Creating a spot meter in a metered M?

[visiondr]

Just a quick question about built-in M meters (M6,7,MP).
Since the meter reads light reflected from the white circle on the first shutter curtain. And that circle's area, position and size determines the area of meter coverage.
Is it possible to black out part of the peripheral area of the circle to create/simulate a spot meter on a metered M?
Has anyone tried this?

 

[Avotius]

It seems to me that it would be a bad choice. Why? If the meter is set to read the area on the white dot then if you black out part of it then doesnt it seem that the camera will be metering black? In other words, really long shutter speeds will be the result.

Just a thought though assuming that the meter only meters that white dot. If it meters the entire plane, then...no problems!

 

[Rafael]

I'm not sure of the answer to your question. But I will say that the M6 meter already behaves very much as a spot meter. I'm not sure how much you would gain by reducing the size of the white dot, especially given the variables involved in framing with an RF.

 

[visiondr]

Hmmm, I may have to think about this.
Assuming that you're correct, then some compensation would be necessary. In that case, you'd have to do quite a few test exposures to determine the appropriate change in shutter speed/aperture combination. Then you could simply set the ISO dial to make the change for an entire roll.

 

[Avotius]

Couldnt you try using some sticky tape and making it black minus a bit in the middle white then stick it on there? Make sure its really thin and flexible. If it doesnt work take it off.

Now that I have said that I think its still a really bad idea. I dont like the idea of monkey'n with the shutter and meter bits on a camera, im not that brave really.

 

[visiondr]

The M6,7,P meters are not spot meters. They act as heavily center weighted meters. I know, I've used them for years.
According to the M6 manual:
"The diameter of the circular measuring field is approximately 2/3 of the short side of the appropriate bright-line frame".
That's not a spot meter in my book.

 

[visiondr]

Couldnt you try using some sticky tape and making it black minus a bit in the middle white then stick it on there? Make sure its really thin and flexible. If it doesnt work take it off.

Now that I have said that I think its still a really bad idea. I dont like the idea of monkey'n with the shutter and meter bits on a camera, im not that brave really.

I really wouldn't like tape coming off and sticking somewhere inside the curtain drums.
I wonder if some thin flat black paint would work?

 

[Rafael]

I didn't say that it was a spot meter, but rather that it behaves similarly to one. Perhaps it would have been more accurate to say that it has strong spot metering tendencies. Anyway, I never meant to imply that you didn't know how the meter behaves. It's an interesting question that you've raised. I look forward to finding out the answer.

 

[Avotius]

Yeah, tape might not be good. A little paint that wont flake when flexed a lot would be better, and if it doesnt work paint another white dot on it?

Or better yet stick that black tape on there just to try out the meter, dont take any pictures, just meter and see the difference.

 

[Roger Hicks]

Not a hope in hell. Vastly reduced sensitivity and it would still be nowhere near spot. Even SLRs are nowhere near true spot meters (1 degree or less).

Cheers,

R.

 

[visiondr]

Roger,
I suspect you're right about the reduced sensitivity. That would probably be the biggest obstacle.

Rafael,
I didn't mean to sound so gruff. You did say the meter is similar to a spot meter and you're correct as it is not at all like average metering.

 

[sepiareverb]

Perhaps you just need a longer lens for the meter cell? 😀

Actually, you need to get an M5 Ron 😀

 

[srtiwari]

It would seem to me that the white dot merely shows the area of coverage. What does painting it black do ? In other words, may be the white paint has nothing to do with its function. One needs to stop all except a small central "spot" from "reading the light", somehow.

 

[Ronald M]

Sure but you will ned to compentate with under exposure. Plus the paint needs to be flexible.

 

[johnastovall]

Why not use use a hand held spot meter?

Seems simpler.

 

[visiondr]

Perhaps you just need a longer lens for the meter cell? 😀

Actually, you need to get an M5 Ron 😀

Ya'know, I've been toying with that idea. A nice three lug chrome M5 would be nice!

Actually the meter cell lens idea is a great one. I imagine a small + lens cemented in front of the current lens could do the trick. Anyone care to DIY that one?

R

 

[srtiwari]

Ronald,
If you were responding to my post, I believe you will not need to compensate, since all you are doing is to reduce the number of readings (from different parts of the dot) going into an average.
If you were not responding to my post, ignore this.

 

[sepiareverb]

...A nice three lug chrome M5 would be nice!...

Wayne, lets get this into the M5 quote list before it's edited away
:angel: :angel: