Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-03-2008, 05:51 PM   #16
Inactive Account




Join Date: Sep 2007
Location: Calgary, AB
Photos: Gallery
Posts: 942
Great post! Missed it somehow the first time 'round. I'm still on the f1.2 fence. I'll have to 'get bored' of the Nokton first before the LBA will urge me to venture farther out (something tells me it might not take too long to get curious tho, heh).

Kelly

10-08-2008, 05:20 PM   #17
Veteran Member
deejjjaaaa's Avatar

Join Date: May 2007
Location: steel city / rust belt
Posts: 2,046
ОК, some examples taken @ 1.2 to show whether it is sharp/not sharp wide open.

Camera = Pentax *istDL (no SR of course), hand held (1/200, no need for SR), manual MF (trap/catch in focus was not used) using split prism focusing screen, ISO200, distance to the target = ~3ft.

1:1/100% image - no cropping, no resizing, no PP, just saved to .JPG - Adobe Photoshop CS3/ACR 4.6 beta was used - essential raw conversion parameters are shown below too (click 'em).



big file - click & click



one more - click & click





Last edited by deejjjaaaa; 10-08-2008 at 06:18 PM.
10-08-2008, 09:24 PM   #18
Veteran Member




Join Date: Feb 2008
Location: Toronto
Posts: 3,915
Original Poster
i was wondering how you got it so sharp, but you've got the "cheats"
looks good tho, but taking pictures of words is easy because it's easy to evaluate sharpness :P

i ended up selling the lens. didn't really know how to apply the thin DOF and i was too inaccurate. didn't want to mess around with installing a split prism screen with the shims and all that stuff. personally prefer using my FA77 for thin DOF applications
10-08-2008, 11:43 PM   #19
Pentaxian
Class A's Avatar

Join Date: Aug 2008
Location: Wellington, New Zealand
Posts: 9,193
Thanks, K100D. That was a fabulous posting!

10-09-2008, 12:44 AM   #20
Senior Member




Join Date: Nov 2006
Location: Downunda
Photos: Gallery
Posts: 212
As another K50/1.2 owner, I'd like to toss in my thoughts about this lens and the digital bodies. As others have noted, at f/1.2 the dof is razor-thin, and this highlights any issues with focusing accuracy. I've used this lens successfully on my LX. I've also used it on *istDS, K10D and K20D bodies, including with a KatzEye screen, and I have not been able to focus it accurately.

I think the problem is that the focusing screen in the digital bodies is not placed accurately at the correct height. The bodies are optimised for auto-focus, which works independently of the focusing screen. I use a tripod, and I can see when the image is correctly focussed on the focusing screen, but the image doesn't come out correctly focused. Live-view backs this up.

What do others think?


PS - I still love the way this lens draws!


Last edited by ChrisN; 10-09-2008 at 12:52 AM.
10-09-2008, 01:14 AM   #21
Pentaxian
fearview's Avatar

Join Date: Apr 2008
Location: Jakarta
Photos: Gallery
Posts: 1,067
QuoteOriginally posted by k100d Quote
i was wondering how you got it so sharp, but you've got the "cheats"
looks good tho, but taking pictures of words is easy because it's easy to evaluate sharpness :P

i ended up selling the lens. didn't really know how to apply the thin DOF and i was too inaccurate. didn't want to mess around with installing a split prism screen with the shims and all that stuff. personally prefer using my FA77 for thin DOF applications
i dont know you alreay sell the a 1.2 brother..
10-09-2008, 07:19 AM   #22
Veteran Member
deejjjaaaa's Avatar

Join Date: May 2007
Location: steel city / rust belt
Posts: 2,046
QuoteOriginally posted by ChrisN Quote
As others have noted, at f/1.2 the dof is razor-thin
it is NOT razor-thin @ portrait distances... finger-thin, yes - but not razor-thin... anybody w/ split-prism focusing screen will not have any issues
10-09-2008, 07:27 AM   #23
Veteran Member
deejjjaaaa's Avatar

Join Date: May 2007
Location: steel city / rust belt
Posts: 2,046
QuoteOriginally posted by ChrisN Quote
I've also used it on *istDS, K10D and K20D bodies, including with a KatzEye screen, and I have not been able to focus it accurately.
I have no issues w/ cheap focusing screen, manually cut from Minolta X700 OEM, in cheapest Pentax body... KatzEyes screens are not always flawless, they might be using CNC to cut them from OEM screens, instead of doing that by hand and certainly their OEM source is better than old stock of Minolta focusing screens (or K1000s in case of jinfinance) - but your copy might be just not exactly good enough (if you claim that the same copy functions identically in 3 different bodies)

10-09-2008, 07:39 AM   #24
Veteran Member
deejjjaaaa's Avatar

Join Date: May 2007
Location: steel city / rust belt
Posts: 2,046
QuoteOriginally posted by k100d Quote
didn't want to mess around with installing a split prism screen with the shims
there are screens that require shims and screens that don't, based
on thickness of the source... cheap screens cut from Pentax K1000 do require shims, but cut from Minolta X700 do not... I had both... if you did not have a split prism focusing screen installed to use w/ that lens then certainly I can understand you selling it
10-09-2008, 08:11 AM   #26
Veteran Member
troyz's Avatar

Join Date: May 2008
Posts: 389
QuoteOriginally posted by ChrisN Quote
As another K50/1.2 owner, I'd like to toss in my thoughts about this lens and the digital bodies. As others have noted, at f/1.2 the dof is razor-thin, and this highlights any issues with focusing accuracy. I've used this lens successfully on my LX. I've also used it on *istDS, K10D and K20D bodies, including with a KatzEye screen, and I have not been able to focus it accurately.

I think the problem is that the focusing screen in the digital bodies is not placed accurately at the correct height. The bodies are optimised for auto-focus, which works independently of the focusing screen. I use a tripod, and I can see when the image is correctly focussed on the focusing screen, but the image doesn't come out correctly focused. Live-view backs this up.

What do others think?
Others think they have the same problem as you:

https://www.pentaxforums.com/forums/pentax-dslr-discussion/35884-front-focusi...n-curable.html

The cause could be manufacturing variation in screens (deejjjaaa's theory?) or in the bodies (Wheatfield's theory).

Kinda hard to tell which because there is great variation in user tolerance for focus error!

The fix, in any case, is to change out a shim in the viewfinder assembly.
10-09-2008, 08:16 AM   #27
Veteran Member
deejjjaaaa's Avatar

Join Date: May 2007
Location: steel city / rust belt
Posts: 2,046
QuoteOriginally posted by troyz Quote
The cause could be manufacturing variation in screens (deejjjaaa's theory?) or in the bodies (Wheatfield's theory).
you can also bend the metal framing holding the focusing screen during the installation process... that framing is not exactly rock solid
10-09-2008, 08:17 AM   #28
Veteran Member




Join Date: Feb 2008
Location: Toronto
Posts: 3,915
Original Poster
QuoteOriginally posted by deejjjaaaa Quote
there are screens that require shims and screens that don't, based
on thickness of the source... cheap screens cut from Pentax K1000 do require shims, but cut from Minolta X700 do not... I had both... if you did not have a split prism focusing screen installed to use w/ that lens then certainly I can understand you selling it
haha deejjjaaaa, i remember a while back we were talking focusing screens and i almost got one. but didn't want to bother with the "operation" and at that time i started using my spot meter a lot so didn't want that to mess up.

QuoteOriginally posted by fearview Quote
i dont know you alreay sell the a 1.2 brother..
yeah ... i like that range of focal length from about 60-115 so this lens fits right in there, but i didn't really enjoy the manual focusing part of it. as well, on the K100D, the A50 1.2 is kind of unbalanced. and i couldn't find a 52mm hood that looked cool on the lens. it was a lot of money i put into the lens and if i wasn't using it, might as well let it go to someone who can make the best of its abilities.

some nice photos there ogl ... i did some pixel peeping and it looked pretty decent to me. just like deejjjaaaa's newspaper sharp.
at 1.2 you get a bit of the "glow" going on too which can add a nice effect when used well
10-09-2008, 08:19 AM   #29
Veteran Member
deejjjaaaa's Avatar

Join Date: May 2007
Location: steel city / rust belt
Posts: 2,046
QuoteOriginally posted by ogl Quote
это наша родина, сынок (ц) анекдот... извини, не удержался :d
10-09-2008, 08:27 AM   #30
Veteran Member
deejjjaaaa's Avatar

Join Date: May 2007
Location: steel city / rust belt
Posts: 2,046
QuoteOriginally posted by k100d Quote
and i couldn't find a 52mm hood that looked cool on the lens.
now we are talking... how about that one (in memory of WendyB, I think I saw this picture in her topic about buying A50/1.2 for like couple of bucks):



it is cool, isn't it ?
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!
50mm, a50, focus, forum, iso, k-mount, lens, lenses, m50, pentax, pentax lens, photos, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
People A Few Photos With a Pentax-F 50mm f/1.7 AF Big Dawg Post Your Photos! 9 03-13-2010 04:28 PM
South Luangwa NP, long series of photos tcom Post Your Photos! 171 10-27-2009 12:26 AM
how long do you work on photos for a job? pete_pf Photographic Technique 8 09-25-2008 08:04 AM
Long walk - lots of photos scott-devon Post Your Photos! 9 05-25-2008 03:21 PM
Saturday Walk.. (long post many photos) scott-devon Post Your Photos! 7 06-24-2007 07:56 AM



All times are GMT -7. The time now is 05:14 PM. | See also: NikonForums.com, CanonForums.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