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01-18-2021, 04:37 PM   #1
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2x teleconverter use on sigma 70-200 f2.8 zoom pentax k mount

Hi folks, Having had to postpone our 7th African photo safari from 2020 to summer 2021, I'm looking once again at my camera equipment. On this trip, we have a smaller weight limit than normal - 33 lbs per person (flying from camp to camp) - and while we can get by with fewer clothes for a one month trip, I'm concentrating on camera equipment also. I have a Sigma 50-500 bigMa, which I am thinking of leaving home this time, but I just can't decide. The two lenses I am definitely taking are both Sigma - 18-250 f3.5-6.3 and 70-200 f2.8 (EX DG OS HSM). Last trip I used both of these lenses much more than the 50-500 and I was quite happy with the pix. So, instead of toting along the big/heavy 50-500, I was considering a 2x teleconverter for use when I want the extra reach, rather than cropping/re-sizing when I get home. I know the 2x will give me a loss of 2 stops, but that isn't horrible if I use it on the f2.8. Two cameras - both Pentax K3. I wouldn't use the 2x all the time, because I do want to take best advantage of the f2.8 lens, especially in the late afternoon when the light starts to fade. I've seen reviews indicating that the 1.4x gives better quality and you only lose one stop, but it seems hardly worth it if the 1.4 on a 200 lens takes me only to 280 while the 2x takes it up to 400.

I did at one time own a 2x converter, but for some reason it would not work on my K3 (or at that time K5) camera, so I sold it.

Carrying a 2x converter (if I can find one compatible with my K3) instead of carrying the 50-500 this time seems a good idea in the direction of carrying less weight and fewer lenses.

Ideas and thoughts? If I decide to go that route, is there a specific 2x teleconverter I should look for in order to have it work on my K3 cameras?

I am looking forward to your comments and reasons for and against.
Thanks much,
Mary Lippold
Los Angeles

01-18-2021, 05:08 PM   #2
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I don't know of any converter that would reliably focus with the Sigma 70-200 f2.8 (EX DG OS HSM) in PD-AF. So far I have tried the DA 1.4x and the Kenko 1.5x Pz-AF SHQ (with SDM contacts). The lens moves focus, hunts around the focus point but stops anywhere, acquiring focus maybe one in 5 times. I only have the A-Version of the Kenko 2x, but I doubt that the Pz-AF 2x would work any better than the 1.4x. I tried on both the K-1 and KP.

Contrast detection AF (life view) is slow but works.
01-18-2021, 05:13 PM   #3
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QuoteOriginally posted by Mary Lippold Quote
Hi folks, Having had to postpone our 7th African photo safari from 2020 to summer 2021, . . .
I'm so jealous

Judy and I have been to Tanzania twice 2016 and 2019

can I ask where you are going ?

on my first trip I had an old Tamron AF 70-300mm F/4-5.6 LD Tele-Macro [1:2] (Model 772D) with my K 5 II

Read more at: https://www.pentaxforums.com/userreviews/tamron-af-70-300mm-f-4-5-6-ld-tele-...#ixzz6jwswyug5

and on the second trip I had both the K 3 and K 3 II along with the D FA 150-450mm and the 55-300 plm that was very useful when the D FA 150-450 fell apart

perhaps you might look at the HD Pentax-DA 55-300mm F4.5-6.3 ED PLM WR RE

Read more at: https://www.pentaxforums.com/lensreviews/hd-pentax-da-55-300mm-f45-63-ed-plm...#ixzz6jwtaObxo

with or without the 1.4 teleconverter ?

Last edited by aslyfox; 01-18-2021 at 05:35 PM.
01-18-2021, 05:34 PM - 1 Like   #4
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QuoteOriginally posted by Mary Lippold Quote
Hi folks, Having had to postpone our 7th African photo safari from 2020 to summer 2021, I'm looking once again at my camera equipment. On this trip, we have a smaller weight limit than normal - 33 lbs per person (flying from camp to camp) - and while we can get by with fewer clothes for a one month trip, I'm concentrating on camera equipment also. I have a Sigma 50-500 bigMa, which I am thinking of leaving home this time, but I just can't decide. The two lenses I am definitely taking are both Sigma - 18-250 f3.5-6.3 and 70-200 f2.8 (EX DG OS HSM). Last trip I used both of these lenses much more than the 50-500 and I was quite happy with the pix. So, instead of toting along the big/heavy 50-500, I was considering a 2x teleconverter for use when I want the extra reach, rather than cropping/re-sizing when I get home. I know the 2x will give me a loss of 2 stops, but that isn't horrible if I use it on the f2.8. Two cameras - both Pentax K3. I wouldn't use the 2x all the time, because I do want to take best advantage of the f2.8 lens, especially in the late afternoon when the light starts to fade. I've seen reviews indicating that the 1.4x gives better quality and you only lose one stop, but it seems hardly worth it if the 1.4 on a 200 lens takes me only to 280 while the 2x takes it up to 400.

I did at one time own a 2x converter, but for some reason it would not work on my K3 (or at that time K5) camera, so I sold it.

Carrying a 2x converter (if I can find one compatible with my K3) instead of carrying the 50-500 this time seems a good idea in the direction of carrying less weight and fewer lenses.

Ideas and thoughts? If I decide to go that route, is there a specific 2x teleconverter I should look for in order to have it work on my K3 cameras?

I am looking forward to your comments and reasons for and against.
Thanks much,
Mary Lippold
Los Angeles
I have the Sigma 70-200 and the matching Sigma 2x (and the 1.4), Tho I haven't used it that much, perhaps for a couple dozen shots, it's been better than I had expected and hunting hasn't been a noticeable problem.

01-18-2021, 05:44 PM   #5
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QuoteOriginally posted by gatorguy Quote
Sigma 70-200
Which Sigma 70-200? As far as I know, Sigma never released a matching converters for the HSM lenses.
01-18-2021, 05:46 PM   #6
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QuoteOriginally posted by JensE Quote
Which Sigma 70-200? As far as I know, Sigma never released a matching converters for the HSM lenses.
In my signature.

OOPS!. Not specific apparently. It's the 70-200 APO DG and APO 2xEX DG and APO 1.4x DG
01-18-2021, 05:51 PM   #7
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I noticed that, but there are four at least four different Sigma 70-200mm f/2.8 lenses - see Sigma Lenses for Pentax: Legacy Zoom Lenses - Pentax Lens Review Database. The question was about the "EX DG OS HSM" - i.e. the last Pentax version.

01-18-2021, 05:55 PM   #8
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QuoteOriginally posted by JensE Quote
I noticed that, but there are four at least four different Sigma 70-200mm f/2.8 lenses - see Sigma Lenses for Pentax: Legacy Zoom Lenses - Pentax Lens Review Database. The question was about the "EX DG OS HSM" - i.e. the last Pentax version.
To the best of my knowledge both Sigma TC's are compatible with the other versions.

EDIT: Just put the combo on one of my K70's and even shooting dining chairs at the end of a fairly darkened room this evening it's still acquiring focus and not really hunting as such, even if it does take an extra second or two in dim light. I've had other lens/TC combos that insisted on full E2E hunting in even better lighting conditions before settling in.

Last edited by gatorguy; 01-18-2021 at 06:11 PM.
01-18-2021, 06:21 PM   #9
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QuoteOriginally posted by Mary Lippold Quote
The two lenses I am definitely taking are both Sigma - 18-250 f3.5-6.3 and 70-200 f2.8 (EX DG OS HSM). Last trip I used both of these lenses much more than the 50-500 and I was quite happy with the pix. So, instead of toting along the big/heavy 50-500, I was considering a 2x teleconverter for use when I want the extra reach, rather than cropping/re-sizing when I get home. I know the 2x will give me a loss of 2 stops, but that isn't horrible if I use it on the f2.8. Two cameras - both Pentax K3. I wouldn't use the 2x all the time, because I do want to take best advantage of the f2.8 lens, especially in the late afternoon when the light starts to fade. I've seen reviews indicating that the 1.4x gives better quality and you only lose one stop, but it seems hardly worth it if the 1.4 on a 200 lens takes me only to 280 while the 2x takes it up to 400.
Carrying a 2x converter (if I can find one compatible with my K3) instead of carrying the 50-500 this time seems a good idea in the direction of carrying less weight and fewer lenses.

Ideas and thoughts? If I decide to go that route, is there a specific 2x teleconverter I should look for in order to have it work on my K3 cameras?
II see that KEH has a Pentax K-mount Sigma 2xTC at a reasonable price.
Sigma 2X APO EX Teleconverter, for Pentax AF at KEH Camera

Note that the Sigma 2xTC probably won't work with any of your other lenses due to the design tho I think there are a few that members have mentioned.
01-18-2021, 06:25 PM   #10
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QuoteOriginally posted by gatorguy Quote
To the best of my knowledge both Sigma TC's are compatible with the other versions.
Unfortunately not, the TCs don't have the power contacts required for HSM lenses - see Pioneer's reviews in Sigma 1.4x DG EX APO Teleconverter Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database and SIGMA APO 2x EX DG Teleconverter Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database
01-18-2021, 06:36 PM   #11
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QuoteOriginally posted by JensE Quote
Huh

Pioneer is the only one to have mentioned having a problem using it with the HSM as far as I can see. He may be 100% accurate but I'd like to see some additional verification that the latest 70-200's won't work with it.

Looking at my paperwork (who keeps that stuff?) both the Canon and Nikon HSM versions work with at least the 1.4TC so why the Pentax wouldn't seems odd. I did have a 70-200 HSM with an issue for a few days but not any longer so I can't test it.
01-18-2021, 06:38 PM   #12
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QuoteOriginally posted by gatorguy Quote
so why the Pentax wouldn't seems odd
see above. They never released updated Pentax TCs in the HSM age.
01-18-2021, 06:43 PM   #13
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QuoteOriginally posted by JensE Quote
see above. They never released updated Pentax TCs in the HSM age.
Perhaps they had one-size-fits-all-generations paperwork but the box holding my 1.4xDG lists compatibility with all other HSM's, just not specifically mentioning the Pentax one, but for that matter they don't mention the 70-200 EX DG either. I'd be happy to loan mine if you have a lens to confirm it with.

Last edited by gatorguy; 01-18-2021 at 06:51 PM.
01-18-2021, 07:13 PM   #14
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I'd seriously consider the Pentax 55-300 PLM lens (HD Pentax-DA 55-300mm F4.5-6.3 ED PLM WR RE Reviews - DA Zoom Lenses - Pentax Lens Reviews & Lens Database). The performance and focus speed get good reviews here, and the effective aperture will be comparable to your Sigma with the 2X TC added. The ease of use (and probably photo quality) will be better than the Sigma with a TC.

I have a bunch of TCs (1.4x, 1.7x (the Pentax autofocusser), and 2x) and they are generally a PITA to use, and don't get much use here, unless I am setting up for tripod operation. You will be happier with an equivalent lens!!
01-18-2021, 07:33 PM   #15
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Sigma never supplied an HSM compatible TC for pentax, their screw drive TC will mount but you are exclusively MF.
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