wow it can do almost everything .
Looks like I just wasted $600 for a Pentax 540 flash.
Don't say that, its a top of line model, big and powerful...
For me, a newbie into flash, wanted to try try first an cheaper alternative before getting a Pentax or equv...
Why Tumax is cheaper ? Here the definition taken from Felixcat's sticky...
http://www.clubsnap.com/forums/pent...hoe-flashes-compatible-3rd-party-options.html
Tumax and Look-Alikes, Under Many Names
There are a number of very similar "generic" flashes made in China and sold in the US under a number of different brands, including Sakar, Digital Concepts, Vivitar (all three brands of the same company); also Bell and Howell, Bower, and Practika.
It appears that the maker is Icorp Enterprises of Hong Kong. The familiar appearance and specifications can be found on the page of products carrying Icorp's own "Tumax" brand, and the corporate web page says:
There are several different models, not all of which are available in the US in US-branded versions, but you can contact Icorp directly for purchase via PayPal. In my experience, the people there are more helpful and responsive than the US relabellers.
It's entirely possible that several other Chinese makers produce some of these models, perhaps with cooperation and perhaps not. No one will officially admit it, almost certainly for perfectly reasonable legal and corporate-agreement reasons. However, all of the models bear striking similarities (and many small differences in the exact specifications, often within the same US model name).
Note: This section due for an update! Until that happens, if you find a flash labeled Vivitar or Bower or etc., take a look at the Tumax product listing page and see if you can find any correlation to one of the listed models. Basically, if it's not labeled Pentax, Metz, Sigma, or Promaster, you'll find a match.
Many of the lower-end, made-in-China Metz models bear a strong resemblance to the Tumax lineup as well. Metz tells me that they are only similar in appearance and that the internals are different ("equipped with a special electronic technology which has been developed by Metz in Germany"), and I generally trust Metz as a company. Still, the appearance and functionality is strikingly similar.
Note: There's at are reports of incompatibility with the Pentax K-5 and of incompatibility with the Pentax K-r. I expect that, following previous patterns, newer works-with-newer-cameras models will silently make it to market eventually — with no announcement or easy way to distinguish between compatible and non-working models. Update: As expected, it's been reported that the Bell & Howell version similar to the DPT383AFZ works fine with the Pentax K-r. (However, make sure you buy from somewhere with a good returns policy, in case you happen to get an older unit.)
Most current versions of this flash have P-TTL support, but older versions do not. I am not aware of a good way to tell which it will be without testing, and I don't think an upgrade is available. The Praktica / Exacta 38AF models are quite certainly all too old, and it seems likely that the Bower and Vivitar branded models (which appeared more recently) are all the new design. Soligor has confirmed that their model uses P-TTL.
The new Tumax/Icorp DPT5 series has rear curtain sync and wireless P-TTL support.