I will write this post to share my knowledge of the use of this flash with Alpha cameras.
Minolta released back in 1991 the Program 3500 xi flash. The flash was meant to be used with the xi series of cameras released back then (like the 7xi SLR).
Now, Ive seen some people asking about this flash and if it will work in a Sony Alpha DSLR (me included).
To begin with, the 3500xi CAN be used with the Alpha line. The flash uses the Minolta hot shoe mount, the mount has its years of service, and luckily for you, the Sony DSLRs also use this hot shoe mount.
The 3500xi has a Max. Guide Number of 35 and of 29 at 50mm. The zoom range is of 28 to 105mm. Manually you can set the zoom to 28, 50, and 105. It has a tilt of 90 degrees, which means it will go from straight to the subject to pointing at the roof (to bounce the light), it doesnt swivel.
It's fed with 4 AA batteries (alkaline or rechargeable), counts with a AF lamp which overrides the AF lamp in your camera (at least in the A700).
This flash has no option of manually setting the intensity released in the burst. However, it does have a button (Lo) which will allow you to reduce the total light emitted to an aproximate of 25%.
One function that will surely trick you its the wireless capability of the flash. You will pop it in the hotshoe mount of your Alpha, set the flash to wireless, half press the shutter to set the flash, remove it from the mount, place it somewhere in the room, do the communication test if you know how (press the AEL button, the camera built in flash will release a test signal to which the flash will reply) and fire..........just to realize the inbuilt one fired but the flash didnt.
Now, why this happens? Why it wont work if it says it can fire wirelessly and the Alphas have the Wireless mode? Why it doesnt fire EVEN IF THE COMMUNICATION TEST IS SUCCESSFUL?!
I had to ask around to get an answer to this question, I asked in the DPR Sony SLR forum and a group of savvy users cleared the issue for me. Gary Friedman also explained this in great detail in his user guide for the A700 (which I recommend you get, or for the A100, A200 and A300-350).
There is one thing you need to know and understand in order to understand why the 3500xi wont work wireless in an Alpha DSLR.
Back in the days of film, wireless flash worked different than today. Since the camera had film instead of a digital sensor, the metering was done differently, in what is called Through-The-Lens-Off-The-Film Metering or TTL-OTF Metering. In these days, the metering is done TTL or with ADI (Advanced Distance Integration). Read the link that says Flash Metering modes explained in order to understand the differences if you dont know them.
Wireless flash in a nutshell works like this:
The in built flash fires a series of bursts of low intensity light. The bursts vary in length, some are long and some are short. This acts like a kind of Morse code the flash (or flashes if you got more than one in wireless) interprets, the bursts tell the camera what intensity they should fire and when.
I may be oversimplying it and leaving a lot of details out the explanation, but I will provide links that will explain the subject in full extent.
The difference is that the protocol for wireless is not the same for film as is for digital. This is because the digital sensors are highly reflective, therefore the triggering mechanism is different. Gary Friedman explains this in his website (first link on the bottom)
So, back to the 3500xi, the flash was designed for FILM, not DIGITAL. Therefore the wireless function wont work with your Alpha, only in a xi series camera (or compatible Minolta SLRs).
The flash can be used as I already said in an Alpha DSLR. But youre limited to 100% or 25% output. The flash detects when you zoom in or zoom out and will adjust itself accordingly (this was tested with a A700 and a SAL 18-200).
The problem of using this flash on a DSLR is that you cant do much with it, basically because its not designed for digital. In order to get good shots with it, you need to control shutter speed, f number and ISO. In my personal opinion, using this flash on a DSLR is like having a high power inbuilt flash, theres a limit to what you can do with it.
If youre using a DSLR (Sony or Minolta), its better you stick to the flashes designed for digital. And same goes for SLRs, stick to film designed flashes, digital wont work properly.
So there you have it, you can use the 3500xi flash on your Alpha DSLR, but be aware of the limits of it.
I HIGHLY recommend reading the following articles, it will give you a comprehensive understanding of wireless flash and how cameras meter when using it.
Wireless flash explained (both film and digital)
Info about the Minolta 3500xi flash
Flash Metering Modes explained
DPR Sony DSLR Forum thread