Pentax DA 18-250 f3.5-6.3 ED AL IF


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creampuff

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Dover
#2
Can't see the link on the Pentax page. Got pulled out.
 

creampuff

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http://www.dpreview.com/news/0710/07100103pentax18250.asp

Sorry, pardon my ignorant, under minimum aperture - f22-f45.

Got f45 one meh?
Yes, nothing unusual about f45. The lens is a variable aperture zoom, meaning that as the lens is zoomed to the longer focal lengths, the effective aperture becomes smaller as less light passes through due to the extension of the lens barrel. It is the same for a lot of lenses today.
 

fengwei

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Lens Specifications:


* Lens mount: PENTAX KAF mount
* Lens construction:········· 16 elements in 13 groups
* Angle of view: 76° ~6.5° (when mounted on a PENTAX digital SLR camera body)
* Number of diaphragm blades: 7
* Minimum aperture: F22 ~ F45
* Minimum focusing distance: 0.45m (1.48ft)
* Filter size: 62mm
* Maximum magnification: 0.28X
* Dimensions & weight:
75mm (maximum diameter) x 85.5mm (length)
(3.0 inch x 3.4 inch);
16.0 oz (455g) (without lens hood)

That's a great focal range for someone who doesn't wanna change lenses all the time, great for travel too. But probably abit too slow on the tele side ...

Good news: The lens will ship in October for US $499.95. That's pretty fast for a Pentax standard :bsmilie:
 

creampuff

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16 elements and only 455g! Let's hope this time round it's better than the previous Pentax SMC-FA 28-200/3.8-5.6 superzoom (a Tamron disguised as a Pentax). :think:
 

dnaxe

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does anyone know if it will have quickshift?
 

fengwei

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does anyone know if it will have quickshift?
From the Features list by Pentax, unfortunately NO :confused:

http://www.pentaximaging.com/produc...reqID--10270902/subsection--Digital_35mm_zoom

* 14x zoom range of 18-250mm makes this the ideal all-around lens
* ED element and two aspherical elements compensate for chromatic and spherical aberration
* Focal length equivalent to 27.5mm to 383mm in the 35mm format
* Lens focuses as close as 18 inches throughout the entire zoom range
* Internal focus mechanism prevents the front lens element and lens barrels from moving during focusing

All the other DA lenses have the QS featured in:
# Responsive “Quick-Shift Focus System” allows instant shift from AF to MF

Guess this time Pentax doesn't even bother doing too much of modification on the Tamron one, that's probably why it's coming out so soon :)

But looking at the lens photo, the MF ring travel range is probably less than 30 degree, very hard to MF anyway:


For a comparison, here is the Tamron one:


And the Sony one:
 

Equatorer

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an attractive lens for travellers..
by comparing tamron18-250 with 18-55 and 50-200 on photozone, the mtf of 18-250 is even superior-looking than two kits...
 

fengwei

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an attractive lens for travellers..
by comparing tamron18-250 with 18-55 and 50-200 on photozone, the mtf of 18-250 is even superior-looking than two kits...
One thing about these mega zoom lenses is that they only reach their declared focal lengthes when focused at infinity. Their actual focal length for a close subject can be alot shorter (and then less magnification) than what the lenses (and EXIF) say.

Here is a comparison between DA50200 and Tamron 18250 done by someone at DPR:


Original thread here:
http://forums.dpreview.com/forums/read.asp?forum=1036&message=24903714

That's why I'd say the DA50-200 still has its niche even after the 18250 released :)

As to the kit lens, there is no cheaper wide angle lens than the kit lens, and it's alot lighter and easier to carry around.
 

Equatorer

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#12
really first heard of this....
does that mean the 250 is even shorter than 200 in terms of viewing angle..
 

fengwei

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really first heard of this....
does that mean the 250 is even shorter than 200 in terms of viewing angle..
Yes, if you compare with a non-mega zoom lens or a prime lens when focused at close subjects :) And I'm sure the subject would look bigger with the DA50-200 @ 200mm than the Tamron 18-250 @250mm if the subject is located at 1.1m to 2m distance.
 

istDeS

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#14
Looks like a nice lens for general use. Find it a bit slow at the tele end but it's a super zoom lens.:D
 

airconvent

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#15
mmm...based on the price, the pentax is almost the same price as the Tamron.
I would go for the Pentax if its here at around the same price. The pentax looks nicer!
However, while they both look alike, the Tamron is slightly lighter (430 g against 455g ).
I wonder when it will reach Singapore (if ever?).

I am assuming its performance would be similar to the Tamron, so same reviews should apply.
In many magazines, I see mixed reviews. Some have given it good marks for best balance of features while another seem to say that the Sigma 18-200 is much better than the 18-250 especially CA (which was absent on the Sigma but obvious on the Tamron).:think:
 

dnaxe

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In many magazines, I see mixed reviews. Some have given it good marks for best balance of features while another seem to say that the Sigma 18-200 is much better than the 18-250 especially CA (which was absent on the Sigma but obvious on the Tamron).:think:
sample variation.
 

dnaxe

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#18
so in the end, in absolute design terms, we will never know which is actually better? :rolleyes:
Well, I think that if you pick a random 18-250 and a random sigma 18-200, the 18-250 is likelt to win.
 

creampuff

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#19
Yes, if you compare with a non-mega zoom lens or a prime lens when focused at close subjects :) And I'm sure the subject would look bigger with the DA50-200 @ 200mm than the Tamron 18-250 @250mm if the subject is located at 1.1m to 2m distance.
This is one little fact that lens makers nowadays don't actually reveal. They can state the magnification ratio on paper but the reality is that the actual images reveal quite a big difference in magnification when at the minimum focusing distance. One of the pitfalls of just looking at specifications alone.

This consumer grade lens isn't getting me excited or interested one bit. Pass. :)
 

fengwei

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#20
This consumer grade lens isn't getting me excited or interested one bit. Pass. :)
Well, I'm a consumer, and this consumer grade lens might interesting me when it surfaces ;) A very good travel lens (plus one or two prime lenses, instead of two zooms).
 

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