Underexposing with Flashpoint/Godox AD200 TTL with Sony A7R3

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WalterJ1959 Regular Member • Posts: 407
Underexposing with Flashpoint/Godox AD200 TTL with Sony A7R3
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I recently switched from Canon to Sony (A7R3) and just got a AD200 (Godox/Flashpoint) flash with the Godox transmitter (X1T-S) for Sony. I updated the firmware. In TTL mode the Sony/Godox slightly underexposes below 1/250 sec. In High Speed Sync (HSS) mode it underexposes much worse (looks like about 3-stops). I do not have my Canon speedlights any more (EX 580) to test but I believe that they worked in TTL-HSS mode much better. From all the reviews I have read of the AD200 I really thought that TTL mode worked very well in HSS. Am I not understanding TTL-HSS or am I doing something wrong? I shot a still life which I will attach that shows the underexposing in TTL problem.

Top Row, Flash in Manual (M) at 1/64 power, iso 100, f/2.8, 90mm Macro lens.

Good exposure in image 1 and 2, As expected image is darker at speeds above sync speed when in HSS (Image 3-4)

Row 2-3, TTL mode so flash should adjust light to exposure.

Below sync speed of 1/250 sec image is underexposed (image 5 and 6), In HSS-TTL large underexposure (images 7-10)

Image 12 is with the AD200 at full power in manual and 1/4000 sec and produced a near correct exposure to show that the flash had enough power at 1/4000 sec to produce an OK image.

My hope for using TTL was for exposures where you set the exposure to 1-2 stops below ambient and let the TTL fill in the main subject to the correct exposure. Like shooting a person outside to bring out the sky but have them correctly exposed.   This test did not give me confidence in the system.  Are my expectations for TTL to high?

Thanks

 WalterJ1959's gear list:WalterJ1959's gear list
Sony Alpha a7R III Canon EF 135mm F2L USM Canon EF 70-200mm F2.8L IS II USM Sony E 50mm F1.8 OSS Sigma 35mm F1.4 DG HSM Art +4 more
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