there is no sharpness at infinity, I want to ask for urgent help

[peter reisz]

Very strange and scary thing after changing the Raptor camera resolution from 8K 17:9 to 4K 17:9, there is no sharpness at infinity on 4k 17:9 (speed-200fps)
however, we were able to focus on everything that was closer than infinity
but, Infinity is sharp in 8k resolution.........
the full camera calibration didn't help either
we tried with these lenses and adapters
looked at it at an open, basic aperture value
ZEISS CP.3 25mm T2.1 Compact Prime Lens
Schneider Xenon FF 25mm T2.1 Lens
Angenieux Type EZ-2 15-40 zoom lens
Tilta rf to pl mount adapter
Wooden rf to pl mount adapter

 

[Phil Holland]

You're backfocus is off. You need to shim your mounts to PL spec, or in the case of the Tilta if it is the model with the integrated adjustment, setting it correctly.

A Denz FDC or similar is typically used for this. If you don't own one, find a rental house and toss them some cash for about 1-2 hours of their time.

 

[Steve Phillipps]

Makes no sense at all that changing the resolution should affect focus - after all, when you change resolution on a RED you're just cropping in to the sensor - nothing else is changing.

 

[Les Hillis]

Soft focus/lack of sharpness at infinity, while having proper sharpness when focusing closer, points to the backfocus being off.

It could be that the crop in to 4K is just revealing the softness that's also there, but not so visible at 8K, especially if the 8K footage is being downscaled to view on a less than 8K monitor, while the 4K footage is being viewed at 100% on the same monitor.

It could be tested by cropping into the 8K footage and seeing if it is in fact sharper than the 4K footage that's already cropped in-camera.