Orion Q70 vs Stratus

[neil groves]

I have been using an Orion Q70 32mm to surf the sky when searching for objects and noticed the stars get very distorted at the edge of the frame, well I popped an Orion Stratus 17mm in last night and the quality at the edge of the field was astounding by comparison, was this due to the focal length difference or the difference in optical quality between the Q70 series and the stratus, both are wide view one being 70º the other being 68º?

Neil.

[ronin]

Would have said most likely was the focal length, or more relevant the field of view, the 17mm will have close to half the field of view of the 32mm  So in effect is picking up the flatter part of the image created by the scope primary, which being curved will be more difficult at the outer part.

[bingevader]

Both probably! The budget 2" 32mm EPs do suffer a bit. To get a well corrected 2" EP at this focal length you need to be prepared to pay rather a lot more. The bigger the piece of glass you put in, the harder it is to correct for any errors.

Mine's the same, where as, my 18mm is fine (it was more expensive too though).