How to tell if the meter is accurate.

GateCityRadio · 11-27-2013, 10:23 PM

I have 3 K-mount film slr's. A K1000, ME, and ME-F.

I've noticed that the pictures on the ME-F seem to come out darker so I thought I would do a little test to see what all of the cameras read using the same settings and light source ( a lamp ).

First I put my m-50 F2 lens on my ME, set it to 100ASA and F4 and pointed the camera at a lamp. It said the recommended shutter speed would be 1/60
Put the same lens on the ME-F with the same settings and it said 1/125....not good.
Put the same lens on my K1000 with the same settings at 1/125 and the needle was all the way at the bottom....it didn't move to center until 1/15. I kinda suspected that the meter is on its way out on this camera anyway.

Even weirder is I put my super-takumar 50/1.4 (genuine pentax adapter) on my ME-F wide open and it said 1/15...

So are these meters that far off or am I doing something wrong?

**dms** · 11-28-2013, 01:06 PM

The ME-F is giving identical readings--given the difference in f/stops.

Anyway different cameras (particularly older ones) and different lenses will not give same values. That is why one test them and works out an adjustment.

Better test is a uniformly lit wall, gray card, etc. I suggest you set aside a light bulb for exposure testing only, and then decide on the testing setup, and always use same setup.

**dms** · 11-28-2013, 01:08 PM

Oops! Your right about the 50mm f.4. Anyway my comment about testing stands.

Blooze · 12-02-2013, 01:55 PM

I read this advice from Jon Goodman over on Apug. Get's you pretty close. The burning question is how to test if your meter is close.

FS: Olympus OM Special APUG only...plus a burning question answered!

**dms** · 12-02-2013, 05:03 PM

Yes you can make your camera into an incident meter, and the dome shape makes it an equivalent of studio light meter (you can purchase a used Sekonic L398 studio light meter--which is calibrated/precise, and can be used w/ any camera)--but it is not a good test of your light meter--because the material you make the incident meter out of is likely rather variable density--it needs to be the correct amount! I do believe they sell (or they used to) a cover for the lens to do this, and I believe a clip to adapt the weston light meter incident light attachment to a lens was made.

But anyway--first verify the meter is accurate, and if not then get it fixed, or see what e.v. adjustment is needed. Then if you want you can make it into a incident meter--although for about $50. you can get a used Sekonic L398 studio light meter.

Blooze · 12-02-2013, 06:03 PM

Of course. But it's a quick check to see if it's close. I tried it with the same lens on 3 different Pentax SLR's (MX, ME Super, K1000), Nikon D200 and D40, and against my Luna Pro SBC and they all matched each other except the ME. It needed the ISO cut in half which was exactly what I was seeing on the negatives. Of course this was incident reading. They all are close enough with reflective now as well for film. The DSLR meters in matrix mode match my film cameras fwiw.

stevebrot · 12-02-2013, 10:23 PM

- Test against a evenly lit blank white wall and filling the full frame.
- Compare against a known good camera/meter

Steve

11-27-2013, 10:23 PM	#1
GateCityRadio Veteran Member Join Date: Oct 2008 Location: Greensboro,NC Posts: 503	How to tell if the meter is accurate. I have 3 K-mount film slr's. A K1000, ME, and ME-F. I've noticed that the pictures on the ME-F seem to come out darker so I thought I would do a little test to see what all of the cameras read using the same settings and light source ( a lamp ). First I put my m-50 F2 lens on my ME, set it to 100ASA and F4 and pointed the camera at a lamp. It said the recommended shutter speed would be 1/60 Put the same lens on the ME-F with the same settings and it said 1/125....not good. Put the same lens on my K1000 with the same settings at 1/125 and the needle was all the way at the bottom....it didn't move to center until 1/15. I kinda suspected that the meter is on its way out on this camera anyway. Even weirder is I put my super-takumar 50/1.4 (genuine pentax adapter) on my ME-F wide open and it said 1/15... So are these meters that far off or am I doing something wrong?

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11-28-2013, 01:06 PM	#2
dms Site Supporter Join Date: Aug 2011 Location: New York, NY Photos: Gallery Posts: 2,192	The ME-F is giving identical readings--given the difference in f/stops. Anyway different cameras (particularly older ones) and different lenses will not give same values. That is why one test them and works out an adjustment. Better test is a uniformly lit wall, gray card, etc. I suggest you set aside a light bulb for exposure testing only, and then decide on the testing setup, and always use same setup.

11-28-2013, 01:08 PM	#3
dms Site Supporter Join Date: Aug 2011 Location: New York, NY Photos: Gallery Posts: 2,192	Oops! Your right about the 50mm f.4. Anyway my comment about testing stands.

12-02-2013, 01:55 PM	#4
Blooze New Member Join Date: Jun 2012 Posts: 22	I read this advice from Jon Goodman over on Apug. Get's you pretty close. The burning question is how to test if your meter is close. FS: Olympus OM Special APUG only...plus a burning question answered!

12-02-2013, 05:03 PM	#5
dms Site Supporter Join Date: Aug 2011 Location: New York, NY Photos: Gallery Posts: 2,192	Yes you can make your camera into an incident meter, and the dome shape makes it an equivalent of studio light meter (you can purchase a used Sekonic L398 studio light meter--which is calibrated/precise, and can be used w/ any camera)--but it is not a good test of your light meter--because the material you make the incident meter out of is likely rather variable density--it needs to be the correct amount! I do believe they sell (or they used to) a cover for the lens to do this, and I believe a clip to adapt the weston light meter incident light attachment to a lens was made. But anyway--first verify the meter is accurate, and if not then get it fixed, or see what e.v. adjustment is needed. Then if you want you can make it into a incident meter--although for about $50. you can get a used Sekonic L398 studio light meter.

12-02-2013, 06:03 PM	#6
Blooze New Member Join Date: Jun 2012 Posts: 22	Of course. But it's a quick check to see if it's close. I tried it with the same lens on 3 different Pentax SLR's (MX, ME Super, K1000), Nikon D200 and D40, and against my Luna Pro SBC and they all matched each other except the ME. It needed the ISO cut in half which was exactly what I was seeing on the negatives. Of course this was incident reading. They all are close enough with reflective now as well for film. The DSLR meters in matrix mode match my film cameras fwiw.

12-02-2013, 10:23 PM	#7
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	- Test against a evenly lit blank white wall and filling the full frame. - Compare against a known good camera/meter Steve