Barlow Magnification Calculations

[pmlogg]

A few days ago I took delivery of a Baader Q Barlow, intending to use the 1.3x front section on the nosepiece of the camera I use for full disk solar imaging. When I tested it the measured magnification appears to be 1.98x for a 32.5mm long nosepiece and 1.86x for one around 28.5mm long. So, a change of 0.12x for a 4mm difference in chip to barlow lens distance. 

As I would like to achieve something under 1.5x a shorter nosepiece might get me there.  15mm ones are available and by the figures above would seem to be  just OK.

However, I’ve found a diagram on the Baader website showing examples of the Q Barlow fitted to a Celestron Skyris and a DMK 31(www.baader-planetarium.de/sektion/s23/bilder/q-turret-gross.jpg) that seems to show less of a change in magnification per mm of altered distance (0.15x to 0.2x for 10.5mm). On the basis of that the 15mm nosepiece would still be too long.  Unfortunately I've not been able to find the focal length of the Q Barlow to use with the standard formula.

Before buying a fourth C Mount to 1.25" nosepiece I’d like to be certain that it will produce what I want.  Any thoughts on why my results seem different from Baader’s and whether the 15mm nosepiece is likely to achieve what I want would be welcome.

[YKSE]

I think you can send maill to Baader support directly, I got to know the focal length of VIP barlow in that way.

[pmlogg]

I started my topic after emailing Baader twice.  No reply yet so presumably nothing to come before Monday at the earliest.

[pmlogg]

After waiting I vain for more than a week for Baader to reply, the Q Barlow is on its way back to the supplier.

So, my opinion of Baader's product support is that it is ____ poor.