[veezchick]

Based on raving reviews and numerous tech awards, I purchased the Tamron AF 18-250mm F/3.5-6.3 Di-II LD Aspherical (IF) Macro lens as my all-in-one zoom for my K10D (and now K20D) cameras last year. Personally, I think this lens blows. When zoomed in on a subject more than say, 15 or 20 feet away, the contrast and clarity are severely lacking and fringing is absolutely horrible – making my images unsuitable for print – and forget about cropping in tight. The lens seems to be in good working order, just really bad glass - or construction – or both. I mostly shoot urban and general nature photography. I tend to use a low ISO, mount the camera on a sturdy, pro tripod and ball head and I use a shutter release and the mirror lock function to minimize camera shake. I use Cokin filters, including polarizer, when/where necessary. And despite perfect exposure, I get the same dismal results (in regards to contrast and sharpness) at all apertures, in both manual and auto-focus, with and without noise and shake reduction, with and without filters, at low and medium ISOs, with and without the lens hood, and with both JPG and RAW image files. I clean my lenses, filters, etc., thoroughly, too. It’s just consistently lousy – even at fast shutter speeds (so the problem doesn’t seem to be from subject movement). I wanted an ‘everything’ zoom in the 18 to 200-300 mm range that would yield large prints with acceptable sharpness. The Tamron 18-250 is NOT it. The ONLY time I get acceptable results is if I’m within several feet of the subject, but that shooting distance seldom works for me. I didn’t realize I was getting a lens with so many caveats. E.g., must be within “X” amount of feet of subject for acceptable sharpness, or cannot print beyond 4x6” before low contrast, softness and fringing become painfully obvious, etc. On the other hand, images made on the same bodies with my Sigma 105 and Pentax 18-55 are awesome. Nevertheless, it’s bad enough that big, fast glass is not widely available for Pentaxians (especially as full DA/AF), but are we left with crummy telezoom options, too? Geez, I just want acceptably sharp photos from minor distances. Heck, I’d settle for reasonably sharp at this point. Is either too much to ask of a telezoom? This is enough to make a P-shooter consider the availability, dependability and versatility of a Canon system. Sigh. Please tell me what am I missing, here.

[Marc Sabatella]

I'd suggest posting samples so we can see if what you are seeing is typical (although one would think maybe you've already seen samples from others).

But meanwhile, I'll guess one or more of the following:

- your copy of the lens is defective
- you and/or your aren't doing a good job of focusing
- your camera settings are killing contrast
- your standards are *far* too high to ever be satisfied by any superzoom - when people rate it highly, they mean, compared to other superzooms, but not necessarily up to real rigorous pixel-peeping professiona large print standards

Since you say you are happy with the results from your 18-55, I'm leaning against the last of one. Most people find the 18-250 performs at least as well as the 18-55, expcept maybe in terms of vignetting and distorition at the 18mm end.

[atupdate]

This is enough to make a P-shooter consider the availability, dependability and versatility of a Canon system. Sigh. Please tell me what am I missing, here.

[Scratches Head] You are having issues with a non-Pentax lens and you think you should switch systems?[/Scratches Head]

[NaClH2O]

Well, first of all I wouldn't call a 18-250 lens a telezoom, I'd call it a super zoom. Super zooms as a class are considered by many to have a great deal of compromise built into the lens. I don't think there are ANY 18-250 lenses that have excellent IQ thru the full zoom range. If you want to go with two lenses in that range I can recommend the Sigma 17-70 and the Pentax A 70-210mm F4.0 as two excellent lenses that will get you what you are missing.

NaCl(super zooms ain't super)H2O

[Alfisti]

Please post comparable images from the 18-55 and the superzoom.

in my experience the superzoom is sharper but has more severe distortion, slightly more fringing and weaker contrast / colour but all three are really barely noticeable.

[séamuis]

[Scratches Head] You are having issues with a non-Pentax lens and you think you should switch systems?[/Scratches Head]

thats exactly what I was thinking. if you purchased a third party lens for your Pentax, and bypassing pentax's own DA 18-250mm, one can only assume you would do the same for a more expensive canon equivalent. correct? and in doing so you would be dissapointed with your lens, regardless of the body attatched to it. I fail to see your reason for questionning the pentax system. as for the lens itself I cannot comment, as I neither own it or the Pentax equivelent.

[deadwolfbones]

As I understand it, the Tamron is nearly identical to the Pentax (same optical formula, just different coatings and exterior).

[veezchick]

I'll guess one or more of the following:

- your copy of the lens is defective
- you and/or your aren't doing a good job of focusing
- your camera settings are killing contrast
- your standards are *far* too high to ever be satisfied by any superzoom - when people rate it highly, they mean, compared to other superzooms, but not necessarily up to real rigorous pixel-peeping professiona large print standards

Thank you so much for such a prompt, productive and intelligent response!

I've actually wondered if my lens is defective. I bought the warranty. 'Guess I can take that up with the seller and try a another one. I've never had to do this before.

I'd love to find out it's my poor focusing skills. At least that's fixable. I usually use AF Spot, lock, then recompose - or MF (though the focsing ring is uber touchy on this lens so MF is tougher for me on this lens compared to my others).

I've toyed with the settings - scrutinizing image data in post looking for a corralation. Nuthin'.

I fear it might very well be the last - standards far too high - in which case I'm doomed to shell out big bucks for an expensive prime lens and/or switch to a system that has better quality zooms available (just not as much to choose from in a Pentax mount).

I'll try to post some examples for comparison (working right now ... well, at work any way).

Thanks!

[Wheatfield]

You are missing the possibility that you may have a defective lens.
Did you try the Pentax 18-250?
Have you tried a different Tamron 18-250?
Have you considered that perhaps a lens in this range just isn't going to be able to give you what you want and you need a two lens system to get the quality you want?
Also, I don't think you can really depend on the AF being really accurate across the entire focal length range with these things.

[heliphoto]

I've actually wondered if my lens is defective. I bought the warranty. 'Guess I can take that up with the seller and try a another one. I've never had to do this before.
...

I had the Pentax version of that lens and it wasn't that bad (though you still haven't shown us your pictures). It didn't live up two the two zooms that are replacing it's range for me (DA* 16-50 + Tamron 70-200mm f/2.8), but I wouldn't expect it to and it's a quarter the price of those two lenses combined...

I hope that you didn't buy the lens new and buy an extended warranty also since Tamron Lenses come with a six year warranty!...

Show us some samples and we can say more, but my quick guess is a bad copy... Get it fixed and you'll be pretty happy with the lens - I miss mine - so versatile!

[veezchick]

as for the lens itself I cannot comment

But, um ... the lens is the basis of this thread.

I could not find enough reviews on the rebranded Pentax (same lens - just different coatings) or see any award winnings to justify the price difference I found at the time of purchase. As for bypassing Pentax's own DA lens, that's not an issue. My Sigma outshines all the Pentax lenses in my arsenal. Had they had a zoom in the price and focal length ranges I wanted at the time of purchase, things would be different. Regardless, my Tamron is not living up to its hype and awards and my goal is to find out why - and fix it. Thanks.

[Ben_Edict]

Thank you so much for such a prompt, productive and intelligent response!

I've actually wondered if my lens is defective. I bought the warranty. 'Guess I can take that up with the seller and try a another one. I've never had to do this before.

I'd love to find out it's my poor focusing skills. At least that's fixable. I usually use AF Spot, lock, then recompose - or MF (though the focsing ring is uber touchy on this lens so MF is tougher for me on this lens compared to my others).

I've toyed with the settings - scrutinizing image data in post looking for a corralation. Nuthin'.

I fear it might very well be the last - standards far too high - in which case I'm doomed to shell out big bucks for an expensive prime lens and/or switch to a system that has better quality zooms available (just not as much to choose from in a Pentax mount).

I'll try to post some examples for comparison (working right now ... well, at work any way).

As you highly praise your kit lens, I doubt your expectations are too high. The kit lens is very good - compared to other kit lenses, but it is certainly not the ultimate measure.

We haven't seen any example images yet, but a superzoom should be stepped down at least two f-stops, to deliver its best quality. Are you sure, you do that regularily?

Your fears, that you should switch systems, to get better glass are really no necessary. Pentax has several lenses within the range of the Tammy, which will satisfy really high expectations. Unless you want to cover the focal lengthes with several lenses at the same time (in which case Canon might offer more to you, but not all of that offer is really that great), you will easily find premium quality glass in the Pentax portfolio.

If you expect premium results, you need to shell out premium money for all makes - especially if you want the versatility of a zoom lens. If you'ld consider a collection of new and old prime lenses, no other brand will serve you better, than Pentax.

In any way: try to get another copy of that T%amron lens and see, whether it performs better. I have bought the Tamron 18-200 for my partner and the results I see from that lens are very useable and much better than my lowly expectations. If the 18-250 is anywhere near that, it should not be that disappointing.

Ben

[veezchick]

I hope that you didn't buy the lens new and buy an extended warranty also since Tamron Lenses come with a six year warranty!

I'll check my paperwork. I know I didn't double-up - probably confusing extended warranty package with another piece o' gear. Thanks!

Will try to post some sample pics tonight.

[Alfisti]

We haven't seen any example images yet, but a superzoom should be stepped down at least two f-stops, to deliver its best quality. Are you sure, you do that regularily?

Nope bot this one, it's most redeeming feature is that it bites wide open below 100mm.

[veezchick]

Nope bot this one, it's most redeeming feature is that it bites wide open below 100mm.

Um ... I don't know what you mean