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18.1 - Introduction

This section will describe the most useful filters.

First, we'll cover some basics.

Filter Diameter

You need to find out what size filters to buy.

Lenses have a diameter measured in millimeters (mm).

Look on the inside surface of your lens cap.

The diameter is usually found there.

The lens cap in the photograph below is from a lens with a diameter of 67mm.


Do You Have More Than One Lens?

If you have more than one lens, you can buy filters to fit the lens with the largest diameter.

Then, use a step-up ring to fit the filters onto your small diameter lenses.

For example, let's say your smaller lens has a diameter of 67mm, and your largest lens has a diameter of 77mm.

To fit a 77mm diameter filter onto the 67mm diameter lens, purchase a 67mm to 77mm step-up ring.


Caution #1

Do not screw filters on tightly.

If you do, you may not be able to remove them.

That's because when you grip the filter, the pressure distorts the circular filter into a slightly oval shape that can't be revolved.

If can't remove a filter, gently press the lens with the stuck filter down onto a mouse pad while revolving the camera.

Or, purchase a filter removal wrench.


Caution #2

Only use one filter at a time, especially if you're using a wide-angle focal length.

Two or more filters may block light from reaching the corners of your photographs, causing dark corners.

Filter manufacturers make thin versions of Polarizing filters.

You may be able to use a thin Polarizing filter with a second filter.


If you have more than one filter, purchase filter stack caps or end caps.

Screw your filters together, and then screw the caps onto the stack of filters.