Linear polarizing filter with canon t-90 in center weighted mode

[kingbuzzie]

From what I've read, the center weighted light metering for the t-90 is near the eyepiece, and it is the spot metering that uses a half silvered area. Does that mean I can use a regular polarizing filter (that I already own) is I don't use the spot? The center weighted metering would be in the same location as my A-1 right?

 

[benjiboy]

Wrong, the T90 has a beam splitter and to meter correctly requires a circular polarizing filter.

Sent from my KFOT using Tapatalk

 

[kingbuzzie]

So am I reading this info wrong?

http://t90.tripod.com/metering.html

 

[AgX]

I never thought of that. But most probably you are right as the two cells are located differently to the main mirror.

 

[benjiboy]

No, the light that comes through the polarizing filter that is reflected up off the mirror from whatever sensor has to go through the beam splitterhttp://en.wikipedia.org/wiki/Beam_splitter located at the bottom of the focusing screen that effects the meter reading which is why the T90 according to the instruction manual needs a circular polarizing filter not a linear one to meter correctly as it also does with the New Canon F1.

 

[AgX]

Interesting point. But so far I could not find a hint at a beam splitter at that location. But I did not dissect the finder assembly either...


Best would be just to check with both kind of filters in the three metering modes for any metering deviation.

 

[benjiboy]

I think the whole point of the question is that the OP wants to avoid having to buy the correct filter.

 

[AgX]

I think so too. But in rummage boxes I find so many polarizers of both tastes. Even if not the right size or quality, it would be sufficient for testing.
I'm lacking time, otherwise I would have done a test at different meter settings myself.

 

[RalphLambrecht]

From what I've read, the center weighted light metering for the t-90 is near the eyepiece, and it is the spot metering that uses a half silvered area. Does that mean I can use a regular polarizing filter (that I already own) is I don't use the spot? The center weighted metering would be in the same location as my A-1 right?

why not just try before buying a new filter.the linear polarizer works fine with my Nikons

 

[John Koehrer]

why not just try before buying a new filter.the linear polarizer works fine with my Nikons

Why? The manual clearly says it has to be circular.

 

[AgX]

The spot-metering will be affected by a linear polarizer. That is why the manual advises a circular polarizer.

That does not necessarily mean that the other two metering settings will be affected too.
This is what this discussion is about.

 

[kingbuzzie]

I'll just give it a try it with the linear (that I already rarely use, as I'm a hobbyist). And yes, I'm trying to avoid buying the correct filter, but that's because my T90 is a beater and could go any day now (I already have near mint linear filter for my A-1).

 

[benjiboy]

I'll just give it a try it with the linear (that I already rarely use, as I'm a hobbyist). And yes, I'm trying to avoid buying the correct filter, but that's because my T90 is a beater and could go any day now (I already have near mint linear filter for my A-1).

Why couldn't you have done that in the first place instead of wasting our time ?

 

[AgX]

He put up an interesting idea I did not think of before, and I shall investigate on it.

 

[benjiboy]

He put up an interesting idea I did not think of before, and I shall investigate on it.

The T90 manual states that the camera requires a circular polariser, end of story.

 

[GRHazelton]

Why couldn't you have done that in the first place instead of wasting our time ?

That sounds a little snarky; the exchange might well have been useful for others.

 

[benjiboy]

That sounds a little snarky; the exchange might well have been useful for others.[/QUOT]
It was intended to.

 

[kingbuzzie]

Benjiboy is probably incorrect, so internet logic dictates he be snarky about it instead of having a bit of class.

 

[benjiboy]

, so internet logic dictates he be snarky about it instead of having a bit of class.

Benjiboy is probably incorrect

Read this http://www.butkus.org/chinon/canon/canon_t90/canon_t90.htm, see page 47, I rest my case

 

[John Koehrer]

Yes, Benji, you're correct. In all SEVEN of your responses.

 

[AgX]

Ben, see post #11.


(This reminds me that I wanted to check on that. Someday...)

 

[cuthbert]

Instead of discussing the thread and arguing against each other why can't anybody use a linear filter on the T90, shoot two or three exposure and show the results?

 

[AgX]

You are questioning the Apug-concept...


By the way, this is not about image results as likely seen when posted, but about metering results.

 

[cuthbert]

If the image is fine the metering is fine too, it seems logical to me even though I noticed that some member s here logic doesn't apply, in a book I have on the T90 the author specifically states p-l filters should not be used because they would "fool" the lightmeter, then if I had to challenge that statement I'd shoot one or two shots, if they come out well exposed these filters can be used, that's it.

 

[AgX]

But that would mean spoiling the fun of posting in endless threads. What should Ben and me do then?