A Review of the William Optics Zenithstar 70ED f:/6.1 refractor
by Steve Cox

I recently purchased a William Optics Zenithstar 70ED f:/6.1 refractor. The purpose of the purchase was to use it as a guide scope, and an imaging refractor. Since I already have the Megrez 110ED, I thought this little refractor would make a nice match. After patiently waiting nearly three weeks it arrived. I was so impressed with how William Optics kept me posted on the status of the scope shipping out to me. The company has been a true delight every time I have used them. When I unboxed this small refractor I was amazed at its weight. At a little over five pounds you can still easily hold it with one hand, but lets not get tricky here, after all it is not inexpensive.

The ZS70ED has a beautiful white power coated tube. The crayford focuser is almost identical to my Megrez 110ED. The only difference I found was this 2” focuser moves on a large single ball bearing located underneath center of the main drawtube. It offers a wonderful 3.25” drawtube and a fully graduated scale. It is easy to read on the black drawtube. This makes focus points for your camera easier to remember when in the field. The focuser has a dual speed 1:10 micro-focuser with a gorgeous gold accented swan on the knob. Other nice feature of this focuser is the ability to rotate a full 360° making it easier than adjusting your camera position.

The dew shield is fully retractable and offers about 2” of travel over the objective. A handsome gold swan signature dew shield cover accents the refractor nicely when not in use. This refractor is an air-spaced doublet. Although William Optics will not discuss the glass type it is officially listed as an ED refractor. Many on other forum sites have noted at this years NEAF astronomy show that representatives of William Optics booth said “the Zenithstar 70ED does not use Japanese O’Hara glass.” They also noted the quality of the abbe’ in this doublet was higher than S-FPL-51, but not quite S-FPL-53. If I had to make an assumption and judging buy the gorgeous purple and cyan tint in the coatings I would say they might be using Schott glass of FK-61 or better. It’s all ‘Greek’ to most of you but given the refractor fan I am, it’s always nice to follow these curious things. It’s the unknown that can make it even more special.