FA31 supposedly not sharp wide open... Really?

Nicolas06 · 07-23-2016, 06:43 AM

Ok so I just received my FA31. Despite the dull weather I took it for a walk around in the local park to get a feeling of it.

People says that the lens is not sharp at f/1.8, lenstip review would complain that FA31 is really bad and unjustified. I knew this was somewhat wrong even through there was possibilities for a bad sample.

So I tested my sample... First post you get in attachment:
- full scene (at f/4)
- f/1.8 crop
- f/2 crop
- f/4 crop.

Sure the f/4 crop is better but I get the impression that even wide open quite nice and already f/2 get a noticable improvement... This K3 24MP 100% crop, so 1/6 of the picture in both direction, equivalent to 280mm on FF.

Last edited by Nicolas06; 01-31-2017 at 02:03 PM.

Nicolas06 · 07-23-2016, 06:48 AM

And now because it is kind of stupid to wonder only of the technique... A few pictures I took at the park. Nothing fancy or extraordinary, but that not a sharpness test at least

If interrested the full picture is available on flickr by clicking on it.

zapp · 07-23-2016, 06:58 AM

Lens tip says that sharpness improves on stopping down and that there are better performing lenses.
You are showing that FA31 is sufficiently sharp.
I don't really see that both opinions disagree. It makes you wonder what some Sigma Art lenses provide at f/1.4.

Nicolas06 · 07-23-2016, 07:13 AM

Originally posted by zapp

Lens tip says that sharpness improves on stopping down and that there are better performing lenses.
You are showing that FA31 is sufficiently sharp.
I don't really see that both opinions disagree. It makes you wonder what some Sigma Art lenses provide at f/1.4.

I am sure Sigma 35 f/1.4 is nice and does a great job. would be too big for me essentially. But I would not be surprized to find very high MTF at f/1.4 - f/2.

But some reviewers (I think ephotozine) would share the joy of using FA31 explaining that it render very well. Photozone would give the lens a high rating. Lenstip conclusion is negative and is not able to explain the rendering. They only find that it flare, soft on borders bellow decency level at wide appertures, has many optical aberrations and that cheap offering of Canikon perform better...

While most of their finding are likely true, I think they missed the point to actually look if the picture taken are good enough in practice or they looked great or bad outside of imatest. I mean even their sample picture that often look so soft popped with the FA31 and showed nice bokeh but they didn't manage to see it.

To me the lens is sharp enough and good enough at f/1.8-f/2 and I think that what is actually relevant. You can use it at all appertures. Well that my point at least

SpecialK · 07-23-2016, 07:16 AM

Sharpness is relative. If you like the results, it's good.

D1N0 · 07-23-2016, 07:27 AM

What is this aliasing effect on the leaves in those cropped shots?

biz-engineer · 07-23-2016, 09:06 AM

Looks good. But how about the corner sharpness wide open on full frame?
You can send it to me, I'll test it on my K1

---------- Post added 23-07-16 at 18:11 ----------

How much is the import tax from the US to France ?

Nicolas06 · 07-23-2016, 09:22 AM

Originally posted by biz-engineer

Looks good. But how about the corner sharpness wide open on full frame?
You can send it to me, I'll test it on my K1

---------- Post added 23-07-16 at 18:11 ----------

How much is the import tax from the US to France ?

I am sure it is nice on the FF... Wider image circlue but also bigger photosites.

Too much to my liking... Its 30% I think but in France the beast is 1200-1400€ new

.

mikeSF · 07-23-2016, 12:21 PM

i don't read lenstip but you proved from your own examples that the lens gets MUCH better by f/4, so like others said, it is all relative. I personally avoid FA31 wide open if possible, but am fine one or two two stops down from open.

Adam · 07-23-2016, 12:26 PM

Wonderful flower shots!

Nicolas06 · 07-23-2016, 12:40 PM

Originally posted by mikeSF

i don't read lenstip but you proved from your own examples that the lens gets MUCH better by f/4, so like others said, it is all relative. I personally avoid FA31 wide open if possible, but am fine one or two two stops down from open.

Agree but I displayed 100% 24MP crops. Even a decent sized 12x16" print would mean the crop would be only 2x3" basically. Using CTRL- with your browser and you'll see that all the sharpness difference is lost. Only dof and constrast difference remain visible... And part of the lost constrast can be got with PP while any lens with same framing and apperture would have the same dof...

Sure f/1.8 is not as good but still good enough. Only the photographer and us gear fanatics look at 100% crops

Nicolas06 · 07-23-2016, 01:07 PM

Originally posted by Adam

Wonderful flower shots!

Thanks !

condor27596 · 07-23-2016, 06:39 PM

I shoot the 31 wide open for daughter portrait year after year. The 3D pop is worth the $800 I paid for it.

If you peeps find fault your eyes much better than mine.

noelpolar · 07-23-2016, 07:00 PM

Originally posted by condor27596

I shoot the 31 wide open for daughter portrait year after year. The 3D pop is worth the $800 I paid for it.

If you peeps find fault your eyes much better than mine.

f stop used for female portrait should start closed down and open one stop for each 5 years of age!

mikeSF · 07-23-2016, 08:20 PM

Originally posted by noelpolar

f stop used for female portrait should start closed down and open one stop for each 5 years of age!

i get it, thats funny!

07-23-2016, 06:43 AM	#1
Nicolas06 Veteran Member Join Date: Nov 2013 Posts: 4,854	FA31 supposedly not sharp wide open... Really? Ok so I just received my FA31. Despite the dull weather I took it for a walk around in the local park to get a feeling of it. People says that the lens is not sharp at f/1.8, lenstip review would complain that FA31 is really bad and unjustified. I knew this was somewhat wrong even through there was possibilities for a bad sample. So I tested my sample... First post you get in attachment: - full scene (at f/4) - f/1.8 crop - f/2 crop - f/4 crop. Sure the f/4 crop is better but I get the impression that even wide open quite nice and already f/2 get a noticable improvement... This K3 24MP 100% crop, so 1/6 of the picture in both direction, equivalent to 280mm on FF. Last edited by Nicolas06; 01-31-2017 at 02:03 PM.

07-23-2016, 12:26 PM	#10
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Wonderful flower shots! Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

07-23-2016, 12:40 PM	#11
Nicolas06 Veteran Member Join Date: Nov 2013 Posts: 4,854 Original Poster	Originally posted by mikeSF i don't read lenstip but you proved from your own examples that the lens gets MUCH better by f/4, so like others said, it is all relative. I personally avoid FA31 wide open if possible, but am fine one or two two stops down from open. Agree but I displayed 100% 24MP crops. Even a decent sized 12x16" print would mean the crop would be only 2x3" basically. Using CTRL- with your browser and you'll see that all the sharpness difference is lost. Only dof and constrast difference remain visible... And part of the lost constrast can be got with PP while any lens with same framing and apperture would have the same dof... Sure f/1.8 is not as good but still good enough. Only the photographer and us gear fanatics look at 100% crops Last edited by Nicolas06; 07-23-2016 at 01:10 PM.

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07-23-2016, 06:48 AM	#2
Nicolas06 Veteran Member Join Date: Nov 2013 Posts: 4,854 Original Poster	And now because it is kind of stupid to wonder only of the technique... A few pictures I took at the park. Nothing fancy or extraordinary, but that not a sharpness test at least If interrested the full picture is available on flickr by clicking on it.

07-23-2016, 06:58 AM	#3
zapp Pentaxian Join Date: Jul 2011 Posts: 2,385	Lens tip says that sharpness improves on stopping down and that there are better performing lenses. You are showing that FA31 is sufficiently sharp. I don't really see that both opinions disagree. It makes you wonder what some Sigma Art lenses provide at f/1.4.

07-23-2016, 07:13 AM	#4
Nicolas06 Veteran Member Join Date: Nov 2013 Posts: 4,854 Original Poster	Originally posted by zapp Lens tip says that sharpness improves on stopping down and that there are better performing lenses. You are showing that FA31 is sufficiently sharp. I don't really see that both opinions disagree. It makes you wonder what some Sigma Art lenses provide at f/1.4. I am sure Sigma 35 f/1.4 is nice and does a great job. would be too big for me essentially. But I would not be surprized to find very high MTF at f/1.4 - f/2. But some reviewers (I think ephotozine) would share the joy of using FA31 explaining that it render very well. Photozone would give the lens a high rating. Lenstip conclusion is negative and is not able to explain the rendering. They only find that it flare, soft on borders bellow decency level at wide appertures, has many optical aberrations and that cheap offering of Canikon perform better... While most of their finding are likely true, I think they missed the point to actually look if the picture taken are good enough in practice or they looked great or bad outside of imatest. I mean even their sample picture that often look so soft popped with the FA31 and showed nice bokeh but they didn't manage to see it. To me the lens is sharp enough and good enough at f/1.8-f/2 and I think that what is actually relevant. You can use it at all appertures. Well that my point at least

07-23-2016, 07:16 AM	#5
SpecialK Pentaxian Join Date: Dec 2006 Location: So California Photos: Gallery Posts: 16,480	Sharpness is relative. If you like the results, it's good.

07-23-2016, 07:27 AM	#6
D1N0 Pentaxian Join Date: May 2012 Location: --- Photos: Gallery Posts: 6,802	What is this aliasing effect on the leaves in those cropped shots?

07-23-2016, 09:06 AM	#7
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,231	Looks good. But how about the corner sharpness wide open on full frame? You can send it to me, I'll test it on my K1 ---------- Post added 23-07-16 at 18:11 ---------- How much is the import tax from the US to France ?

07-23-2016, 09:22 AM	#8
Nicolas06 Veteran Member Join Date: Nov 2013 Posts: 4,854 Original Poster	Originally posted by biz-engineer Looks good. But how about the corner sharpness wide open on full frame? You can send it to me, I'll test it on my K1 ---------- Post added 23-07-16 at 18:11 ---------- How much is the import tax from the US to France ? I am sure it is nice on the FF... Wider image circlue but also bigger photosites. Too much to my liking... Its 30% I think but in France the beast is 1200-1400€ new .

07-23-2016, 12:21 PM	#9
mikeSF Pentaxian Join Date: Jan 2009 Location: East Bay Area, CA Photos: Gallery Posts: 6,620	i don't read lenstip but you proved from your own examples that the lens gets MUCH better by f/4, so like others said, it is all relative. I personally avoid FA31 wide open if possible, but am fine one or two two stops down from open.

07-23-2016, 01:07 PM	#12
Nicolas06 Veteran Member Join Date: Nov 2013 Posts: 4,854 Original Poster	Originally posted by Adam Wonderful flower shots! Thanks !

07-23-2016, 06:39 PM	#13
condor27596 Veteran Member Join Date: Sep 2012 Location: Raleigh, NC, USA Posts: 870	I shoot the 31 wide open for daughter portrait year after year. The 3D pop is worth the $800 I paid for it. If you peeps find fault your eyes much better than mine.

07-23-2016, 07:00 PM	#14
noelpolar Veteran Member Join Date: Oct 2013 Location: Goolwa, SA Photos: Gallery Posts: 4,310	Originally posted by condor27596 I shoot the 31 wide open for daughter portrait year after year. The 3D pop is worth the $800 I paid for it. If you peeps find fault your eyes much better than mine. f stop used for female portrait should start closed down and open one stop for each 5 years of age!

07-23-2016, 08:20 PM	#15
mikeSF Pentaxian Join Date: Jan 2009 Location: East Bay Area, CA Photos: Gallery Posts: 6,620	Originally posted by noelpolar f stop used for female portrait should start closed down and open one stop for each 5 years of age! i get it, thats funny!