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01-20-2012, 09:22 PM   #1
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Fisheye Face-off: Pentax 10-17mm vs Samyang/Rokinon 8mm

I just received my Rokinon 8mm fisheye lens today, and I'll work on comparing this lens to my current fisheye lens, the Pentax 10-17mm. I know many people are considering getting a fisheye lens but don't want to spend too much money on such a novelty lens, so there's a lot of interest in the 8mm fisheye, especially compared to Pentax's own 10-17. I haven't seen a direct comparison between the 2, maybe because no one actually owns both lenses? Anyway, I'll compare these two lenses, and eventually I will keep only one of them. I think it will be the 8mm though, because I rarely ever use the zoom function on my 10-17!

I don't have a Pentax DSLR with me at the moment, so the actual image comparison on APS-C will have to wait, although I can do some preliminary tests on M4/3 with my adapters.

For now, however, I'll write briefly on the physical attributes of the 2 lenses. They both weigh about the same and are around the same diameter at the barrel. However, the Rokinon is wider at the front lens element. Both lenses are made of plastic and metal, but the plastic on the Pentax feels just slightly better. The Pentax's hood is made of metal but the Rokinon's is plastic. Same with the hood - Pentax's slip on cap is made of metal and is held on by friction while Rokinon's is made of plastic and has a pinch clip.

The focusing ring on the Rokinon is really well-damped and is a joy to manual focus, although I don't think there's much manual focusing that needs to be done with this lens. The Pentax has quick-shift, although that makes it very loose and easily bumped, especially when I'm shooting with it on my M4/3 in manual focus. In this regard, I personally prefer the Rokinon's manual focus and its smooth focusing ring.

One thing I noted is the Rokinon's focus ring markings are way off compared to the actual focus. When I'm focusing at something about 2m away, the lens must be set to about 0.5m. Turns out this is a common issue because they don't seem to calibrate the focus for the individual lens mounts so most lenses are off. The fix is easy enough (loosen some screws under the focus ring rubber and calibrate it to focus at infinity) but it's also possible to just set the lens to 1m and f/8 and shoot since the DOF will be more than sufficient for fisheye shots.

Here are some photos of the 2 lenses:











01-20-2012, 10:39 PM   #2
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Thank you for these preliminary comments. An in-depth comparison would be very valuable to the PF members and I hope that you could conduct a solid one. When I was looking for a fisheye, I was reading many similar threads and none answered my queries. As such your comparison could be most valuable.

Ultimately I bought the DA10-17mm Fisheye and I do not regret it. I enjoy the convenience of having a fisheye and an wide angle lens all in one: at 10 mm, the DA10-17 is a fisheyere. At 14-17mm, it is a wide angle.
01-20-2012, 10:46 PM   #3
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QuoteOriginally posted by hcc Quote
Thank you for these preliminary comments. An in-depth comparison would be very valuable to the PF members and I hope that you could conduct a solid one. When I was looking for a fisheye, I was reading many similar threads and none answered my queries. As such your comparison could be most valuable.

Ultimately I bought the DA10-17mm Fisheye and I do not regret it. I enjoy the convenience of having a fisheye and an wide angle lens all in one: at 10 mm, the DA10-17 is a fisheyere. At 14-17mm, it is a wide angle.
I hope to be able to do a comprehensive comparison, but I'm not sure what to focus on, so it would be good if I could get suggestions on what aspects to test, and how to go about it. I plan to do a FOV test, a PF/CA test, a sharpness test (f/3.5, f/8) at center and corner, maybe a flare/ghost test.

I personally don't like the "wide-angle" aspect of the 10-17 because it's too curvy to me.
02-04-2012, 06:22 PM   #4
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i am facing this conundrum as well. i dont know if i should cash out for gold and buy the Pentax or am i happy with something that looks like gold and feels like gold.

at the moment i think i might save the money on the samyang and buy some more equipment with what i save. maybe a flash

02-04-2012, 07:26 PM   #5
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DA 10-17 should really be a DA 10-17 takumar I think it's built better than my DA 40 limited. It's really only missing the buttery focusing.
02-05-2012, 09:17 AM   #6
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I have both, but the Pentax will probably go. As far as fish-eye goes the Samyang has a better projection and is less susceptible to purple/blue fringing. The zoom on the Pentax is useful though.

Samyang : Samyang 8mm Fisheye Set - a set on Flickr
Pentax : 10-17mm Fisheye Set - a set on Flickr
02-06-2012, 08:45 AM - 1 Like   #7
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I have no experience of the Pentax, and if i had it I'd probably only use it at 10mm... However, I recently acquired the Samyang and I love it!
It is hard to discern the correct focus point since pretty much everything is in focus, but on mine the 1m mark was suitable for everything. I've just loosened the three screws and reset the ring so that infinity is true, and the 0.3m mark is now correct as well (from the sensor, not the front of the lens).

The resolution is very high, and I've been using the Fisheye Hemi plugin to straighten verticals (or horizontals, depending on orientation).

One word of warning - I'd used the lens on the K-5 and it was fine. Then I tried it on the K-7, and found that I couldn't remove the lens. After some mild panic I discovered that on that body it can't be removed while on the 'A' setting, since the movable 'A' contact pin is dropping into the slightly-depressed contact on the lens mount. Turning it away from 'A' retracts that pin and the lens then releases normally. It releases normally on the K-5, K20D and *ist DL2 as well, so it seems that the contact on the K-7 is allowing it to protrude too far into the hole and thus locking it in place.

Outdoors the 8mm introduces an interesting problem, in many cases the choice is between having the sun in the picture or your shadow in the picture - it is that wide!

I've posted the first shots here in this forum.

02-06-2012, 09:21 AM   #8
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really nice shot there. i just decided to buy the samyang as well so i am excited now. prob getting it at end of week
02-06-2012, 09:45 AM   #9
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QuoteOriginally posted by karma mechanic Quote
One word of warning - I'd used the lens on the K-5 and it was fine. Then I tried it on the K-7, and found that I couldn't remove the lens. After some mild panic I discovered that on that body it can't be removed while on the 'A' setting, since the movable 'A' contact pin is dropping into the slightly-depressed contact on the lens mount. Turning it away from 'A' retracts that pin and the lens then releases normally. It releases normally on the K-5, K20D and *ist DL2 as well, so it seems that the contact on the K-7 is allowing it to protrude too far into the hole and thus locking it in place.
No such problem with my copy on a K-7. Focus calibration needed setting though, easy to do with a bit of trial and error.
02-07-2012, 12:42 PM   #10
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Why not start with: The Pentax lens is a zoom lens with focusing ring and AF coupling while the Samyang has a completely misaligned focusing ring (crap), has no AF and is not a zoom.
02-07-2012, 03:54 PM   #11
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QuoteOriginally posted by darrenleow Quote
I hope to be able to do a comprehensive comparison, but I'm not sure what to focus on, so it would be good if I could get suggestions on what aspects to test, and how to go about it. I plan to do a FOV test, a PF/CA test, a sharpness test (f/3.5, f/8) at center and corner, maybe a flare/ghost test.
There is also this very good (but very technical) test of the Samyang/Rokinon 8mm, which includes a comparison to popular fisheyes including the Tokina variant of the Pentax 10-17mm zoom. See the clickable "movies" (about halfway down) of the same shot as seen through the different lenses!

The Samyang definitely has a different fisheye projection, which is actually "less fishy" than the 10-17mm @10mm but harder to correct for the distortion. If you aren't correcting it, then the prime beats the zoom if you like that type of distortion!

Personally, I use the 10-17mm all the time at 10mm, and I've learned to correct the CA and the edge softness at wider apertures. However, I'm shooting full-spherical panoramas, so my use is far from "typical."
02-07-2012, 05:29 PM - 1 Like   #12
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QuoteOriginally posted by panoguy Quote
However, I'm shooting full-spherical panoramas, so my use is far from "typical."
That's what I also use it for : 360Cities (the more recent panos are taken with the Samyang).

With the Samyang it is easy to do a 360 panorama with four shots plus nadir and zenith. In fact, by angling the four shots slightly up from horizontal, you don't really need the zenith shot at all. The Pentax requires at least six shots plus nadir and zenith. Six is much harder to do handheld - guessing a 90 degree rotation is easy, 60 degree much less so

Because of the projection, stitching the Samyang shots is much easier - the critical frame edges are not as 'squashed' as they are with the Pentax.

On the Samyang it is easy to recalibrate the focus ring. In practice focusing with a 8mm is hardly critical because of the enormous DoF even at f3.5. Autofocus is a bit of a waste of time on fisheyes, unless you are shooting moving objects in close up or can't cope with manual focus. Un-fishing the Samyang shots with PTLens is not that hard either : Flickr

The zoom on the Pentax is handy though for times when you don't want the full fisheye effect.

Last edited by kh1234567890; 02-07-2012 at 05:48 PM.
02-13-2012, 10:37 AM   #13
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Would love to see comparison shots from each lens. I'm just starting to debate the same choice in my head.
02-13-2012, 12:49 PM   #14
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These two lenses are for different things really...

Pentax is fun lens with macro capability, Samyang is for panoramic shots where you need to have everything in detail. I have 8mm but sometimes want to get Pentax fisheye purely for the focusing distance it offers and more "fun" distortion.

The point of Samyang that is not found anywhere else is stereographic projection, which retains more balanced stereo angle per pixel over the frame than traditional fisheye projection such as Pentax does. The consequence is that on Samyang shots, the objects look smaller at the center but larger near the edges than on Pentax shots, so Pentax is good if all you care about is the central object and funny distortions.

This makes 8mm better for spherical panoramas - if your software knows about this lens, of course, since the non standard projection requires different math than traditional fisheyes do.
02-14-2012, 05:16 AM - 2 Likes   #15
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Just a quick comparison - an uninspired shot of a bookcase and junk







Both taken on a tripod with the same camera position and angle. K-7, f5.6, manual focus on centre of frame, processed with Silkypix 5 (natural sharpen, CA correction, contrast up a touch). For the pixel-peepers amongst you, the original PEF files are at http://tinyurl.com/PentaxFish and http://tinyurl.com/SamyangFish and the full size JPGs are on Flickr.

There is not much in it, image quality-wise. The Pentax is slightly sharper (look for example at the doorhandle and key of the glass door on the left), both have about the same susceptibility to purple fringing (e.g. the shiny TV aerial in bottom right). The Pentax also seems to have a touch better colours and a little more contrast. The difference between 8 and 10mm is considerable and the different (better ?) projection of the Samyang is obvious.

And an overlay comparison (Samyang is the bigger one) :
Attached Images
View Picture EXIF
PENTAX K-7  Photo 

Last edited by kh1234567890; 02-14-2012 at 09:26 AM.
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