Hi everyone, first post on here! It involves a couple of different questions, so thanks in advance for your attention...
I've recently upgraded from a compact to a used Hugyfot DSLR housing for my Nikon D500 that I already used for topside photography. The purchase included: Sigma 10mm EX DC HSM f/2.8 fisheye lens, 20mm & 50mm extension rings, 6.5" acrylic dome port (note: I do not know if the true diameter of the dome is 6.5"; it is not a full hemisphere, but I don't have it to hand right now to measure).
In addition to this, I already have a Sigma 105mm OS HSM f/2.8 macro lens and a Tamron 10-24mm Di II VC HLD rectilinear wide-angle (both good lenses in their own right - at least above water) that I am hoping to be able to use with the housing.
My first questions are: does anyone have experience using the Sigma macro and Tamron wide-angle lenses underwater, and if so are they worth building my setup with? The Nikkor 105mm VR Micro is the direct competitor of the Sigma, but I would prefer not to have to upgrade if possible.
If they are indeed worth using underwater, does anyone know the correct extension rings for using i. the Sigma with a Hugyfot flat port, and ii. the Tamron with the 6.5" dome port? Hugyfot lens compatibility charts aren't super comprehensive, and I don't trust myself to correctly identify the entrance node of the Tamron. I am also considering selling the 6.5" dome port and getting the 7" fisheye port instead if the dome optics with the Tamron wide-angle would work fine, but I can't find any comparative info using my lenses.
Final question has to do with some wear on the housing anodisation itself. It seems that something rough has come into contact with the rear of the housing and (I think) exposed the aluminium in two small areas (the damage is half the size of a pea). Thankfully the housing was mostly used in a freshwater pool previously, but obviously I want to prevent any corrosion ASAP and would welcome any advice on this. I attach a photo of this damage.