polariser question

[swiftflo]

I have this Hoya Pro1 Digital PL Filter, screw in.On the outer adjustable ring there is a small triangle. Does this triangle denote where the darkest point on the filter is or is it something else.

 

[PhilH04]

Probably just a reference mark, judging the effect is normally through the viewfinder/screen. To use as a reference, if you cannot use a viewfinder or a screen, look through the filter whilst rotating, note where the mark is when you get the effect you want, then screw onto the lens and set the reference mark to the same position.

HTH

 

[chuckles]

There are many factors that dictate how Polarisers work effectively in Photography. But to answer your question, the Index is set to point to the Sun to have maximum effect. However, just turn it to the effect you want! Be aware that for Digital cameras, Circular Polarisers are used rather than Linear.

Here's a good basic guide to all things Filter

 

[HoppyUK]

Some polarisers don't have any mark, but when they do, it's just a reference point and often filters are not actually locked very firmly in position inside their mounts.

The most accurate way to adjust rotation is visually though the viewfinder or rear screen, as it will vary. Easy to see, or with some cameras that adjust brightness of the LCD automatically, check how the exposure settings change. When you've found the position of maximum polarisation, the position of minimum polarisation will be at exactly 90 degrees rotation, and back to max again at 180 degrees.

Circular and linear polarisers work the same in every respect. It's just that linear polarisers are said to upset the metering and/or AF of some cameras, so a circular polariser has a quarter-wave plate on the rear surface that 'depolarises' the light.