Sony A7IV paired with 200-600 5.6-6.3 OSS GM-man focus

[Marsha Kirschbaum]

I cannot get this lens to hold manual focus.  The focus on the lens is in manual.  The camera setting is in manual.  I can focus the lens and first image is tack sharp.  If I either turn camera off, or the energy saver kicks in at 1 minute, I lose focus.  I understand there is no focus hold on lens.  What can I do to keep the focus on this lens from shifting.   At first I thought it was a defective lens and traded back in for a new one.  The same behavior occurs.  Recently my first image was taken at 4:46 a.m.; my next image w/out touching focus, but turning off camera was taken at 5:01 and is totally soft.   The prior new lens shifted focus working with an intervalometer.  Every time I stopped camera to check focus, it was out.  Any clues or workaround for this behavior would really be appreciated.  Auto focus works just fine.  

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[Pieter]

I think this behaviour is normal for most - if not all - focus-by-wire lenses: the focus position is reset when the camera powers off.

[Marsha Kirschbaum]

2 hours ago, Pieter said:

 

Any idea on how to turn this reset feature off?  Or set to hold same focal length?    I was really hoping to use this lens with my tracker for star photography.  

[Marsha Kirschbaum]

2 hours ago, Pieter said:

think this behaviour is normal for most - if not all - focus-by-wire lenses: the focus position is reset when the camera powers off.

Any way that turn this feature off or have it reset to existing focus?   Trying to use lens with my tracker for star photography.  

[Pieter]

Best I can think of is to prevent the camera from powering off, e.g. to disable Power Save mode and/or plug in a power supply via USB.