"Exposed Threads" Front Ports - Optical Glass

The "Exposed Threads" Front Ports by Outex show how to find the thread size in mm for custom filters, not the focal range.

The Outex "Exposed Threads" Front Ports feature optical glass, labeled parts, custom ports, and external threads for filters on DSLR cameras.

Two Outex "Exposed Threads" Front Ports – Optical Glass, with external filter threads, are stacked and slightly overlapping on a white background.

The Outex "Exposed Threads" Front Ports features optical glass for Canon cameras with large lenses and external filter threads, shown in clear protective sleeve.

A brown Outex box with "Exposed Threads" Front Ports - Optical Glass; black waterproof lens cover and Outex branding are visible on the front.

These are "custom" versions of our Front Ports with two important differences:

1. The threads that attach to the lens are exposed. (See Questions page for details)

2. These Front Ports have external, exposed front threads that enable use with Polarizers or external filters. 49-thru-72mm sizes have external threads of 77mm. 77, 82, and 86mm sizes external threads are 89mm, which is not an industry standard, so you can use the Outex 89-95mm Step Up Adaptor with any 95mm filter or polarizer in the market. Product available in Shop By Parts.

Outex front glass works in combination with Outex cover to create a waterproof seal and attaches to a lens filter threads to become one with the lens. Outex patented design is simple, lightweight, and compact. Outex supports all of the industry standard sizes, ranging from 49 to 105mm thread sizes, and users can also utilize step-up rings to accommodate different sizes.

Dome Size Guide

**120mm dome** — Compact, lighter, more portable. Great value for most underwater and split-level work.

**180mm dome** — Larger dome = better optical correction, especially for wide-angle lenses and split-level photography. Recommended for professional and demanding use. Heavier and bulkier than the 120mm.

For a full comparison, visit our [Dome Size FAQ](https://outex.com/blogs/faqs/dome-lens-overview-and-advantages).

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