Forgot Password
Pentax Camera Forums Home

Show Printable Version Search this Thread
02-19-2013, 12:47 AM   #1
Veteran Member

Join Date: Dec 2012
Photos: Gallery
Posts: 696
Parfocal zoom, hallelujah!

Guess what? I think my K-01 50-200 lens is 'parfocal'.

If this is true, it is REALLY NEAT. Because it means that I can zoom it all the way out... to 200mm... focus carefully... and then it will stay in focus after that at any zoom setting, all the way down to 50mm... without having to touch the focus ring ever again.

Just tested it in dim interior light, with the lens wide-open at f/4, handheld at 1/20, ISO 800. The top pic below shows the image -- after focusing at 200, then zoomed it back down to 50mm ... and the bottom pic shows a 100% crop of the Starbucks cup I focused on... still sharp! So move over, Steven Spielberg. Hollywood, here we come!

Attached Images
02-19-2013, 02:59 AM   #2
Na Horuk's Avatar

Join Date: Feb 2012
Location: Slovenia, probably
Photos: Gallery | Albums
Posts: 11,189
I think you are right. Also, check this thread out:
02-24-2013, 04:04 PM   #3
Veteran Member

Join Date: Dec 2012
Photos: Gallery
Posts: 696
Original Poster
Na -- thanks for that parfocal list!

Today, tested my kit 50-200mm zoom against an older 50mm Pentax A f/1.4... both with the K-01 on A Aperture.

Now, I KNOW the old lens is sharper... and if I had it on M Manual I could stop it down to prove that, but I wanted to see how the K-01 dealt with it in A mode. Took the picture with the focus magnifier set to 6X. Looked nice and sharp on the screen.

Then, I put on the 50-200mm zoom... and focused with it set at 200, again using 6X focus magnification. Wow! You can really get in close. Next, because the 50-200 is a parfocal lens, I just zoomed down to 50 -- without touching the focus ring again -- and the result was a much sharper image than that from the f/1.4.

Not too bad for a kit lens. And easy to do, if you have a few seconds... just zoom out, focus, zoom back in. Parfocal!
Attached Images

  • 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!
focus, k-01, k01, lens, mirrorless, pentax k-01, pic
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
List of Parfocal Zoom Lenses mgvh Pentax SLR Lens Discussion 74 08-28-2015 12:56 AM
sigma 17-50 parfocal? everydaylife Pentax SLR Lens Discussion 1 12-21-2012 11:40 AM
200 zoom versus 300 zoom EyeSpy Troubleshooting and Beginner Help 18 01-08-2012 06:02 AM
Zoom/Power zoom on flashes: why? hray Troubleshooting and Beginner Help 11 03-03-2011 03:02 PM
Is the Pentax or Tamron 18-250 a parfocal lens? BobG Pentax SLR Lens Discussion 7 01-11-2009 08:45 PM

All times are GMT -7. The time now is 08:27 PM. | See also:, 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?
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]