MAY 14TH - STARSENSE EXPLORER 8INCH DOB, SVBONY 3-8MM ZOOM AND THE MOON.

[paulastro]

I went out at 8.55pm, when of course its far from being dark,  to have a look at the Moon with the 8 inch Starsense Explorer Dob.  I was particularly keen since I had been without it for a few months.  I had done a deal with a good friend of mine on SGL to swap. it for his 10 inch version. For various reasons we had both decided to swap back to our original scopes. As the 10 is much bigger than the 8 I had not used it much - mainly for medical reasons.  Hence I was keen to use the 8 again now it had returned home.

I chose to use the SvBony 3-8mm zoom.  This performs very impressively with my StellaMira 125 ED doublet and Askar 103mm triplet, but I wanted to see how the 8inch f6 Dob would fare with it.  The zooms range with it would be x125 up to x400. The seeing was good, but nothing exceptional and as it wasn't fully dark I wondered what the highest mag it could be usefully used with on the night.

I tried it out carefully on the lunar terminator, especially in the region of Hommel and Pitiscus where there was a lot of interesting detail.  Starting at 8mm I gradually worked along the click stops up to the 3mm setting.

Well, I have to admit it was far better than my expectations.  It could be usefully used on the full range of magnifications.  In fact there was very little change in sharpnessas as I increased the magnifications. What little difference there was, was more to do with the seeing than the eyepiece or telescopes optics. At x400 the sharpness was as good as at other mags, but due to the seeing it had more 'off' moments than at other settings.  At any of the settings the sharpness was such that it was performing like you'd expect a very good fixed focal length to perform, quite astonishing for what it costs.

In addition there were no ghosts or flarring and no noticeable CA either on crater edges along the terminator at or any part of the limb.

Despite having astigmatism in both eyes, I did all the testing without glasses. - though it was comfortable with my glasses on to 5mm and useable after that with a restricted field.  Without glasses  the views were comfortable at any focal length.  For use on the Moon I'll probably use it at 5mm most of the time.  Not because it is less sharp at higher mags, but because I preffered the available field at 5mm.   For planets and double stars I'll use the mag best suited to the subject and the conditions of course.

I really don't feel the need to use fixed eyepieces when using mono vision, and will be very happy with the views the zoom delivers.  If it was £300 it would still be a price worth paying in my view, for the £129 I paid from Amazon with a discount, it's a no brainer.  Don't hesitate if you're thinking of buying one and have the pennies. It's a remarkable buy.

Edited May 16 by paulastro