FLI Proline - cross pattern

[TobiasLindemann]

Hi,

a friend of mine has problems with his FLI Proline PL4240 CCD-Camera. Sometimes there is a strange patten through the whole field. You can see the pattern in the lights and in the flats. It is present on every filter in more or less the same strength, but if there is no filter, it seems that the pattern is more visible.
You can see a very wide stretched flat below as an example. The pattern is very pale, but clearly visible after processing. The crazy thing is, that the pattern is sometimes there and sometimes not.
Does anybody has an idea what can be the cause of this pattern?

Even if it looks like, the telescope looks not through a wire-mesh fence ;-)

Greetings
Tobias

[lucchett]

If that happens with short exposures, it could be the shutter.
You can check it taking a number of frames in sequence, combining them and analyzing the rejection map.
Andrea

[TobiasLindemann]

If that happens with short exposures, it could be the shutter.
You can check it taking a number of frames in sequence, combining them and analyzing the rejection map.
Andrea

Thanks for your answer Andrea, but it is also visible on long exposures. So it can´t be the shutter.

[Carlos Milovic]

Does it happen even when using batteries? Is he using USB extensions? I would change the cables, and avoid using any usb extension or cable longer than 3m.

[TobiasLindemann]

Hi Carlos,
he is using USB to LAN for the transmission and only short USB-Cables. Using batteries could be an idea for testing. Thanks Carlos.

Greetings
Tobias