Pentax lenses - Resolution performance at various apertures

mole · 12-24-2015, 02:59 PM

Thanks so much for taking the time to create the database, and thanks for sharing this very useful information!

**Kerrowdown** · 12-24-2015, 03:11 PM

Originally posted by pathdoc

I know there are charts for much older lenses (M, A, even K)

Really... is it possible you could point me in the right direction for those, well at least the A series, as I can't honestly I've seen the lowdown on my Ladies.

**hjoseph7** · 12-24-2015, 03:13 PM

This is very useful since I often don't know what the optimal resolution is for a lens and have to guess. I'll have to create a list for the lenses I have. thanks

averagehitman · 12-24-2015, 03:52 PM

Thanks for the information. I can now use "aperture versatility" as another factor on what lenses to buy.

bertwert · 12-25-2015, 08:16 AM

Originally posted by BigMackCam

I also took the plunge and registered a Google account so I believe this gives me the capability to to store it online and allow access to it.

Yes it does.
You can have it publically viewable and then link it in this thread.

**beachgardener** · 12-26-2015, 04:37 PM

Thanks for that mate, excellent stuff, cheers. I can see it expanding into a wonderful resource for information on many lens sweet spots

SpecialK · 09-15-2016, 06:36 PM

I only found this chart today and linked it into a current resolution thread. Thanks for the work, though I own no Pentax.

**BigMackCam** · 09-16-2016, 12:16 AM

You're welcome. I've been meaning to expand on it, and I will get round to it eventually!

ANGUS YOUNG · 09-23-2016, 02:56 AM

Thanks a lot for sharing. I would like to see also the result with the FA85*

FantasticMrFox · 09-27-2016, 07:13 AM

It seems a very useful tool, but after a quick look two things stand out to me: DA 18-55 'excellent' wide open at f/3.5?!

I don't think so. And I'd rate the DA 35 f/2.4 'very good' at f/2.4 and f/2.8, and excellent beyond.

**BigMackCam** · 09-27-2016, 11:43 PM

Originally posted by FantasticMrFox

It seems a very useful tool, but after a quick look two things stand out to me: DA 18-55 'excellent' wide open at f/3.5?!

I don't think so. And I'd rate the DA 35 f/2.4 'very good' at f/2.4 and f/2.8, and excellent beyond.

A couple of things to bear in mind:

(1) This spreadsheet shows resolution performance - it does not take into account aberrations
(2) The data used was collated from major test sites such as LensTip and Photozone - not my own measurements
(3) The tests will have been performed on different resolution sensors, some of them now quite old (what was "excellent" back then may only be "acceptable" now)

I wouldn't recommend using this for absolute assessments of a lens' performance, or comparing absolute performance of multiple lenses. Rather, it's most useful for assessing a single lens' relative performance across a range of common aperture settings, at the frame centre and borders.

That said, looking at the DA18-55 results, I think I've made a transcription error there. I'll look at it when I next review the spreadsheet - thanks for pointing it out

zapp · 10-02-2016, 10:01 AM

Results will change for different pixel pitches - not only for maximum resolution, but also for diffraction limitation for large f/numbers.
As a general hint this chart is really nice, but not yet comprehensive.

**BigMackCam** · 10-02-2016, 02:44 PM

Originally posted by zapp

As a general hint this chart is really nice, but not yet comprehensive.

Indeed not. Hopefully I'll get round to doing some more updates shortly, but otherwise it stands as testament to the fact that you get what you pay for

GreenRich · 04-18-2022, 01:26 PM

Really interesting, looks like I need to stop using f8 so much on a couple of lenses

**GUB** · 04-18-2022, 01:47 PM

The only issue I have with this is labelling the soft corners as "poor."
These "portrait " lenses have their uses.
Otherwise who would lust after the 8 element 50 1.4?

People paid a premium new for these 50mms
The alternative was the entry 55mm f2

Even back then they instinctively knew sharpness wasn't the only quality.

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12-24-2015, 02:59 PM	#31
mole Veteran Member Join Date: Nov 2009 Location: Tennessee Photos: Gallery Posts: 1,432	Thanks so much for taking the time to create the database, and thanks for sharing this very useful information!

12-24-2015, 03:11 PM	#32
Kerrowdown PEG Moderator Join Date: Aug 2008 Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake Photos: Gallery Posts: 57,819	Originally posted by pathdoc I know there are charts for much older lenses (M, A, even K) Really... is it possible you could point me in the right direction for those, well at least the A series, as I can't honestly I've seen the lowdown on my Ladies.

12-24-2015, 03:13 PM	#33
hjoseph7 Site Supporter Join Date: May 2014 Location: Minnesota Photos: Gallery \| Albums Posts: 2,047	This is very useful since I often don't know what the optimal resolution is for a lens and have to guess. I'll have to create a list for the lenses I have. thanks

12-24-2015, 03:52 PM	#34
averagehitman New Member Join Date: Dec 2015 Posts: 22	Thanks for the information. I can now use "aperture versatility" as another factor on what lenses to buy.

12-25-2015, 08:16 AM	#35
bertwert Veteran Member Join Date: Jun 2015 Location: Golden, BC Posts: 15,173	Originally posted by BigMackCam I also took the plunge and registered a Google account so I believe this gives me the capability to to store it online and allow access to it. Yes it does. You can have it publically viewable and then link it in this thread.

12-26-2015, 04:37 PM	#36
beachgardener Site Supporter Join Date: Sep 2013 Location: Australia Photos: Gallery Posts: 3,842	Thanks for that mate, excellent stuff, cheers. I can see it expanding into a wonderful resource for information on many lens sweet spots

09-15-2016, 06:36 PM	#37
SpecialK Pentaxian Join Date: Dec 2006 Location: So California Photos: Gallery Posts: 16,481	I only found this chart today and linked it into a current resolution thread. Thanks for the work, though I own no Pentax.

09-16-2016, 12:16 AM	#38
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,674 Original Poster	You're welcome. I've been meaning to expand on it, and I will get round to it eventually!

09-23-2016, 02:56 AM	#39
ANGUS YOUNG Junior Member Join Date: Mar 2015 Posts: 41	Thanks a lot for sharing. I would like to see also the result with the FA85*

09-27-2016, 07:13 AM	#40
FantasticMrFox Veteran Member Join Date: Oct 2014 Location: Munich Posts: 2,339	It seems a very useful tool, but after a quick look two things stand out to me: DA 18-55 'excellent' wide open at f/3.5?! I don't think so. And I'd rate the DA 35 f/2.4 'very good' at f/2.4 and f/2.8, and excellent beyond.

09-27-2016, 11:43 PM	#41
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,674 Original Poster	Originally posted by FantasticMrFox It seems a very useful tool, but after a quick look two things stand out to me: DA 18-55 'excellent' wide open at f/3.5?! I don't think so. And I'd rate the DA 35 f/2.4 'very good' at f/2.4 and f/2.8, and excellent beyond. A couple of things to bear in mind: (1) This spreadsheet shows resolution performance - it does not take into account aberrations (2) The data used was collated from major test sites such as LensTip and Photozone - not my own measurements (3) The tests will have been performed on different resolution sensors, some of them now quite old (what was "excellent" back then may only be "acceptable" now) I wouldn't recommend using this for absolute assessments of a lens' performance, or comparing absolute performance of multiple lenses. Rather, it's most useful for assessing a single lens' relative performance across a range of common aperture settings, at the frame centre and borders. That said, looking at the DA18-55 results, I think I've made a transcription error there. I'll look at it when I next review the spreadsheet - thanks for pointing it out

10-02-2016, 10:01 AM	#42
zapp Pentaxian Join Date: Jul 2011 Posts: 2,385	Results will change for different pixel pitches - not only for maximum resolution, but also for diffraction limitation for large f/numbers. As a general hint this chart is really nice, but not yet comprehensive.

10-02-2016, 02:44 PM	#43
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,674 Original Poster	Originally posted by zapp As a general hint this chart is really nice, but not yet comprehensive. Indeed not. Hopefully I'll get round to doing some more updates shortly, but otherwise it stands as testament to the fact that you get what you pay for

04-18-2022, 01:26 PM	#44
GreenRich Senior Member Join Date: Apr 2015 Location: Derbyshire Photos: Gallery Posts: 141	Really interesting, looks like I need to stop using f8 so much on a couple of lenses

04-18-2022, 01:47 PM	#45
GUB Loyal Site Supporter Join Date: Aug 2012 Location: Wanganui Photos: Gallery \| Albums Posts: 5,760	The only issue I have with this is labelling the soft corners as "poor." These "portrait " lenses have their uses. Otherwise who would lust after the 8 element 50 1.4? People paid a premium new for these 50mms The alternative was the entry 55mm f2 Even back then they instinctively knew sharpness wasn't the only quality.