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02-13-2015, 05:38 PM   #136
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What is the difference between AW and WR, or I should ask, what makes AW better than WR?

02-13-2015, 06:09 PM   #137
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QuoteOriginally posted by Newtophotos Quote
What is the difference between AW and WR, or I should ask, what makes AW better than WR?
Well, you'd have to ask the engineers, but AW has always been positioned above WR, which has been described as "simplified" sealing.
02-13-2015, 06:37 PM   #138
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Yes AW is supposedly better than WR. All Weather against Weather Resistant.
02-13-2015, 09:38 PM   #139
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QuoteOriginally posted by Newtophotos Quote
What is the difference between AW and WR, or I should ask, what makes AW better than WR?
There is also a lesser third level that is found in lenses such as the kit lens 18-55 WR as well as the 18-135mm.

02-13-2015, 09:39 PM   #140
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QuoteOriginally posted by thibs Quote
Indeed. Variable aperture I guess.
That was the only thing I could see that would hold it back. It has 3 ed elements in it.
02-13-2015, 11:14 PM   #141
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QuoteOriginally posted by filoxophy Quote
Well, you'd have to ask the engineers, but AW has always been positioned above WR, which has been described as "simplified" sealing.
Also AW has been used (but not put up front) from the release of 16-80 and 50-135.
All DA* (and DFA* it seems) are AW, not simple WR.

---------- Post added 14-02-15 at 07:15 ----------

QuoteOriginally posted by Blue Quote
That was the only thing I could see that would hold it back. It has 3 ed elements in it.
Agreed, can't see anyting else, specially with all those focus buttons etc.
02-14-2015, 01:35 AM - 1 Like   #142
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QuoteOriginally posted by Blue Quote
That was the only thing I could see that would hold it back. It has 3 ed elements in it.
The number of ED* elements alone cannot determine the performance of the lens, it is the grade of ED glass used and how they are employed in the optical design that makes a difference. It appears to me that Pentax is using High grade ED glass as it is expensive and use of exotic glass types is a requisite for apochromatic lens design - but the upshot is with high grade ED glass that you can get away with using less of it to obtain a high degree of optical correction. I will point out that the Sigma 100-300mm f/4 APO EX DG has only four SLD** elements in it and while it is a superb lens, it still suffers from a small amount of chromatic aberration.

*Extra-low Dispersion - was historically made using regular borosilicate glass with thorium dioxide added to it, this glass type was discovered to be potently radioactive and was phased out. Modern ED glass is typically composed of a small percentage of Lanthanum along with other elements such as titanium dioxide added to stabilize the glass structure and improve durability - however with high amounts of lanthanum, even with these additives ED glass can become very soft compared to standard optical grade borosilicate glass.

**Super-Low Dispersion - the differences in chemistry between this and standard ED glass is an increase in the percentage of lanthanum dioxide, along with zirconium dioxide which adds to the expense of production as this glass requires the use of Platinum crucibles in order to make it.

Last edited by Digitalis; 02-14-2015 at 01:51 AM.
02-14-2015, 01:43 AM   #143
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QuoteOriginally posted by Newtophotos Quote
What is the difference between AW and WR, or I should ask, what makes AW better than WR?
Here is a quote from a Pentax "Lenses and Accessories" catalogue dated 13 January 2013:
Water and Dust Protection

Humidity and dirt are the natural enemies of high performance electronics and precision optics. AW lenses provide maximum weather-resistant and dustproof performance preventing the intrusion of drizzle and dust into the lens barrel.
The next category of “all weather” PENTAX lenses is designated as WR or weather-resistant. These affordable lenses utilize a simplified weather-resistant construction, making it more difficult for water to enter the lens and are designed to repel a light splash of water.
Up to now, AW was mainly or entirely reserved for the DA* lenses and the HD DA 560mm F/5.6 ED AW.

02-14-2015, 07:47 AM   #144
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QuoteOriginally posted by Digitalis Quote
The number of ED* elements alone cannot determine the performance of the lens, it is the grade of ED glass used and how they are employed in the optical design that makes a difference. It appears to me that Pentax is using High grade ED glass as it is expensive and use of exotic glass types is a requisite for apochromatic lens design - but the upshot is with high grade ED glass that you can get away with using less of it to obtain a high degree of optical correction. I will point out that the Sigma 100-300mm f/4 APO EX DG has only four SLD** elements in it and while it is a superb lens, it still suffers from a small amount of chromatic aberration.

*Extra-low Dispersion - was historically made using regular borosilicate glass with thorium dioxide added to it, this glass type was discovered to be potently radioactive and was phased out. Modern ED glass is typically composed of a small percentage of Lanthanum along with other elements such as titanium dioxide added to stabilize the glass structure and improve durability - however with high amounts of lanthanum, even with these additives ED glass can become very soft compared to standard optical grade borosilicate glass.

**Super-Low Dispersion - the differences in chemistry between this and standard ED glass is an increase in the percentage of lanthanum dioxide, along with zirconium dioxide which adds to the expense of production as this glass requires the use of Platinum crucibles in order to make it.
You are preaching to the choir Digi. The non-* lens announced is has a higher MSRP than the faster * lens. The 1st Pentax lens to carry a * was the M* 300/4. It nor the A* 300/4 that replaced it seem to have any special glass while the A* 300/2.8 had 2 elements made of Extra-Low Dispersion glass. Best I can tell, there has never been a variable aperture * zoom lens.

Last edited by Blue; 02-14-2015 at 07:55 AM.
02-14-2015, 07:43 PM   #145
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Hey, guys. I know most of us were wondering just how big these lenses would be on a K-3. Well, the other forum has a report from CP+ with both lenses on a K-3. Check it out. They are not small.

Jack
02-14-2015, 07:50 PM - 1 Like   #146
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QuoteOriginally posted by jbinpg Quote
the other forum has a report from CP+ with both lenses on a K-3. Check it out. They are not small.
These D-FA zoom lenses are intended to be high performance full frame lenses, did you really expect them to be small?

Last edited by Digitalis; 02-14-2015 at 10:42 PM.
02-14-2015, 08:00 PM   #147
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QuoteOriginally posted by jbinpg Quote
Hey, guys. I know most of us were wondering just how big these lenses would be on a K-3. Well, the other forum has a report from CP+ with both lenses on a K-3. Check it out. They are not small.

Jack
As Digitalis said, these are some serious zooms and the 70-200 is f2.8 on top of that which is considered fast, especially for a zoom.
02-14-2015, 08:08 PM   #148
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Having handled these lenses briefly, they are truly massive and very well built. DPR just posted some pictures and impressions from CP+.

CP+ 2015: Ricoh gets serious with new Pentax full-frame zooms: Digital Photography Review

When you get your hands on one of these, you'll wonder whether to mount it to a camera or dock it to a space station.
02-14-2015, 11:33 PM   #149
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QuoteOriginally posted by JPT Quote
When you get your hands on one of these, you'll wonder whether to mount it to a camera or dock it to a space station.
If they perform well, and are built tough for many years of reliable use, few will be-grudge them their weight or size.
02-15-2015, 01:00 AM   #150
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QuoteOriginally posted by Blue Quote
The 1st Pentax lens to carry a * was the M* 300/4. It nor the A* 300/4 that replaced it seem to have any special glass
Actually I'm 99% sure those two lenses have ED glass in them. As a proof I have copies of the original Dutch Pentax price lists from that era listing them as SMC Pentax-M* and A* 300mm F4 ED!
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