[PentaxPoke]

Some have read that I finally got a good copy of a DA*16-50. I thought I would test my observation that the DA* is not as sharp across the field of view as the Tamron 17-50. (This is consistent with the Photozone observation.) Here is the setup:

Tamron 17-50 at f2.8
Pentax DA*16-50 at f/5.6

I will be showing both center crops, as well as crops near to the right hand side (not the edge) of the field of view. The lens at f5.6 should have a strong advantage right????

Tamron is shown first, then the DA* Center crops. Note both are about the same sharpness, with possibly the DA* a bit better.




Now for the crops closer to the edge (Tamron first)



So both are about the same in the center, but the Tamron is better at the edge. Remember, the Tamron was at f2.8, and the DA* was at f5.6! This is consistent in all my tests.

Comments?

[maxwell1295]

No contest, but are you 100% sure that you have a good copy of the 16-50? That 5.6 edge crop is pretty bad....

[nulla]

I agree with above... you may have a poor DA 18-50 copy.

The examples above show that even the tree on the right of the crop is out of focus... and take a look at the brickwork top level middle and right hand side of the crop



Neil

[PentaxPoke]

Believe it or not, this is my third DA*16-50 copy, and it is by FAR better than the other two that I had. The first one was decentered. The second one was so bad that all around the edge of the field of view, you would see double. littlelaker said it made him "dizzy." This lens is much better than my other two.

The results seem consistent with the Tamron vs. Tokina info on the Photozone site. I'd like to get some more opinions here, but I am thinking that I might just send this lens back to B&H and get a credit I can use on other gear. Having a sealed lens that focuses a bit quieter is not worth the loss in IQ I think.

[davebris33]

its a bit messy, but the colour is far better in the pentax, contrast too. the tamron renders the sky cyan, which is pretty bad (imho)

dave

[PentaxPoke]

its a bit messy, but the colour is far better in the pentax, contrast too. the tamron renders the sky cyan, which is pretty bad (imho)

dave

I don't think that is a fair comparison. The pictures were taken on two different days at two different times, with two different cloud covers, in two different seasons, under two very different lighting conditions. What I am focusing on is the relative sharpness between center and edge.

Believe me, I want the DA* to win! There is a big difference in the price I paid!

[sinus007]

Hi,
With all due respect, I'm a bit sceptical about this test:
a)the shots with Pentax and Tamron were made at different times = different lighting, different position & focus
b) photozone states: Please note that the tests results are not comparable across the different systems! and they tested the tamron w/Sony Alpha
Just my $0.02
Regardless, I'm interested in more opinions of the Tamron. Thanks for yours.

[PentaxPoke]

Hi,
With all due respect, I'm a bit sceptical about this test:
a)the shots with Pentax and Tamron were made at different times = different lighting, different position & focus
b) photozone states: Please note that the tests results are not comparable across the different systems! and they tested the tamron w/Sony Alpha
Just my $0.02
Regardless, I'm interested in more opinions of the Tamron. Thanks for yours.

With regards to this test and sharpness across the field of view, none of that matters. I am talking about relative sharpness from the center, across the field of view.

Look, its very simple: Both the Tamron and DA* lenses are sharp in the center crops, so there is no issue regarding focus. The difference is that the DA* lens is very soft towards the edges. The DA* had the added advantage of being stopped down 2 stops from wide open. Also, the crops are not taken at the extreme edges at the field of view, so the softness starts away from the extreme edge. I don't feel like wasting bandwidth with scores and scores of shots that show the same thing. I posted one example that was convenient and typical, but I have more.

[Imagination4]

Hi,
With all due respect, I'm a bit sceptical about this test:
b) photozone states: Please note that the tests results are not comparable across the different systems! and they tested the tamron w/Sony Alpha

Actually, Photozone has both the Tokina's DA* cousin and the Tamron tested under Nikon - so both were tested on the same system. Taking both center and border into consideration, the Tamron bettered the Tokina at the wide end 16mm/17mm; and pretty much across the f.l. at f/2.8. The Tokina faired much better against the Tamron at mid- to longer f.l. and slower speeds.

I'm pretty much in the same boat, as my third DA* 16-50mm (while vastly better than the first 2 that I've tried) is still softer through a significant portion of the right side of the frame. And according to the Tokina vs. Tamron tests, it is highly unlikely that the Tokina/Pentax is going to match the Tamron across the FOV. Although the center is excellent, for an expensive lens that I'm looking to capture wide expanses with - I'm not sure that it is up to the task and it is a steep incremental cost for the weatherproof benefit.

[PentaxPoke]

Imagination,
Have you decided what you are going to do yet? I am just about to look for $700 worth of gear at B&H...

[Imagination4]

Imagination,
Have you decided what you are going to do yet? I am just about to look for $700 worth of gear at B&H...

Well, I just picked up my third one a couple of days ago and still have about 12 days to decide whether to keep it or not. I already have some photos (trees and such) with the latest DA* that exhibit the softness on the right side - and I'm just taking about how a non-cropped image looks like when viewed at 600x900 (not pixel peeping). As for now, I'm planning on going out Friday and/or Saturday with it, see how the results are at various distances, and then likely decide by next week Monday whether to keep it or get a refund.

[Imagination4]

I will have to say that I am impressed with the off axis IQ of the Tamron 17-50mm f/2.8 lens that you have. Maybe I'll have to consider one of those to join the 90mm f/2.8 macro in the bag.

OTOH, the Tokina 16-50mm f/2.8 (on Nikon) actually tested better than the Canon 16-35mm L lens at 16mm, 24mm, and 35mm f.l. at f/2.8. So while the Pentax/Tokina may not be as good wide open as the Tamron 17-50mm f/2.8, it is not out of place either for its stature in the line-up. The Tamron 17-50 (Canon) bested the Canon 16-35 L lens at f/2.8 as well.

[Ex Finn.]

I think this is as good as the DA*16-50 gets?

No way!. Can not be! Not this bad, 3 times a round!.(yes, that does look way bad).
I am using a 16-50, about 3 weeks old from B&H, takes my breath away with it`s sharpness and color rendering. I would put it right in with 12-24 and 50 1:1.7 in the
" output is pleasing to the eye" gategory.
Just my opinion, don`t have to agree with it.

Cheers Mike.

[Canada_Rockies]

I think this is as good as the DA*16-50 gets?

No way!. Can not be! Not this bad, 3 times a round!.(yes, that does look way bad).
I am using a 16-50, about 3 weeks old from B&H, takes my breath away with it`s sharpness and color rendering. I would put it right in with 12-24 and 50 1:1.7 in the
" output is pleasing to the eye" gategory.
Just my opinion, don`t have to agree with it.

Cheers Mike.

My opinion agrees with yours!

[jamesm007]

The reason for this is given in the review-
"Many dedicated APS-C lenses suffer from performance problems towards the corners of the image field but, surprisingly, the Tamron AF 17-50mm f/2.8 SP XR is one of the few lenses that which are capable to break this trend."

So overall MTF looks to be close and maybe favor the Tamron, although the Pentax does start at 16mm, and a good copy behaves as most lens do. For example my Sigma 17-70mm at 17mm f2.8 has this problem of if your close to something flat the optimum focus point for the center may not be true for the corners, you have to find a happy middle or stop it down to say f5.6 it because of field curvature in wide angle lens. This is why the Pentax 16-45mm is well regarded it also has low field curvature at 16mm another quote from Photozone-

"A welcome aspect of the DA 16-45mm is its very flat focus field (low field curvature). As a result extreme borders have a lesser (later) tendency to loose focus compared to other standard zoom lenses."

So at f5.6 the Pentax 16-45mm has just slightly better performance than the Tamron, and it may be another lens to look at. I am kinda of sorry I did not get this lens and might get it while they are going down in price and before its hard to get them. The lens starts wide 16mm and has good performance at 16mm. I have not read of to many complaints on that lens.
Just my 2cents worth.