Forgot Password
Pentax Camera Forums Home

Show Printable Version Search this Thread
09-06-2015, 10:00 PM   #1
Site Supporter
Site Supporter
bwDraco's Avatar

Join Date: Jul 2010
Location: New York
Photos: Albums
Posts: 1,061
Lost in translation: New Pentax D FA lenses use anomalous partial dispersion glass

I noticed that between the US and Japanese documentation, there are discrepancies as to the special glass used in the Pentax D FA 150-450mm and D FA* 70-200mm lenses.
  • The US product page states that the D FA 150-450mm lens has 3 ED elements and 1 Super ED element. However, the Pentax Japan product page says the lens has 3 ED elements and one anomalous partial dispersion element.
  • For the D FA* 70-200mm lens, the Pentax Japan product page states that there are 2 ED elements, 2 Super ED elements, and 4 anomalous partial dispersion elements. However, the US press release has an incorrect translation for the underlying Japanese for "anomalous dispersion" as "super-low dispersion". This is not the same as Super ED.
To understand the difference, I will note that dispersion is the breaking up of light into its constituent colors (wavelengths). High dispersion results in chromatic aberration, so low dispersion glass makes it easier to correct to CAs. Super ED glass is a type of glass with extremely low dispersion, more so than ED (extra low dispersion) glass. Anomalous partial dispersion glass have non-linear light dispersion profiles, where dispersion is higher or lower in a limited range of wavelengths than in the rest of the spectrum. Both types of glass can be very expensive, and play a key role in reducing chromatic aberration in today's high-performance lenses.

In other words, Ricoh is using far more exotic glass than you may have expected in the upcoming D FA* 70-200mm lens.


---------- Post added 09-07-15 at 01:05 AM ----------

Even the Pentax DA 18-50mm retractable kit lens uses anomalous partial dispersion glass.

Last edited by bwDraco; 09-06-2015 at 10:26 PM.
09-06-2015, 10:19 PM   #2
Site Supporter
Site Supporter
Digitalis's Avatar

Join Date: Mar 2009
Location: Adelaide.
Posts: 10,116
QuoteOriginally posted by DragonLord Quote
in other words, Ricoh is using far more exotic glass than you may have expected in the upcoming D FA* 70-200mm lens.
Considering that Sigma have been using their ED and FLD glass, Nikkor using high grade ED and ELD, Canon using Fluorite and ED glass in their 70-200mm f2.8 lenses. Pentax shoud do the same to keep up with the competition.
09-06-2015, 10:55 PM   #3
Veteran Member

Join Date: Mar 2013
Photos: Gallery
Posts: 374
I have came across with similar discrepancies too.
May be it comes from the translation Jp-En.
This lens - "1 Super ED element" or "one anomalous partial dispersion element" - is surely made of special dispersion material.

  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
70-200mm, dispersion, elements, fa*, glass, k-mount, lens, lenses, page, pentax, pentax lens, product, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
Lost in Translation Paul Ewins Pentax Medium Format 5 03-03-2015 08:14 AM
Nikon - lost in Translation.... Dirk Non-Pentax Cameras: Canon, Nikon, etc. 2 09-26-2013 08:48 AM
People Bec, lost in translation alan_smithee_photos Post Your Photos! 2 01-30-2011 06:41 AM
Lost in translation Damn Brit Post Your Photos! 8 05-23-2008 01:16 PM
lost in translation Gooshin General Talk 16 03-06-2008 08:15 PM

All times are GMT -7. The time now is 02:45 PM. | See also:, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]