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04-16-2014, 10:58 PM   #1
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Erroneous In Depth Review: Sigma 17-70mm F2.8-4 DC Macro HSM

I took delivery today of a brand-new Sigma 17-70mm F2.8-4 DC Macro HSM (Contemporary) and was very pleased with the build and initial optical qualities of the lens. The initial run through on the lens was marred, however, by the discovery that one of the features (a big one), mentioned twice in the PF review seemed to be missing.

Where is the quick-shift/full-time manual focus feature? The review is quite explicit in that manual override of AF is possible full-time as with most Pentax-DA lenses and the feature is called out in the conclusion as a bullet point in the "Pros" section. When I took the lens out of the box, on of the first things I did was to see how the quick-shift implementation worked. Hmmm...seems to be sort of not moving, better check the manual. A few minutes with the instruction sheet provided a paragraph where it explicitly states that one should not attempt manual focus with the lens on the AF setting.

So much for quick shift, eh?

The presence of this feature was a major point in favor of the purchase and I am not happy that it is not there. So, here are a few questions to ponder:
  • Did Sigma change specification after lenses were put out for review, but before they actually went to market (bait and switch)?
  • Why does the review on this site not include an addendum indicating that a change in specification has occurred? This issue was brought up on an earlier thread (https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/238812-sigm...-override.html), so the issue is not new to this site.
  • If indeed Sigma changed specification, how valid is the remainder of the review, specifically the points regarding optical quality? Sigma and other lens makers used to do this sort of thing in the past and it saddens me to see it apparently happening again. Perhaps a big red disclaimer box on page one of the review might be in order.
I am sorry this has upset me, but I am fairly disappointed. I have wanted a reasonably-priced, quality alternative to the Pentax 18-55 kit for quite some time and now am more than a little disappointed.


Steve

04-16-2014, 11:21 PM   #2
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QuoteOriginally posted by stevebrot Quote
I took delivery today of a brand-new Sigma 17-70mm F2.8-4 DC Macro HSM (Contemporary) and was very pleased with the build and initial optical qualities of the lens. The initial run through on the lens was marred, however, by the discovery that one of the features (a big one), mentioned twice in the PF review seemed to be missing.

Where is the quick-shift/full-time manual focus feature? The review is quite explicit in that manual override of AF is possible full-time as with most Pentax-DA lenses and the feature is called out in the conclusion as a bullet point in the "Pros" section. When I took the lens out of the box, on of the first things I did was to see how the quick-shift implementation worked. Hmmm...seems to be sort of not moving, better check the manual. A few minutes with the instruction sheet provided a paragraph where it explicitly states that one should not attempt manual focus with the lens on the AF setting.

So much for quick shift, eh?

The presence of this feature was a major point in favor of the purchase and I am not happy that it is not there. So, here are a few questions to ponder:
  • Did Sigma change specification after lenses were put out for review, but before they actually went to market (bait and switch)?
  • Why does the review on this site not include an addendum indicating that a change in specification has occurred? This issue was brought up on an earlier thread (https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/238812-sigm...-override.html), so the issue is not new to this site.
  • If indeed Sigma changed specification, how valid is the remainder of the review, specifically the points regarding optical quality? Sigma and other lens makers used to do this sort of thing in the past and it saddens me to see it apparently happening again. Perhaps a big red disclaimer box on page one of the review might be in order.
I am sorry this has upset me, but I am fairly disappointed. I have wanted a reasonably-priced, quality alternative to the Pentax 18-55 kit for quite some time and now am more than a little disappointed.


Steve
Thanks for bringing this up- I hadn't seen the later replies to that thread. I'm afraid we can't make changes to the review without testing a 2014 copy hands-on, so it sounds like we're going to make to take a second look at the lens. I'm really curious now, since as unlikely as it may seem, the reviewer may have made a simple mistake (i.e. accidentally left the switch in MF). But somehow I doubt that as it would be quite apparent during field shooting. The copy we reviewed was from the first batch that B&H received in May, 2013, and the complaints were posted in October, so a spec change certainly can't be ruled out. What's interesting though is that replies in that thread suggest that B&H originally states that the lens has full-time override, but after checking the product page here, that information seems to have been pulled.

Long story short: we have to, and will, test the lens again.

Adam
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04-17-2014, 06:15 AM   #3
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Thank you Adam.


Steve
04-17-2014, 09:34 AM   #4
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No mention of it here:

17-70mm F2.8-4 DC Macro (OS)* HSM | C | Sigma Corporation of America

I'll have to check mine when I get home.

The usual ---> * The appearance, specifications, and the like of the product are subject to change for improvement without notice.

04-17-2014, 09:57 AM   #5
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I've seen a similar comment about the DA 50mm f/1.8 prime-- some online reviews that claim that it has quick-shift, when in fact it does not (the Pentax Forums lens database entry for the DA 50 f/1.8 is correct that it lacks QS)

See for example:

Pentax SMC DA 50mm f/1.8 Lens Review
QuoteQuote:
"The Pentax 'Quick Shift' focusing system has been implemented on this lens, which means manual adjustments can be applied once the lens has focused automatically."
Lens Test: Pentax-DA 50mm f/1.8 | Popular Photography
QuoteQuote:
"The Quick Shift feature that permits manual focusing in AF mode worked less elegantly than on other lenses. The turning action was unusually stiff, causing us to suspect that we might be harming the focusing helicals."
(I assume the turning action was stiff because there is NO quick shift!)
04-17-2014, 11:23 AM   #6
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There's no "quick shift" on mine. It wasn't something I was expecting because I missed seeing that feature listed as being there in the review. I suppose if that was the feature that helped make me decide to get that lens over another lens, I would feel differently. Regardless, this needs to be corrected. If Sigma has changed the specification without notice, it's a big one to drop.
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