Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
05-24-2010, 01:51 PM   #1
New Member




Join Date: Apr 2008
Location: Norway
Posts: 17
Is my FA50mm performing ok?

Hi

I have an FA50 f/1.4 and I suspect something is out of order with it. So I compared it to my M-50 f/1.4, and here are the results:

FA50, Iso200, 1/60 sec exposure, f/1,4


M50, Iso200, 1/60 sec exposure, f/1,4


What I did was to set up the camera on a tripod and, with the M50, first put all the settings right and take the photo. Then switched to the FA50 while ensuring nothing was changed. The photos are resized to 50% and cropped.

So what is up here? The poor result of the FA50 surprises me, and it makes me suspect something is wrong with my FA. Having a quick look at the lens reviews here indicate and big design issues. And I also repeated the test to check for user error.

Can someone please comment upon this?



Thanks.

05-24-2010, 02:03 PM   #2
Veteran Member
PentaxPoke's Avatar

Join Date: Jan 2008
Location: Oklahoma
Posts: 1,411
I'm not sure I see the problem. The FA50 looks fine. Especially considering it is wide open where it should be a bit soft. To my eye it also seems to have a gentler and more pleasing transition from sharp center to soft.

Maybe I am missing something.
05-24-2010, 02:11 PM   #3
Pentaxian
jimH's Avatar

Join Date: Apr 2009
Location: South Central Nebraska - USA
Photos: Gallery | Albums
Posts: 1,413
Could be a front focusing problem. It seems to me that the handle on the paper clip is more in focus with the FA50 than with the M50. You might want to try again with strictly center focus on the FA50. Take another look at both photos, that's what I think I see.
05-24-2010, 02:13 PM   #4
Pentaxian
jimH's Avatar

Join Date: Apr 2009
Location: South Central Nebraska - USA
Photos: Gallery | Albums
Posts: 1,413
Looking at it again, I'm not so sure, there isn't much difference between the two on the paper clip handle

05-24-2010, 02:19 PM   #5
Veteran Member
PentaxPoke's Avatar

Join Date: Jan 2008
Location: Oklahoma
Posts: 1,411
I don't see any BF or FF or motion blur at all. To me it just simply looks like the M50 might have slighly better center sharpness at f/1.4. It is relatively small though. The FA may be different in design, with different coatings etc. I don't know enough about the differences between the two lenses.
05-24-2010, 02:20 PM   #6
Inactive Account




Join Date: Mar 2009
Location: Pennsylvania
Posts: 152
Normal. The fa 50/1.4 is just soft like that if wide open.
05-24-2010, 02:29 PM   #7
Egl
New Member




Join Date: Apr 2008
Location: Norway
Posts: 17
Original Poster
It is not a focusing problem. Perhaps its not so easy to see but the rock is fairly flat and in both the samples the point of focus is about in the middle, but perhaps not exactly the same place. However in both the pictures there is something in front and behind the point of focus (the right side being further away than the left).

M-50 has alot more details and more contrast. The difference becomes more obvious at 100% zoom.
05-24-2010, 03:07 PM   #8
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,485
I'm seeing Camera Shake in Both photos. Looking at the handle on the clamp.



05-24-2010, 03:59 PM   #9
Egl
New Member




Join Date: Apr 2008
Location: Norway
Posts: 17
Original Poster
Seems like I can conlude this is normal behaviour then. Good to know. Thanks for the help.

Also I see from Bojidar Dimitrov's pages that the design is a little different in the two lenses.

Im not selling my FA anyway. Im too bad at manual focus. And after all sharpness doesnt really mean much to the total quality in most photos. At f/1.4 its all more or less a blurry mess and that is fine.
05-24-2010, 04:22 PM   #10
Senior Member




Join Date: Jul 2009
Location: Ireland
Posts: 267
I can see a softness that I did not notice with my fa50/1.4 copy. Focus transition imho discounts focus problem. I vote for camera shake.
05-24-2010, 07:46 PM   #11
Senior Member




Join Date: Mar 2010
Location: VA
Photos: Albums
Posts: 227
I think that's CA not shake. If he's getting shake on a tripod at 1/60, we need to revisit mirror slap issue, and no one wants to go there, right?
05-24-2010, 08:00 PM   #12
Administrator
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 40,977
If you want to compare lenses, the circumstances really need to be more controlled IMO. Use MLU and a high shutter speed so as to eliminate shaking as the culprit.

These two photos don't scream "huge difference" at me at all. The FA 50 is a great lens, but it's no FA* wide-open. The 50/1.7 is better there.

Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)



PentaxForums.com's high server and development costs are user-supported. You can help cover those costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

05-24-2010, 10:56 PM   #13
Pentaxian
Dr_who's Avatar

Join Date: Jun 2009
Location: Edmonton, Alberta, Canada
Photos: Gallery | Albums
Posts: 686
If you did set it up on a tripod make sure you turned off camera shake reduction as well.

Also post a photo of somethign further away. This subject looks like its bording the lens min focus distance.
05-25-2010, 04:43 AM   #14
Egl
New Member




Join Date: Apr 2008
Location: Norway
Posts: 17
Original Poster
New test, new result

Hello again

I repeated the test in better light. 1/180 sec shutter time now, and also SR if off. The 2 second shutter delay is on (as yesterday). This time around the differences is much smaller. Still the M remains slightly sharper. There is a tiny bit more sandy texture to the surface, but the difference is really minimal.

What surprises me now is how difficult it is to use these fast lenses wide open. I did these tests at a tripod with live view, and taking several shots and having all the time I want and a static subject. Still its difficult to get it precise.

Anyway, thanks for the help. The difference is absolutely nothing to worry about then.

FA50 at f/1.4


M50 at f/1.4
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
exposure, f/1.4, fa50, iso200, k-mount, m50, pentax lens, sec, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
FA50mm f1.7 bobmaxja Pentax SLR Lens Discussion 9 06-24-2010 11:45 PM
FA50mm F1.4 vs. FA50mm F1.7 switters Pentax SLR Lens Discussion 33 06-24-2010 11:19 PM
FA50mm f/1.4 domfijac Pentax SLR Lens Discussion 11 12-15-2009 10:57 AM
video of K-7 performing firmware update WJGS Design Pentax DSLR Discussion 1 06-19-2009 12:25 PM



All times are GMT -7. The time now is 07:48 PM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top