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Selecting the Front Glass Sizes - Outex Front Lens

Selecting the right optical glass underwater port for your camera lens

The Outex front glass ports match your lens’ filter thread diameter size. This design optimizes the optical positioning of the Outex port so that it becomes one with the lens in use, just like a filter, or polarizer would. It moves withe lens, so it's always in the best optical position for image capture, eliminates vignetting, and you can focus on content creation rather than the equipment. All/any of our ports are interchangeable, including the domes, and we support all/any industry standard size.

The front lens filter thread size is different from your focal length or zoom range (See images below). The Outex front glass will thread onto your lens just like a UV filter or polarizer.

The filter thread size usually matches your lens cap size in millimeters, and it's usually printed/written somewhere on your lens (front or side), or on the lens cap - depending on the brand/make/model lens with the symbol "⏀", such as ⏀77. 


selecting the front glass for your Outex kit


Selecting the Right Size Outex Front Glass Optical Lens


Selecting the Outex front glass size based on filter thread diameter size

Outex front ports are made of glass - not acrylic or plastic.

All Outex front glass ports use professional-grade optical glass (not acrylic/plastic), and are American made (not made in China). Outex products offer all of the industry-standard sizes, and you can use our PRODUCT page drop-down menu to look for the matching number on your lens if that helps you.

  • Don't confuse the thread size with a lens focal length (and/or zooming range).  In the example below, you have a focal length/zooming of 24-105mm and the lens has a 77mm filter thread size.   The other numbers indicate the focal length, F-stop, aperture ranges, etc.
  • All of our font glass solutions work with all/any of our cover sizes, and you can purchase as many as you need to use with the same Outex housing/cover, or kit - same kit, multiple front glass covers.
  • Outex also works with UNthreaded, fixed-hood, or fisheye lenses.  For those, you will need an Outex Dome Lens, which like the rest of our system is modular.  Consult our FAQs and NEWS pages for additional information.
  • If still in doubt, search the internet for your exact make & model, then look under specifications for filter thread size. Contact us if you have any questions. The Outex system is also compatible with step-up rings, which we also sell in any/all sizes.  Just add it/them to your shopping cart and let us know the sizes you need.  However, we don't recommend stacking step up lenses as it may result in vignetting - especially in wide-angle lenses.  Just get the sizes you need to match each lens to avoid that problem.

Outex front glass size selection based on filter thread sizes

Purchase as many Outex front ports as you need in Shop By Parts to match your lenses.  They are exchangeable and fit all cover sizes.  

Step Up Rings

Step up rings can be used inside Outex front glass ports with lenses that have filter threads. We offer every/all industry standard sizes thru our Shop By Parts online store, or you may use your own, making the Outex system compatible with every lens made.

Keep in mind that step up rings introduce physical distance between your lens and the Outex port, which MAY cause vignetting on wide-angle focal-lengths (specially wider than 24mm). By using the correct Outex front port, you eliminate vignetting. So think of using step up rings as a "cheat". It's cheaper than having the right size front glass port, but may introduce vignetting. It's your choice. We don't make/sell step down rings - only step up rings - as step down rights introduce vignetting 100% of the time at every focal length by restricting the lens' required field of view.

Follow the Installation page critical steps not to over-thread step up rings, filters, or polarizers onto the Outex front ports, just like you don't want to over-tighten the port onto the lens.


Lenses withOUT filter threads 

If your lens does not accommodate filters and therefore does not have filter threads, as is common with fisheye, curved, and hooded lenses, you will need to use the Outex Domes. Both/either domes work on any/all lenses thru adaptors or clamps that optimal position and secure the dome to your un-threaded lens. There are several pages about domes in our Questions page. 

Lenses without filter threads require Outex Dome ports

Flat vs dome ports of the Outex underwater housing system

The above photo show 2 Pro Kit systems, showing the Flat vs. Dome ports in use.

Like the flat ports, the Domes are interchangeable with any/all of the covers and accessories, and can be used independently. There are several entries on the differences between flat vs. dome ports in our Questions pages.

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