Finding the Right Filter Size for Your Pentax Lens

Filter size finder: Which filter size does your Pentax lens take?

What filter size does your Pentax lens take?

Start typing the lens (focal length is enough). The filter thread, hood, and where to buy appear below.

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Here are the lens diameters and corresponding filter sizes for Pentax lenses.

I’m concentrating here on lenses that accept screw-in filters on the front. Some lenses, such as very wide-angle or fisheye lenses, don’t have a filter thread on the front and can’t accept this style of filter. And some very long telephoto lenses use a system of drop-in filters at the rear of the lens.

Some focal lengths have multiple lenses, so it’s important to match the other parts of the name. Just because they might have the same focal lengths doesn’t mean that they use the same filter sizes.

If you don’t see your lens listed here and want to find out the filter size, it’s often marked on the lens itself. For a more detailed guide, see my post on finding the lens diameter.

A quick way to filter down from this long list is to use the chart’s search bar to narrow it down by focal length (eg. type in “70-200”).

Pentax lens codes

As you can see from the tables above, over the years, Pentax has used a bunch of different codes in naming their lenses. I’ve put together a guide separate on how to decode Pentax lens codes to know what they mean.

Step-up & step-down rings (the money-saving trick)

You don’t necessarily need to buy a separate filter for every single diameter listed above. In fact, a common money-saving strategy used by pros is to buy filters for their largest lens and adapt them to the smaller ones with step-up rings. (NB: This only makes sense for creative filters like polarizers and ND filters, not for protection filters (UV/Haze, etc).)

For example, high-quality filters are expensive. A pro-grade Circular Polarizer might cost $150. Rather than buying a 52mm version, a 62mm version, and a 77mm version (costing you $450 total), you can simply buy the 77mm filter and use inexpensive rings to fit it onto the smaller lenses.

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These rings come in two varieties:

• Step-Up Rings (Recommended): These allow you to attach a larger filter to a smaller lens thread.
  • Example: If you have a lens with a 52mm thread but want to use your 77mm filter, you would use a 52-77mm Step-Up Ring.
  • Why use them: This is the safest method. Because the filter glass is physically larger than the lens requires, there is zero risk of vignetting (dark corners).
• Step-Down Rings (Use Caution): These allow you to attach a smaller filter to a larger lens thread.
  • Example: If you have a lens with a 77mm thread and try to attach an old 67mm filter using a 77-67mm Step-Down Ring.
  • Why use them: Generally, you shouldn’t. Because the filter is smaller than the front of the lens, you will likely see the black edges of the filter in your image (vignetting), especially on wide-angle lenses. An exception might be if you are switching a full-frame camera into APS-C mode.

I have more information on how to use step-up and step-down filter adapters separately, but the general rule of thumb is: Buy Big, Step Up. It is the most economical way to build a versatile filter kit.

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