Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
06-17-2020, 07:58 PM   #1
New Member




Join Date: Jun 2020
Posts: 2
Spotmatic F with SMC Takumar Lens Open Aperture Metering Issue

Hello,

I recently got a Spotmatic F with an SMC Takumar 1:1.8/55 lens because I read that I would be able to do open metering instead of having to stop down before every shot.

I noticed that when I adjust the shutter speed, the meter will sometimes jump from the very bottom to the very top and never stay in the middle. Also the meter does not move when I adjust the aperture unless I stop down the lens.

Is this an issue with my lens? The camera seems to work fine with my Helios 44m when I use it in stop down metering mode, so I'm not sure if it's something with the connector that is supposed to allow me to do open metering with my SMC Takumar lens.

Should I just stop down my future shots with my SMC Takumar on my spotmatic F or will the meter not be accurate doing this?

---------- Post added 06-17-20 at 08:16 PM ----------

Nevermind, I just tested it some more and I was just way overexposed, when I readjusted the shutter speed, the aperture did function correctly when open metering

06-17-2020, 09:59 PM   #2
Otis Memorial Pentaxian
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 37,371
QuoteOriginally posted by erikcorneau Quote
The camera seems to work fine with my Helios 44m when I use it in stop down metering mode
Welcome to the Pentax Forums!

I'm glad you got your problem with the SMC Tak figured out, but I would caution in regards to the Helios 44M and other non-Takumar lenses with your SP F. The SP F camera manual is a bit indirect in how it is stated, but they designed the camera to work with Asahi-made lenses, both the S-M-C/SMC Takumar and and previous Super Takumar models. How and why this is relates to the open-aperture metering feature and how the mount was constructed to make it work. Below is a labeled photo of the SP F mount...



Number 4, labeled "Tab for relative aperture detection" is designed to engage a coupling on S-M-C/SMC lenses to relay aperture ring position to the meter. This is something that happens just before the lens snugs against the mount face. On other rotations, the silver aperture actuator pin is intended to smoothly pass through the deep slot in the tab without catching. On Asahi-made lenses, this happens quite nicely for both the S-M-C/SMC and earlier models having the pin.

Unfortunately, lenses from other makers may not work properly with this feature. My Helios 44M is one such lens in that the pin is fatter than that used by Asahi and will catch on the coupling on its last rotation rather than passing through the slot. While attaching the lens, this is felt as fairly stiff resistance just as the silver "A"/"M" switch is moving across the top of the mount. If this happens, don't attempt to turn the lens further. There is risk of damaging the body coupling and/or the lens becoming stuck on the body.

I will send you a private message as well.


Steve
06-18-2020, 05:16 PM   #3
New Member




Join Date: Jun 2020
Posts: 2
Original Poster
QuoteOriginally posted by stevebrot Quote
Welcome to the Pentax Forums!

I'm glad you got your problem with the SMC Tak figured out, but I would caution in regards to the Helios 44M and other non-Takumar lenses with your SP F. The SP F camera manual is a bit indirect in how it is stated, but they designed the camera to work with Asahi-made lenses, both the S-M-C/SMC Takumar and and previous Super Takumar models. How and why this is relates to the open-aperture metering feature and how the mount was constructed to make it work. Below is a labeled photo of the SP F mount...



Number 4, labeled "Tab for relative aperture detection" is designed to engage a coupling on S-M-C/SMC lenses to relay aperture ring position to the meter. This is something that happens just before the lens snugs against the mount face. On other rotations, the silver aperture actuator pin is intended to smoothly pass through the deep slot in the tab without catching. On Asahi-made lenses, this happens quite nicely for both the S-M-C/SMC and earlier models having the pin.

Unfortunately, lenses from other makers may not work properly with this feature. My Helios 44M is one such lens in that the pin is fatter than that used by Asahi and will catch on the coupling on its last rotation rather than passing through the slot. While attaching the lens, this is felt as fairly stiff resistance just as the silver "A"/"M" switch is moving across the top of the mount. If this happens, don't attempt to turn the lens further. There is risk of damaging the body coupling and/or the lens becoming stuck on the body.

I will send you a private message as well.


Steve
I did notice some resistance when I screwed on that lens, going forward I'll just keep that one on my original spottie.

thanks for the in depth explanation!
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, camera, issue, lens, lens open aperture, meter, pentax help, photography, shutter, smc, smc takumar lens, spotmatic, takumar, troubleshooting
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Force aperture wide open in M mode without aperture ring? Igor123 Pentax DSLR Discussion 12 11-06-2016 06:32 AM
Spotmatic F Open Aperture Metering SeventyCam Pentax Film SLR Discussion 1 06-18-2013 06:58 PM
Spotmatic F - open aperture metering filmamigo Pentax Film SLR Discussion 12 03-19-2009 06:47 AM
Spotmatic F Takumar metering question drewdlephone Pentax Film SLR Discussion 5 12-31-2008 05:28 AM



All times are GMT -7. The time now is 05:49 AM. | 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