Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-03-2013, 09:04 AM   #1
Inactive Account




Join Date: Feb 2013
Photos: Gallery | Albums
Posts: 150
SMC PENTAX 1.4/50 mm Aperture on K30

Hi all,

I have a K30 and some kit and Tkumar lenses, every thing works fine, but with the SMC PENTAX 1.4/50 mm I have the following problem.
On video mode it works fine when I move the aperture ring it changes the exposure, the picture in the display gets darker as I go to a higher f stop.
But in Av and M mode, it does not matter where I set the aperture ring, nothing changes in the display, in the metering readings, or in the final picture, it seems to me
that it just stays full open at 1.4 no matter what I do with the ring.
When I take the lens out and I move the ring, it operates properly openning and closing the blades.
Have anyone here have experinced a similar problem? are there some setting or trick that I am missing?

Thanks in advance for any hint you can give me

03-03-2013, 09:28 AM   #2
Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: Liverpool, NY
Photos: Gallery
Posts: 12,309
Manual K-mount lenses work differently than M42 lenses. PKM lenses only work in M mode with stop down metering (Green Button). In AV mode they will always be wide open. You can make them behave like an M42 by removing the aperture lever.

https://www.pentaxforums.com/forums/pentax-beginners-corner-q/110658-using-ma...x-dslrs-f.html
https://www.pentaxforums.com/forums/pentax-beginners-corner-q/60081-usage-green-button.html

K-Mount lenses were designed for open aperture metering from the start. On a non-crippled K-mount camera the aperture information is passed to the camera via a mechanical aperture coupling. The lens is not stopped down until the shutter release is pressed. A crippled K-mount lacks the aperture coupling, so the meter does not know what the aperture is set to. Pressing the Green Button in M mode will stop the lens down and allow the camera to take a meter reading. The camera will then stop down the lens when the shutter release is pressed. (If you have not already done so you will need to set Using the aperture ring to permitted in the Custom menu).

Last edited by boriscleto; 03-03-2013 at 09:36 AM.
03-03-2013, 09:52 AM   #3
Inactive Account




Join Date: Feb 2013
Photos: Gallery | Albums
Posts: 150
Original Poster
QuoteOriginally posted by boriscleto Quote
Manual K-mount lenses work differently than M42 lenses. PKM lenses only work in M mode with stop down metering (Green Button). In AV mode they will always be wide open. You can make them behave like an M42 by removing the aperture lever.

https://www.pentaxforums.com/forums/pentax-beginners-corner-q/110658-using-ma...x-dslrs-f.html
https://www.pentaxforums.com/forums/pentax-beginners-corner-q/60081-usage-green-button.html

K-Mount lenses were designed for open aperture metering from the start. On a non-crippled K-mount camera the aperture information is passed to the camera via a mechanical aperture coupling. The lens is not stopped down until the shutter release is pressed. A crippled K-mount lacks the aperture coupling, so the meter does not know what the aperture is set to. Pressing the Green Button in M mode will stop the lens down and allow the camera to take a meter reading. The camera will then stop down the lens when the shutter release is pressed. (If you have not already done so you will need to set Using the aperture ring to permitted in the Custom menu).
Thanks, then how do I remove the aperture lever, and is it worth doing it?

Thanks
03-03-2013, 10:13 AM   #4
Administrator
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 40,984
QuoteOriginally posted by dltorre Quote
Thanks, then how do I remove the aperture lever, and is it worth doing it?

Thanks
It's not worth doing. You can stop the lens down using the DOF preview button if you want to see what the image will look like when stopped down.

Just follow these steps and you'll be set:
https://www.pentaxforums.com/forums/pentax-lens-articles/110657-how-use-meter...k-x-k-7-a.html


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:

03-03-2013, 11:54 AM   #5
Veteran Member
kcobain1992's Avatar

Join Date: Dec 2010
Location: Bucharest, Romania
Photos: Gallery
Posts: 1,409
QuoteOriginally posted by dltorre Quote
Thanks, then how do I remove the aperture lever, and is it worth doing it?

Thanks
Do not do that!
03-03-2013, 01:14 PM   #6
Inactive Account




Join Date: Feb 2013
Photos: Gallery | Albums
Posts: 150
Original Poster
QuoteOriginally posted by kcobain1992 Quote
Do not do that!
Thanks a lot you all! I got it working now in Manual and using the gree buttom, I can see the shutter speed changing and I can see clearly the different DOF on the picture I am taking.
My question now is do I have to use the green buttom also with Takumard M42? because I see the light intensity changing on the M42 while I move the aperture ring.
Also the gree buttom does not seem to work on Av mode does that mean that Av mode is not usable with manual K mount? and yes it is usable with M42?

Thanks guys
03-03-2013, 01:30 PM   #7
Pentaxian




Join Date: Jan 2010
Location: Vancouver, BC
Posts: 1,421
You've got it. K and M lenses in M mode, green button to meter. M42 lenses in Av mode, stop down to meter (turning the aperture ring).
03-03-2013, 01:39 PM   #8
Inactive Account




Join Date: Feb 2013
Photos: Gallery | Albums
Posts: 150
Original Poster
Thanks for your time and patience!

03-03-2013, 01:44 PM   #9
Veteran Member
kcobain1992's Avatar

Join Date: Dec 2010
Location: Bucharest, Romania
Photos: Gallery
Posts: 1,409
I actually use my M42 lenses in M mode, since I find the metering to be more reliable.
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!
aperture, display, matter, mm, move, pentax, pentax help, picture, smc pentax
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pentax SMC FA 50 mm f/1.4 Standard Autofocus Lens Utkarsh Pentax K-5 4 03-14-2012 03:19 PM
SMC Pentax-A 1:2 50 mm camera janet20 Visitors' Center 2 02-11-2012 02:48 AM
For Sale - Sold: SMC PENTAX-FA 1:1.7 50 mm (Worldwide) Curbster54 Sold Items 5 05-23-2011 04:21 AM
For Sale - Sold: Pentax ME Super (Black) plus 50 mm 1.4 SMC -M Pentax Lens (Worldwide) dutz57 Sold Items 4 11-13-2010 06:25 PM
Sigma 50 mm F1.4 EX DG HSM vs SMC Pentax FA 50 mm F1.4 JoepLX3 Pentax SLR Lens Discussion 27 09-03-2010 09:03 AM



All times are GMT -7. The time now is 11:17 AM. | 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