Disappointed with Pentax-A 2.8/28mm

Iberia · 09-13-2015, 01:30 AM

Hi,

I have bought a Pentax-A 2.8/28mm: the glass is clean, as are the blades and the focus ring is nicelly stiff but the image quality was a major disappointment.
Center is sharp but corners are soft/fuzzy at all apperture settings wider than f/11...the DA 21mm isn't particularly sharp in the corners either but it's definitelly not as bad.
Could this be a bad copy?

I was planning to get a Pentax-A 50mm next but I now feel like giving up on Pentax-A lenses altoghether.

Cheers,
Ric

**clackers** · 09-13-2015, 01:53 AM

You should read the reviews in this site and check the appropriate lens club.

If they're better than what you're getting, Rick, unfortunately you may have drawn a lemon. :-(

Na Horuk · 09-13-2015, 02:04 AM

Hm, let's just make sure its working right.
First of all, make sure the lens' aperture ring is in A mode. You need to press a little button on the aperture ring to get it there. Once its locked in A, leave it there. In the camera's Menu, make sure you Enable Aperture ring use (near the back of the Menu)
If you have the wrong lens/camera settings, the camera will not stop it down properly. If the LCD says Av mode, even though you selected another mode, then you need to make sure the lens is in A on aperture ring.

Next, make sure you input the correct focal length into the camera. Put in 28mm, not any sort of crop multiplication.
For the tests, SR should be off. ISO needs to be low as possible, and shutter speed should be at least 1/125. Focus on something that is just a little further from the minimum focus distance. This is to test center sharpness.
Also, make sure the aperture stops actually move as they should. When indoors, switch to M mode and make aperture f8, shutter 1 second. Does the aperture move as it should? My M 28mm developed a problem where the aperture blades became slow, so they didn't keep up with the camera and thus the image quality was poor.

mythguy9 · 09-13-2015, 02:31 AM

Can you show some photos for illustration? Na Horuk raised a few good points that you should make sure.

H. Sapiens · 09-13-2015, 03:00 AM

I also have that lens and while mine appears to be "like new" the performance is so that I can make acceptable prints It just can't stand up to pixel peeping at 100%. That is unlike other "oldies" I have and the a-50 you mention is in a different league. But the a-28 was never a lens which is regarded highly on digital, was it?

Adam · 09-13-2015, 03:19 AM

Definitely post some samples and we'll take a look!

Iberia · 09-13-2015, 04:23 AM

Thanks to all for your replies.

I shot the following JPEG/sRGB samples with a k-5IIs mounted on a tripod in manual mode at 100 ISO, self-timer and SR off.
I left "Using the Aperture Ring" off because I have no intention to set f/ stop on the lens.

f/11 - https://farm1.staticflickr.com/690/21192011150_7eafaf19fe_o.jpg

f/8 - https://farm1.staticflickr.com/602/21192041060_1d66594e49_o.jpg

f/5.6 - https://farm6.staticflickr.com/5661/20757487694_fcc8732d2c_o.jpg

Cheers,
Ric

---------- Post added 13-09-15 at 12:28 ----------

I chose this lens because I intended to use it using zone focusing on TAv mode for street photography, since manual focus lenses have a stiffer focusing ring that is harder to turn accidentally.

Would the FA 28mm perform better or should I skip that as well and go for a Contax or a Leica?
I used the Contax SLR system for over a decade in the film days and the image quality was quite good...

Ric

manntax · 09-13-2015, 04:34 AM

Originally posted by Iberia

Thanks to all for your replies. I shot the following JPEG/sRGB samples with a k-5IIs mounted on a tripod in manual mode at 100 ISO, self-timer and SR off. I left "Using the Aperture Ring" off because I have no intention to set f/ stop on the lens. f/11 - https://farm1.staticflickr.com/690/21192011150_7eafaf19fe_o.jpg f/8 - https://farm1.staticflickr.com/602/21192041060_1d66594e49_o.jpg f/5.6 - https://farm6.staticflickr.com/5661/20757487694_fcc8732d2c_o.jpg Cheers, Ric

To avoid the repetition, (and before you do anything) take a look here : https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/295986-soft...ml#post3261344

Iberia · 09-13-2015, 04:44 AM

Thanks, that was useful, although I have on intention of "adapting" to a lens' shortcomings.
Cameras and lenses, like screwdrivers, are just tools and if they don't do their job properly they have to go.

Earlier this year I used a Canon 28mm pancake on a 7D and a Panasonic 20mm pancake on an OM-D EM-5 and got considerably better results than what I get with this lens...
The DA 21mm is not as bad as the A 28mm but it's too wide for my taste.

R

glasbak · 09-13-2015, 04:50 AM

Originally posted by Na Horuk

Hm, let's just make sure its working right.
First of all....

And before that, make sure no filter is attached to the lens.

manntax · 09-13-2015, 04:52 AM

Originally posted by Iberia

Thanks, that was useful, although I have on intention of "adapting" to a lens' shortcomings. Cameras and lenses, like screwdrivers, are just tools and if they don't do their job properly they have to go. Earlier this year I used a Canon 28mm pancake on a 7D and a Panasonic 20mm pancake on an OM-D EM-5 and got considerably better results than what I get with this lens... The DA 21mm is not as bad as the A 28mm but it's too wide for my taste.

Also remember you are talking about a Takumar-A lens, a budged version of wide angle -there really ARE better options for not much more.. see reviews section

**Kerrowdown** · 09-13-2015, 04:59 AM

Originally posted by Iberia

I shot the following JPEG/sRGB samples

Unless your a professional brick wall photographer...

How does the lens perform in normal use and are edges/corners as noticeable with real images... to the point of being unacceptable?

Originally posted by Iberia

but I now feel like giving up on Pentax-A lenses all together.

The 28mm was not maybe the sharpest tool in the box, but I wouldn't give up on all the A series lenses based on just this one, others may well fair better. For example... the attached was taken with the 85mm in dull poorish light, handheld and is full sensor size (K20D) with no cropping.

**boriscleto** · 09-13-2015, 05:03 AM

Please go find a system that is good for taking pictures of brick walls. I'm sure that is the only way you will ever be happy.

Iberia · 09-13-2015, 05:13 AM

Originally posted by boriscleto

Please go find a system that is good for taking pictures of brick walls. I'm sure that is the only way you will ever be happy.

If that's your best contribution you might as well be quiet.

R

---------- Post added 13-09-15 at 13:15 ----------

Originally posted by manntax

Also remember you are talking about a Takumar-A lens, a budged version of wide angle -there really ARE better options for not much more.. see reviews section

The lens in question is an SMC Pentax-A 2.8/28mm (see topic title).

R

---------- Post added 13-09-15 at 13:23 ----------

Originally posted by Kerrowdown

How does the lens perform in normal use and are edges/corners as noticeable with real images... to the point of being unacceptable?

I do shoot architecture from time to time but that is not the subject I will be photographing with this lens...

Originally posted by Kerrowdown

The 28mm was not maybe the sharpest tool in the box, but I wouldn't give up on all the A series lenses based on just this one, others may well fair better. For example... the attached was taken with the 85mm in dull poorish light, handheld and is full sensor size (K20D) with no cropping.

That image looks good but unfortunately I have no use for an 85mm lens.

Originally posted by Kerrowdown

How does the lens perform in normal use and are edges/corners as noticeable with real images... to the point of being unacceptable?

It is quite unacceptable, that is why I started this topic.
I wish to know if this is a lens problem or if my copy is not functioning properly.

I need a high performing lens with 24mm or 28mm focal length for a Pentax body, preferably manual focus for the reason stated above.

Cheers,
Ric

H. Sapiens · 09-13-2015, 05:32 AM

Okay, so now at least we have established you are not basing your judgement on your brick wall test alone.

I just had a quick glance at your website, and if our two A-28 are alike, I agree, it is not up to the task. The quality of mine matches yours - a bit fuzzy. Not terrible, but I don't use mine on digital where even da cheap 35mm is much sharper.

09-13-2015, 01:30 AM	#1
Iberia Senior Member Join Date: Dec 2012 Posts: 135	Disappointed with Pentax-A 2.8/28mm Hi, I have bought a Pentax-A 2.8/28mm: the glass is clean, as are the blades and the focus ring is nicelly stiff but the image quality was a major disappointment. Center is sharp but corners are soft/fuzzy at all apperture settings wider than f/11...the DA 21mm isn't particularly sharp in the corners either but it's definitelly not as bad. Could this be a bad copy? I was planning to get a Pentax-A 50mm next but I now feel like giving up on Pentax-A lenses altoghether. Cheers, Ric

09-13-2015, 03:19 AM	#6
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Definitely post some samples and we'll take a look! 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:

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09-13-2015, 01:53 AM	#2
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	You should read the reviews in this site and check the appropriate lens club. If they're better than what you're getting, Rick, unfortunately you may have drawn a lemon. :-(

09-13-2015, 02:04 AM	#3
Na Horuk Veteran Member Join Date: Feb 2012 Location: Slovenia, probably Photos: Gallery \| Albums Posts: 11,186	Hm, let's just make sure its working right. First of all, make sure the lens' aperture ring is in A mode. You need to press a little button on the aperture ring to get it there. Once its locked in A, leave it there. In the camera's Menu, make sure you Enable Aperture ring use (near the back of the Menu) If you have the wrong lens/camera settings, the camera will not stop it down properly. If the LCD says Av mode, even though you selected another mode, then you need to make sure the lens is in A on aperture ring. Next, make sure you input the correct focal length into the camera. Put in 28mm, not any sort of crop multiplication. For the tests, SR should be off. ISO needs to be low as possible, and shutter speed should be at least 1/125. Focus on something that is just a little further from the minimum focus distance. This is to test center sharpness. Also, make sure the aperture stops actually move as they should. When indoors, switch to M mode and make aperture f8, shutter 1 second. Does the aperture move as it should? My M 28mm developed a problem where the aperture blades became slow, so they didn't keep up with the camera and thus the image quality was poor.

09-13-2015, 02:31 AM	#4
mythguy9 Senior Member Join Date: Jun 2012 Photos: Albums Posts: 276	Can you show some photos for illustration? Na Horuk raised a few good points that you should make sure.

09-13-2015, 03:00 AM	#5
H. Sapiens Pentaxian Join Date: Feb 2011 Posts: 328	I also have that lens and while mine appears to be "like new" the performance is so that I can make acceptable prints It just can't stand up to pixel peeping at 100%. That is unlike other "oldies" I have and the a-50 you mention is in a different league. But the a-28 was never a lens which is regarded highly on digital, was it?

09-13-2015, 04:23 AM	#7
Iberia Senior Member Join Date: Dec 2012 Posts: 135 Original Poster	Thanks to all for your replies. I shot the following JPEG/sRGB samples with a k-5IIs mounted on a tripod in manual mode at 100 ISO, self-timer and SR off. I left "Using the Aperture Ring" off because I have no intention to set f/ stop on the lens. f/11 - https://farm1.staticflickr.com/690/21192011150_7eafaf19fe_o.jpg f/8 - https://farm1.staticflickr.com/602/21192041060_1d66594e49_o.jpg f/5.6 - https://farm6.staticflickr.com/5661/20757487694_fcc8732d2c_o.jpg Cheers, Ric ---------- Post added 13-09-15 at 12:28 ---------- I chose this lens because I intended to use it using zone focusing on TAv mode for street photography, since manual focus lenses have a stiffer focusing ring that is harder to turn accidentally. Would the FA 28mm perform better or should I skip that as well and go for a Contax or a Leica? I used the Contax SLR system for over a decade in the film days and the image quality was quite good... Ric

09-13-2015, 04:34 AM	#8
manntax Veteran Member Join Date: Jan 2012 Photos: Albums Posts: 1,972	Originally posted by Iberia Thanks to all for your replies. I shot the following JPEG/sRGB samples with a k-5IIs mounted on a tripod in manual mode at 100 ISO, self-timer and SR off. I left "Using the Aperture Ring" off because I have no intention to set f/ stop on the lens. f/11 - https://farm1.staticflickr.com/690/21192011150_7eafaf19fe_o.jpg f/8 - https://farm1.staticflickr.com/602/21192041060_1d66594e49_o.jpg f/5.6 - https://farm6.staticflickr.com/5661/20757487694_fcc8732d2c_o.jpg Cheers, Ric To avoid the repetition, (and before you do anything) take a look here : https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/295986-soft...ml#post3261344

09-13-2015, 04:44 AM	#9
Iberia Senior Member Join Date: Dec 2012 Posts: 135 Original Poster	Thanks, that was useful, although I have on intention of "adapting" to a lens' shortcomings. Cameras and lenses, like screwdrivers, are just tools and if they don't do their job properly they have to go. Earlier this year I used a Canon 28mm pancake on a 7D and a Panasonic 20mm pancake on an OM-D EM-5 and got considerably better results than what I get with this lens... The DA 21mm is not as bad as the A 28mm but it's too wide for my taste. R

09-13-2015, 04:50 AM	#10
glasbak Veteran Member Join Date: Apr 2009 Location: Netherlands Posts: 369	Originally posted by Na Horuk Hm, let's just make sure its working right. First of all.... And before that, make sure no filter is attached to the lens.

09-13-2015, 04:52 AM	#11
manntax Veteran Member Join Date: Jan 2012 Photos: Albums Posts: 1,972	Originally posted by Iberia Thanks, that was useful, although I have on intention of "adapting" to a lens' shortcomings. Cameras and lenses, like screwdrivers, are just tools and if they don't do their job properly they have to go. Earlier this year I used a Canon 28mm pancake on a 7D and a Panasonic 20mm pancake on an OM-D EM-5 and got considerably better results than what I get with this lens... The DA 21mm is not as bad as the A 28mm but it's too wide for my taste. Also remember you are talking about a Takumar-A lens, a budged version of wide angle -there really ARE better options for not much more.. see reviews section

09-13-2015, 05:03 AM	#13
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,475	Please go find a system that is good for taking pictures of brick walls. I'm sure that is the only way you will ever be happy.

09-13-2015, 05:13 AM	#14
Iberia Senior Member Join Date: Dec 2012 Posts: 135 Original Poster	Originally posted by boriscleto Please go find a system that is good for taking pictures of brick walls. I'm sure that is the only way you will ever be happy. If that's your best contribution you might as well be quiet. R ---------- Post added 13-09-15 at 13:15 ---------- Originally posted by manntax Also remember you are talking about a Takumar-A lens, a budged version of wide angle -there really ARE better options for not much more.. see reviews section The lens in question is an SMC Pentax-A 2.8/28mm (see topic title). R ---------- Post added 13-09-15 at 13:23 ---------- Originally posted by Kerrowdown How does the lens perform in normal use and are edges/corners as noticeable with real images... to the point of being unacceptable? I do shoot architecture from time to time but that is not the subject I will be photographing with this lens... Originally posted by Kerrowdown The 28mm was not maybe the sharpest tool in the box, but I wouldn't give up on all the A series lenses based on just this one, others may well fair better. For example... the attached was taken with the 85mm in dull poorish light, handheld and is full sensor size (K20D) with no cropping. That image looks good but unfortunately I have no use for an 85mm lens. Originally posted by Kerrowdown How does the lens perform in normal use and are edges/corners as noticeable with real images... to the point of being unacceptable? It is quite unacceptable, that is why I started this topic. I wish to know if this is a lens problem or if my copy is not functioning properly. I need a high performing lens with 24mm or 28mm focal length for a Pentax body, preferably manual focus for the reason stated above. Cheers, Ric

09-13-2015, 05:32 AM	#15
H. Sapiens Pentaxian Join Date: Feb 2011 Posts: 328	Okay, so now at least we have established you are not basing your judgement on your brick wall test alone. I just had a quick glance at your website, and if our two A-28 are alike, I agree, it is not up to the task. The quality of mine matches yours - a bit fuzzy. Not terrible, but I don't use mine on digital where even da cheap 35mm is much sharper.