[Marc Sabatella]

As I mentioned earlier, I only shoot full manual. If I had been using metering, I may have never noticed the problem.

Shooting manual doesn't mean you aren't using metering, but now that I know that, I guess I'd say, this sounds as likely to be a combination of aperture and T-stop (light transmission). Like the aperture is a fraction of a stop worse than f/2.8 (or better than f/2.8 on the other lens, but that's less likely), plus the light transmission is a fraction of a stop worse, and combined, this might add up to the better part of a full stop.

[jsherman999]

Just fantastic captures, Ed! These expressions and situations are endearing, and you and the lens did very well here.

When I started in this forum, the 28-75 was being talked about all the time, then that recognition died off a bit, came back, and died off again - now maybe it's due for another renaissance!

It is like a bag of f/2.8 primes, and has a very handy FL range on both aps-c and FF. I had to buy one again after selling my copy.

Thanks. The same files are sharper on Flickr & Facebook, this softens somewhat. Shooting a bit wide is necessary for dance. Dress rehearsals are gold because there is no audience to disturb and I can hang off the stage. Buffers fill quick so two bodies, 12-24 on one and 28-75 on the other works well. If I get a second chance, a 50-135 in mid theater works well and when I'm stuck WAY in the back for performances, a 100-300/4 Sigma loose on ball head, wide open. The Jazz company tends to use very low lighting so ISO 3200 and good luck on focus. Manual metering, single point focus, thumb on AF button, index on shutter, left hand on zoom, DNGs with lots of 16 GB cards. And it helps to know the dancers, music and choreography.

[Soap]

What about a comparision against the DA*16-50 on a K-x?
It's a not totally in the same range, but in rendering, sharpness, etc?

[Edgar_in_Indy]

What about a comparision against the DA*16-50 on a K-x?
It's a not totally in the same range, but in rendering, sharpness, etc?

My motivation for starting this thread was to rave how much lens you can get for $300 in the form of the Tamron 28-75mm f/2.8. No matter how good the Pentax 16-50mm may be, it can never claim to be the incredible bargain that the Tamron 28-75mm is, since the Tamron goes for $300 - $350 and the Pentax goes for $800 - $1000.

That being said, I've heard good things about the Pentax 16-50mm, but I'm sure I would go with the new Sigma 17-50mm and save about $200, get a 4-year warrranty (vs 1-year for the Pentax) and avoid any SDM stress or grief. I'm not trying to be controversial since I know there are a lot of 16-50mm fans around here, but that's just my thinking process.

[sajah]

Lovely shots! I have one question, do you often find it not wide enough? I'm thinking to get this lens for when I'm shooting event. But I'm worried I would find it not wide enough too often that I'd change lens anyway and thus defeat my primary intention to use zoom instead of my primes. Thank you.

[Marc Sabatella]

I don't have the 28-75, but one thing I'd observed is that the type of shots that require wide angle tend to not be very time-sensitive in event photography. The 28-75 plus the DA15 seems like it would make a great pair. Mount the 15 for a couple shots of the room while things are at their peak, but the 28-75 would likely cover most else. Yes, I know there are also nice effects from using the 15 close up and still showing a lot of background, so by all means, keep the 15 handy, but I also think that from the perspective of documenting the event, 28mm would normally be wide enough for those shots.

[Jewelltrail]

The only real optical weakness I noticed with the 17-50mm was noticeable vignetting in certain situations. But this is typical for lenses designed for APS-C, as opposed to lenses designed for full-frame (such as the 28-75mm).

Edgar, these are excellent examples of what the 28-75mm can do. I used this lens on my K20d to shoot family portraits in particular. For landscapes, I relied heavily upon my 17-50mm 2.8. I took more than 15,000 shots with the 17-50 before I sold it to help fund my Nikon full-frame kit.

I want to respond to your above quotation because it is inaccurate. The 17-50 is actually superior to the 28-75 in vignette control. However, to show you this, we must translate your apple to orange discussion into and apple to apple discussion. NATURAL vignetting, inherent to all lens designs, is more problematic for wide-angle lenses. The 28-75, on APS-c, is not wide angle. If you want to compare its vignette performance to a 17-50 range, you must do so at equivalent focal ranges. In this case, it is easy to do.

The 17-50 covers almost the identical focal range on APS-c that the 28-75 covers on full-frame. Looking at the Photozone tables for vignetting for each lens my point becomes more obvious. First the 28-75:











Looking at the results, you can clearly see the 17-50 covers a similar focal range (apples to apples) as does the 28-75 with superior vignetting performance. Also, looking at more of the Photozone review for the 28-75, the lens really shows its weaknesses on full-frame. In fact, the 28-75, although designed specifically for FF, is rated higher on APS-c than it is on FF--this is mostly the product of the sweet spot which materializes when mounted on APS-c. However, as a tradeoff, the lens loses its original wide-angle utility.

The discussion can get complicated, since there is more than 1 kind of vignetting--see, for example, this discussion: Vignetting

In conclusion, the 17-50 does not show, as you say, “optical weakness” for vignetting control when compared with the 28-75. In fact, the 17-50, “Apples to Apples,” actually controls vignetting in a manner superior to the 28-75.

Moreover, one would generally expect a lens at 28mm (on the same format and with the same max aperture) to control vignetting better than a lens at 17mm. Of course, this has nothing to do with optical inferiority/superiority; rather, it has everything to do with vignetting (Natural) rearing its ugly head more prominently at wider angles.

[Edgar_in_Indy]

I want to respond to your above quotation because it is inaccurate. The 17-50 is actually superior to the 28-75 in vignette control. However, to show you this, we must translate your apple to orange discussion into and apple to apple discussion.
...
In conclusion, the 17-50 does not show, as you say, “optical weakness” for vignetting control when compared with the 28-75. In fact, the 17-50, “Apples to Apples,” actually controls vignetting in a manner superior to the 28-75.

Jewelltrail,

Thank you for the compliments on my shots. You make a good point about natural vignetting at wider focal lengths, but focal length ranges notwithstanding, I still believe that the 28-75mm is superior to the 17-50mm in this regard.

If you want to do an apples-to-apples comparison, then I think you should take your vignetting data for both lenses from an APS-C camera. It looks like you took your vignetting data from the FF review of the 28-75mm. On a FF sensor the 28-75mm loses much of its magic. If you go to the APS-C version of the review at the following link:

Tamron AF 28-75mm f/2.8 SP XR Di LD Aspherical (IF) (Nikon) - Review / Lab Test Report

You will find the following vignetting data for the 28-75mm:



And here is the 17-50mm data again (also on APS-C, obviously):



If you compare the numbers, you will see that not only does the 28-75mm beat the 17-50mm in vignetting control at similar focal lengths, it trounces it.

This data bears out my non-scientific, real-world observations of much better vignetting control on the 28-75mm. I can tell you that I NEVER feel the need to correct for vignetting on my 28-75mm, but during the short time I had the 17-50mm I saw noticeable vignetting on a lot of my f/2.8 shots. I expect the problem would have been even worse if my 17-50mm actually opened up to a true f/2.8.

[Edgar_in_Indy]

Lovely shots! I have one question, do you often find it not wide enough? I'm thinking to get this lens for when I'm shooting event. But I'm worried I would find it not wide enough too often that I'd change lens anyway and thus defeat my primary intention to use zoom instead of my primes. Thank you.

Marc beat me to it and gave an excellent answer.

When shooting people, I almost never have a problem with the 28-75mm being not-wide-enough. At 6-8 feet from your subject, you can get a full body shot of most children (shooting the camera in portrait orientation, ie vertical). At 10-12 feet you would be able to fit an adult's full-body in the frame. If you're wanting to shoot just the upper body, or the head, then obviously a lot less space is required. And if you have 15-20 feet to work with you can get group pictures (with the camera held horizontally).

When shooting things other than people, however, 28mm can feel a bit narrow. If you're wanting to shoot wide vistas, tight interior spaces, or get a wide view of an area without backing up a lot, then you'll definitely feel limited by the 28mm wide-end.

The 28-75mm paired with the 15mm ltd would be an excellent general-purpose kit. You could carry your camera with the 28-75mm in one of those very compact camera bags, and keep the 15mm in one of the bag pockets, or even in one of your pockets. I'm currently trying to decide between the Sigma 10-20mm or the Pentax 15mm. The Sigma would give me more photographic options, but I would have to carry a larger camera bag to fit a second lens. The 15mm, on the other hand, would fit in the front pocket of my small camera bag.

[sajah]

Thanks Marc and Edgar! Pairing with DA15 seems like a very good plan, didn't think of that but I've thought about pairing with 12-24 that I own. I don't shoot event often so when I do I'm willing to bring bigger bag. I just wasn't sure if the cut / the switch at 28mm is a wise choice, compare to other options such as one of those xx-50mm zooms.

You both quite convinced me that a cut at 28mm shouldn't be much a problem. Well, it's certainly better than a cut at 50mm if I buy xx-50mm and then switch to prime or other 50-xx zoom (which I also don't have) when 50mm just too short.

[Edgar_in_Indy]

You both quite convinced me that a cut at 28mm shouldn't be much a problem. Well, it's certainly better than a cut at 50mm if I buy xx-50mm and then switch to prime or other 50-xx zoom (which I also don't have) when 50mm just too short.

That's kind of what I've been thinking. Since I already have the Sigma 50-150mm f/2.8, I thought about selling my Tamron 28-75mm f/2.8 and replacing it with the new Sigma 17-50mm f/2.8. That way I'd be covered all the way from 17mm to 150mm in two lenses. But that 50mm cut-off has me worried.

I spend so much time between 40 to 75mm, that I think I would be constantly trying to decide between the 17-50mm and 50-150mm, and be changing lenses a lot more than I do now. The 28-75mm, on the other hand, keeps my in my favorite focal range most of the time. When distances are longer, I then switch to the 50-150mm.

[Jewelltrail]

Jewelltrail,

Thank you for the compliments on my shots. You make a good point about natural vignetting at wider focal lengths, but focal length ranges notwithstanding, I still believe that the 28-75mm is superior to the 17-50mm in this regard.

If you want to do an apples-to-apples comparison, then I think you should take your vignetting data for both lenses from an APS-C camera. It looks like you took your vignetting data from the FF review of the 28-75mm. On a FF sensor the 28-75mm loses much of its magic. If you go to the APS-C version of the review at the following link:

Tamron AF 28-75mm f/2.8 SP XR Di LD Aspherical (IF) (Nikon) - Review / Lab Test Report

You will find the following vignetting data for the 28-75mm:



And here is the 17-50mm data again (also on APS-C, obviously):



If you compare the numbers, you will see that not only does the 28-75mm beat the 17-50mm in vignetting control at similar focal lengths, it trounces it.

This data bears out my non-scientific, real-world observations of much better vignetting control on the 28-75mm. I can tell you that I NEVER feel the need to correct for vignetting on my 28-75mm, but during the short time I had the 17-50mm I saw noticeable vignetting on a lot of my f/2.8 shots. I expect the problem would have been even worse if my 17-50mm actually opened up to a true f/2.8.

Edgar:

Did you read my post? I ask because your response sounds as though you did not. The 28-75 was designed for full-frame--the 17-50 was designed for APS-c. When each lens is mounted on its intended sensor, it covers almost exactly the same focal range. If you compare each of the 2 lenses discussed, you will see that the 17-50 does a better job with vignetting on APS-c, than the 28-75 does on full frame.

Did you read the link I provided on vignetting? I do not think so. Obviously, on APS-c mount, a full-frame lens will handle vignetting better than an APS-c lens will, all other things being equal. Even more so when the full-frame lens starts @ 28mm and the APS-c lens starts @ 17mm. This in no way makes the 28-75 superior for handling vignetting; rather, the 28-75 is merely taking advantage of its sweet spot.

Many times before you posted the vignette numbers for the 28-75 on APS-c, I had read them. I always research a lens thoroughly before making the purchase.

Let me repeat my point:

Edgar in Indy: The only real optical weakness I noticed with the 17-50mm was noticeable vignetting in certain situations. But this is typical for lenses designed for APS-C, as opposed to lenses designed for full-frame (such as the 28-75mm).

The vignette control on the 17-50 is good--it is not an "optical weakness" as you describe it. Also, vignette problems are not typical for lenses designed for APS-c; rather, it is much more typical for lenses designed for full-frame--just look @ the Photozone scores for FF vignetting. Also, natural vignetting, which is connected to the famous cos4 law of illumination falloff, is not always a bad thing. It is used by lens makers as a tradeoff when balancing aberration control, or for better contrast & sharpness.

In summary, if you take any full-frame lens, by any manufacturer, and mount it on APS-c, it is expected to handle vignetting better than an APS-c designed lens, particularly if the APS-c lens covers wide angle & the FF lens covers near normal to short telephoto.

For example, if you look at the Nikon Dx 17-55 2.8 (an APS-c designed lens) vignette numbers, and compare them to the 24-70 2.8 (FF designed lens) you will see the 24-70 easily trounces the 17-55. But this is not due to any optical weakness of the 17-55 lens-rather & again, it is due to the sweet spot advantage the 24-70 enjoys on APS-c. Accordingly, if you look at the 24-70mm vignette numbers on FF, you will see they drop significantly, even with the Nikon automatic vignette control in effect.

Your discussion is APS-c centric.

[Edgar_in_Indy]

Did you read my post? I ask because your response sounds as though you did not. The 28-75 was designed for full-frame--the 17-50 was designed for APS-c.

I certainly did read your post. But I still don't think it's an apples-to-apples comparison to compare vignetting of the 28-75mm on FF to the 17-50mm on APS-C, when we're only talking about APS-C cameras.

Since Pentax doesn't even make a full-frame DSLR, I really fail to see the value of comparing the 28-75mm on a theoretical full-frame sensor versus the 17-50mm on an APS-C sensor. Why would that matter to any Pentax DSLR user trying to decide on a lens? Taken as a whole, your post kind of seems to dismiss the vignetting advantage of the 28-75mm. You really should have included the APS-C numbers to paint the full picture.

The original purpose of this thread was to point out what a great value the Tamron 28-75mm f/2.8 is for Pentax DSLR users. It really doesn't concern me whether a lens was originally designed for full-frame or APS-C. All that matters is how it works on my camera. And in regards to the current discussion, the bottom line is that a Pentax DSLR user will experience much less vignetting than with the 17-50mm.

But yes, I admit that everything you said was technically correct.

[Lurch]

As a person who...well, doesn't like kids much - I *really* like your shots here.
There is a certain vibrancy and life to them.
I may have to go source one of these baby's (pun intended)... ebay I assume? (for the lens, not the kid - LOL)