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

kingbuzzie · Apr 2, 2015

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 · Apr 3, 2015

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

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kingbuzzie · Apr 6, 2015

So am I reading this info wrong?

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

AgX · Apr 6, 2015

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

benjiboy · Apr 7, 2015

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 · Apr 8, 2015

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 · Apr 8, 2015

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

AgX · Apr 8, 2015

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 · Apr 8, 2015

kingbuzzie said:
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 · Apr 8, 2015

RalphLambrecht said:
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 · Apr 8, 2015

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 · Apr 13, 2015

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 · Apr 13, 2015

kingbuzzie said:
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 · Apr 13, 2015

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

benjiboy · Apr 13, 2015

AgX said:
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 · Apr 13, 2015

benjiboy said:
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 · Apr 13, 2015

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

kingbuzzie · Apr 13, 2015

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

benjiboy · May 30, 2015

kingbuzzie said:
, 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 · May 30, 2015

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

AgX · May 31, 2015

Ben, see post #11.

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

cuthbert · May 31, 2015

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 · May 31, 2015

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 · Jun 1, 2015

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 · Jun 1, 2015

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

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

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