopping down to f1.8 or perhaps f2 gets you past these. Swapping copies to find a good one with a minimum of de-centering can be a problem. Perhaps buying through LensRentals - they would be game to look for a good one, plus they have an optical bench that they run all their lenses through. We both saw the lonely speck review.
  • The Sigma 35/f1.4 is an excellent lens - but apparently tends to have more coma problems. Stopping down to about 2.8 gets by that.
  • Sigma 24-35mm f/2 is the apparent equivalent to the crop sensor18-35/f1.8 - however, the lens does not come in a Pentax K mount. Sigma is dropping support for Pentax mounts.


QuoteOriginally posted by FozzFoster Quote
:P my two cents say keep the K-70 and buy a 11-18mm f/2.8.

Sure, you lose some stoppage, but you will still get incredibly great images.
You can get incredibly great images with a darn kit lens!
You definitely don't "need" f/1.8 or 1.4 to take a good image.

Sure, you could stitch to get the same field of view, but then you are taking SO many images to not only cover the same field of view, but then the multiple exposures for each stitched shot. I would rather have the wider field of view with the 11-18mm and stack those images rather than stitch together narrower images.
The 11-18 is a great lens. Yes, you loose aperture not only going to f2.8, but since the focal length is shorter and wider, that f2.8 aperture in absolute physical area decreases significantly. Also, the 18-35 is pretty much one of the best lenses out there. I have never shot with the 11-18, nor have I compared it with the 8-16 (f4 aperture).

The other aspect is image quality and detail. The wider you go, the more detail you loose. Again the 18-24mm range seems to have a good field of view, while supporting the fast aperture aspect in terms of collecting as much light as possible.



02-19-2021, 10:15 AM   #5
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Your follow-up post #4 shows you already knew what I wrote. Leaving it here anyway as additional confirmation.

QuoteOriginally posted by interested_observer Quote
...Rokinon 24/f1.4...
That lens is potentially great, assuming your friend can find a good copy. There is a lot of sample variation. I returned 3 of them before giving up. Daylight photos looked okay but stars showed bad decentering or excessive coma, in 3 different ways on the 3 lenses I handled. Stopping down to f2.8 did not fix things.

The f1.4 design is sensitive to alignment issues. Maybe Rokinon/Samyang has improved their manufacturing quality control since my experience.
02-19-2021, 01:58 PM   #6
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QuoteOriginally posted by DeadJohn Quote
Your follow-up post #4 shows you already knew what I wrote. Leaving it here anyway as additional confirmation.

That lens is potentially great, assuming your friend can find a good copy. There is a lot of sample variation. I returned 3 of them before giving up. Daylight photos looked okay but stars showed bad decentering or excessive coma, in 3 different ways on the 3 lenses I handled. Stopping down to f2.8 did not fix things.

The f1.4 design is sensitive to alignment issues. Maybe Rokinon/Samyang has improved their manufacturing quality control since my experience.
Yea, that's one of the major problems with this lens. My friend does not have a lot of free time between now and October - his next day off is March 11 - we are thinking of trying to go out and do an early season milky way shoot. Getting a bad copy would just wreck some havoc on stuff. He's considering buying from LensRentals and hoping to find one with the least amount of decentering (since they all seem to have some, regardless).

02-19-2021, 07:18 PM   #7
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QuoteOriginally posted by interested_observer Quote
Yea, that's one of the major problems with this lens. My friend does not have a lot of free time between now and October - his next day off is March 11 - we are thinking of trying to go out and do an early season milky way shoot. Getting a bad copy would just wreck some havoc on stuff. He's considering buying from LensRentals and hoping to find one with the least amount of decentering (since they all seem to have some, regardless).

If your friend is considering renting a copy from Lens Rental or purchasing a used copy from their sales company, Lens Authority, he need not be too concerned about manufacturing defects and quality control issues. Lens Rental tests every new lens that comes into their facility. If any issues are found they either reject it or repair it. Also, after every rental is returned they clean, test, and repair (if necessary) every lens. They can't afford not to. On a side note, Roger Cicala of Lens Rental puts out the best reviews of anyone, totally unbiased.
02-19-2021, 11:02 PM - 1 Like   #8
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QuoteOriginally posted by interested_observer Quote

So, over the last week he has been looking at the K1II again with probably the Rokinon 24/f1.4. The K1II should yield a 1 to 1.5 stop advantage over the K70. The 24/1.4 should also provide an additional 1.5 stops beyond what the 18-30/f1.8 is providing at 18mm. The 24mm field of view should be pretty similar to 18mm on the crop sensor. The new combination should provide about a 3 stop advantage over his current equipment. That's about the most he can expect.
It looks like other posters have beaten me to it, but I would strongly caution against making any camera choices expecting to use the Samyang/Rokinon 24mm F1.4 anywhere near wide open.

I've purchased two copies previously (ie EF mount) and both were completely unusable below F2.8, due to a combination of field curvature and spherical aberration. In order to match the Sigma 18-35mm F1.8 (shoot wide open) in terms of point shaped stars, they needed to be at F3.5 on one copy, and F4 on the other.

The Sigma 18-35mm F1.8 does have some astigmatism/coma that is noticeable in the edge of the frame, but I confidently shoot it wide open whenever I do landscape astrophotography. I've never felt that way about either of the Samyang lens I've tried, even when stopping down. In addition to the 2 copies of the 24mm, I also tried a 14mm F2.8, and have the 8mm fisheye. Its, always the same story unfortunately.

For reference, my solution to the problem of maximising lens aperture/sensor size is to use the combination of a Sigma 18-35mm with a KP, mounted on a nodal panorama head. A three position pano shot at around 22mm will match the Samyang 24mm F1.4 FoV, with an effective aperture of F1.05.


Last edited by Eye.n.Eye; 02-19-2021 at 11:13 PM.
02-20-2021, 12:42 AM   #9
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QuoteOriginally posted by DWS1 Quote
If your friend is considering renting a copy from Lens Rental or purchasing a used copy from their sales company, Lens Authority, he need not be too concerned about manufacturing defects and quality control issues. Lens Rental tests every new lens that comes into their facility. If any issues are found they either reject it or repair it. Also, after every rental is returned they clean, test, and repair (if necessary) every lens. They can't afford not to. On a side note, Roger Cicala of Lens Rental puts out the best reviews of anyone, totally unbiased.
I've been reading so much, across this that I can't find it now - but Roger Cicala of Lens Rental in one of his blogs (I've been reading him for years now), that most of his Rokinon's have de-centering issues. Now, it's become an issue of minimizing the problem. It's really a shame, since there are not that many lenses available to select from.

When I was shooting with my K5 and the 18-35, I felt very lucky with the lens, since it's only weakness was AF and I was always shooting manual focus. Every lens available has some optical design problem.

QuoteOriginally posted by Eye.n.Eye Quote
It looks like other posters have beaten me to it, but I would strongly caution against making any camera choices expecting to use the Samyang/Rokinon 24mm F1.4 anywhere near wide open.

I've purchased two copies previously (ie EF mount) and both were completely unusable below F2.8, due to a combination of field curvature and spherical aberration. In order to match the Sigma 18-35mm F1.8 (shoot wide open) in terms of point shaped stars, they needed to be at F3.5 on one copy, and F4 on the other.

The Sigma 18-35mm F1.8 does have some astigmatism/coma that is noticeable in the edge of the frame, but I confidently shoot it wide open whenever I do landscape astrophotography. I've never felt that way about either of the Samyang lens I've tried, even when stopping down. In addition to the 2 copies of the 24mm, I also tried a 14mm F2.8, and have the 8mm fisheye. Its, always the same story unfortunately.

For reference, my solution to the problem of maximising lens aperture/sensor size is to use the combination of a Sigma 18-35mm with a KP, mounted on a nodal panorama head. A three position pano shot at around 22mm will match the Samyang 24mm F1.4 FoV, with an effective aperture of F1.05.
That's pretty much why I made this post. A lot of the reviewers are reasonably positive. There are not that many folks posting a lot on other forums - and I really haven't gone looking for a lot of posts on the lens for other bodies.

It's discouraging hearing that about Rokinon/Samyang.

02-24-2021, 09:28 PM - 1 Like   #10
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QuoteOriginally posted by interested_observer Quote
Somewhat of a deceptive title. But, I have a friend who has been shooting his K70 for 2 years now and is thinking hard about upgrading to a K1II. Prior to this he only shot with a smart phone. He has an excellent eye for composition. Here are some examples from his InstaGram page.A little backstory. We met out in the field shooting the Milky Way. He had just had his K70 for a couple of weeks and just had an old 28/f2.8. So, I pulled my GPS and 18-30 lens, set up his body, calibrated and shot the Milky Way. The image came up and he was very happy. I stood there with my jaw on the ground - because, the Milky Way color was as good as my K1 and 15-30/2.8. This K70 is absolutely excellent for wide field astro and night landscapes.

My reasoning is that the K70 with the Acceleration Chip has a 1.5 stop boost starting at ISO 630. This just happens to match the K1, the K70's Acceleration Chip essentially making up for the difference in sensor size.The K1II also using the Acceleration Chip is another 1.5 stop boost again starting around ISO 630. Also, the closest I can get to comparing dark current on the cameras is hereI tossed in the Canon 6D as a baseline comparison because Rodger Clark a PhD Astronomer notes that it has the best dark current read available. The K1, K1II and the K70 show well here. The K1II and K70 compare very well up through ISO 1600-2000.

He has been using his K70 with a Sigma 18-30/f1.8 and has been getting extraordinary excellent images. I've packaged up a number of my raw images for him to process and compare. He has been looking at the two sets, and finding little difference between them - which I would expect.

So, over the last week he has been looking at the K1II again with probably the Rokinon 24/f1.4. The K1II should yield a 1 to 1.5 stop advantage over the K70. The 24/1.4 should also provide an additional 1.5 stops beyond what the 18-30/f1.8 is providing at 18mm. The 24mm field of view should be pretty similar to 18mm on the crop sensor. The new combination should provide about a 3 stop advantage over his current equipment. That's about the most he can expect.

A year ago, I suggested that he just stay with the K70. Now, his images are so good, that another 3 stops of light he can really put to use.

Any additional suggestions?

I don't know if this helps you, but I owned a Rokinon/samyang/bower (forget which one) 24mm 1.4 and shot astro with my K-1. It did have some issues wide open, but I wouldn't say terrible. At least my copy, because apparently that's an issue. Not sure how it compares to what he has. Certainly stopping down would be your best bet to clear up any issues. I ended up choosing to keep my Rokinon 14mm 2.8 instead mostly for focal length reasons. I liked getting more of the night sky in one shot. I felt like the light advantages weren't as big a deal for me since I've been moving more into stacking images and using astro tracer.

Here's an album with a few night shots with the 24mm 1.4 wide open on the K-1
Bower/samyang/rokinon 24mm 1.4 | Flickr

for comparison, here are two shots from the same location between the 24mm 1.4 wide open and the 14mm 2.8 wide open on the K-1. (Excuse the bad light painting).

24mm
IMGP0340v3

14mm
Milky Way Over Road 14mm
02-24-2021, 10:36 PM   #11
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QuoteOriginally posted by Snapppy Quote
I don't know if this helps you, but I owned a Rokinon/samyang/bower (forget which one) 24mm 1.4 and shot astro with my K-1. It did have some issues wide open, but I wouldn't say terrible. At least my copy, because apparently that's an issue. Not sure how it compares to what he has. Certainly stopping down would be your best bet to clear up any issues. I ended up choosing to keep my Rokinon 14mm 2.8 instead mostly for focal length reasons. I liked getting more of the night sky in one shot. I felt like the light advantages weren't as big a deal for me since I've been moving more into stacking images and using astro tracer.

Here's an album with a few night shots with the 24mm 1.4 wide open on the K-1
Bower/samyang/rokinon 24mm 1.4 | Flickr
\]
Thanks for posting the side-by-side comparisons, and especially for uploading the full resolution images to Flickr. Being able to view any astro photo at 1:1 is a pixel peeper's dream when it comes to assessing lenses.

For what its worth, it looks like you have about as good a 14mm copy as you can hope for from Samyang. If I owned that copy I'd be very happy! The focal plan is fairly flat and basically no spherical aberration to my eye.

The 24mm lens wide open is showing excessive spherical aberration (for my taste), but its still looking better than either of the copies of this lens I tried out.

Maybe I'll need to try at least one more Samyang lens before I right them off forever. The 135mm F2 is the most tempting, but maybe the 16mm F2 would be worth a roll of the dice. Surely I'm due for a good one eventually!!
02-25-2021, 05:47 PM   #12
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QuoteOriginally posted by Snapppy Quote
I don't know if this helps you, but I owned a Rokinon/samyang/bower (forget which one) 24mm 1.4 and shot astro with my K-1. It did have some issues wide open, but I wouldn't say terrible. At least my copy, because apparently that's an issue. Not sure how it compares to what he has. Certainly stopping down would be your best bet to clear up any issues. I ended up choosing to keep my Rokinon 14mm 2.8 instead mostly for focal length reasons. I liked getting more of the night sky in one shot. I felt like the light advantages weren't as big a deal for me since I've been moving more into stacking images and using astro tracer.
Thanks for the examples. This is really the first time I personally have been limited by the lens selection available for Pentax.
  • I called LensRentals and they could cherry pick both a K1 (for white dots) along with whatever lens models that they carry (alogn it) with the 100% of rental fee applied to the purchase (within the rental period). They have stopped offering Rokinon lenses other than the Ciene lenses for the most part. The un-spoken inference being that they were just tired of the de-centering problem.
  • I also called and talked with Sigma about their remounting service. It's only available for lenses that originally are offered with the Pentax mount as an option, not a lens where the Pentax mount is not available.
Also considered both IRIX and Lawoa. IRIX also suffers from the de-centering problem and Lawoa does not offer their fast aperture lenses in a Pentax mount (just mirrorless).

That narrows the field down to ....
  • Sigma 35/f1.4 - somewhat narrow, but you still need to stop down to ~f2, f2.4, f2.8 to get past some coma issues
  • Pentax 15-30/f2.8 - I already have the lens, and my friend was hoping to just not replicate something that we have access to.
  • Pentax FA 31/f1.8 - I have the lens, and years ago I shot with it a bit and I remember it having some coma, but need to go back and check - and possibly try it again. Others have had some excellent success.
So, right now the hunt and the "thinking out of the box" .... continues. It would be really nice to be able to try and get a "pre tested" cherry picked Rokinon.

03-16-2021, 04:41 PM   #13
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Another good lens for astro/landscapes is the Tamron 17-50 f2.8 xr. I use this lens on a K5, it does everything nicely.
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