Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-24-2013, 12:46 AM   #1
New Member




Join Date: Jan 2013
Posts: 3
Light meter on my pentax MX not showing 'correct' exposure

Hi guys, I hope its okay I post here for my first post


I 'inherited' my fathers Pentax MX a few months ago and only recently go around to shooting with it. The light meter works the only problem I have is that its not showing what should be the 'correct' exposure according to the light meter. I adjust the shutter speed and aperture and it would be underexposed then skip straight to over exposed. I have also been carrying around my dSLR to use as a make shift light meter for situations and a scene at 1/500th @ f/8.0 on ISO400 (I'm using Portra 400 in the MX) that is correctly exposed on my dSLR is underexposed according to the Pentax MX.


Does anyone have any ideas on what the problem might be? I'd really like to continue shooting with it but don't want to waste money on film if I'm going to ruin each roll (I have no problem with underexposed imagery but I don't think that the image will be underexposed when I press the shutter)

Thanks in advance

01-24-2013, 01:14 AM   #2
Administrator
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 40,978
Have you tried changing the battery? It could be that it is almost dry.

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:

01-24-2013, 01:19 AM   #3
Junior Member




Join Date: Nov 2012
Posts: 30
pretty sure that it's just the battery – if the light meter still works in low light situations the battery will be empty
01-24-2013, 01:20 AM   #4
New Member




Join Date: Jan 2013
Posts: 3
Original Poster
QuoteOriginally posted by nild Quote
pretty sure that it's just the battery if the light meter still works in low light situations the battery will be empty
I put new batteries in before I started shooting though and was still experiencing the same problem

01-24-2013, 04:12 AM   #5
New Member




Join Date: Jan 2013
Posts: 3
I shoot with an MX too and my light meter recently went bad. After I exhausted everything that was within my comfort level to fix the problem myself, I brought it down to the local camera shop and they repaired in just a couple of days it for 80 USD, along with replacing the light seals and giving it a full tune up. Very worth it in my opinion. Good luck
01-24-2013, 05:11 AM - 2 Likes   #6
Veteran Member
kcobain1992's Avatar

Join Date: Dec 2010
Location: Bucharest, Romania
Photos: Gallery
Posts: 1,409
Exposure value - Wikipedia, the free encyclopedia
And you will not miss an exposure ever again.
01-24-2013, 09:43 AM   #7
Site Supporter
gofour3's Avatar

Join Date: Oct 2008
Location: Vancouver, Canada
Posts: 5,124
The meter probably needs to be recalibrated, so I would send it to Eric for a CLA.
He can also do the light seals, so you will basically have a new camera after he is done.

Here is Eric's web site:

Home

Phil
01-24-2013, 10:23 AM   #8
Site Supporter




Join Date: Jun 2011
Location: Texas
Photos: Gallery
Posts: 1,116
Agree on sending to Eric. The MX meter circuit wraps over the top of the prism, with flat pots to adjust the meter. There are foam pads under the cover on top of this area which turn gummy and foul the pots. Probably just needs cleaning and adjust - and Eric is very reasonable for this.

01-24-2013, 11:58 AM   #9
Veteran Member
Finn's Avatar

Join Date: Feb 2007
Location: Phoenix
Photos: Gallery
Posts: 1,056
Eric fixed the meter on my MX, but after i got it back from him it turned out to underexpose by exactly 2 stops (I calibrated it against a couple of handheld meters). This is actually kind of great, because now I can shoot Tmax 3200 on it with no problems. So I decided not to send it back for adjustment...it's not a bug, it's a feature!
01-24-2013, 12:41 PM - 1 Like   #10
Site Supporter




Join Date: Jan 2010
Location: Michigan
Photos: Gallery
Posts: 2,073
Hit3k
There is one condition where the MX will do do as you describe in normal operation.
If you set iso 800 or 1600, the metering will be disabled below 1/4 and 1/8 sec respectively, and in this case the "under" red led comes on.
So when you shift from 1/8 to 1/15, the leds can change from "under" to 'over" without transition through the yellow and green leds.

But as you mention it is skipping yellow and green at iso 400 and 1/500, then I agree it must be faulty.
01-24-2013, 02:18 PM   #11
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 26,216
I had a similar problem with my KX that I figure was due to a "dry" capacitor. After some use with a fresh battery, the meter set itself right, though I expect that a meter repair is in my future.


Steve
01-26-2013, 03:21 AM   #12
New Member




Join Date: Jan 2013
Posts: 3
Original Poster
Thanks for the info guys. I'd like to send it to Eric however I'm too cheap to pay for international shipping (I'm located in Australia) so I'll source an Aussie camera repair shop.
01-26-2013, 10:57 AM   #13
Junior Member




Join Date: Dec 2012
Location: Brisbane, Australia
Posts: 29
hit3k
before sending it off for service try cleaning the battery compartment and cover with some electrical contact cleaner on a cotton bud/qtip. Jaycar will have it as well as most electrical suppliers like Turks or Ideal electrics. If there is any corrosion evident in there a gentle rub with a pencil eraser helps as well. I also clean the batteries with contact cleaner before inserting them.
if you are going to leave batteries in the camera for extended periods silver oxide cells are much longer lasting than alkalines and seem to have a much more stable discharge over time. Its a real pity we don't have easy access to Eric down under. Hope this helps.
02-27-2016, 08:44 PM   #14
Senior Member
hooverfocus's Avatar

Join Date: Aug 2010
Location: back home
Photos: Gallery
Posts: 188
QuoteOriginally posted by wombat2go Quote
Hit3k
There is one condition where the MX will do do as you describe in normal operation.
If you set iso 800 or 1600, the metering will be disabled below 1/4 and 1/8 sec respectively, and in this case the "under" red led comes on.
So when you shift from 1/8 to 1/15, the leds can change from "under" to 'over" without transition through the yellow and green leds.

But as you mention it is skipping yellow and green at iso 400 and 1/500, then I agree it must be faulty.
Sorry for resurrecting this thread, but thank you for this specific passage. I just popped some ISO800 film in my MX and started flipping out at the weird behaviour until I stumbled upon your explanation.

On a sadder note, though, I still found out that my Eric-CLA'ed MX's meter seems to indicate 1 stop overexposure compared to what is right. I checked against a handheld meter with a freshly installed battery as well as another MX I had lying around which I tested with the same battery and lens as the first MX.

Any thoughts on this? Possible causes, fixes (other than sending it again to Eric, which is a no go because of shipping fees and all)?
03-02-2016, 10:22 AM   #15
Senior Member
Johnny Rod's Avatar

Join Date: Jan 2015
Posts: 115
Adjustment is possible with the pots under the top cover. If you;re unhappy with that then just set the ISO to double the box (rated) speed. Depending on your film and preference, some people set ISO to double box speed on any camera. Overexposure is mostly preferable to underexposure. Two of my old 1960s 35mm rangefinders overexpose by 1-2 stops, more in bright light (hello selenium meters), but are also prone to some stray light on the meter anyway so it's as broad as it's long.
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!
dslr, exposure, light, light meter, meter, mx, pentax, pentax mx, post
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
MX light meter calibration Silasslack Pentax Film SLR Discussion 3 09-20-2012 07:24 PM
Pentax ES II: Light meter does not work in a manual mode ? svn.ictus Pentax Film SLR Discussion 5 09-04-2011 06:47 PM
K1000 exposure meter does not register in low light Capslock118 Pentax Film SLR Discussion 15 10-29-2010 08:29 AM
Light Meter won't work on my Asahi Pentax KX AnthonyG Troubleshooting and Beginner Help 3 12-04-2009 03:14 PM
Asahi Pentax ME, Light Meter not Working MacetheAce Photographic Technique 12 10-04-2008 02:31 PM



All times are GMT -7. The time now is 03:33 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