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03-28-2012, 06:40 AM   #16
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I was hoping someone would post the number of elements, front element size, blades etc of all these different designs. I would, but I'm too busy right now. I shouldn't even be reading.

03-28-2012, 06:45 AM   #17
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QuoteOriginally posted by Designosophy Quote
A bit off topic, but speaking of the Tamron 18-250 and the Tamron 18-270, why isn't there a version of the 18-270 in Pentax mount?
Pentax is making their own
03-28-2012, 07:57 AM   #18
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QuoteOriginally posted by lytrytyr Quote
As controversial as the DA 18-135 has become,
it would be nice to be able to blame someone other than Pentax for it!
Why? What's wrong with the DA 18-135?

Seriously, I bought it a few months ago, knowing the controversy and having read all the bad reviews. I'm pretty paranoid when it comes to dust/moist and I just refuse to exchange lenses when conditions aren't 100% ideal. So I needed this WR superzoom for the not so good conditions. Even if the optical performance would be moderate at best.

Turned out that it is not THAT bad at all. It clearly outperformed my DA 16-45, so I sold that one. According to Photozone.de the DA 18-135 is best used as a doorstop, but I definitely don't agree.
03-28-2012, 08:22 AM   #19
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I have a good 18-135, it outperforms my DA L 18-55 and my wife's DA 18-250, but it is not as sharp as my 16-45mm. Copy variability is high in all of these consumer zooms.

03-28-2012, 09:16 AM   #20
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QuoteOriginally posted by Clavius Quote
Why? What's wrong with the DA 18-135?
I said it was "controversial."

Looking at the two preceding posts,
one says the DA 18-135 is "not as sharp as [the] 16-45,"
while the other says it "clearly outperformed [the] DA 16-45."

That's controversy!
03-28-2012, 09:23 AM   #21
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QuoteOriginally posted by lytrytyr Quote
I said it was "controversial."

Looking at the two preceding posts,
one says the DA 18-135 is "not as sharp as [the] 16-45,"
while the other says it "clearly outperformed [the] DA 16-45."

That's controversy!
I love the DA 16-45mm, but it is a bit sloppy mechanically. Mine went out of whack after a couple of years of use. There was nothing obviously wrong with the performance, but I just knew from past experience it was no longer up to scratch. I tested it to confirm before I sent it for warranty repair. Fortunately it came back as good as new.
03-28-2012, 10:55 AM   #22
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QuoteOriginally posted by audiobomber Quote
Copy variability is high in all of these consumer zooms.
I would hope that goes without saying, but there are some consumer lenses that don't seem as "variable" (I'm thinking of the DA 55-300, but there are probably others). Also, the DA*16-50mm isn't exactly a consumer zoom, but it's just as "controversial" when it comes to QC and copy variability.

The whole point isn't that the DA 18-135 is a bad lens, or should be slagged because it's (possibly) a Tokina, but rather that some folks might make a different purchase decision based on who designed and manufactures a lens, despite the label on it. In this case they could stick with a two lens kit, forgo WR, maybe save up for a constant aperture zoom... lots of things! But just looking at labels, I've noticed how the Pentax badged lens is normally considered to be "a safer bet" in the face of these variables. (Heck, some people won't even buy the Samsung rebadges of well-known Pentax glass like the FA 35/2 or DA 10-17! Most common reason I've read: resale value. Then the idea perpetuates itself!)
03-28-2012, 11:18 AM   #23
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OK, I confess, I designed the DA 18-135. Pentax asked me for a design based on my 20 classes of lens design back in the 60's. I threw together a few sketches on a napkin and faxed it off to them. I'm pretty sure it's the one they used.

03-28-2012, 12:05 PM   #24
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QuoteOriginally posted by normhead Quote
OK, I confess, I designed the DA 18-135. Pentax asked me for a design based on my 20 classes of lens design back in the 60's. I threw together a few sketches on a napkin and faxed it off to them.
Damn it Norm, you should have gone with a 67mm filter size instead of 62, to eliminate vignetting.
03-28-2012, 12:09 PM   #25
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QuoteOriginally posted by audiobomber Quote
QuoteOriginally posted by normhead Quote
OK, I confess, I designed the DA 18-135. Pentax asked me for a design based on my 20 classes of lens design back in the 60's. I threw together a few sketches on a napkin and faxed it off to them. I'm pretty sure it's the one they used.
Damn it Norm, you should have gone with a 67mm filter size instead of 62, to eliminate vignetting.
And your 20 classes didn't include logic like "focus ring at the front, zoom ring at the back?" The 60's weren't kind to you... were they?
03-28-2012, 01:21 PM   #26
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QuoteQuote:
And your 20 classes didn't include logic like "focus ring at the front, zoom ring at the back?" The 60's weren't kind to you... were they?
If you remember the 60's you weren't there. My prof in his wisdom never got beyond the optical physics. You have to remember this was a Physics Ph.D asked to design an optics course for a sub-univerity Photography program. He actually spent a lot of his time explaining his passion, road rallying, and the formulas he used to calculate getting back on schedule if they had to stop for a stop sign. No one ever said "hey! Aren't we supposed to be learning about optical physics." So lets see, a theoretical physicist who's hobby is road rallying teaching lens design. I have to say as a result of his prowess I don't confuse convex and concave very often, and I know the difference between reflection and refraction.. wait, I learned that stuff in high school. I must have learned something from the dude... oh ya, if you're in a road rally and you get in an accident, take your rally papers out of the car, if the insurance company finds out you were road rallying your insurance is void. See, it wasn't a total waste of my time.
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