Vignetting or Worse

[mickw]

After the fiasco with the ISS last night, I had another look at my practice shots taken during the day and also a couple of night shots (without lens cap).
Sony DSLR - 2x Barlow - Lidlscope f10 700mm fl
http://www.cig.canon-europe.com/ph/AIG/JmwnfKSnKrCq0cac1o03ks3kskXL0003kskXLzCrJ0sCi.jpg
Is this classed as vignetting or is it something iffy with the optics, poor choice perhaps ?
The night shots still have similar sharp contrast between the bright centre and the rest of the image.
My previous experiences with vignetting are a gradual shift from the centre to the edge.
Thanks
Mick

[JohnP]

Mick,

Definitely looks like some kind of vignetting - If I was you try it without the X2 barlow & see what you get - I know when I tried my DSLR with 1 1/4 inch connections I had vignetting issues though not quite as extreme as you - so everything is 2-inch now when I use the DSLR. There may be something going on with the optics though...

Cheers,  John

[mickw]

Thanks John,
Could be right about the barlow, it's OK visually without it, unfortunately it's a combo barlow/T ring adapter.
I'll try the barlow on the ETX tonight to see if there is a problem with it.
I can hook up the SLR to the ETX without the barlow at prime, but being a clumsy sod I will probably break something if I try for ISS 

Mick

[mickw]

Thanks again John,
Barlow OK for visual on the ETX also but a waste of time with the SLR.
Makes sense really, SLR not really happy trying to see through a skinny pipe.
Bad mix of equipment   

Mick