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01-22-2017, 04:41 PM - 6 Likes   #1
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A test of 4 ultrawides on a K-1

I own 4 ultrawide lenses. I purchased them in this order:
  1. Tamron SP AF 10-24mm F/3.5-4.5 Di II: This was my first ultrawide, bought for use in big cities. It's a good lens for interior shots because it goes so wide. I think I still had a K-r body at the time.
  2. Samyang 14mm f2.8: The improved low light performance of the K-5 increased my interest in night photography. The Samyang was bought primarily for Milky Way shots, since it's sharper and faster than Tamron.
  3. Pentax DA 15 Limited (the pre-HD version): Purchased for the legendary starburst and flare resistance. This is a great lens for landscapes that include the sun in frame, and for night cityscapes.
  4. Pentax DFA 15-30: Bought this with my K-1. Got a package deal just under $1100 for the lens. None of my other ultrawides are WR.

My plan is to see which of the other 3 lenses sit idle now that I have the 15-30, then sell some of them. I started the process by checking vignetting. Photos below show results. They are in the same purchase order as listed above, but there are 2 for the Tamron at 10mm and 15mm. All photos are SOOC jpg, no corrections applied, aperture f8.

Vignetting: The 15-30 and Samyang show no substantial vignetting. The Tamron 10-24 has major vignetting at 10mm but it's mostly gone by 15mm; darkening at the corners would probably be completely gone at 16mm. The DA 15 is only usable in 1:1 crop mode.

Field of view: The Samyang has the widest usable field. The Tamron and 15-30 tie for 2nd. If you need vertical field for cropping 1:1 or portrait, the Tamron at 10mm or the DA 15 work well (but it would make more sense to hold the camera in portrait orientation and crop less).

Sharpness: This wasn't intended to be a sharpness test and I didn't take time to perfect focus. All of the lenses are acceptably sharp, expected at f8. The 15-30 and Samyang look sharper across the frame than the DA 15 and Tamron.

Flare: Both Pentax lenses do very well; I see one flare smudge in each (in different spots) and the ceiling lights have well defined edges. the Tamron and Samyang show more glare around the lights.

Starbursts: The DA 15 wins with sharp, clearly defined starbursts around ceiling lights. The 15-30 is good but spike are more numerous, therefore less noticeable. The Samyang spikes are "sloppy", and the Tamron doesn;t show any spikes.

Distortion: My composition makes it difficult to assess distortion.

Further testing will happen as time and weather permit. I want to test flare with street lights, try Milky Way shots to assess sharpness and coma, and additional images to see the color rendering.

Tamron @10


Tamron @15


Samyang


Pentax DA 15


Pentax DFA 15-30 @15


01-22-2017, 07:56 PM   #2
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I find the DFA 15-30 is a flare monster. Mostly rainbows. It's pretty good otherwise.
01-22-2017, 08:10 PM   #3
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The Tamron 10-24 looks interesting at 15mm.
How would the edges/corners fare in terms of sharpness at 16mm, 17mm, 18mm?
If its even a good 17-24mm (even 18-24mm), its already plenty good imo.
01-22-2017, 08:13 PM   #4
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Also a good idea to test at different apertures.

01-22-2017, 09:19 PM   #5
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Thanks for the comparison!

FWIW: The Tammy 10-24 at 15mm, looks quite usable and better than my Sigma 10-20 f3.5 at 15.
The Siggy, does not vignette that badly (from 14 - 20mm) but the corners are pretty mushy (on my copy at least) unfortunately. Oh and distortion quite obvious on the siggy too.
I might post some photos on a thread if there is interest.

Last edited by kiwi_jono; 01-22-2017 at 09:28 PM.
01-22-2017, 10:18 PM   #6
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This is a really great post. Thanks for taking the time to put this together. I kind of figure that if I ever want to move to the K-1 that my SMC DA 15 would anchor the wide end. Seems like it could do, but after the corners are cropped out, it won't be that wide. Kind of a fun problem to have I guess.
01-23-2017, 08:09 AM   #7
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Observation: Presumably the camera was tripod-mounted and not moved when lenses changed. If you look at the pictures along the walls at extreme left and right, both the Tammy @15mm and the Samyang include significantly more than the Pentax 15~30 does @ 15mm. I suspect the Tammy indicator for 15mm is not accurate and it's getting closer to 14mm or a bit wider.

01-23-2017, 10:39 AM   #8
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QuoteOriginally posted by WPRESTO Quote
Observation: Presumably the camera was tripod-mounted and not moved when lenses changed. If you look at the pictures along the walls at extreme left and right, both the Tammy @15mm and the Samyang include significantly more than the Pentax 15~30 does @ 15mm. I suspect the Tammy indicator for 15mm is not accurate and it's getting closer to 14mm or a bit wider.
Correct, tripod.

Some of the lenses showed a change in field of view as I focused. Things might be different with a subject at infinity.
01-23-2017, 11:37 AM   #9
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Another minute detail I noticed. The Tammy @ 15mm (nominally) and the Samyang have almost identical coverage horizontally*, but the Samyang has perceptibly more vertically. In the Samyang image, there's extra wire shown for the ceiling projector, plus a bit more of the leg on the nearest corner of the bench at the bottom of the image.

* The Samyang records a bit more horizontally, noticeable in how much of the focusing section of the big telescope is shown at the far right edge.
01-23-2017, 12:59 PM   #10
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For info, DxO Optics Pro lens modules for the K-1 with all of the lenses tested here are available. I think Lightroom has optical correction profiles for them all too.

These profiles can be very handy, particularly when using ultra-wides.
01-23-2017, 03:34 PM   #11
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QuoteOriginally posted by Paul the Sunman Quote
I find the DFA 15-30 is a flare monster. Mostly rainbows. It's pretty good otherwise.
Are you getting the flare from sun or artificial lights? I'll see if I can provoke rainbow flare with my copy.

The single comparison I did here suggests the 15-30 is well behaved with regards to flare. Flare can be tough to test; sometimes a lens does well with a flare source, but shift the composition a little and it gets bad from the same light source.

---------- Post added 01-23-17 at 05:38 PM ----------

QuoteOriginally posted by mikesbike Quote
Also a good idea to test at different apertures.
Agreed. I'll probably remove the DA 15 Limited from further testing due to the vignetting, and do more with the other 3 lenses.
07-25-2018, 01:34 AM   #12
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Low Flare FF Ultra Wides.

On Full frame ultra wides, many people complain about flare on the 15-30mm design, as they do on Nikon 14-24mm. I have a similar Tokina 16-28mm. It's a similar design and also a flare monster !

I find the DA 15mm LTD, or any flat front lens, are endlessly better for bright, sunny conditions shooting into the light.

I recently acquired a rare new old stock, Sigma UC 18-35mm PK mount and have used the very similar EX and DG Sigma 17- 35mm. They have low distortion, good sharpness and stopped down are very good edge to edge. They're not brilliant wide open and probably weren't meant to be. The 15-30mm and 16-28mm F/2.8 obviously are sharper on the edge at wider apertures, but how often do you need wide angle and shallow depth of field? Usually you want maximum depth of field.

These 17-35mm models are also good with flare, as is my Sigma 10-20mm.

If you can find them them the 17-35mm are good everyday FF options to the 15-30mm /14mm flare monsters. These bulbous front models work best indoors or at night.
07-25-2018, 04:58 AM - 1 Like   #13
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Long time later comment or observation. Pity you did not have either or both a Venus/Laowa 12mm or an Irix 11mm, although I think the latter had not been released when you ran your tests. Get one of each and re-run your tests. As an outsider, I can casually assault your bank account.
05-24-2021, 05:10 AM   #14
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After reading this post, I bought the Tamron 10-24 from KEH, thinking it would make a nice affordable wide angle for my K-1 II, figuring that I would use it at 15mm and up.

My results were quite different from OP. There was significant vignetting at 15mm, even after vignette correction with the lens profile in Lightroom.

Here is an example image taken with the lens, without lens correction, that shows the vignetting.



Worse, to me, the image is just soft all around. Certainly way softer than the Sigma 10-20 f4-f5.6 that I sold to a forum member because it had a black circle in FF mode. At least the lens was always sharp in APS-C mode. This lens is just blah.

I have taken it upon myself to print test targets to look at things like corner sharpness at various focal lengths and aperture. I don't do things halfways, so I printed 9 targets of 13x19 each, so I could properly test the ultra-wide angle lens. That's a 39 x 57 target. Not perfectly flat, mind you, as they are all taped together (that took a while!). But I checked with other lenses known to be sharp (my D FA 28-105) and it was more than acceptable to test.

I put my camera on tripod at ISO 100. SR disabled. Focus was done in live view, then camera was put into MF mode. Shot with IR remote with 3 second delay.
All the test shots below have had lens correction applied in LR. They look even worse without it in terms of vignetting and distortion.

I tested full-frame mode at 15mm, 20mm and 24mm, at all apertures from wide open to f16.
At 15mm, corner sharpness was horrible regardless of aperture. Here it is at 15mm f16.



At 17.5mm, vignetting isn't quite as bad. Sides are still unsharp. Corners not easy to evaluate due to where they fall.
Here it is wide open at f4.5 .



And at f8 .



At 24mm, sides and corners are still blurry at f4.5 wide open.


Corners and sides improve somewhat by f8, and more at higher apertures, but remain uneven. Top left corner seems sharpest. Here is what it looks like at f16.



I also tested with the Tamron MC4 1.4x PZ-AF teleconverter.
First, I tested at 11.25mm, or 15.75mm with the TC. Wide open, still poor results in corners/edges.



Edge/corner sharpness is still poor at f8. It looks better at f16.
The 15.75mm/f16 image below might almost be a serviceable image in some cases, but the vignetting remains bad, and even 200 setting for vignette correction in Lightroom doesn't fix it all.



I also tested at 12.5mm on the lens which is 17.5mm with the TC. Results are pretty similar to the 11.25/15.75 setting. Vignette still not fully correctable. I'll spare you the images. I didn't test at any other focal length with the TC.

Finally, I tested the lens with the camera in APS-C mode, without TC, ie. the intended usage for the lens as it was designed.
At 10mm, f3.5 (wide open), it's actually not half bad. LR did a good job of completely correcting the vignette.



It gets better at f8, and better yet at f16 as shown below :



I also tested in APS-C mode at 16.88mm and 24mm. I don't have a lot to say about them. The lens is OK wide open and decent stopped down.

Clearly, the Lightroom lens correction works very well when the camera is in APS-C mode. Not so well at all when it's in FF mode. And forget FF mode with the TC. Guess one would need to reprofile the lens for full-frame. But it's not actually worth it.

I think if shooting on full-frame, you really have to use a teleconverter with this lens, and stop it way down. Otherwise, you are simply better off putting the camera in APS-C mode. I'll probably return the lens to KEH, unless someone at Pentaxforums wants it to shoot in APS-C mode, in which case I think it does the job, but that's not the job I bought it for.

I'm not sure if I want to continue to play the game with trying another wide angle APS-C lense on full-frame. The Pentax 15-30 is probably the way to go, but it costs an arm and a leg. I see many Tamron 15-30 for Canon and Nikon in the $600-$800 range on ebay. No used one for Pentax. Brand new is $1300.

Are there any other full-frame ultrawides for Pentax ? The Sigma 12-24 DG comes to mind, but I don't know if it's any good. Lots of them on ebay for $300 - $400, but in Nikon mount. Two for Pentax at nearly $600 in Japan. I don't think I will bite as it's an older design and non EX / HSM version. And too much hassle to return to Japan if not good enough.
05-24-2021, 06:50 PM   #15
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QuoteOriginally posted by madbrain Quote
After reading this post, I bought the Tamron 10-24...
Sorry the lens didn't work for you. My test was indoors in dim light rather than the bright sky you tested with, and in hindsight my test may have missed some vignetting.

I never did get around to doing more extensive comparison testing. I committed to the Pentax 15-30 and sold my Samyang and Tamron.

I'll update the top post to tell people to scroll down to yours for more info.I guess I won't. My posts from 2017 (not just the top one) have no edit button.
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