[keith.s]

Hi all,

Recently I bought the 16-45 f/4 and have been pretty much disappointed with it. I can almost never get a focus lock below 28mm. Probably it's just a bad copy but I can't return it as shipping costs back to the US doesn't make it worth the hassle. I have been trying to work around this issue by locking focus at the longer end and zooming out to re-compose before taking the shot. However, the pictures taken don't impress. Lots of OOF, few keepers. For panoramas and other shots where time is not an issue, I just manual focus. Overall it's been a very disappointing experience as I can't get the shot I want, when I want it due to the slowness and unpredictability. Yesterday, driving back from the desert, I was tempted to chuck it in the bin with the rest of the garbage from our beach BBQ. The FA 50 f/1.4 however saved the day with some lovely shots, and is one of the reasons why I'm still sticking with my Pentax.

So, coming back to the subject of this post, I'm in dire need of a walkaround lens. Which of the Tammy's above would you recommend (based on optical performance alone). Range-wise I'm more inclined to the 28-75 as I don't intend to dispose off the 16-45. Do any of these two Tammys have variable quality issues? I'm not really interested in playing another lottery.

Cheers,
Keith

[Parallax]

I had a 28-75. The IQ was great but it had serious BF (or FF, can't remember which) problems and apparently this was quite common. That would make me shy away from the 28-75. I would hope that by now, a full year later, Tamron has resolved the issue with current production. Based on IQ alone, I don't think you would see a difference between the two and if you are like most people most of your "walk around" shots will be taken below 50mm so I would opt for the 17-50. FWIW, I now use the Pentax 17-70 and couldn't be happier with the performance and IQ. It is 1 stop slower than the Tamron, but 1 step up on the ISO setting makes up for it and for me the SDM makes the f stop sacrifice worth it.

[keith.s]

Parralax. Thanks. Just read some user reviews on the 28-75 and it's FF/BF problems. Regarding the Pentax 17-70, I had considered it earlier but settled for the 16-45 due to user complaints about soft images above 50 (and also, glowing reviews on the 16-45). I suspect you don't use that (>50) range often, but can you confirm if the IQ is poor above 50? If the 17-70 is good in the <50 region and has no variable quality issues, I might just go for it instead of the Tammy 17-50.

Cheers,
Keith

[Bactman]

I have the 28-75mm and really like it. Have you checked the EXIF data to see what length you shoot most often? That may help - for me, I tend to shoot wider than I anticipated with the 28-75mm. Good luck with your decision.

[Parallax]

Here is a link Pentax SMC DA 17-70mm f/4 AL [IF] SDM - Review / Test Report to Photozone's review of the 17-70. My experience with it is pretty much on par with their review. Notice that at 70mm it is just barely below the "excellent" range. I doubt that many people can see the difference between 1900 and 2100 LW/PH resolution with the naked eye even if they are looking for it. I will say that not every shot I take is a keeper but unfortunately I can't blame any of it on the lens.
If you wan statistics on your shooting habits, try this free program called Exposure Plot vAndel.nl - The Wega2 site

[winglik]

Parralax. Thanks. Just read some user reviews on the 28-75 and it's FF/BF problems. Regarding the Pentax 17-70, I had considered it earlier but settled for the 16-45 due to user complaints about soft images above 50 (and also, glowing reviews on the 16-45). I suspect you don't use that (>50) range often, but can you confirm if the IQ is poor above 50? If the 17-70 is good in the <50 region and has no variable quality issues, I might just go for it instead of the Tammy 17-50.

Cheers,
Keith

I'm going to get a Tamron 28-75mm soon, I'm wondering if any one know which production series has issue with FF/BF? I saw some user review from amazon also had issue with FF/BF with this lens.

[Jewelltrail]

So, coming back to the subject of this post, I'm in dire need of a walkaround lens. Which of the Tammy's above would you recommend (based on optical performance alone). Range-wise I'm more inclined to the 28-75 as I don't intend to dispose off the 16-45. Do any of these two Tammys have variable quality issues? I'm not really interested in playing another lottery.

I bought the 17-50mm last year for my K20 as a walk-around lens. I am very happy with this choice. I bought it from B & H because I knew, if I had any problems, I could return it to them hassel free. I would advise you pick the focal range you want, then buy from a reputable dealer. Both of these lenses are very good performers. I believe bad copies can be found in any make of lens. Best of luck.

[Andi Lo]

My 28-75 have a really light BF problem at 75mm. I recently discovered that BF/FF doesnt always take place in all conditions. While using it at 75mm on the focus chart angled 45 degrees vertically, I get slightly backfocused shots, but none when the chart is angled 45 degrees horizontally.

Problem disappears when I use it in normal conditions though, seems like the lens only backfocused where there is a point to focus slightly below the focus point when the camera is on landscape mode. This might a be a problem for me one day when shooting macro (closeup) but for what I use it for it's negligible.

I've also heard that this lens will slightly BF / FF at either 28 or 75mm by nature of the design. I don't know how much of this is true since Gus / Igligan's copy seems wonderful at all focal lengths (so is mine so far) . My copy is perfect minus this one "defect" at 75mm that I can live with since it doesnt affect RL images. I definitely would recommend buying from a source that you can refund to....

Sorry to hear about your 16-45 though. I'm looking forward to upgrading to that lens one day. The K20D focus adjustment can't save the lens either I suppose?

Serial# A09 502331