Identifying a Minolta filter. It is a polarizing filter but it is not marked as a "Circular"
Posted on: Tue, 02/05/2008 - 2:44am
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Identifying a Minolta filter. It is a polarizing filter but it is not marked as a "Circular"
Hi folks,
I just received my "new" used Maxxum 24mmf2.8 lens which includes two filters made by Minolta. One is a Skylight 1A the other a polarizer which is obviously made for the wide angle lens since the glass extends several mm further than the 55mm screw mount. The stock number on the original box is #7255-210(55)
. . .so far I have been over to Denmark at M. Hohner's excellent database and although this filter is not listed I did find a similar model cpl ending with the -210 designation. It is a 7277-210 77mm cpl filter.
here the link
http://www.mhohner.de/minolta/camera_acc.php#filters
So I tried taking a couple of skyline images with it mounted on the 24mm and on my a100 dslr. Everything seems to work excellently?
My question is: If this was not a CPL filter would it still work on my auto-focus and metering or would it cause me problems? I do not know what to expect from a linear polarizer on the focus system???
Any insight to how this should work and/or if you can confirm this model is a true cpl please educate this old 4x5 camera user?
Thanks,
__________________
Paul
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a100, Maxxum 7,
How to test if it's Circular.....
A "Circular" Polariser actually consists of a polariser in front and a depolariser behind it. Now it's convenient that LCD displays work by polarisation too, or if you have polarised sunglasses they can be used for the test too. The method is to look at the LCD through the polariser then turn the polariser the "wrong" way around and look again. At least one way around it should be possible to make the display darken completely (or the view through polarised sunglasses). If the display darkens with the filter facing both directions, it is not "Circular", if darkening is only observed in one diection, the filter is "Circular".
HTH
Paul.
Thank You Paul,
I used my old HP laptop and was able to make the screen go fully black and then back again with about a 30% turn so it is a real cpl and I am so glad because I got it with the wide angle lens and of course it is a true Minolta branded filter too. . . ;-)
That was a great tip thanks for the help.
Paul
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a100, Maxxum 7,