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09-08-2015, 10:40 AM   #1
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K-5IIS and Sigma 50-500

I recently purchased a Sigma 50-500 for Pentax K-Mount. I tried it on my Pentax K-5IIS, and it would focus at the lower ranges, but at 400 it was sometimes hesitant, and at 500 most of the time it would not even move. Please know that before I bought it, I noted that it was advertised to be "for Pentax DSLR" and "K Mount". The seller messaged me saying that some camera bodies sensors will not allow enough light into the APS-C sensor for it to focus at 500 mm. Why would it be advertised as for Pentax K-Mount DSLR camera bodies when it does not fully function (not compatible) with a K-5IIS, which is a common Pentax DSLR. I am curious as to if the K-3 or K-3II users have any type of effective function. I have the 150-500 and it functions smoothly all around with my K-5 and K-5IIS. It really surprises me that I am not able to utilize the 50-500 after it being advertised as compatible with Pentax camera K Mount bodies. I was looking forward to it giving me the range at the lower end and still giving me nice IQ and AF at the rest of the range (up to 500), but I guess that is not an alternative.

I would appreciate any relevant opinions.

Thank you.


Last edited by C_Jones; 09-08-2015 at 11:58 AM.
09-08-2015, 10:56 AM   #2
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The only issue I can think of is whether the lens, at 500mm, lets in enough light for the AF to work sufficiently well in all but bright light. But it still should focus. Sounds to me like a broken lens. Where did you buy said lens?

I had an early version of the Bigma, and it certainly focused at 500mm. Not fast enough, but it focused.
09-08-2015, 11:09 AM   #3
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This was in broad daylight. My Sigma 150-500 never had any type of problem on either my K-5 or K-5IIS. It focuses quickly and accurately at all focus lengths. I am in the process of returning the lens at this time, so I am going to be discrete and not mention the seller name at this point, but it is an authorized Sigma dealer, and the person I communicated with said in an e-mail that the lens was not defective, and that the compatibility was due to the camera body. I had expected the lens to perform with the K-Mount.
09-08-2015, 11:15 AM   #4
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C_Jones I also have been using this compo for more than 2 years with excellent results! The 50-500 focuses at 500mm even at low light WITHOUT any problem at all without hunting and quite fast as well!

Your lens has a problem if the body works well with other lenses. I would suggest you to look at the metal K-mount of the lens and whether it attaches firmly to the K-5IIs, as when the lens zooms out and becomes front heavy, if there is a connection problem in combination with wrong supporting of the whole system the lens might looses contact with the body and its functioning dies!

I had a Nikon version of the bigma 50-500 attached to a D7000 that had this issue. Suddently while working fine it went dead but you could see that it had a "long" movement when you were steering the lens against the body (zooming in and out). I took the lens to the Sigma repair shop, they changed the mount with a new one and the problem was fixed! Never happened again and the lens mounted really firmly on the body.

I hope that I've helped you. In no way the Bigma 50-500 has low light transmission issues or other strange diseases! It's a fine and the combination is excellent when used properly!

09-08-2015, 11:56 AM   #5
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Redpit,

I appreciate your input. Everything was mounted/attached properly when I tested. I am glad someone has had success. At first I reacted like you and defined it as a defect as my reason to return it. One of the seller employees e-mailed me and said it was not defective, and that some camera bodies do not have fully functioning AF with it. As I mentioned, I have had success with my 150-500 and expected similar success with the 50-500 while also getting more range. In part of the description of the item it says the following:


"Sigma 50-500mm f/4.5-6.3 DG OS HSM APO Lens - Pentax"

"This 50-500mm lens is designed for use with Pentax DSLR cameras--with an APS-C-sized sensor, the effective zoom range is approximately 75-750mm in 35mm equivalent. Note: The Pentax mount tele converter cannot be used with this lens.

Note: Pentax mounts do not have an aperture ring--some functions may not work depending on the camera model.

Note: It is not possible to use the AF and the built-in OS function of this lens when attaching it to film SLR cameras as well as Pentax *ist series and K100D."


It says the lens is designed for Pentax DSLR cameras with an APS-C size sensor. If I had a similar problem to that of which you had with the D7000, you would think that the seller would possibly know something about this situation or which Pentax cameras would not function with the lens and list them in the description/qualifications of the lens.

Last edited by C_Jones; 09-08-2015 at 12:02 PM.
09-08-2015, 12:17 PM   #6
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QuoteOriginally posted by C_Jones Quote
If I had a similar problem to that of which you had with the D7000, you would think that the seller would possibly know something about this situation or which Pentax cameras would not function with the lens and list them in the description/qualifications of the lens.
My problem with the D7000 was something radom, not a well known and recorded issue. The lens mount was defective (obviously) and had a loose fit with the camera and when turned sometimes the lens-body connection was lost and the lens went dead! If you turned the lens the opposite direction the mount pins were aligned again and the connection-functionality was recovered. There was/is no problem with the D7000 or my K-5IIs I used a few hours ago being using APS-C sensors. In general the lens work as every other K-mount AF lens with the K-5IIs and I know many PF members are still utilizing this combo and produce great pictures.
09-08-2015, 12:40 PM   #7
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My 50-500 focuses well at all focal lengths on the K-5. I've used the combo a few years.

The K-5ii has improved low light AF and should work even better. I think you have a defective lens.
09-08-2015, 12:57 PM   #8
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From what I had read in the forums, I had basically assumed that the 50-500 would have nice IQ, along with accurate/quick focus in reasonable conditions, along the lines of the 150-500, but with more of a zoom range. Like you are saying, I believed the K-5IIS was compatible, and according to you that is correct. As I mentioned, I am in the process of returning this lens, and the seller seems to have a definition of the capability of this lens which I have never heard of, defining it as non-defective even though it does not fully function. I have seen reviews saying that they have had defective products sent to them, which I originally thought was this case.

You and others on the forums actually express the fact that the combination of the K-5IIS and the Sigma 50-500 for Pentax K Mount is functional, and to an obviously effective/satisfying degree. I will just return this lens and avoid disagreement. In the future, if I am still interested, maybe I can confide in another Sigma dealer, clarify to them that I have the K-5IIS, and ask them if the Sigma 50-500 for Pentax K Mount is compatible in all functions. If the dealer recognizes that it is compatible without compromise of function, I may order it.

Thank you for your valuable opinions/information.


Last edited by C_Jones; 09-08-2015 at 01:03 PM.
09-08-2015, 01:09 PM   #9
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QuoteOriginally posted by C_Jones Quote
Thank you for your valuable opinions/information.
You're welcome! It's a nice thing that we and PF have helped you!

I end up with a quick piece of advice. If you can wait for the price to drop or can afford it get the new DFA 150-450! It's a better lens in every aspect (apart from the zoom range and that is a bit heavier).
09-08-2015, 07:34 PM   #10
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I have the Sigma 150-500, and it does very well with my K-5IIS. The thing I was looking for in the 50-500 was the range advantage. The 150-450 seems to be a nice lens from what I have seen in reviews and comments.
09-08-2015, 10:43 PM   #11
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If you look at the staff reviews and the user reviews of the 50-500mm f/4.5-6.3 DG OS HSM APO, you will notice that AF is one of its greatest strengths. Nothing about the 150-500 compared to the 50-500 should make it a quicker focusing lens - speed on the long end is equal. As others have indicated, you most likely have a sub-optimal AF in the 50-500. It would help if you could locate another body, possibly newer to give you more certain confirmation. A newer body would give you a modern, more capable, live view system as yet another confirmation of the issue. Most of the older LV designs struggle closed down beyond f/5.6, so the CDAF test wouldn't be valid on the K-5 series.
09-09-2015, 08:59 AM   #12
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DeadJohn stated:

"My 50-500 focuses well at all focal lengths on the K-5. I've used the combo a few years.

The K-5ii has improved low light AF and should work even better. I think you have a defective lens."

ScooterMaxi Jim,

That would be a good way to test it, but obviously this model of the 50-500 was manufactured during the K-5 - K5IIS series for the K Mount along with the newer K-3 series. I am not saying you are wrong, and the newer K-3 - K3II series would probably be another effective test of the lens credibility, which having the K-5 and K-5IIS I could not do. Actually I only tested it on my K-5IIS. I see what you mean, in that for example a test with the K-3II would show if the latest munufacture of the lens would perform with one of the latest Pentax cameras.

I have initiated my return of the lens (FedEx), and am now contemplating a 16-85 (portrait, group, landscape) to compliment my Sigma 150-500 (birding, wildlife). I have also considered the K-3II, to replace my K-5 (which has AA filter) to maintain detail. I looked at the 18-135, but the 16-85 seems to be a more refined performer. Of course the 135 length may come in handy for some people, but 16 gives a nice wide angle, and up to 85 covers a good amount of range. I know some primes would most likely deliver great images at fixed lengths, but I want some versatility without losing any significant IQ or AF performance.

Thanks for the helpful input, I definitely appreciate it.

Last edited by C_Jones; 09-09-2015 at 09:08 AM.
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