FYI Ikelite + Sigma 150mm = very very tight fit

I just got my replacement gear from my flood of last month. I replaced my Canon 100mm macro with the Sigma 150mm macro.

Dimensions for the 150 are

Length 5.4" (137mm)

Maximum Diameter 3.1" (80mm)

Weight 2 lb (895 g)

Compaired to the canon

Length 4.7"

Maximum Diameter 3.1"

Weight 1.32 lb

Now the Canon was a tight fit in an Ikelite port with takes a maximum lens diameter of 3.2 inches. Since the specs claim same diameter I figured it was worth a try.

Well it fits, sort of.

If you just put the port over the lens the lens fits in there easy.

But when the camera is in the housing not so much. The "maximum diameter" may be 3.1 inches but thouse 3.1 inches isnt centered around the center of the lens. The AF range button sticks out quite a bit on the left side of the lens.

You can push the port over the lens and get it to seal with the housing without too much force BUT you can tell that the port has pushed the lens off center. You look at the front of the port and the lens isnt centered, it is off to the left.

Ill be diving next week and Ill find out then if the slight non parallelness between the front element and the port effects the image quality or anything else. I'm optomistic but am slightly worried that this may not work.

So moral fo the story, if you were planning on getting a 150mm macro for your Ikelite housing, wait untill I get a chance to try it out.

William, O-ring's are designed to substain equal or even pressure, the fact the port has pressure on one side mean it will not seal as properly on the other side, if you do proceed, please keep a thigh surveillance on you moisture alarm specially in the shallow, you are doing risky business here my friend.

Regards

The pressure on the port is very slight. It shouldnt be a problem. (and it doesnt leak in the bath tub.....)

Perhaps Ikelite housings/canon cameras/sigma lens are not enginered to the precision of your Aquatica and Fuji camera/nikon lens but it all kinda wobbles around easily. There really is only a miniscule amount of force on the port required to move the end of the lens a millimeter.

But hey, even if it is risky. It isnt nearly as risky as leaving the port o-ring on the boat.....

My comment where not in any way directed at the enginering skill of Ikelite, Ike as been making housing since the dawn of time and obviously knows how to make things watertight, my concern is anything with an O-ring require equal pressure, trust me, I have seen a few Nikonos flooded in the rinse tank because of a little side pressure on the lens from other equipment leaning on it, and your right about leaving the o-ring on deck, been there done that, can't really blame the massive flood on anybody but the guy in the mirror. Darn why you had to remind me of that

Cheers

O-ring seals are more vulnerable to leakage when at the surface compared to when at depth. They need to be compressed to function.

Tom