Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
05-06-2012, 04:09 AM   #1
New Member




Join Date: Apr 2012
Posts: 10
Pentax 67 TTL metering in auto and manual

Hi,

I have a probably very basic newbie question about how to use the meter of my Pentax 67 TTL pentaprism correctly with the lens in manual and auto mode. I'm a little confused here since the meter is showing different readings according to what mode I am in (that is it reads more light when in auto mode)... and I am not sure if this is right..

So, basically, do I have to meter the light in manual mode to get a proper reading and only set the lens to auto if I want to set the focus with a brighter viewfinder? Or should I be able to have the lens in auto mode all the time, and get correct light metering from the pentaprism? (probably not, right?)

I guess this is a very stupid, basic question for all veteran users

H

05-06-2012, 06:12 AM   #2
Den
Veteran Member
Den's Avatar

Join Date: Jan 2012
Location: California
Posts: 927
The lens needs to be set in AUTO mode for the prism to read correctly.
Go here for the manual: http://www.pentaximaging.com/support/download-details/579

Last edited by Den; 05-06-2012 at 06:25 AM.
05-06-2012, 06:29 AM   #3
Giveaway winner!
MysteryOnion's Avatar

Join Date: Dec 2007
Location: beantown
Photos: Albums
Posts: 889
Hello H,

It is good to check with the manual as Den points out, but the difference in readings is sometimes due to either a slightly oxidized contact either under the prism or inside the camera where the voltage is activated from the pin inside the release pin. Depending on age and use, it is possible that one half of the meter is showing signs of component failure. Usually the AUTO side is likely to go out first. The difference you mentioned, have you check to see which side seems correct?
05-07-2012, 12:18 AM   #4
New Member




Join Date: Apr 2012
Posts: 10
Original Poster
Thanks to both of you.
Ok, Auto setting it is. I compared with another light meter and the readings seem to be correct in AUTO mode.
But then, what is MAN mode for? The manual said, it's for use with accessories between body and lens that require stop-down metering. I have no idea what that might be.. But maybe I don't need to, since - obviously - I don't have such accessories ...

BTW, Mystery Onion, I'm still working on that on/off switch. I will be back home this week and have my measuring and soldering equipment... So hopefully I will be able to fix this. It still doesn't switch off no matter what mode I'm in. I can't really do anything but to take out the battery - and leave it out of the camera for quite some time, otherwise it will be on again as soon I put the battery back in. (Taking off the lens, switches it off as well, but the same here, as soon as the lens is back on again, the meter is on ... :evil:

05-07-2012, 12:25 AM   #5
New Member




Join Date: Apr 2012
Posts: 10
Original Poster
and by the way, it's a considerable difference in reading ... getting bigger the higher the f-stop number
05-07-2012, 10:13 AM   #6
Giveaway winner!
MysteryOnion's Avatar

Join Date: Dec 2007
Location: beantown
Photos: Albums
Posts: 889
bienemaya, the meter still stays on if you pop off the TTL and back on?
05-07-2012, 10:44 AM   #7
New Member




Join Date: Apr 2012
Posts: 10
Original Poster
oh, I haven't checked that.. The camera is at a friend's at the moment, who knows his way around electronics and soldering components far better than me. Do you happen to have any schematics of the TTL's circuit board?
05-07-2012, 10:56 AM   #8
Pentaxian




Join Date: Feb 2009
Location: Arizona
Posts: 868
Only use the manual mode if you are using a lens with a manual diaphragm (400mm, 600mm Takumar etc.) or using the helicoid extension tube.

05-08-2012, 06:23 AM   #9
Giveaway winner!
MysteryOnion's Avatar

Join Date: Dec 2007
Location: beantown
Photos: Albums
Posts: 889
bienemaya, I have not an up to date info copy of the first version of the camera and first version of the TTL. I'm currently mapping the circuits myself, but have not the time to finish. If your friend is good with electronics, could you ask him what he thinks the BA705 is for? It looks like a regulator or amplifier, but I have yet to see it in a flat circuit layout form.

Thanks... sorry I could not help with up to date circuits, but if you would like, I can scan a copy of the old version maybe as a guide.
05-09-2012, 01:59 AM   #10
New Member




Join Date: Apr 2012
Posts: 10
Original Poster
MysteryOnion,

I will ask him. Though it might take a while, cause I don't know when he will have time for my TTL and he usually does electronics for audio gear..
If you could scan me a copy of the old version, that would be really great!
05-09-2012, 05:37 AM   #11
Giveaway winner!
MysteryOnion's Avatar

Join Date: Dec 2007
Location: beantown
Photos: Albums
Posts: 889
I'll start scanning and let you know when ready.
05-10-2012, 06:08 AM   #12
New Member




Join Date: May 2012
Posts: 2
The camera's battery is 6V, so BA705 indeed sounds like a regulator (5V).

Found this:
"The BA705 is an advanced lamp current feedback dimming control IC. This ballast control IC provides all of the necessary features to implement wide range dimming control, soft start and constant power consumption for intelligent electronic ballast systems. ..."

Will have to look more closely for a datasheet.
05-10-2012, 06:22 AM   #13
Giveaway winner!
MysteryOnion's Avatar

Join Date: Dec 2007
Location: beantown
Photos: Albums
Posts: 889
Thanks WillyTheBee, I've looked a few months back and never found it, however the data sheet is still hard to find.
05-10-2012, 08:49 AM   #14
New Member




Join Date: May 2012
Posts: 2
I looked around and can't find the data sheet either. MysteryOnion, if you happen to find it (could even be in Japanese), please let us know. I read Japanese, so that shouldn't be a problem.
05-10-2012, 10:20 AM   #15
Giveaway winner!
MysteryOnion's Avatar

Join Date: Dec 2007
Location: beantown
Photos: Albums
Posts: 889
I sure will. Thanks
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!
auto, camera, lens, light, meter, mode, pentaprism, pentax, pentax 67 ttl, pentax help, photography, question, ttl
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Manual Metering on Pentax DSLRs with Manual and Automatic Lenses Adam Pentax DSLR and Camera Articles 20 01-06-2016 03:38 AM
Pentax 6x7 TTL meter only works with stopped-down metering trip9 Pentax Medium Format 14 08-11-2011 08:22 PM
P-TTL/Auto/Manual Flash Recommendation Please geekette Flashes, Lighting, and Studio 5 05-13-2011 11:52 AM
Auto Lenses on Pentax Kx..stop down metering..HELP CLYNN0928 Pentax DSLR Discussion 7 11-10-2010 03:54 AM
camera metering with an auto/ttl flash jshurak Flashes, Lighting, and Studio 3 03-04-2008 01:48 PM



All times are GMT -7. The time now is 01:16 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