Pentax 31mm Lenstip Review

taurus9 · 10-14-2011, 09:58 PM

There is a review of the FA 31mm on LensTip.com - lens review, lenses reviews, lens specification - Lenstip.com. I like their reviews since they measure things that other websites don't such as astigmatism, coma, and autofocus.

However, I see their point about the value proposition of the FA31 relative to the competition, and in general, they were not seemingly impressed by the lens overall.

They don't really comment much on the +'s that the forums speak much about such as the smooth bokeh.

I doubt the review will change the minds of those who love the lens but I am somewhat puzzled that the review is at odds with the general consensus of the lens within the online community. And the website does mention that this lens was not the first Pentax lens that did not test well, but was well regarded.

wlachan · 10-14-2011, 10:32 PM

Just check out their resolution pics. The wide open one is clearly OOF because no lens will be that blurry. This makes you wonder how valid their tests are.

taurus9 · 10-14-2011, 11:11 PM

Perhaps it's OOF. And the review also raised the possibility of QC issues as well.

However, in my experience, it is a stretch to say that shooting with the lens wide open is sharp, so the results were not completely surprising.

wlachan · 10-14-2011, 11:15 PM

This was taken with my FA31 wide open. I think it's pretty sharp.

calsan · 10-15-2011, 12:35 AM

That's pretty disappointing for a 'legendary' lens and following hard on the heels of the 16-50's poor showing on this forum.

I'm sorry, but the photo above looks washed out and lacking detail. Maybe this is what makes it great for portraits? The sample photos on Lenstip were equally low contrast and hazy with awful purple fringing.
Have a look at the top right corner of the above photo - it's soft and a purple smudge, and that isn't even the true top right of the lens - it's designed for full frame, so goodness knows how bad it must really get on 35mm?

Robert Donovan did a posting with a comparison between the FA31 and DA18-55 - DA18-55 looks pretty decent by comparison.

Another point that should be raised - why can Sigma make and assemble lenses in Japan yet they're cheaper and with modern designs, better coatings and frequently have exotic glass like flourite included in the design? Pentax's are made in a third world communist country where workers are poorly paid and have little in the way of rights. Yet Pentax's lenses cost more? Where's the difference going? Here's hoping Ricoh return Pentax to Japan, or at least ensure work and quality matches Japan. Sigma proves that doesn't mean higher costs to lens buyers. Seriously time to do something about modernizing some of the lenses to match the excellent performance of the bodies.

vrrattko · 10-15-2011, 03:02 AM

Well I think that lenstip came moreless to same conclusions as photozone - wide open the FA31 is a bit soft (sorry wlachan but your photo is not that sharp) and doesn't have much contrast. It is definitely less contrasty than FA24 or FA43 at least in my experience. However on stopping down it gains quickly on resolution. But FA31 has a different tricks in sleeve which gained it cult following. For me it is beautiful colour reproduction (just awesome with skin colours, greens and blues), nice smooth bokeh and maybe most important for me is its sort of 3-dimensionality of rendering. I agree with Taurus - you shouldn't await yhis lens to be sharp at f1.8 or f2 - it will give you decent results but you need to stop down more to get really sharp.

**Digitalis** · 10-15-2011, 03:22 AM

Originally posted by calsan

Another point that should be raised - why can Sigma make and assemble lenses in Japan yet they're cheaper and with modern designs, better coatings and frequently have exotic glass like flourite included in the design? Pentax's are made in a third world communist country where workers are poorly paid and have little in the way of rights. Yet Pentax's lenses cost more? Where's the difference going? Here's hoping Ricoh return Pentax to Japan, or at least ensure work and quality matches Japan. Sigma proves that doesn't mean higher costs to lens buyers. Seriously time to do something about modernizing some of the lenses to match the excellent performance of the bodies.

quite a few misinformed and prejudiced statements there but I will point out that I have yet to come across a sigma lens that was every bit as flare resistant as an equivalent Pentax SMC lens. Sigma lenses also typically aren't as well built as the FA limited line of lenses are, the FA limited lenses are extremely well constructed.To answer your comments about modernised lens designs: I will inform you that the FA31 lens design incorporates a moulded aspherical lens, ED and HRLD glass types are also used,just because a lens uses exotic glass types doesn't necessarily indicate it is a superior lens. I own apochromatic lenses that are capable of outperforming lens designs incorporating exotic ED glass by significant margins. Also the FA limited lenses were all designed within the last ten years- last time I looked that counts as pretty modern for instance Canon have the EF35mm f/1.4L which uses a 40 year old optical design - and you don't hear people complaining.

Last edited by Digitalis; 10-15-2011 at 03:35 AM.

RonHendriks1966 · 10-15-2011, 03:26 AM

Maybe their K-5 (or handling it) is the main problem with OOF pictures.

They do have a point that it is expensive!

TOUGEFC · 10-15-2011, 03:43 AM

"I would expect there was a standard lens available - something optically better, faster and cheaper than its full frame equivalent....
the company offered its users a lens slower, optically worse, old and much more expensive."

Looks like it didnt do that well.

**kiwi_jono** · 10-15-2011, 03:46 AM

The Photozone review was actually very positive (Highly Recommended). Looking at their resolution figures (even though you can't compare numbers) it indicates that its resolution is very good wide open. Comparing the shape of the resolution charts the lenstip one seems to have a much steeper increase in resolution from wide open. So it may be that this is a case of sample variation. Regarding focus accuracy - Lenstip do focus accuracy tests I understand and surely they would take that into account???

Regarding pricing - I have often seen it said on forums that you pay more for Canikon glass to get the same quality as Pentax but as far as optical quality goes is that really the case?

**Rondec** · 10-15-2011, 05:13 AM

The biggest quibble really is that it's expensive for what it is. In the conclusion, they are comparing it to the Nikon 35mm f1.8, which is 700 dollars cheaper. Understandably, the differences in build and bokeh seem small in comparison to that difference in price.

I like the focal length, but ended up getting a Sigma 30mm f1.4. Maybe it doesn't have as nice rendering of out of focus areas, but it is half the price.

axl · 10-15-2011, 07:29 AM

Originally posted by Digitalis

Also the FA limited lenses were all designed within the last ten years- last time I looked that counts as pretty modern....

Last time I checked, FA43 uses the same layout as any Pentax K mount 50/1.4 including the oldest from 1975 and FA77 uses the same layout as A*85 which is what, mid 80s? AFAIK only 31 was new design in FA ltd line...

climit · 10-15-2011, 09:31 AM

Well, the test results aren't that bad! Moreover the 31 ltd. is a very solid construction to serve you for decades. In the meantime you have plenty of time to learn to use it ... ! ;-)

sjwaldron · 10-15-2011, 10:10 AM

So does anyone with negative comments here actually have the lens?

At f1.8 ISO 2500:

http://www.flickr.com/photos/dslrninja/6247039580/sizes/o/in/photostream/

Expecting a large aperture like that to be sharp except on a thin focal plane doesn't make sense at all. That above photo is sharp... look at the foreground plants. Unless the focal plane and focus itself is perfect in tests then the edges will be more oof than they should be. I'm not saying the review isn't correct because I didn't bother looking in detail about their results besides reading the article text.

Maybe you should check out my review that isn't solely about measurebation.

The reviewer seemed to have a chip on their shoulder, especially aimed at raking on Pentax. Not exactly professional if you ask me.

wlachan · 10-15-2011, 10:35 AM

Originally posted by sjwaldron

Expecting a large aperture like that to be sharp except on a thin focal plane doesn't make sense at all. That above photo is sharp... look at the foreground plants. Unless the focal plane and focus itself is perfect in tests then the edges will be more oof than they should be.

I probably sounds like defending but that's what I thought. It's f1.8 we are talking. If the pic was taken at f8, then it's not good.

10-14-2011, 09:58 PM	#1
taurus9 Senior Member Join Date: Jan 2010 Location: British Columbia Posts: 120	Pentax 31mm Lenstip Review There is a review of the FA 31mm on LensTip.com - lens review, lenses reviews, lens specification - Lenstip.com. I like their reviews since they measure things that other websites don't such as astigmatism, coma, and autofocus. However, I see their point about the value proposition of the FA31 relative to the competition, and in general, they were not seemingly impressed by the lens overall. They don't really comment much on the +'s that the forums speak much about such as the smooth bokeh. I doubt the review will change the minds of those who love the lens but I am somewhat puzzled that the review is at odds with the general consensus of the lens within the online community. And the website does mention that this lens was not the first Pentax lens that did not test well, but was well regarded.

10-15-2011, 10:10 AM	#14
sjwaldron Veteran Member Join Date: Aug 2009 Photos: Gallery Posts: 1,235	So does anyone with negative comments here actually have the lens? At f1.8 ISO 2500: http://www.flickr.com/photos/dslrninja/6247039580/sizes/o/in/photostream/ Expecting a large aperture like that to be sharp except on a thin focal plane doesn't make sense at all. That above photo is sharp... look at the foreground plants. Unless the focal plane and focus itself is perfect in tests then the edges will be more oof than they should be. I'm not saying the review isn't correct because I didn't bother looking in detail about their results besides reading the article text. Maybe you should check out my review that isn't solely about measurebation. The reviewer seemed to have a chip on their shoulder, especially aimed at raking on Pentax. Not exactly professional if you ask me. Last edited by sjwaldron; 10-15-2011 at 10:18 AM.

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10-14-2011, 10:32 PM	#2
wlachan Veteran Member Join Date: Sep 2006 Location: Canada Photos: Albums Posts: 2,625	Just check out their resolution pics. The wide open one is clearly OOF because no lens will be that blurry. This makes you wonder how valid their tests are.

10-14-2011, 11:11 PM	#3
taurus9 Senior Member Join Date: Jan 2010 Location: British Columbia Posts: 120 Original Poster	Perhaps it's OOF. And the review also raised the possibility of QC issues as well. However, in my experience, it is a stretch to say that shooting with the lens wide open is sharp, so the results were not completely surprising.

10-14-2011, 11:15 PM	#4
wlachan Veteran Member Join Date: Sep 2006 Location: Canada Photos: Albums Posts: 2,625	This was taken with my FA31 wide open. I think it's pretty sharp.

10-15-2011, 12:35 AM	#5
calsan Pentaxian Join Date: Nov 2008 Location: Perth, Australia Photos: Gallery Posts: 1,548	That's pretty disappointing for a 'legendary' lens and following hard on the heels of the 16-50's poor showing on this forum. I'm sorry, but the photo above looks washed out and lacking detail. Maybe this is what makes it great for portraits? The sample photos on Lenstip were equally low contrast and hazy with awful purple fringing. Have a look at the top right corner of the above photo - it's soft and a purple smudge, and that isn't even the true top right of the lens - it's designed for full frame, so goodness knows how bad it must really get on 35mm? Robert Donovan did a posting with a comparison between the FA31 and DA18-55 - DA18-55 looks pretty decent by comparison. Another point that should be raised - why can Sigma make and assemble lenses in Japan yet they're cheaper and with modern designs, better coatings and frequently have exotic glass like flourite included in the design? Pentax's are made in a third world communist country where workers are poorly paid and have little in the way of rights. Yet Pentax's lenses cost more? Where's the difference going? Here's hoping Ricoh return Pentax to Japan, or at least ensure work and quality matches Japan. Sigma proves that doesn't mean higher costs to lens buyers. Seriously time to do something about modernizing some of the lenses to match the excellent performance of the bodies.

10-15-2011, 03:02 AM	#6
vrrattko Veteran Member Join Date: Jun 2010 Photos: Albums Posts: 753	Well I think that lenstip came moreless to same conclusions as photozone - wide open the FA31 is a bit soft (sorry wlachan but your photo is not that sharp) and doesn't have much contrast. It is definitely less contrasty than FA24 or FA43 at least in my experience. However on stopping down it gains quickly on resolution. But FA31 has a different tricks in sleeve which gained it cult following. For me it is beautiful colour reproduction (just awesome with skin colours, greens and blues), nice smooth bokeh and maybe most important for me is its sort of 3-dimensionality of rendering. I agree with Taurus - you shouldn't await yhis lens to be sharp at f1.8 or f2 - it will give you decent results but you need to stop down more to get really sharp.

10-15-2011, 03:22 AM	#7
Digitalis Site Supporter Join Date: Mar 2009 Location: Melbourne, Victoria Photos: Gallery Posts: 11,694	Originally posted by calsan Another point that should be raised - why can Sigma make and assemble lenses in Japan yet they're cheaper and with modern designs, better coatings and frequently have exotic glass like flourite included in the design? Pentax's are made in a third world communist country where workers are poorly paid and have little in the way of rights. Yet Pentax's lenses cost more? Where's the difference going? Here's hoping Ricoh return Pentax to Japan, or at least ensure work and quality matches Japan. Sigma proves that doesn't mean higher costs to lens buyers. Seriously time to do something about modernizing some of the lenses to match the excellent performance of the bodies. quite a few misinformed and prejudiced statements there but I will point out that I have yet to come across a sigma lens that was every bit as flare resistant as an equivalent Pentax SMC lens. Sigma lenses also typically aren't as well built as the FA limited line of lenses are, the FA limited lenses are extremely well constructed.To answer your comments about modernised lens designs: I will inform you that the FA31 lens design incorporates a moulded aspherical lens, ED and HRLD glass types are also used,just because a lens uses exotic glass types doesn't necessarily indicate it is a superior lens. I own apochromatic lenses that are capable of outperforming lens designs incorporating exotic ED glass by significant margins. Also the FA limited lenses were all designed within the last ten years- last time I looked that counts as pretty modern for instance Canon have the EF35mm f/1.4L which uses a 40 year old optical design - and you don't hear people complaining. Last edited by Digitalis; 10-15-2011 at 03:35 AM.

10-15-2011, 03:26 AM	#8
RonHendriks1966 Banned Join Date: Jan 2009 Photos: Gallery Posts: 9,675	Maybe their K-5 (or handling it) is the main problem with OOF pictures. They do have a point that it is expensive!

10-15-2011, 03:43 AM	#9
TOUGEFC Veteran Member Join Date: Nov 2009 Location: Brisbane Photos: Gallery Posts: 3,561	"I would expect there was a standard lens available - something optically better, faster and cheaper than its full frame equivalent.... the company offered its users a lens slower, optically worse, old and much more expensive." Looks like it didnt do that well.

10-15-2011, 03:46 AM	#10
kiwi_jono Loyal Site Supporter Join Date: Dec 2009 Location: Christchurch, New Zealand Photos: Gallery \| Albums Posts: 2,437	The Photozone review was actually very positive (Highly Recommended). Looking at their resolution figures (even though you can't compare numbers) it indicates that its resolution is very good wide open. Comparing the shape of the resolution charts the lenstip one seems to have a much steeper increase in resolution from wide open. So it may be that this is a case of sample variation. Regarding focus accuracy - Lenstip do focus accuracy tests I understand and surely they would take that into account??? Regarding pricing - I have often seen it said on forums that you pay more for Canikon glass to get the same quality as Pentax but as far as optical quality goes is that really the case?

10-15-2011, 05:13 AM	#11
Rondec Loyal Site Supporter Join Date: Mar 2009 Location: Gladys, Virginia Photos: Gallery Posts: 27,653	The biggest quibble really is that it's expensive for what it is. In the conclusion, they are comparing it to the Nikon 35mm f1.8, which is 700 dollars cheaper. Understandably, the differences in build and bokeh seem small in comparison to that difference in price. I like the focal length, but ended up getting a Sigma 30mm f1.4. Maybe it doesn't have as nice rendering of out of focus areas, but it is half the price.

10-15-2011, 07:29 AM	#12
axl Veteran Member Join Date: Mar 2007 Location: Nove Zamky, Slovakia Photos: Gallery \| Albums Posts: 7,183	Originally posted by Digitalis Also the FA limited lenses were all designed within the last ten years- last time I looked that counts as pretty modern.... Last time I checked, FA43 uses the same layout as any Pentax K mount 50/1.4 including the oldest from 1975 and FA77 uses the same layout as A*85 which is what, mid 80s? AFAIK only 31 was new design in FA ltd line...

10-15-2011, 09:31 AM	#13
climit Senior Member Join Date: Aug 2010 Location: Kalamata Posts: 224	Well, the test results aren't that bad! Moreover the 31 ltd. is a very solid construction to serve you for decades. In the meantime you have plenty of time to learn to use it ... ! ;-)

10-15-2011, 10:35 AM	#15
wlachan Veteran Member Join Date: Sep 2006 Location: Canada Photos: Albums Posts: 2,625	Originally posted by sjwaldron Expecting a large aperture like that to be sharp except on a thin focal plane doesn't make sense at all. That above photo is sharp... look at the foreground plants. Unless the focal plane and focus itself is perfect in tests then the edges will be more oof than they should be. I probably sounds like defending but that's what I thought. It's f1.8 we are talking. If the pic was taken at f8, then it's not good.