A: Honestly all flash heads would work.
your real problem would be
1. the connections - if they are hot shoes or plugs etc.
2. you cant use the 3D matrix metering
3. you can't use +/- flash compensation
You can use A and Manual
Right after the shot you can decide on how the image looks and adjust from there. To be on the safe side establish your "standard" so that you would be guessing all the time.
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Comments: 1
You will not be able to do TTL flash. You can use an optical slave unit and block the on camera flash enough just to trigger the slave. The trigger voltage on a Sunpack would fry the circuitry of the camera. If you had the hotshoe attahcment for the flash you might try a Wein Safe-Synch adapter from B&H.