Why do some cameras give you perfect exposures (and why don't the others)?

[RobC]

I have a series of ND filters for testing this but it isn't easy to do.

Why not?

 

[cliveh]

Because you are at one with the instrument.

 

[MartinCrabtree]

Is Quality Light Metric still in business? I would like to have my Minolta Spotmeter F looked at since it is about 20+ years old and I'm not sure if it has retained calibration/linearity.

No idea who is still around that is qualified.

Mine was done 5 years ago. The phone number is 323-467-2265. His most recent yelp review is from March 2015 so I'd say he's still open.

 

[RobC]

all things are relative and no less so in photography. Providing your meter responds in stop increments through its range then that is fine. Your EI testing will factor in any consistent error of say a 1/3 of a stop across the range. So why would you expect your spot meter to be as accurate as a fully calibrated lux meter. If you need that level of precision then buy a lux meter and compare your spot meter to the lux meter. But I have no idea why you would need that level of accuracy for a photographic meter unless you are doing scientific work and if you were, you wouldn't be using a minolta Spot Meter F.

Infact you can probably buy one these new and use it as your reference. They are cheap enough and bargains are to be found for new ones if you look around and would cost marginally more than getting your spot meter looked at.
Then you can just adjust your monitor brighness from black to white taking readings with both meters and compare the readings. Voila you have an accurate way to test your spot meter with a new factory calibrated lux meter.

http://www.bhphotovideo.com/c/produ...401_346_Illuminometer_i_346_Light_Meter.html#!

 

[Ian Grant]

All my cameras give me perfect exposures, it's all about how you use meters whether hand held or the camera's own which may be TTL or just a Selenium or CDS cell coupled or sometimes uncoupled (Pentax SIa, Zenit E etc).

Of course that assumes that the shutter speeds are all OK which in my case they are with all the LF lenses I use.

Ian

 

[OptiKen]

Because perfection is a rare and beautiful thing.

 

[RobC]

the sekonic lux meter will also allow you to set your IPad screen to a specific lux output for your other testing by adjusting brightness until you get the lux you are wanting to use.

And I note you have been quoting a lux seconds value of 0.8. I have no idea where you get that value from. Reciprocity kicks in for most films at around lux seconds 10-3 (1/1000 second and shorter).

 

[RobC]

if you search for "lux meter" in amazon you get loads of cheap meters.

https://www.amazon.com/s/ref=nb_sb_...url=search-alias=aps&field-keywords=lux+meter

it begs the question, why are photography light meters so damn expensive. If you have the lux values for EV in your head or carry a little lux to EV chart with you, then one of these cheap meters is all you would ever need instead of paying 10 or 20 times as much because its for photography.

 

[RobC]

the sekonic lux meter will also allow you to set your IPad screen to a specific lux output for your other testing by adjusting brightness until you get the lux you are wanting to use.

And I note you have been quoting a lux seconds value of 0.8. I have no idea where you get that value from. Reciprocity kicks in for most films at around lux seconds 10-3 (1/1000 second and shorter).

apologies I mis-read what you you used which was infact .008 lux seconds.

 

[Vaughn]

I find that all my cameras tend to expose very close to what I set them at...and most of the time I set them pretty close to what they should be. A second or under can be a little dicey with barrel lenses...