Light path lengths & Problems with focus

[RobertM]

Yes, I checked that last night and it was about a 70 ADU hill across the middle, it just looks worse when it's stretched.  I would still check with SX to make sure this is ok, also ask them what the bias level shoud be.

[Mac]

Here are a few more Fits. for you to chew on.

1) 5 Min
2) and another 5 Min
3) 10 Min
4) Single Bias
5) 30 Bias frames stacked in DSS. (I think 've done this one correctly.

http://www.macrhon.co.uk/website/oasphotos/darks/5mindark.2.1.fit
http://www.macrhon.co.uk/website/oasphotos/darks/5mindark.2.2.fit
http://www.macrhon.co.uk/website/oasphotos/darks/10mindark.2.fit
http://www.macrhon.co.uk/website/oasphotos/darks/BIAS.fit
http://www.macrhon.co.uk/website/oasphotos/darks/ave.fit

[RobertM]

Mac, your Bias average looks suspiciously like it's been converted to colour, size should be the same as the original bias it was made from i.e. abt 2.8Mb

[Mac]

I thought the file was a tad on the large size,
I've had another go, and uploaded the new file, this time it is the correct size.
I think i had the drizzle checked before.