Is this copy of FA20mm good enough?

**sholtzma** · 03-30-2015, 03:29 PM

After using my DA 12-24 much more than I expected when on a trip, and with another trip upcoming, I wondered if I could find a sharper, better WA lens. I just picked up an FA 20mm f2.8 and want to get your judgment about its sharpness (and any other criteria you wish to comment on).

The first image, of a yard, was shot at low ISO, high shutter speed, and f2.8. Handheld, with SR. Focus was intended to be on the birdbath roughly 20-25 feet away. Then there are crops of the birdbath area near the center and of an edge that should have included the plane of focus.

The next set of images, of a piece of metal wall art hanging on an outside wall about 2-3 feet away, were controlled. Camera was on a tripod, without SR, and with self-timer at 2 seconds. Focus was on the area near the center that I then show cropped. Various ISO and shutter speeds were used to test the lens at f2.8, f4, f5.6, and f8.

All images shot in RAW and processed in ACR 4 using only the defaults, then resized to fit the PF guidelines.

To be fair, I expect I'd use this lens not so much close up as at or near infinity--for landscapes, scenic, architecture, and the like.

Are my tests fair so far? Should I test it further? What do these tests show, especially for those of you who have (and who rave over the sharpness of) this lens?

Attached Images

View Picture EXIF

View Picture EXIF

**sholtzma** · 03-30-2015, 03:31 PM

And here is the wall art image shot at f8 along with its center crop...

Na Horuk · 03-30-2015, 04:52 PM

Are you sure the aperture is stopping down correctly? Make sure the aperture ring is in A position (press little button) and make sure the camera successfully stops it down.
You can try another test where you take a photo of a newspaper or something laid near the minimum focus distance at a 45 degree angle to the sensor plane. Try to position it such that the focus is near the middle of the page. That way you can see whether the text is sharp, how the DoF changes, and so on. Take one photo wide open and one at f8.
Beyond that, I cannot help since I don't have that lens. It does seem a little soft, then again it is an UWA and might need some PP

**dms** · 03-30-2015, 05:14 PM

I suggest you take pictures with same FL with both lenses--zoom and 20 mm, at about f/5.6, at intermediate distance and infinity with careful focusing (maybe use the lens scale if you have trouble manual focusing). Pick something like trees with lots of branches in the distance, and for the intermediate distance something with a lot more surface texture. And then view/post at 100%. Actually the pictures you post seem very low in resolution and/or contrast.

**sholtzma** · 03-30-2015, 05:31 PM

I can confirm that the lens passes all its mechanical and "eye" tests. Glass is clear with little dust. Aperture blades are snappy and clean. Aperture stops down correctly by hand, and the camera reads that it is stopping down the lens electronically. Focus ring moves smoothly throughout the range, and again, on the camera it reads in focus quickly and at all distances. The lens shows very little wear externally.

I can try the newspaper test. I cannot compare this lens with my zoom, since KEH is re-repairing the zoom for another week or so.

I don't want to have unrealistic expectations for this lens, but I'm willing to send it back if it's not what it should be. Or, perhaps it just needs to be sent in for adjustment?

Dlanor Sekao · 03-30-2015, 05:50 PM

For a FA 20mm 2.8 ??? I personally thought it just isn't quite there.....looked a tad bit soft to me.
Sorry , but that was my first impression looking at the crops.
It all depends on what YOUR expectations are and what YOUR going to be using it for......So only YOU can figure out if its a keeper or not !
I would try adding some in camera lens profile correction on it and see if that helps ?
Also......your shooting a wall close ......so is it focusing on the wall , or on the decorative metal ? Remember ...even though WA lenses have incredible depth of field , up close that diminishes the loser you get !
Something just does not look right its not got much contrast and the yard shots are just dull and lack sharp resolution.
Don't give up.....test it very very thoroughly before passing judgment for the final call !

**sholtzma** · 03-30-2015, 06:02 PM

Originally posted by Dlanor Sekao

For a FA 20mm 2.8 ??? I personally thought it just isn't quite there.....looked a tad bit soft to me.
Sorry , but that was my first impression looking at the crops.
It all depends on what YOUR expectations are and what YOUR going to be using it for......So only YOU can figure out if its a keeper or not !
I would try adding some in camera lens profile correction on it and see if that helps ?
Also......your shooting a wall close ......so is it focusing on the wall , or on the decorative metal ?
Something just does not look right its not got much contrast and the yard shots are just dull and lack sharp resolution.
Don't give up.....test it very very thoroughly before passing judgment for the final call !

Well, that's my first impression too: something just isn't right. But, yes, you are right; I will test it much further and in a variety of different ways. My basic criterion is that it needs to be significantly better than the 12-24, or else it's not worth my keeping it.

Should I have send it to KEH for alignment/adjustment?

Dlanor Sekao · 03-30-2015, 06:08 PM

Originally posted by sholtzma

Well, that's my first impression too: something just isn't right. But, yes, you are right; I will test it much further and in a variety of different ways. My basic criterion is that it needs to be significantly better than the 12-24, or else it's not worth my keeping it.

Should I have send it to KEH for alignment/adjustment?

Try an in camera lens correction profile first.
And test it about 6' on a flat wall with something of texture and moderate contrast.
If it doesn't meet your expectations .........send it back !
I went through a similar dilemma with a Samyang 14mm and it ended up being a keeper.
Don't give up too quick until all the variables are covered.

**dms** · 03-30-2015, 06:10 PM

The following are the tests by Yoshihiko Takinami, and as you see f/2.8 is low in resolution. Although your outdoors pictures seem low in contrast and resolution even for f/2.8. Nevertheless you should not expect much wide open in a rather fast 20 mm lens of older optical design. I suggest you use f/8 and repeat your tests.
smc PENTAX-A 20mm f/2.8 (A20/2.8, #5863***)
f/2.8
55
55/55
49/49
49/44
44/39
f/4
78
78/69
69/55
49/49
49/39
f/5.6
78
78/78
78/69
69/62
62/55
f/8
78
78/78
78/78
69/69
69/55
f/11
78
78/78
69/62
69/62
55/49
f/16
69
62/62
62/62
55/49
49/44
f/22
55
49/49
49/44
44/39
39/35

osv · 03-30-2015, 08:08 PM

Originally posted by sholtzma

Are my tests fair so far? Should I test it further? What do these tests show, especially for those of you who have (and who rave over the sharpness of) this lens?

upload the original unaltered birdbath pic to a place like dropbox, where people can download it and look at it.

if you are going to be shooting outdoor landscapes, then post up test shots of big wide landscape pics to that upload link.

**csa** · 03-30-2015, 08:32 PM

I've taken the liberty of sharpening this photo. You can see the original was very soft.

**lmd91343** · 03-30-2015, 08:39 PM

Do you have a tripod? Remote control/cable release? Do you have a shot of a newspaper taped to a wall visible in both the corner and center?

**southlander** · 03-30-2015, 08:45 PM

Was this with autofocus done through the viewfinder or with live view? Auto-focus calibration needs to be eliminated as a contributing factor to any apparent softness before an opinion can truly be passed on the lens alone. If not done already, test with live view focus and see if the results improve. Better still if you can pop the camera on a tripod and use the 2 second timer to eliminate camera movement. Also, if you were autofocusing through the viewfinder, did you use spot focus with the garden scene or multipoint focus (which could have selected a target some distance away from the birdbath).

robthebloke · 03-31-2015, 04:36 AM

I've got an A20, and my opinion of it is quite low. It's not particularly sharp, and contrast is a bit lacking. The DA12-24, and DA21 are in a different league. The older M20 and K18 are somewhere inbetween. (My opinion on having owned all of them)

Your tests appear to match my experience with the A20. It's a bit underwhelming, and I'm not sure why it scores so highly on PF reviews. Maybe it's just been out resolved by the k5/k3? I did find that a circular polariser was a must for that lens on apsc though. But even then it can't match the DA21.

Na Horuk · 03-31-2015, 05:47 AM

Originally posted by robthebloke

Maybe it's just been out resolved by the k5/k3?

This is possible. Modern cameras have high pixel density, no AA filter.. so old UWA designs will struggle more than modern UWA lenses.
Adding a polarizer might help with contrast, and a lens hood as well (a hood for equivalent FoV, so for 30mm). You can PP to add contrast, clarity, and sharpness, make a profile to reduce CA (this will improve sharpness as well) and fringing. If you do all of this, the lens could be acceptable and good.

If I had just gotten that lens and those tests are correct (as in, no other variables affected sharpness other than lens), then I would really think about the lens as well. It being a little soft at f2.8 is expected (UWA, old design) but by f5.6 and f8, I would want it to be sharper. Then again, the Samyang 14mm spoils me
Anyway, I would make sure the aperture is really really correct. In a relatively dark room, choose the lowest ISO, f8 and a long shutter time, then just look into the lens as the camera takes the photo to make sure the aperture is stopped down correctly. Because that is the main problem for me with those sample photos - the image doesn't improve that much from f4 to f8

03-30-2015, 05:50 PM	#6
Dlanor Sekao Veteran Member Join Date: Jul 2013 Posts: 1,457	For a FA 20mm 2.8 ??? I personally thought it just isn't quite there.....looked a tad bit soft to me. Sorry , but that was my first impression looking at the crops. It all depends on what YOUR expectations are and what YOUR going to be using it for......So only YOU can figure out if its a keeper or not ! I would try adding some in camera lens profile correction on it and see if that helps ? Also......your shooting a wall close ......so is it focusing on the wall , or on the decorative metal ? Remember ...even though WA lenses have incredible depth of field , up close that diminishes the loser you get ! Something just does not look right its not got much contrast and the yard shots are just dull and lack sharp resolution. Don't give up.....test it very very thoroughly before passing judgment for the final call ! Last edited by Dlanor Sekao; 03-30-2015 at 06:04 PM.

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03-30-2015, 04:52 PM	#3
Na Horuk Veteran Member Join Date: Feb 2012 Location: Slovenia, probably Photos: Gallery \| Albums Posts: 11,186	Are you sure the aperture is stopping down correctly? Make sure the aperture ring is in A position (press little button) and make sure the camera successfully stops it down. You can try another test where you take a photo of a newspaper or something laid near the minimum focus distance at a 45 degree angle to the sensor plane. Try to position it such that the focus is near the middle of the page. That way you can see whether the text is sharp, how the DoF changes, and so on. Take one photo wide open and one at f8. Beyond that, I cannot help since I don't have that lens. It does seem a little soft, then again it is an UWA and might need some PP

03-30-2015, 05:14 PM	#4
dms Site Supporter Join Date: Aug 2011 Location: New York, NY Photos: Gallery Posts: 2,192	I suggest you take pictures with same FL with both lenses--zoom and 20 mm, at about f/5.6, at intermediate distance and infinity with careful focusing (maybe use the lens scale if you have trouble manual focusing). Pick something like trees with lots of branches in the distance, and for the intermediate distance something with a lot more surface texture. And then view/post at 100%. Actually the pictures you post seem very low in resolution and/or contrast.

03-30-2015, 05:31 PM	#5
sholtzma Site Supporter Join Date: Sep 2007 Location: Salisbury, NC Photos: Gallery Posts: 1,043 Original Poster	I can confirm that the lens passes all its mechanical and "eye" tests. Glass is clear with little dust. Aperture blades are snappy and clean. Aperture stops down correctly by hand, and the camera reads that it is stopping down the lens electronically. Focus ring moves smoothly throughout the range, and again, on the camera it reads in focus quickly and at all distances. The lens shows very little wear externally. I can try the newspaper test. I cannot compare this lens with my zoom, since KEH is re-repairing the zoom for another week or so. I don't want to have unrealistic expectations for this lens, but I'm willing to send it back if it's not what it should be. Or, perhaps it just needs to be sent in for adjustment?

03-30-2015, 06:02 PM	#7
sholtzma Site Supporter Join Date: Sep 2007 Location: Salisbury, NC Photos: Gallery Posts: 1,043 Original Poster	Originally posted by Dlanor Sekao For a FA 20mm 2.8 ??? I personally thought it just isn't quite there.....looked a tad bit soft to me. Sorry , but that was my first impression looking at the crops. It all depends on what YOUR expectations are and what YOUR going to be using it for......So only YOU can figure out if its a keeper or not ! I would try adding some in camera lens profile correction on it and see if that helps ? Also......your shooting a wall close ......so is it focusing on the wall , or on the decorative metal ? Something just does not look right its not got much contrast and the yard shots are just dull and lack sharp resolution. Don't give up.....test it very very thoroughly before passing judgment for the final call ! Well, that's my first impression too: something just isn't right. But, yes, you are right; I will test it much further and in a variety of different ways. My basic criterion is that it needs to be significantly better than the 12-24, or else it's not worth my keeping it. Should I have send it to KEH for alignment/adjustment?

03-30-2015, 06:08 PM	#8
Dlanor Sekao Veteran Member Join Date: Jul 2013 Posts: 1,457	Originally posted by sholtzma Well, that's my first impression too: something just isn't right. But, yes, you are right; I will test it much further and in a variety of different ways. My basic criterion is that it needs to be significantly better than the 12-24, or else it's not worth my keeping it. Should I have send it to KEH for alignment/adjustment? Try an in camera lens correction profile first. And test it about 6' on a flat wall with something of texture and moderate contrast. If it doesn't meet your expectations .........send it back ! I went through a similar dilemma with a Samyang 14mm and it ended up being a keeper. Don't give up too quick until all the variables are covered.

03-30-2015, 06:10 PM	#9
dms Site Supporter Join Date: Aug 2011 Location: New York, NY Photos: Gallery Posts: 2,192	The following are the tests by Yoshihiko Takinami, and as you see f/2.8 is low in resolution. Although your outdoors pictures seem low in contrast and resolution even for f/2.8. Nevertheless you should not expect much wide open in a rather fast 20 mm lens of older optical design. I suggest you use f/8 and repeat your tests. smc PENTAX-A 20mm f/2.8 (A20/2.8, #5863***) f/2.8 55 55/55 49/49 49/44 44/39 f/4 78 78/69 69/55 49/49 49/39 f/5.6 78 78/78 78/69 69/62 62/55 f/8 78 78/78 78/78 69/69 69/55 f/11 78 78/78 69/62 69/62 55/49 f/16 69 62/62 62/62 55/49 49/44 f/22 55 49/49 49/44 44/39 39/35

03-30-2015, 08:08 PM	#10
osv Veteran Member Join Date: Mar 2007 Location: So Cal Photos: Gallery Posts: 2,080	Originally posted by sholtzma Are my tests fair so far? Should I test it further? What do these tests show, especially for those of you who have (and who rave over the sharpness of) this lens? upload the original unaltered birdbath pic to a place like dropbox, where people can download it and look at it. if you are going to be shooting outdoor landscapes, then post up test shots of big wide landscape pics to that upload link.

03-30-2015, 08:39 PM	#12
lmd91343 Site Supporter Join Date: Jul 2009 Location: Los Angeles, CA USA Photos: Gallery \| Albums Posts: 1,027	Do you have a tripod? Remote control/cable release? Do you have a shot of a newspaper taped to a wall visible in both the corner and center?

03-30-2015, 08:45 PM	#13
southlander Site Supporter Join Date: May 2012 Location: Adelaide Photos: Gallery \| Albums Posts: 1,364	Was this with autofocus done through the viewfinder or with live view? Auto-focus calibration needs to be eliminated as a contributing factor to any apparent softness before an opinion can truly be passed on the lens alone. If not done already, test with live view focus and see if the results improve. Better still if you can pop the camera on a tripod and use the 2 second timer to eliminate camera movement. Also, if you were autofocusing through the viewfinder, did you use spot focus with the garden scene or multipoint focus (which could have selected a target some distance away from the birdbath).

03-31-2015, 04:36 AM	#14
robthebloke Veteran Member Join Date: Sep 2013 Location: Sydney Photos: Albums Posts: 844	I've got an A20, and my opinion of it is quite low. It's not particularly sharp, and contrast is a bit lacking. The DA12-24, and DA21 are in a different league. The older M20 and K18 are somewhere inbetween. (My opinion on having owned all of them) Your tests appear to match my experience with the A20. It's a bit underwhelming, and I'm not sure why it scores so highly on PF reviews. Maybe it's just been out resolved by the k5/k3? I did find that a circular polariser was a must for that lens on apsc though. But even then it can't match the DA21.

03-31-2015, 05:47 AM	#15
Na Horuk Veteran Member Join Date: Feb 2012 Location: Slovenia, probably Photos: Gallery \| Albums Posts: 11,186	Originally posted by robthebloke Maybe it's just been out resolved by the k5/k3? This is possible. Modern cameras have high pixel density, no AA filter.. so old UWA designs will struggle more than modern UWA lenses. Adding a polarizer might help with contrast, and a lens hood as well (a hood for equivalent FoV, so for 30mm). You can PP to add contrast, clarity, and sharpness, make a profile to reduce CA (this will improve sharpness as well) and fringing. If you do all of this, the lens could be acceptable and good. If I had just gotten that lens and those tests are correct (as in, no other variables affected sharpness other than lens), then I would really think about the lens as well. It being a little soft at f2.8 is expected (UWA, old design) but by f5.6 and f8, I would want it to be sharper. Then again, the Samyang 14mm spoils me Anyway, I would make sure the aperture is really really correct. In a relatively dark room, choose the lowest ISO, f8 and a long shutter time, then just look into the lens as the camera takes the photo to make sure the aperture is stopped down correctly. Because that is the main problem for me with those sample photos - the image doesn't improve that much from f4 to f8