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06-05-2019, 01:56 PM   #1
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Zenitar 16mm vs Rokinon (Samsung) 14mm

Hi, I'm looking for a budget ultra wide angle lens. Mostly for astrophotography and also general landscape shots. My research has lead me to these two. I realise the zenitar is a FE - I'm fine with that, as I shoot raw so I can either correct the distortion or leave it as an effect.
I'll by mounting on my K5ii which I understand will give an equivalent field of view of a 11-12mm rectilinear.

In Australia, I can get the zenitar for about $250 or the Rokinon for about $450. I am on a tight budget so $450 is already a stretch for me, so please no "this other lens is only $600". At this stage in life I can't justify that kind of money on lenses.

Im basically wondering if the Rokinon is worth almost double the cost. Has anybody had experience with both? Manual focus doesn't worry me, although the auto aperture would be handy. But the Rokinon is HUGE and the smaller zenitar appeals to me. If the consensus is that the Rokinon is good "when stopped down" (for astro), I'll lean towards the zenitar because that's what I'm hearing about that lens too.

06-05-2019, 04:35 PM   #2
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I'd say go with Rokinon, but I'd suggest looking at the marketplace here in the forums, you'll usually find one cheaper used but in good condition.

---------- Post added 06-05-19 at 04:42 PM ----------

I just noticed you said you're Australia *smacks own head* sorry, dont know if shipping will be too much or if you have to pay any import fees/taxes/etc.

Last edited by disconnekt; 06-05-2019 at 04:43 PM.
06-05-2019, 09:05 PM - 1 Like   #3
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The Rokinon's a modern lens with an aspherical element, Kman, that Zenitar won't be in the same ballpark when it comes to such things important to astro as management of coma.
06-05-2019, 11:51 PM   #4
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QuoteOriginally posted by kman42 Quote
Hi, I'm looking for a budget ultra wide angle lens. Mostly for astrophotography and also general landscape shots. My research has lead me to these two. I realise the zenitar is a FE - I'm fine with that, as I shoot raw so I can either correct the distortion or leave it as an effect.
I'll by mounting on my K5ii which I understand will give an equivalent field of view of a 11-12mm rectilinear.

You've done your arithmetic incorrectly. On your K-5ii, with it's APSC sensor, the 14mm will be a "21mm-equivalent" and the 16mm will be a "24mm-equivalent", assuming comparison to a full-frame 35mm camera.


The 16mm is a "full-frame" fish eye on a 35mm camera. With an APSC camera only using the central portion of the image, distortion can be less obvious than you might expect, if framed appropriately.


I have neither of these specific lenses, so can't make any sort of comparison, but I do use a my Fujinon 16mm fish-eye on my APSC cameras occasionally with good results.


The difference between a 21mm and a 24mm on a 35mm camera is quite noticeable, so the same will be true between a 14mm and a 16mm on APSC. Only you can really decide an what you want/need, but, if you can, buy second-hand. That way, if you're not happy, you're more likely to recover most if not all of your initial outlay.


If you really want to go "ultra-wide" and don't mind the fish-eye effect, one of the old Peleng (or similar) 8mm (12mm-equivalent) full-circle fisheye lenses can give quite spectacular results for a good price


Good luck

06-06-2019, 01:24 AM   #5
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QuoteOriginally posted by kypfer Quote
You've done your arithmetic incorrectly. On your K-5ii, with it's APSC sensor, the 14mm will be a "21mm-equivalent" and the 16mm will be a "24mm-equivalent", assuming comparison to a full-frame 35mm camera.
Sorry, I wasn't referring to the full frame equivalent focal length. I have read that the fish eye distortion of the zenitar creates a similar field of view to an 11mm or 12mm rectilinear lens.
06-06-2019, 04:56 AM - 1 Like   #6
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If you can find a used Irix 15 within your budget that might be worth considering. There is currently one on Amazon for $400 but I don't know what that translates to in Australian dollars or what shipping would be. I haven't checked ebay. Most reviews on this lens are very good.

Being retired I'm in the same financial situation as you so I can relate. This year I've been trying to slowly assemble a lens kit of primes for my K-1 and it's been very difficult, even though all of them are used.
06-06-2019, 05:17 AM   #7
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QuoteOriginally posted by kman42 Quote
Sorry, I wasn't referring to the full frame equivalent focal length. I have read that the fish eye distortion of the zenitar creates a similar field of view to an 11mm or 12mm rectilinear lens.


Sorry, can't see how that can be ... sounds like a bit of pseudo-science to me!


The horizontal angle-of-view of a 16mm lens is the same whether it's uncorrected (fisheye) or rectilinear (corrected).


As for differences in coverage in the corners of the frame, I don't know. It's possible that a fisheye may "see" more than a corrected lens, but whether you consider one or the other to be "correct" is debatable. The human eye has a relatively limited field of view, so the presentation of a wide-angle 3-dimensional view as a two-dimensional image can only ever be an interpretation. As to how much of the image circle the photographer chooses to use, ie. full-frame 35mm, APSC, m4/3 etc. will depend on how much of the perceive distortion he wishes to portray


If someone wants to loan me a rectilinear 16mm I'll happily do a comparison with my Fujinon. M42 or PK for preference, but I do have a Samsung NX with a range of adaptors that I can use if necessary.


In the meantime ... keep snapping
06-06-2019, 05:33 AM   #8
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I just checked out the Irix lens, the cheapest I could find was $900 from Europe!! The frustrating thing about living in Australia.

I just came across the Pentax 17mm F4 fisheye - it's cheap and is meant to be a great lens. Anybody have experience with it doing astro shots??

06-06-2019, 05:48 AM   #9
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QuoteOriginally posted by kypfer Quote
The horizontal angle-of-view of a 16mm lens is the same whether it's uncorrected (fisheye) or rectilinear (corrected).
Not from what I gather, see for example the da 10-17 (100 deg horizontal at longest fl) compared to da 17-70 (70deg at widest and same 17mm fl)
I admit I only looked at these numbers and didn't do much more research past finding a just one post with formulae on how to calculate the angle of view given focal length and projection (last link), so maybe there's more to it

SMC Pentax-DA 17-70mm F4 AL [IF] SDM Reviews - DA Zoom Lenses - Pentax Lens Reviews & Lens Database
SMC Pentax-DA 10-17mm F3.5-4.5 Fish-Eye ED [IF] Reviews - DA Zoom Lenses - Pentax Lens Reviews & Lens Database
https://photo.stackexchange.com/questions/93682/how-is-focal-length-defined-...fisheye-lenses

---------- Post added 06-06-19 at 08:51 AM ----------

QuoteOriginally posted by kman42 Quote
In Australia, I can get the zenitar for about $250
I don't know Australian prices, but as another option you may be able to find a used but not abused da 10-17 for not much more than that, I recently got that lens and it's a pleasant surprise
06-06-2019, 06:18 AM   #10
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QuoteOriginally posted by kman42 Quote
Sorry, I wasn't referring to the full frame equivalent focal length. I have read that the fish eye distortion of the zenitar creates a similar field of view to an 11mm or 12mm rectilinear lens.
Be aware that if you plan on de-fishing the pictures to "straighten" things out, you will introduce distortion. I'd recommed reading this article for general knowledge of fish eye lenses etc, but these pages address de-fishing specifically:

Rokinon 8mm vs. 10mm vs. Sigma 8-16mm vs. Pentax 10-17mm Ultra-wide Showdown Review - Rectillinear vs "Defishing" | PentaxForums.com Reviews

I have the SMC 17/4, and it is a nice lens. I have not done astro with it, so I can't address that angle, but one of the nice things is you'll be set for full frame if you grab one.
06-06-2019, 08:32 AM   #11
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QuoteOriginally posted by kman42 Quote
I just came across the Pentax 17mm F4 fisheye - it's cheap and is meant to be a great lens. Anybody have experience with it doing astro shots??
I have used it for astro once. It is slow and requires stopping down to atleast f/8 to keep the CA under control. It is really soft wide open as well. However it does give a huge area of the sky. Getting a starfield, some of the brighter larger DSOs, star trails, or time lapse it would seem to work great for those. I'm not sure how well it would work for a milky way shot but I would like to give that a try some time. Expect usable exposure times for 20 to 30 seconds per shot before trailing becomes evident. Do not use a fisheye with astrotracer.

Given all that I like my M42 S-M-C 17mm f/4 fishsye takumar, and really like it on APS-C where the field of view is not so overwhelming. 180 degrees corner to corner was a lot to manage with my Spotmatic.
06-06-2019, 08:55 AM - 1 Like   #12
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QuoteOriginally posted by aaacb Quote
Not from what I gather, see for example the da 10-17 (100 deg horizontal at longest fl) compared to da 17-70 (70deg at widest and same 17mm fl)
I admit I only looked at these numbers and didn't do much more research past finding a just one post with formulae on how to calculate the angle of view given focal length and projection (last link), so maybe there's more to it

SMC Pentax-DA 17-70mm F4 AL [IF] SDM Reviews - DA Zoom Lenses - Pentax Lens Reviews & Lens Database
SMC Pentax-DA 10-17mm F3.5-4.5 Fish-Eye ED [IF] Reviews - DA Zoom Lenses - Pentax Lens Reviews & Lens Database
How is Focal Length defined for 180-degree fisheye lenses? - Photography Stack Exchange


Those numbers are incomplete, the first set quotes angles for 17mm and 70mm, the second set only quotes for 10mm, NOT 17mm ... I'm sure it's an "honest oversight", but very misleading nevertheless! I'd be inclined to dig about on the Pentax website and find the original spec sheets for these lenses.
06-06-2019, 11:48 AM   #13
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There is a Rokinon is the marketplace here in the forums for $200 USD (here Rokinon 14mm 2.8 - PentaxForums.com), dont know the seller btw.

But like I said, don't know how much shipping would be for you or if you'll get hit with any import fees/taxes
06-06-2019, 02:12 PM   #14
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Unfortunately the Pentax 10-17 is also quite expensive here

I don't have any fisheye lenses to personally compare field of view, but all the sample shots I've seen show a 16mm FE to have similar FOV as a 12mm rectilinear lens, and the Pentax 17mm FE to be roughly equivalent to 14.5mm RL.
06-07-2019, 12:00 AM   #15
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QuoteOriginally posted by kman42 Quote
Unfortunately the Pentax 10-17 is also quite expensive here

I don't have any fisheye lenses to personally compare field of view, but all the sample shots I've seen show a 16mm FE to have similar FOV as a 12mm rectilinear lens, and the Pentax 17mm FE to be roughly equivalent to 14.5mm RL.

Unfortunately even the Pentax website is ambiguous with the information it publishes for these two lenses (10-17 & 17-70) so I'm going to withdraw from this discussion.


Without "hard evidence", in the shape of two lenses on the same camera body, the published information on the internet is simply too inaccurate, incomplete or otherwise apparently incorrect to be of any real use!
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