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Old Mar 21, 2010, 10:46 AM   #21
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Well, don't get me wrong, the tamron is still a good lens. But your right, in bright sunlight it does seem to show more of that purple fringing and maybe that's the reason why it seems to be a little softer at maximum zoom. I plan to keep mine because it has the macro feature which will work out for some other uses. For the price you really can't go wrong with that tamron lens.
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Old May 8, 2010, 8:30 AM   #22
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Thanks for all the work on these. From what I've read, and this was years ago in a Keppler article in Modern Photography, the difference between a Sigma, Tamron or other non-camera brand, is that they don't do as many tests on each lens as do the camera companies. This came to light when Minolta was branding a lens as Minolta that was actually made by Tamron. The non-camera companies have a higher tolerance for problems so there is less consistency in their lenses than in the camera companies who supposedly won't sell lenses that don't meet their standards. This rings true based on other threads in this forum that talk about Sigma and Tamron, but especially Sigma, having, say, some 18-200 lenses very sharp and some not so much.
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Old May 8, 2010, 10:02 AM   #23
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Originally Posted by MadMikeSS View Post
The Tamron 70-300mm is definitely a pretty good lens for the price you pay for it. I got mine used from a forum member on a different forum and I really like it. But I do notice that it's a little soft at 300mm. I can say though that I've had issue with FF/BF with 3rd party lenses on my K20D and I've tried many times to adjust for it. My Sigma 24-135mm is the same. Was always sharp with my old *istDL but I had to tweak for FF/BF to get the same results with the K20D. But that being said, I recently bought a Pentax DA 55-300mm lens and so far I can say that it's definitely better than the Tamron at 300mm. I also paid 4x more for the Pentax. But I think I need to do something similar to what was done here and compare the two lenses at 300mm. Nice job with the comparison though.



Madmike I know this post was old but i couldnt find a way to PM you about this as I do not use AIM (memory eater)

but what do u mean by tweaking the K20 FF and BF? Im still relatively new to K20d and dont know about optimizations. How did u tweak the camera to get sharper focusing? this would help alot thanks!
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Old May 8, 2010, 10:25 AM   #24
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Madmike I know this post was old but i couldnt find a way to PM you about this as I do not use AIM (memory eater)

but what do u mean by tweaking the K20 FF and BF? Im still relatively new to K20d and dont know about optimizations. How did u tweak the camera to get sharper focusing? this would help alot thanks!
The K20D has an auto-focus adjustment setting. If you go into the Menu then Custom Settings and go to option #35 AF Adjustment. Set it to On, then you can set how much adjustment you want to apply to either all lenses or just to the current lens. While I never had any problem with my Sigma 24-135mm lens with my old *ist DL, with the K20D I find that I started having a backfocus problem so I've had to set it to +6 with the K20D to be closer to the proper focus. There is a focus test/adjust sheet you can print out that helps you to determine if you have front/back focus and helps you to set that adjustment.

As far as AIM goes, I don't use the actual AIM software, I use a program called pidgin. It's an open source application that handles a few different instant messaging services. I also use a program called Digsby which does the same thing, which I'm running on my netbook that only has 2gb of memory.

Last edited by MadMikeSS; May 8, 2010 at 10:27 AM.
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Old May 8, 2010, 11:04 AM   #25
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Hey Mike,

Off topic but i use pidgin all the time b/c the regular aim program is such a nuisance. Great program!

Thanks for directing me to this link btw from my other thread, i think i'm going to have to seriously consider this because the two lenses are pretty close.
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Old May 10, 2010, 2:31 PM   #26
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Well, here's my quick and dirty with the Tamron 70-300 vs the Pentax 55-300 @ 300mm.

Info beforehand:
K20D
All shot at F8
These are all cropped heavily to peep in close at the spot where I was focusing in on.
EXIF info is included for those who can view it.
Both sets of photos were shot from a tripod with SR turned off.

First couple, look pretty much identical, can't really tell any difference in quality at all here. They both seem to focus the same here.

Tamron 70-300mm @ 300mm F8


Pentax 55-300mm @ 300mm F8


Here's is where you can see the difference the most:

Tamron 70-300mm @ 300mm F8


Pentax 55-300mm @ 300mm F8


In the 2nd set you can definitely see the difference in sharpness at 300mm between the two lenses. Of course, this is nearly pixel peeping so you know... But it at least is a side by side comparison.

The CA is very apparent in the Tamron lens. The second shots the Pentax is defintely sharper.
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