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10-31-2009, 07:23 AM   #1
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Pentax DA 55-300mm vs Tamron 70-300mm at long end (brickwall)

Okay, I got at Pentax DA to replace my Tammy 70-300 as I found there to be a bit much CA on the long end of the Tamron.

I did my first real world test of the Pentax today and most of the shots seemed to be front focused. Can't re-create it in controlled environment ... I guess that's good ..

So, I decided to see how ut did against the old one.

Setup is against a brick wall that's about 15 meters from my bedroom window, set at a nice angle (for the focus test). Cloudy flat light, tripod, remote trigger, 2sec timer (for mirror lockup).

Imported in lightroom 2 - default setting, except sharpen=0.


100% crops from the center of the shot - focus was on the white vertical bar in the center.

260mm f/5.6 - Tamron, then Pentax:




The Tamron seems sharper.

300 f/5.6 - Tamron, then Pentax (at 5.8):




Again, the Tamron seems a bit sharper. Less so then at 260.

300 f/8.0 - Tamron, then Pentax




Pentax seems quite a bit sharper here.

So the Tamron is sharper wide open, but doesn't get much better stopped down at 300. Sunny day, bring the Pentax.


Last edited by tcdk; 10-31-2009 at 07:37 AM. Reason: Add conclusion..
10-31-2009, 07:41 AM   #2
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I'm really interested to see your test results but unfortunately the pictures are not showing for me.
10-31-2009, 12:08 PM   #3
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Sorry - fixed - a refresh should give you images..
10-31-2009, 01:41 PM   #4
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Hmm is it me or does the Tamron look just a little bit better then Pentax in your samples?!

10-31-2009, 01:50 PM   #5
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That's what the OP said already...

If you've noticed a FF issue with the 55-300, you'd do well to rectify the issue first before doing the test, given that even the slightest of focusing errors can cause image softness. Apologies if you did adjust focus for the FF problem...
10-31-2009, 01:57 PM   #6
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the sharpness results agree with the photozone results
10-31-2009, 10:38 PM   #7
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Both lenses look soft in these photos. Something must be off.

QuoteOriginally posted by jake123 Quote
the sharpness results agree with the photozone results
I've done resolution tests twice with my Tamron 70-300 and 55-300 and both times the tests confirmed my opinion; the Pentax is sharper, especially at the long end and especially wide open. There are variations in individual lenses of course, but lots of people think the Photozone results for the 55-300 don't show its capabilities. They even mentioned in the test that the lens was decentered. The test at PopPhoto is much more favourable. "Sharpness and contrast were in the Excellent SQF range at all tested focal lengths" Pentax - Lens Review from Experts at Popular Photography- Photo Tips
10-31-2009, 11:04 PM   #8
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Was this done with AF? They both look softer than they should be given that you were using a tripod.
A better test would be to use MF and three second timer with remote, I don't trust the 2 second timer
I believe there can still be residual vibration from the mirror slap.

10-31-2009, 11:43 PM   #9
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maybe I have a magical copy of the 55-300, but mine appears quite a bit sharper. Likewise, when comparing to the tammy the 55-300 blew it out of the water. Maybe I can find those test shots somewhere....
11-01-2009, 01:06 AM   #10
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the photo results appear too soft for the 55-300, which is very unlikely. are you sure it's the 55-300?
11-01-2009, 01:56 AM   #11
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Ash: I couldn't recreate the FF in tests. I did a chart test from 1m and that was, more or less, spot on. Looking at the brick test, the focused area seems like the sharpest.

Damn Brit: When I look across the photo, the centered area is the sharpest (that's why I selected an angled subject, as this started out as my focus test). But you are right - there may be some residual shake from the mirror slap. What's the 3 sec mirror lockup? I was using a RF602 for remote triggering (I also have an 3rd party IR trigger).

Pentaxor: I've been comparing images in LightRoom where the full lens name is available. Rather sure I haven't mixed them up.

I'll try and see if I can't get a chance to re-do the test - maybe another test, using flash and less distance to lessen the chance of shake having an impact.

Oh, BTW SR was off during the tests...
11-01-2009, 05:33 AM   #12
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QuoteOriginally posted by Damn Brit Quote
Was this done with AF? They both look softer than they should be given that you were using a tripod.
A better test would be to use MF and three second timer with remote, I don't trust the 2 second timer
I believe there can still be residual vibration from the mirror slap.
Why would you think the 3 second timer produces less shake than the two second timer w/MLU?

The 12 second timer and 3 second timer do not include mirror lock up. All timer settings turn off shake reduction.
11-01-2009, 06:44 AM   #13
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Hm, did a bit more testing....

Shooting at 1/180 at my Opteka 85mm , lighted with a flash.

f/5.6 - Pentax then Tamron:




The purple fringing is, as known quite bad on the Tamron, but the Pentax actually has quite a log of bleed...

f/8.0 - Pentax then Tamron:




Both are doing a bit better, but the Tammy only has fringing on the white/black contrasts, and the Pentax is still bleeding on the yellow edges.

Not sure what the conclusion is...
11-01-2009, 09:14 AM   #14
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I don't have the Tamron, but I do have the DA 55-300. I was really disappointed in the one I bought, figured I just didn't like consumer lenses or something. After a while I decided to really see if mine was OK or not - sent it to Pentax repair where it was promptly replaced. The new one is significantly better - much sharper. Maybe your DA is defective?
11-01-2009, 10:50 AM   #15
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QuoteOriginally posted by yeatzee Quote
maybe I have a magical copy of the 55-300, but mine appears quite a bit sharper. Likewise, when comparing to the tammy the 55-300 blew it out of the water. Maybe I can find those test shots somewhere....
Other than slow in the f-stop category, I agree. I tend to not like zooms but optically this one is pretty good.
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