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03-18-2012, 06:31 PM   #1
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Sigma or Tamron for Kr?

Have not been happy with my Pentax 18-135 lens. Most photos are VERY soft except at close up/macro type pictures or extended zoom range
which seems to be the 'opposite' of most reviews I have read of this lens. Plus it doesn't have the reach I need.
So, thinking about the Tamron 28-300 or the Sigma 18-250. Both seem to get good reviews. Suggestions? Considerations?

03-18-2012, 07:04 PM   #2
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The lenses you mention are not better. Either you have a defective copy, or you are making some mistakes using the lens which is preventing you getting sharp photos, or your standards are too high and the lens is fine.

If you could post examples that would help a lot.
03-18-2012, 07:33 PM   #3
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I agree, sounds like a problem with the lens. How does it focus in Live View? Do you get better results (especially with manual focus)?

If not it likely has a problem, and should be sent back or sent in for repair.

If it helps, the focus should be adjusted - typically camera and lens are adjusted to match each other.


If you still need longer reach, I believe the Pentax DA 18-250 (based on the Tamron 18-250) is the better choice. Or you could just add a DA(L) 55-300.
03-18-2012, 09:14 PM - 1 Like   #4
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I remember your other topic about this lens. What conclusions, if any, did you draw from the advice offered in it? I have to wonder, based on a couple things you said in it, if you're just expecting too much from the full size images viewed on a regular monitor. Unless making very large prints, not many people use the full size shots. They scale them down in an editor to a common screen size, which makes them appear much sharper.

In any case, if you're going to get a different lens with more reach, here's another vote for the DA or DA-L 55-300. As far as 300mm zooms go, it's probably the best optically of the lowish priced ones. It should surpass both the Tamron and Sigma 70-300 zooms, anyway.

You will probably not be any happier with the 18-250 or 28-300. The greater the range of these so-called "superzooms", the lower their overall image quality. It's just a limitation of engineering and materials, and physics to some extent. It's a sacrifice some people are willing to make, for the convenience of having a lot of focal lengths available in one lens, but if you're going for sharpness and better IQ, you do not want something with a 10x range. A lens with a 3-4x range of zoom will generally produce better images, and of course a prime lens will generally surpass those.

03-18-2012, 09:48 PM   #5
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QuoteOriginally posted by Philoslothical Quote
I remember your other topic about this lens. What conclusions, if any, did you draw from the advice offered in it? I have to wonder, based on a couple things you said in it, if you're just expecting too much from the full size images viewed on a regular monitor. Unless making very large prints, not many people use the full size shots. They scale them down in an editor to a common screen size, which makes them appear much sharper.

In any case, if you're going to get a different lens with more reach, here's another vote for the DA or DA-L 55-300. As far as 300mm zooms go, it's probably the best optically of the lowish priced ones. It should surpass both the Tamron and Sigma 70-300 zooms, anyway.

You will probably not be any happier with the 18-250 or 28-300. The greater the range of these so-called "superzooms", the lower their overall image quality. It's just a limitation of engineering and materials, and physics to some extent. It's a sacrifice some people are willing to make, for the convenience of having a lot of focal lengths available in one lens, but if you're going for sharpness and better IQ, you do not want something with a 10x range. A lens with a 3-4x range of zoom will generally produce better images, and of course a prime lens will generally surpass those.
I just checked out the thread myself - the photos seemed pretty standard fare for a given kit lens type of zoom. Some of the examples were mis-focused (the small tree in the fore-ground for instance), and for the most part any short comings looked to be from lack of experience with a dslr.

The 28-300mm will be way worse than the 18-135, it is a carry-over from the film era and will likely perform poorly at best on a current dslr. At least the sigma 18-250 is a designed for digital lens, but even it is pretty dated. Perhaps you could try out a 55-300mm (the DA L version can be found under $200 used), which from experience and all accounts is an excellent telephoto lens. It won't be an all-in-one, but when it comes to lenses, the jack of all trades is an ace of none, so to speak. A good standard zoom and a good telephoto will be quite a bit better than a single mega-zoom.
03-18-2012, 09:51 PM   #6
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The photos in that thread don't seem too bad. An upgrade would be a Tamron 17-50 + Pentax DA 55-300. A more significant upgrade would be some primes < 50mm (DA15 + FA35 for instance) plus the DA*50-135mm for over 50mm. That's not cheap though.
03-19-2012, 02:20 AM   #7
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I have a sigma 28-300 and although I didn't expect much from this kind of superzoom I must say that I was disapointed. All photos where both soft and fuzzy (kind of hard to explain it).

Regarding photos you have posted in the other thread, I just have 2 simple questions:

1. Did you use lens hood?
2. Did you use any filter (UV, protective, etc).

The softness comes many times if you have a well lit scene, with rather high dynamic range (shooting towards the source of light), perhaps with some light coming from the side and get diffuzed on a protective filter giving that "hazy" look you seem to have in your photos. So try to take a photo with lens hood, no filter and with your main source of light in the back. Add then filter and compare the result and so on...

Regarding those "superzooms" thus far I have found one that is virtually a stellar performer: Sigma 50-500mm f4-6.3 (nicknamed Bigma). But it is by no means a cheap lens.

On the other hand if you still want to keep your kit to a couple of zooms, you can try tamron or sigma 17-50mm f2.8, tamron 28-70mm or some 17/18-70mm f2.8-4. For longer focal range there is DA 55-300mm, but even a Sigma 70-300mm f4-5.6 APO macro (super of you can find it) is a great lens.

Last edited by stanislav; 03-19-2012 at 07:44 AM. Reason: tippo
03-19-2012, 02:42 AM   #8
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QuoteOriginally posted by New Englander Quote
So, thinking about the Tamron 28-300 or the Sigma 18-250. Both seem to get good reviews. Suggestions? Considerations?
With Tamron you will loose on the wide end (where each mm of focal length can be quite significant). With Sigma you are unlikely to gain any improvements in IQ dept. Also both would have the same QC problem - one sample may be stellar while another only mediocre.

I'd suggest you consider bringing your Pentax zoom for repairs. It may be cheaper and easier than to work towards getting a replacement lens.

03-19-2012, 04:04 AM   #9
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Posting some pics. Some better than others. The close-ups and long ends are better than mid-range.
No hood, no filters. Maybe I am expecting too much, having come from film just a bit over a year ago?
Or perhaps there IS a 'loose screw' behind the lens...
Pic exif's:

Wood/axe: iso 400, 36mm, 1/50 this one isn't too bad actually.
Lake: iso 400, 18mm, f6.3, 1/400. Water is great, trees very soft. Believe I was focusing on trees...
1st sugarhouse: iso 200, 40mm, f7.1, 1/320
2nd sugarhouse: iso 125, 88mm, f8.0, 1/400
3rd sugarhouse: iso 400, 31mm, f7.1, 1/500 yes, overexposed.
Attached Images
         
03-19-2012, 04:13 AM   #10
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One more pic.
To me, this one is VERY soft all around.
iso 200, 36mm, f7.1, 1/60
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03-19-2012, 07:20 AM   #11
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Well, I think you're expecting too much here. The first set to me looks pretty decent. The lake/forest shot is reasonable as well - at the pixel level it is likely lacking detail as the subject is, well, detailed! I've no doubt the first set would look nice printed, and at the sizes you've posted they look reasonably sharp and in focus (the lake one is probably focused on the lake as that is where the higher contrast is with the shimmering water).

The 2nd photo posted looks either out of focus, and/or possibly a little blurred due to shake. Nobody is 100% happy with all of their photos, and photos definitely don't come out technically perfect 100% of the time!

If you're looking for better photos, Stanislav's suggestion to give some shorter range, higher end zooms a go is a good one.
03-19-2012, 12:06 PM   #12
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Studying the images, I think it's not a lens issue. The last photograph that you mention that it's very soft, well, your shutter speed is low and I think what I'm seeing is also not in focus properly. I suggest that you re-exam your lens, place your camera on a sturdy tripod, use lowest ISO, set your image quality to highest, turn off lens calibration, take series of photos using apertures from f/3.5 to f/13.
03-19-2012, 04:08 PM   #13
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Ok, great feed back...thanks! A long as you think it's not a lens issue that calms me down alot.
I will play around with the f-stop and I do iso settings,
Again, thanks. knowing my pics are normal is good.
03-19-2012, 04:15 PM   #14
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im kind of with twitch here..... You can expect a huge compromise all around in IQ from a superzoom. None are great !
Far far better to split into two. Like a 17-50 and 70-200 etc.
03-19-2012, 05:51 PM   #15
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Yup, understand. Would like to get a nice prime as you say for the "low end" but not in my wallet right now.
Thanks for your feedback and sticking with me!
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