I have not used either the "SX Extension Ring" or the "Extension Ring 40", but to house my 105mm macro without swapping port systems would require stacking them. In order to do that I would need them to each lock properly into the next component.
I assume each of them has a locking mechanism like that built into the housing. Is that the case? The product shots don't show enough for me to ascertain if this is the case so I'm keen to get info from someone with direct experience of these extension rings.
The SX Extension Ring
The Extension Ring 40
Thanks,
Martyn
The extension rings can be stacked. There is no locking mechanism to stop them rotating as there is no locking mechanism between extension ring and port. However they are quite stiff and I have seen no rotating.
I am quite surprised that you say you have to stack rings to house a macro lens. On Nikon the 105mm fits happily in a normal macro port with 40mm extension.
Thanks Mark, that's interesting. It certainly gives me a simple option for the new macro lens.
I assume you're talking about the Nikkor 105mm, which is probably a well designed lens. The Sigma extends into the middle of next week when you get near 1:1. The spec sheet says overall length ~95mm. It doesn't mention that it goes up to about 160mm at 1:1!
I've now got to decide whether to go for this approach or swap over to the compact macro port system.
Thanks again,
Martyn
Well, I got my rings, courtesy of lightning fast service from Heather at Marine Cameras (aka Alan James). As you say Mark, they don't have locking mechanisms after the housing interface, but I found that it was disturbingly easy to turn the port and potentially flood the housing. So, gaffer (duct) tape to the rescue, preventing the interfaces from slipping against each other.
Hopefully job done. The 105mm Sigma now fits in the port, and hopefully the "chubby" port solution will provide more lift than the compact macro port system would have. We shall see.
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