SLR housing with glove for cameras and strobe

For your kind of application, we would recommend one of the following ewa-marine housings, depending on the lens you have and intend to use. Both housings are designed for cameras like the Canon EOS 1D or 5D, 80D, the Nikon D510 or D5 and the Leica S-Series:

U-BFX100

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ewa-marine U-BFX100 SLR underwater housing left side for use with short lenses. Normally these would be shorter, fixed focus lenses.
for lenses with 77mm and 82mm filter thread
(smaller lenses can be used with the correct step-up adapter)

U-BFXZ100

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for use with larger zoom lenses
for lenses with 77mm and 82mm filter thread
(smaller lenses can be used with the correct step-up adapter)

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If you want to use multiple bodies in the housing, please keep in mind, that you can always use a smaller boddy in a larger housing. But using a large body in a housing that we consider too small will likely lead to the housing failing some time in the future, even if it seems to work, with a squeeze, the first few times.
Using a smaller camera in a larger housing poses no risks, but will defenitely decrease ease of handling and ergonomics a bit.