[MRCDH]

I have a K3 and K10D and the following lenses: Pentax FA 43mm f1.9; Pentax DA 50mm 1.8;Pentax FA 77mm f1.8; Pentax FA 28-200 mm f3.8-22 zoom; Sigma 17-70 f2.8 zoom;Sigma 18-250 zoom; Sigma 50-500 zoom (Bigma). Recently, I was reading reviews on this forum and became quite intrigued about the Sigma 18-35mm f1.8, which is described as a combination of primes from 18 to 35 mm with outstanding sharpness, bokeh, overall value, and its uniqueness in providing f1.8 from 18 through 35mm. The negatives mentioned were some observed problems with autofocus (which can be corrected with micro focus adjustment) and the lens is quite heavy; however the later is basically due to the overall build quality of the lens. I would appreciate some feedback from those who might have a similar grouping of lenses as I do and decided to add the Sigma 18-35 to their collection and what prompted their decision. I have not used the video capability of the K3 to date (but would like to) and I understand that the Sigma 18-35 does an excellent job when used with video. Do my existing lenses go a good to excellent job with the video capability from your experience?

In summary, I have a number of lenses that cover the spectrum from 18-35; however, is the Sigma lens so significantly better that it is worth including it into the mix. My Sigma 17-70 takes very good pictures and gives some addition at the long end,but the Sigma 18-35 will allow more flexibility in low light situations with increased sharpness. Has anyone used some of my lenses for video applications and what were the results? Thanks in advance for any and all comments/feedback on the above.

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Last edited by MRCDH; 01-22-2016 at 04:51 PM. Reason: correction

[silver_dragon]

People on this forum are going to have contrary opinions to mine, some most likely saying something to the tune of "avoid like the plague".

I have the 18-35, mine appears to be a fairly good copy that only has focusing issues from what i can tell at F1.8 only and appears to nail focus virtually every time at any other aperture and distance. For others this might pose a problem but for me it is no drama flicking the camera to live view to take that F1.8 shot.

If you can find a good copy from a store with a quick and easy returns policy, I'd definately recommend this lense.

[Edgar_in_Indy]

If you can find a good copy from a store with a quick and easy returns policy, I'd definately recommend this lense.

Or you could just buy from some hapless person on eBay selling a used copy, and then make them eat the cost of the return if you aren't 100% super duper delighted. Apparently eBay's policy is to force sellers to accept returns, and pay the return shipping, on lenses even when the lens is perfectly good. (But I'm not bitter or anything)

[RainMan]

I also have the 18-35 and from my experience, believe that Sigma should include the "optional" calibration dock as part of the sale. The copy I have required several calibration dock and test iterations to finally produce reliable and repeatable results. My application and use for this range has recently changed, and unfortunately its lack of weather sealing keeps it firmly on the shelf 99.9% of the time, so, it is for sale.

Cheers,

RM-

[interested_observer]

I have a copy. I acquired it knowing about the focus issue. Essentially focusing with the viewfinder is a hit or miss proposition even with the micro-focusing adjustments - your mileage may vary. I acquired mine mainly because of the relatively wide focal length and the f1.8 aperture for astro landscapes. Where I am able to autofocus (and I am usually up on a tripod), I use liveview which is reliable, or manual focusing. So, for me it has performed reasonably.

Last summer I was back in Boston for several weeks. I hauled the lens around to shoot the area in the evenings (with a tripod). It is heavy. The AF issues were ok for me when I used the viewfinder most of the time (and I also took several shots to try to make sure). Also, you really do NOT want to shoot into the sun with it. I like the FA 31Ltd better for the 30mm, and the Contax Zeiss at 28mm. I really have nothing better or faster for the wide end at 18mm.

I see them being sold here on the marketplace used in the ~$500 - $600 range. If you are inclined to acquire it, I would buy used, since the AF issues are probably not going to change between new and used. I also understand that the AF problem is seen across all the mounts - Canon, Nikon as well as Pentax.

Here is a couple of threads that pretty much sums up the lens....

• https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/277499-sigm...es-thread.html
• https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/304670-a...a-18-35mm.html

[Digitalis]

also have the 18-35 and from my experience, believe that Sigma should include the "optional" calibration dock as part of the sale.

I agree with this. But even having the dock will not prevent the lens from the issue of randomly misfocusing.

from 18 to 35 mm with outstanding sharpness, bokeh, overall value,

The lens is very sharp, even at wide apertures but it loses to the Pentax FA31 regarding overall image quality*. Especially in regards to bokeh, which on this lens can be highly variable:


Left: Sigma 18-35mm f/1.8 @ 31mm f/1.8. Right: Pentax FA31mm f/1.8 @ f/1.8 - 100% center crops, both lenses were focused at the 2m mark

Though in all fairness the Sigma 18-35mm f/1.8 does very well at wide apertures at close focus distances:


Pentax K5IIs - Sigma 18-35mm f/1.8 @ 35mm ISO 400 f/1.8 1/250th

Though you would be hard pressed to find a lens in this focal length range that doesn't do well regarding bokeh at close focusing, even a takumar 35mm f/2 would probably do just as well.


As for value, if the dock came free with the lens I'd consider it good value- but at present that isn't the case.

The negatives mentioned were some observed problems with autofocus (which can be corrected with micro focus adjustment)

Micro focus adjustments cannot account for the random misfocusing this lens suffers from. I have subjected my lens to considerable scrutiny regarding AF calibrations and it still is only accurate with AF 79% of the time. YMMV.

* and general reliability with Autofocus.

[Kiwipixter]

The IQ is definitely worth it for me. I am only an average shooter with a K50 who didn't noticed the mis-focused shots until I pixel peeped after reading the threads on this site. Low light, wide apertures f1.8-f2.5 definitely has problems, but I have learned to live with it. My biggest complaint is its weight.

[Digitalis]

My biggest complaint is its weight.

...that which doesn't kill us, makes us stronger..

[jddwoods]

I have a copy. I acquired it knowing about the focus issue. Essentially focusing with the viewfinder is a hit or miss proposition even with the micro-focusing adjustments - your mileage may vary. I acquired mine mainly because of the relatively wide focal length and the f1.8 aperture for astro landscapes. Where I am able to autofocus (and I am usually up on a tripod), I use liveview which is reliable, or manual focusing. So, for me it has performed reasonably.

Last summer I was back in Boston for several weeks. I hauled the lens around to shoot the area in the evenings (with a tripod). It is heavy. The AF issues were ok for me when I used the viewfinder most of the time (and I also took several shots to try to make sure). Also, you really do NOT want to shoot into the sun with it. I like the FA 31Ltd better for the 30mm, and the Contax Zeiss at 28mm. I really have nothing better or faster for the wide end at 18mm.

I see them being sold here on the marketplace used in the ~$500 - $600 range. If you are inclined to acquire it, I would buy used, since the AF issues are probably not going to change between new and used. I also understand that the AF problem is seen across all the mounts - Canon, Nikon as well as Pentax.

Here is a couple of threads that pretty much sums up the lens....

• https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/277499-sigm...es-thread.html
• https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/304670-a...a-18-35mm.html

Two colleagues of mine at work, one with a Canon 70 D and the other with a Canon 7D bought this lens. Both say the autofocus through the viewfinder is virtually unusable. They either focus manually or use live view. Clearly it is not a Pentax only problem. My only reason to consider this lens would be the quiet autofocus, but knowing of this issue for me I will just happily keep the bag of primes it would replace: DA 15, 21 and 40 Limiteds and save the money for something else.

[WPRESTO]

Question: How often realistically do you need f1.8 instead of f2.8? would the Pentax 20~40mm serve better (it's less expensive and substantially smaller/lighter). How about the Sigma 18~50 f2.8 which is also smaller/lighter/cheaper, and can in fact be had second hand at exceptional bargain prices? If you REALLY, REALLY need f1.8 and high IQ, I would go for the Pentax 35mm f1.8, which seems to be about the best lens available in K-mount.

[Digitalis]

I would go for the Pentax 35mm f1.8, which seems to be about the best lens available in K-mount.

Don't you mean the FA31mm f/1.8?

[dadipentak]

I like my Sigma 18-35/1.8 a lot.

[WPRESTO]

Don't you mean the FA31mm f/1.8?

Yes. Slipped in a few extra mm. Excuse on the basis of an aging film shooter who can only think of 28-35-50-55.

[Rupert]

Go over in the K5IIs thread and look at the posts by FS...he has a ton of 18-35 Art shots and they are spectacular.








Of course, you do have to keep in mind that FS is one of those guys that can mount the bottom of a fruit jar and beat 90% of the shooters I know.

Regards!

[MRCDH]

People on this forum are going to have contrary opinions to mine, some most likely saying something to the tune of "avoid like the plague".

I have the 18-35, mine appears to be a fairly good copy that only has focusing issues from what i can tell at F1.8 only and appears to nail focus virtually every time at any other aperture and distance. For others this might pose a problem but for me it is no drama flicking the camera to live view to take that F1.8 shot.

If you can find a good copy from a store with a quick and easy returns policy, I'd definately recommend this lense.

Thank you for your input, the more I reflect on the matter I come to the conclusion that I have some classic primes that should be able to handle what the 18-35 is offering, albeit with somewhat less wide angle capabilities. If they get the autofocus under control I will consider it in the future.

---------- Post added 01-23-16 at 04:39 PM ----------

Or you could just buy from some hapless person on eBay selling a used copy, and then make them eat the cost of the return if you aren't 100% super duper delighted. Apparently eBay's policy is to force sellers to accept returns, and pay the return shipping, on lenses even when the lens is perfectly good. (But I'm not bitter or anything)

Given the autofocus question I will hold off on purchasing for the time being.

---------- Post added 01-23-16 at 04:42 PM ----------

I also have the 18-35 and from my experience, believe that Sigma should include the "optional" calibration dock as part of the sale. The copy I have required several calibration dock and test iterations to finally produce reliable and repeatable results. My application and use for this range has recently changed, and unfortunately its lack of weather sealing keeps it firmly on the shelf 99.9% of the time, so, it is for sale.

Cheers,

RM-

Rainman, currently I feel that I would come to your conclusion if I purchased the 18-35 given the autofocus situation; if the autofocus is resolved sometime in the future it might be worth considering, but I have some excellent primes that should fill the gap for now.

---------- Post added 01-23-16 at 04:44 PM ----------

I have a copy. I acquired it knowing about the focus issue. Essentially focusing with the viewfinder is a hit or miss proposition even with the micro-focusing adjustments - your mileage may vary. I acquired mine mainly because of the relatively wide focal length and the f1.8 aperture for astro landscapes. Where I am able to autofocus (and I am usually up on a tripod), I use liveview which is reliable, or manual focusing. So, for me it has performed reasonably.

Last summer I was back in Boston for several weeks. I hauled the lens around to shoot the area in the evenings (with a tripod). It is heavy. The AF issues were ok for me when I used the viewfinder most of the time (and I also took several shots to try to make sure). Also, you really do NOT want to shoot into the sun with it. I like the FA 31Ltd better for the 30mm, and the Contax Zeiss at 28mm. I really have nothing better or faster for the wide end at 18mm.

I see them being sold here on the marketplace used in the ~$500 - $600 range. If you are inclined to acquire it, I would buy used, since the AF issues are probably not going to change between new and used. I also understand that the AF problem is seen across all the mounts - Canon, Nikon as well as Pentax.

Here is a couple of threads that pretty much sums up the lens....

• https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/277499-sigm...es-thread.html
• https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/304670-a...a-18-35mm.html

Thank you for your input and the threads on the 18-35, for now I willl focus on the lenses that I have and keep my ear to the ground concerning the autofocus problem and its solution.

---------- Post added 01-23-16 at 04:50 PM ----------

I agree with this. But even having the dock will not prevent the lens from the issue of randomly misfocusing.



The lens is very sharp, even at wide apertures but it loses to the Pentax FA31 regarding overall image quality*. Especially in regards to bokeh, which on this lens can be highly variable:


Left: Sigma 18-35mm f/1.8 @ 31mm f/1.8. Right: Pentax FA31mm f/1.8 @ f/1.8 - 100% center crops, both lenses were focused at the 2m mark

Though in all fairness the Sigma 18-35mm f/1.8 does very well at wide apertures at close focus distances:


Pentax K5IIs - Sigma 18-35mm f/1.8 @ 35mm ISO 400 f/1.8 1/250th

Though you would be hard pressed to find a lens in this focal length range that doesn't do well regarding bokeh at close focusing, even a takumar 35mm f/2 would probably do just as well.


As for value, if the dock came free with the lens I'd consider it good value- but at present that isn't the case.


Micro focus adjustments cannot account for the random misfocusing this lens suffers from. I have subjected my lens to considerable scrutiny regarding AF calibrations and it still is only accurate with AF 79% of the time. YMMV.

* and general reliability with Autofocus.

Digitalis, thanks for the input and the dock certainly could aid in the selling of the lens. I am going to suggest to Sigma that they have someone address the questions on this forum for I feel that they are losing a lot of potential customers for this lens which has wonderful possibilities.

---------- Post added 01-23-16 at 04:52 PM ----------

Two colleagues of mine at work, one with a Canon 70 D and the other with a Canon 7D bought this lens. Both say the autofocus through the viewfinder is virtually unusable. They either focus manually or use live view. Clearly it is not a Pentax only problem. My only reason to consider this lens would be the quiet autofocus, but knowing of this issue for me I will just happily keep the bag of primes it would replace: DA 15, 21 and 40 Limiteds and save the money for something else.

I concur with your observation "I will just happily keep the bag of primes it would replace: DA 15, 21 and 40 Limiteds and save the money for something else."

---------- Post added 01-23-16 at 04:57 PM ----------

Wpresto, I have two of the "three amigos" (43, 77); I have held off on the 31 because of some issues I have read concerning this lens. Thanks for your input, your point about how much it would add versus the lenses I already have is a good point.

---------- Post added 01-23-16 at 05:00 PM ----------

I like my Sigma 18-35/1.8 a lot.

Dadipentak, what has your experience been with the 18-35? Didn't you have any autofocus issues?

---------- Post added 01-23-16 at 05:01 PM ----------

Go over in the K5IIs thread and look at the posts by FS...he has a ton of 18-35 Art shots and they are spectacular.








Of course, you do have to keep in mind that FS is one of those guys that can mount the bottom of a fruit jar and beat 90% of the shooters I know.

Regards!

I agree these shots are excellent