October 10, 2009: Henry Coe and 190mm Orion Mak-Newt

Mark Johnston

Equipment Report on Orion 190mm Mak-Newt that has just been re-designed and re-released.

After picking up the Orion 190mm f/5.3 Mak-Newt this last week it was time for a short field test Saturday. Short because the moon would be up just before 12 and short because I also had my trusty big dob. Here are some thoughts after a brief description of the night.

As Julien has reported, Julien Lecomte, Peter Krottje and myself were at Henry Coe overflow lot. The plus side of the night was that San Jose light was greatly blanketed in marine layer so we were treated to a very dark sky (by Henry Coe standards). SQM was 20.8 at 10 and then 21.16 (30 degrees east of Zenith). Quite a bit of lower level muck with the most workable sky looking good at 6.2+ NELM in TRI. Very enjoyable company and chats throughout the short observing session that was terminated as Mr Moon switched on the lights at 11:45. I only observed about 10 objects which for me is pitifully but I had decided that this was a night to putz around with new equipment and try my post-CalStar fixed drive system on my StarMaster. So mission was fully accomplished and with great company as well.

Mark

The rest is the Report on 190mm Mak-Newt

Had picked up this mid-sized beast to serve as a fairly wide field semi-grab-and-go scope. The big dob is anything but grab-and-go. My vision for this scope is to make an alt-az sit-down mount for this guy so that I can use this scope in different ways which will include quick visual in the back-yard to perhaps Hogue park or visiting friends types of situations. I like the non-reversed FOV, flat optics, broad FOV and reasonable light gathering prospects of this combination as well as the option to mess with pictures 'if I dare'. So a compromise to fit holes in my current scope collection. Last night it was on an Atlas EQ-6 which is a bit pressed for a scope of this size at an OTA weight of 25lbs but the Atlas is my quickest mount that I have just now for this scope. Stability was an issue but my Losmandy G-11 is the mount I had envisioned using for this scope when more stability is needed.

The mirror end of the scope has a very wide 3" hole that a plate can be removed from to cool the mirror quicker than a closed back end. This has holes for a fan as well WHICH I did not buy but it looks like the mounting holes will fit very nicely with an Intel CPU fan from a PC that I have laying round. I may not bother as I think the hole being there is good enough given any slight breeze. The mirror is right there about 1/2 inch inside of that plate.

This scope has a broad 128 minute FOV at 38x with the 26mm Nagler and the stars are very good way out in the field. Nicely framed Pleadies and a whole lot of M31 as well as full double cluster and a whole lot of CA or NAmerican Nebula all were very much as I had hopped. Stars were very sharp way out to near the edge and objects like the double cluster showing the little pinpoint tiny asterisms and hints of color that add the extra touches to that fine set of clusters.

I also enjoyed the height of the eyepiece was generally in a good place for either standing or sitting in most areas I was looking at even on the EQ mount. Used to have an f/4 8" newt for years and tube rotation was tricky on that beast. But I have noticed tube rotation on these rings is not bad at all so that is good. (it uses 235mm rings).

The mirror on this one looks very good. I was surprised to see very large numbers of rings. I generally don't see many rings but here I was able to see many tiny rings inside and outside of focus.

Here are some things to know on the minus side in case anyone has been thinking about this scope. Although the focuser works very well, it has MANY things going against it being 'fine'.

• My focuser is sturdy and an 11/1 ratio is very nice BUT it came from the factory with I think the knobs pushed in too tight so it makes an annoying squeaking sound as you turn it (give the impression of a flaky setup but actually works nicely). May just need some lightweight lube.
• Cannot do an out of focus star test without manually backing out the nagler a quarter inch to get the outside focus.
• A 22mm panoptic cannot reach focus at all unless I backed it out around 1/8 inch out from where it would sit normally. I think they made the focus tube extender too short is the issue. It worked fine for my type 6 collection and my 26mm Nagler as well as a 25mm Plossel. Have not tried others yet.