Anyone noticed HD 31 mm lost one element....?

**Henrico** · 05-25-2021, 02:32 AM

Hide & seek...

Attached Images

AfterPentax Mark II · 05-25-2021, 02:51 AM

Maybe that is why it is cheaper than the older version! It is not only missing one element, the extraordinary low-dispersion element has changed to an anomalous dispersion glass one, which if I have it right is cheaper as well. Explains a lot, wonder about the other Ltd's that did become cheaper and got HD coating.

**Digitalis** · 05-25-2021, 03:02 AM

I anticipate the price for the Classic FA31Limited to skyrocket, people already raise prices for the made in Japan versions Vs Assembled in Vietnam ( there's no detectable difference between MIJ and AIV versions).

**aslyfox** · 05-25-2021, 03:05 AM

Originally posted by Digitalis

Expect the price of the Classic FA31Limited to skyrocket...

but would anyone who has one sell it

not me

**Digitalis** · 05-25-2021, 03:10 AM

Originally posted by aslyfox

but would anyone who has one sell it

yeah, I wouldn't part with mine. It has been a solid performer for me.

Paul the Sunman · 05-25-2021, 03:22 AM - **1 Like**

No. Nine elements in 7 groups for both. Look at the official Pentax page.

Sandy Hancock · 05-25-2021, 03:29 AM - **2 Likes**

I suspect that is an error.
Surely leaving out that rear element would create *major* issues. The rest of the optical formula looks the same, so it just doesn't gel.

....but I'll be hanging on to my MIJ silver FA 31/1.8 regardless

**aslyfox** · 05-25-2021, 03:29 AM

so the diagram of the interior glass here is wrong ?

HD Pentax-FA 31mm Limited F1.8 Reviews - FA Prime Lenses - Pentax Lens Reviews & Lens Database

Sandy Hancock · 05-25-2021, 03:34 AM - **1 Like**

I'm not saying *which* one is wrong, but *one* of them probably is....

**aslyfox** · 05-25-2021, 03:39 AM

even if there is the same number of elements, this appears to be a true change:

Originally posted by AfterPentax Mark II

. . . the extraordinary low-dispersion element has changed to an anomalous dispersion glass one, which if I have it right is cheaper as well. . . . .

is that different " language " for the same thing or a true difference ?

I'm keeping my MIJ black FA 31mm Limited regardless

house · 05-25-2021, 03:59 AM - **2 Likes**

I've seen mistakes like that in both Leica and Zeiss marketing.

However the JP site shows the last element so the pf diagram is wrong not the one on the ricoh site.

I thought anomalous dispersion was more expensive and rare than ed glass but what do I know.

slartibartfast01 · 05-25-2021, 04:07 AM

Originally posted by aslyfox

even if there is the same number of elements, this appears to be a true change:

is that different " language " for the same thing or a true difference ?

I'm keeping my MIJ black FA 31mm Limited regardless

This is the spec page for the SMC version on the Ricoh website.
http://www.ricoh-imaging.co.jp/english/products/lens/k/wide/smcpentax-fa31/
The drawing there uses the words anomalous dispersion glass as well.

Andrea K · 05-25-2021, 04:07 AM

Each image has an error: on the left is it wrong the "yellow" label on the right is it wrong the missing element

**Henrico** · 05-25-2021, 04:08 AM - **1 Like**

I picked the diagrams here from Pentax Forums... I suppose the one who made the new diagram had to go home early because of the curfew :-)

The second diagram would never result in sharp images, so this is clearly a mistake. My opinion is that both lenses share exactly the same formula, only the coatings and the layout differ somewhat.

Andrea K · 05-25-2021, 04:18 AM

Originally posted by aslyfox

so the diagram of the interior glass here is wrong ?

HD Pentax-FA 31mm Limited F1.8 Reviews - FA Prime Lenses - Pentax Lens Reviews & Lens Database

yep, PF has to use this for the HD:

and this for the smc:

05-25-2021, 02:32 AM	#1
Henrico Loyal Site Supporter Join Date: Jun 2013 Location: Utrecht Photos: Gallery Posts: 255	Anyone noticed HD 31 mm lost one element....? Hide & seek... Attached Images

05-25-2021, 02:51 AM	#2
AfterPentax Mark II Pentaxian Join Date: Mar 2021 Posts: 1,462	Maybe that is why it is cheaper than the older version! It is not only missing one element, the extraordinary low-dispersion element has changed to an anomalous dispersion glass one, which if I have it right is cheaper as well. Explains a lot, wonder about the other Ltd's that did become cheaper and got HD coating. Last edited by AfterPentax Mark II; 05-25-2021 at 02:54 AM. Reason: added some info

05-25-2021, 03:02 AM	#3
Digitalis Site Supporter Join Date: Mar 2009 Location: Melbourne, Victoria Photos: Gallery Posts: 11,694	I anticipate the price for the Classic FA31Limited to skyrocket, people already raise prices for the made in Japan versions Vs Assembled in Vietnam ( there's no detectable difference between MIJ and AIV versions). Last edited by Digitalis; 05-25-2021 at 03:09 AM.

05-25-2021, 03:29 AM	#8
aslyfox Seeker of Knowledge Join Date: Aug 2016 Location: Topeka, Kansas Photos: Gallery \| Albums Posts: 24,581	so the diagram of the interior glass here is wrong ? HD Pentax-FA 31mm Limited F1.8 Reviews - FA Prime Lenses - Pentax Lens Reviews & Lens Database Last edited by aslyfox; 05-25-2021 at 03:39 AM.

05-25-2021, 03:59 AM - 2 Likes	#11
house Pentaxian Join Date: May 2015 Photos: Albums Posts: 3,306	I've seen mistakes like that in both Leica and Zeiss marketing. However the JP site shows the last element so the pf diagram is wrong not the one on the ricoh site. I thought anomalous dispersion was more expensive and rare than ed glass but what do I know. Last edited by house; 05-25-2021 at 04:05 AM.

05-25-2021, 03:05 AM	#4
aslyfox Seeker of Knowledge Join Date: Aug 2016 Location: Topeka, Kansas Photos: Gallery \| Albums Posts: 24,581	Originally posted by Digitalis Expect the price of the Classic FA31Limited to skyrocket... but would anyone who has one sell it not me

05-25-2021, 03:10 AM	#5
Digitalis Site Supporter Join Date: Mar 2009 Location: Melbourne, Victoria Photos: Gallery Posts: 11,694	Originally posted by aslyfox but would anyone who has one sell it yeah, I wouldn't part with mine. It has been a solid performer for me.

05-25-2021, 03:22 AM - 1 Like	#6
Paul the Sunman Pentaxian Join Date: Aug 2011 Location: Melbourne Photos: Gallery Posts: 4,843	No. Nine elements in 7 groups for both. Look at the official Pentax page.

05-25-2021, 03:29 AM - 2 Likes	#7
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,272	I suspect that is an error. Surely leaving out that rear element would create major issues. The rest of the optical formula looks the same, so it just doesn't gel. ....but I'll be hanging on to my MIJ silver FA 31/1.8 regardless

05-25-2021, 03:34 AM - 1 Like	#9
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,272	I'm not saying which one is wrong, but one of them probably is....

05-25-2021, 03:39 AM	#10
aslyfox Seeker of Knowledge Join Date: Aug 2016 Location: Topeka, Kansas Photos: Gallery \| Albums Posts: 24,581	even if there is the same number of elements, this appears to be a true change: Originally posted by AfterPentax Mark II . . . the extraordinary low-dispersion element has changed to an anomalous dispersion glass one, which if I have it right is cheaper as well. . . . . is that different " language " for the same thing or a true difference ? I'm keeping my MIJ black FA 31mm Limited regardless

05-25-2021, 04:07 AM	#12
slartibartfast01 Pentaxian Join Date: May 2015 Photos: Gallery Posts: 1,931	Originally posted by aslyfox even if there is the same number of elements, this appears to be a true change: is that different " language " for the same thing or a true difference ? I'm keeping my MIJ black FA 31mm Limited regardless This is the spec page for the SMC version on the Ricoh website. http://www.ricoh-imaging.co.jp/english/products/lens/k/wide/smcpentax-fa31/ The drawing there uses the words anomalous dispersion glass as well.

05-25-2021, 04:07 AM	#13
Andrea K Pentaxian Join Date: Mar 2009 Location: Rome, Italy Posts: 822	Each image has an error: on the left is it wrong the "yellow" label on the right is it wrong the missing element

05-25-2021, 04:08 AM - 1 Like	#14
Henrico Loyal Site Supporter Join Date: Jun 2013 Location: Utrecht Photos: Gallery Posts: 255 Original Poster	I picked the diagrams here from Pentax Forums... I suppose the one who made the new diagram had to go home early because of the curfew :-) The second diagram would never result in sharp images, so this is clearly a mistake. My opinion is that both lenses share exactly the same formula, only the coatings and the layout differ somewhat.

05-25-2021, 04:18 AM	#15
Andrea K Pentaxian Join Date: Mar 2009 Location: Rome, Italy Posts: 822	Originally posted by aslyfox so the diagram of the interior glass here is wrong ? HD Pentax-FA 31mm Limited F1.8 Reviews - FA Prime Lenses - Pentax Lens Reviews & Lens Database yep, PF has to use this for the HD: and this for the smc:

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