OK, went downstairs to the studio and grabbed a Godox TT600 manual flash it does NOT pre-flash so I guess that eliminates the problem coming from the camera.
Continuing, I've replaced camera batteries with freshly charge versions and tried flash in both i-TTL and manual mode. I'm still getting two pre-flashes. Exposure looks good though. Oh, thanks Rab-Eye for your quick response. If I solve this I'll let all know what I did but it is still unsolved. I have three manual flashes I should try.
As a far-out possibility I replaced the batteries with a freshly charged set.
One of my first attempts was to press the "reset" button combination on the flash and no luck. After reading your suggestion I searched the manual and online and could find no red-eye reduction mode which I usually recommend against in my classes and have never purposely used.
I have a problem which appeared recently and I'm unable to solve. I have a Nikon D850 and am using a Godox TT685 flash. When I turn the flash on and take a photo the flash flashes twice and then the photo is taken on the third "normal" flash. I've been shooting for over 60 years and I have taught photography but I can't get rid of those annoying pre-flashes. This had never happened previously using the same camera and flash for maybe a year.
I figured a way to get 7 but 6 makes the most sense to me.
My favorite example is the time I was shooting in manual mode, using studio flashes, also in manual mode, and scratching my head wondering why every shot was a different exposure. Auto-bracketing was turned on.
I sorry I wasn't clear but I did not mean to say that KEH does not sell the charger, what I was saying is that they don't have any at this time. I did check.
To continue, KEH does not have chargers, and I well know how much I've spent on the equipment I have but I feel as though Nikon is virtually attempting to steal money at their charger price. If I have to I will but I will desperately try to avoid paying what I consider an insane price. As I said earlier the charger I have is working and giving me the results in operation that I expect. The only problem is I have to charge more often and I'm not willing to pay Nikon's price for that convenience. I am not cutting off my nose to spite my face here, my face still works.
The battery I'm having trouble with is the EN-EL18b which gives me 2 extra frames per second burst shooting. I went for the Nikon brand $154 battery but the charger just seemed over-the-top. Even at 65% charge, it DOES work and gives me the higher frame rate. I don't shoot a lot of bursts so ...?
Had not thought of that cjc2, I'll check now.
I purchased a Nikon brand EN-EL18b for my D850. The Nikon brand charger is $369 so I bought a Wasabi charger which in photos seemed to be the exact same charger as the Nikon brand without the Nikon name. My battery will only charge to 65%. Has anyone else had a similar problem?