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Old Mar 18, 2010, 10:06 AM   #11
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Dawg - Ha Ha - luckily noisy or not really doesn't bother me (I don't think I even notice it - I am usually so focused on my subject) ! It's all about the IQ for me !

Mike - Excellent. I hope you don't mind but I downloaded them so I could present them in the same format as the OP. The Pentax really shines in the 2nd photo but strangely (since all the photos are taken at 300mm and f8) the Tamron is (very fractionally) sharper in the 1st photo. Any chance of camera shake from MLU in the 2nd photo with the Tamron?

Pentax on the left and Tamron on the right.
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Old Mar 18, 2010, 10:52 AM   #12
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I used my wireless remote to fire the shutter on all shots so I really doubt camera shake played a part. The tree branch shots it was really hard for me to tell the difference, looking at the bark they both pretty much looked the same, but looking to the right at that rope around the branch and it seemed to me that the pentax lens had a little tiny edge in sharpness. But they are definitely hard to tell apart there. Why it's so much different with the chimney shot I don't know, I could try shooting that one again later and see if there was some user error there.
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Old Mar 18, 2010, 12:54 PM   #13
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Hey guys,
Nice job with the comparison shots. interesting how close they are.
I'm not certain how fair it is though to compare one at 300mm and the other at 280mm, shouldn't it be the same focal length for each?
Mike, on the chimney shot, was the distance to the focal point about the same as it was for the log shot? Could it be the tammy had trouble finding focus? It does seem rather strange they'd be so close on one shot and not the other.
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Old Mar 18, 2010, 1:05 PM   #14
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Thanks GW.

I just took the photos quickly before the light faded and guessed at where 300mm was (the markings only show 200 and then 320). However the Tamron is supposed to be softer at 300 and the Pentax at 280 is well short of it's 320 max so this should have helped the Pentax out-perform the Tamron, yet it still didn't, (but you are still right though)
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Old Mar 18, 2010, 1:19 PM   #15
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Quote:
Originally Posted by Frogfish View Post
Thanks GW.

I just took the photos quickly before the light faded and guessed at where 300mm was (the markings only show 200 and then 320). However the Tamron is supposed to be softer at 300 and the Pentax at 280 is well short of it's 320 max so this should have helped the Pentax out-perform the Tamron, yet it still didn't, (but you are still right though)

Ah, now I understand. thanks.
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Old Mar 18, 2010, 2:14 PM   #16
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An interesting thread. From what I've read the Pentax FA 80-320 is supposed to be very reasonable, but not exceptional. Your comparison shots bear that out - the Tamron is supposed to be really very good, for a long time considered best in it's class. So I would expect it to be sharper than the older Pentax.

What I think is more interesting is Mike's comparison shots between the Tamron and the Pentax DA 55-300. The last time I saw comparison shots between the Tamron and the DA 55-300, what struck me that the lenses appeared to be very close in sharpness, with the DA having better control of CA and purple fringing. Your shots lead me to believe that the DA could be sharper than the Tamron, it all depends on sample variation.
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Old Mar 18, 2010, 6:39 PM   #17
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Well, it's supposed to be a nice day again tomorrow, so I will try and get out and re-take the chimney shots with both lenses several times and see if that shot with the tammy was just an error. But I will say, particularly with the shot of the branches, the tamron definitely has a lot more of the purple fringing. You can really see it. I don't notice it so much with the DA. I noticed the softness at 300 when I went to the airshow last year so I don't think I'm entirely dreaming it with these shots. But who knows, I am not trying to rip on the lens, I still like it. But so far I feel like the 55-300 is superior in quality at the long end. More testing I guess.

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Old Mar 18, 2010, 8:24 PM   #18
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Hi guys,

I could very well be wrong, and I truly appreciate the work done here, but I think that both tests in this thread aren't neccessarily conclusive. To my eye, there are varying amounts of vertical camera shake in just about all of the examples. This usually happens because of mirror slap (which only has a vertical component), and while most apparent in low contrast areas, it also can give the appearance of general softness to high contast borders. The way I look for this is comparing vertical edges to horizontal edges. If you see greater "sharpness" in vertical edges, then mirror slap is the most likely munchkin, and this includes shots taken at relatively fast shutter speeds, though it's usually a lot less visible, if at all. Another possibility is mashing the shutter button. This usually results in a slight rotational "shake", and is harder to see in most images.

I think that the chimney shot illustrates this most easily. Look at the square grating that appears as a relatively thin section across the shaft of the chimney. In the Pentax shot, the grating is clearly square. In the Tamron shot, the vertical wires are more contrasty than the horizontal ones. The vertically elongated look of the holes in the power pole shots also show this. If this was due to lens softness, there would be little or no difference between vertical and horizontal, and the holes would be round and equally soft in both planes.

I won't say the conclusions would be different shot from a tripod with MLU, but I think the differences would probably be somewhat smaller. . .

A handheld test isn't worthless though, by any means. . . it can show you which lens is more capable of giving YOU a higher percentage of keepers handheld, whether it's from weight, balance issues, focusing speed, or ergonomics that just fit YOU better -- it's just not the best way to judge ultimate IQ, IMO.

One way I check out my tele lenses is to shoot a feather at from Minimum Focusing Distance to about 20 feet and at various apertures indoors with a flash. This might sound wierd for a long tele shooter, but I shoot at 300-715mm under 20 ft away at least half the time (and under 40ft @ 75%), and the flash essentially equalizes technique errors, so this is not as unreasonable as it might sound at first. I seem to buy most of my lenses in the winter, so it was a convenience/comfort thing also. . . By doing this, I get a good idea of what the lens/body can do under optimal conditions, which gives me a good baseline to judge whether to blame the gear, or the nut behind the VF for any blown results in the field. Needless to say, the "nut" is mostly to blame. . .

BTW, something that IS pretty noticeable in Mike's test (the log shot) is that the Tamron's bokeh is a bit more "frantic" than the Pentax's, even though the background elements are pretty far away. . .

Scott
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Old Mar 19, 2010, 12:42 PM   #19
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What you said certainly makes sense and I hadn't taken many shots so I could really tell if you were right or not since I didn't have multiple attempts with the same lens to compare against. So I went out today and took 3 shots with each lens of the same target with and without shake reduction turned on. I cropped the best shot from each set and here they are. I have to say that the conclusion isn't any different than before. The tamron is slightly softer than the pentax.

Tamron with SR off:


Pentax with SR off:


Tamron with SR on:


Pentax with SR on:
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Old Mar 21, 2010, 9:36 AM   #20
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Scott - thank you for that post above, I have learnt something I definitely didn't know. Great educational post. Agree about the Bokeh but I actually liked the Tamron's Bokeh today in the macro shots - very soft and smooth.

MM - thanks for all your sterling efforts ! Seems no doubt the Pentax 55-300 is a better lens. I tried out the Tamron yesterday in macro mode (bright sunshine, cherry blossom) and was utterly dismayed at the amount of CA. However today (late in the day, 17.00 and light just fading) and there was no sign of the CA (macro or tele). I had a CP on both days so I'm not sure if that had any effect - I would have expected a positive one under bright conditions.

Think I'll put the P 80-320 and T 70-300 on the market and upgrade to a 55-300 instead !
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