Originally posted by Talisker My Tamron 90mm is a 55mm filter size and the Sigma 180mm needs a 72mm filter size. Here's my thought process:
There is no adapter for 55mm or 72mm lenses, the Sigma has both available.
Pentax will for sure work well with the K10D and K20D p-ttl system.
Sigma probably will too, but I worry about 100% compatibility.
Both have a modeling feature - I like this. Whether they use LEDs or the flash tubes for the modelling light doesn't matter to me much.
The 14 vs 16 GN difference is no biggie as they are both more than adequate for macro work IMHO.
The Sigma will control wireless flashes, but unsure if that means only other Sigma strobes or if it would control a AF540 or AF360 wirelessly. Would be a bonus to be able to use one of those as a backlight. The Pentax ringflash makes no mention of wireless capabilities, or high-speed sync (unless I missed it).
Pricing in Canada will probably be similar, and both are likely special orders only.
Right now if they were both available at the same price, I'd probably go for the Pentax out of fear of compatibility, then fuss with adapting it to my macro lenses. <sigh>
When the time comes I hope to be able to make a whole lot more informed decision.
Maybe around Christmas...
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dbh - really wanting one of these.