View Full Version here: : WO Megrez 90?

06-03-2011, 03:06 PM

thinking about a William Optics Megrez 90 and P-Flat 4 combo for astroimaging. Thinking about shifting to a refractor for imaging as I'm over having to collimate my Newt every time I set it up or rotate the Tube. The Newt takes great pics, but I now want something that just works, so I can relax, have a glass of wine and chat with other imagers. Us Newt guys seem to be forever fiddling, whilst the refractor guys are relaxed and unstressed. I'm too old for constant playing - I used to enjoy it, now I want stuff that just works. I'll be fitting it to a Vixen GPD2 which I love after my abortive Skywatcher EQ-6 disaster. It just works, just tracks, and is easily portable.
The Megrez 90 and P-Flat4 are in my price bracket....has anyone used this combo? Is it flat to the edge with a QHY8 (which just works!!) there seem to have been a few versions, WO has them direct for US$998 plus freight, whilst Andrews has them for OZ$998, however they call it the Megrez 90B, is this a gotcha?

What do you think as a no nonsense image machine?

06-03-2011, 04:30 PM
My suggestion would be ... Make sure you find someone with exactly the combination of M90 revision and PFlat4 revision you're thinking of buying and check they get acceptable results, before you buy.

William Optics is natorious for subtally changing their refractors and field flatteners without calling them a different name. At last I knew there were 3 revisions of the M90 and some worked with the PFlat4 and some didn't.

I have a M90 second revision which was supposed to work with the Flat v3, but it didn't. I sold the Flat v3 and bought a Borg DGL. The combination of M90 rev2 and Borg DGL produces perfect results.

For me it took a lot of time and some frustration and various attempts before I got a combination which worked. I would be hesitant to say buying a william optics scope is going to give you that "it just works" winning ticket. There seems to usually be fiddling involved to get the right combination of things to produce perfect images. They are built to a price not perfection. Their construction is good but are let down in some areas.

If you want "it just works" I'd be going Tak, TeleVue, Borg, etc (with field flatteners), or higher priced WO like the FLT132 which from my experience, with it's field flattener, "just works".

I know it's hard to go past the M90's for their price though, hence I ended up with keeping mine and am now happy with the combination I have.

07-03-2011, 04:23 AM
Hmmm. Another flattener for me to look into.
I have the M90FD (v2) too... fell victim to the WO adverts that their Flat4 works with their M90's... yes they do, but only the current production run with the white focuser body. Trying to sell the flattener now. I noticed WO have finaly fixed their website regarding the M90 / P-flat4 compatibility.

07-03-2011, 06:55 AM
So the old mark 3 is the best bet for the old model then?

07-03-2011, 08:58 AM
Thanks for the replies guys,

it looks like its too much hassle ensuring that everything is going to work with the William Optics stuff. Don't want to spend the money and find I'm back where I started. Probably going to rebuild the newt and make it work like it should. Nothing else is really in my price range. Wish I could afford some quality gear.......


07-03-2011, 03:35 PM
Mark 3 of flattener 4? (lol)
No unfortunately, that is why I am selling.
It only works with the new M90, the FLT's and apparently, the various ED80's around.
If I can't sell it I'm toying with the idea of modifying it.

Ah.. just realised you may have got that idea from my sig.
Sorry that was before it was found not to work, just never fixed it.
I don't have the EQ6 anymore either.. sig fixed.

07-03-2011, 04:35 PM
When you say mark 3 you could be meaning the third revision of the PFlatv4 for the Flatv3, they are completely different. Confusing isn't it. Either way, the answer is no. I tried the Flatv3 and it seems others have tried the PFlatv4 (various revisions).

07-03-2011, 04:47 PM
I think, (from memory, it was a while ago when I researched), that the only WO flattener that did work with the older M90's was their FF2 flattener and although it worked, it had some serious vignetting.

07-03-2011, 06:17 PM
I have the F6.9. Is that the first version, or was there a second revision of the F6.9? :shrug:

I know the current one is an F6.2.

07-03-2011, 06:22 PM
It appears that there never was an f6.9 version. The lens was incorrectly marked - several people have tested and verified that it always was an f6.2 !!


07-03-2011, 06:37 PM
Hmmm, tricky.
There are so many versions.
I have seen many models:
Black focuser with silver(aluminium) drawtube and no 'L' bracket,
Black + black drawtube w/o 'L' bracket,
Black + black drawtube incl. 'L' bracket (mine, F6.9)
White + silver drawtube incl.'L' bracket
White + black drawtube w/o 'L' bracket

I would not be surprised if there are more!
That is why Roger said the WO products are confusing.
It would have been real nice if WO, with each change, actually marked their products as such.. with Megrez90 MkI or MkII or MkIII etc etc

Hmmm... that actually gives me an idea... I might start a website, where owners can pool their knowledge of their own WO gear with other owners.... Identifying features, what works and what doesn't, serial numbers, date purchased(if new), photo's etc.
Might help eliminate some confusion.

07-03-2011, 10:47 PM
I have this one as well - by the looks of it the borg is the way to go for this scope then...

07-03-2011, 11:07 PM
that is mine, and it is f/6.9

08-03-2011, 07:15 AM
For AUD$1000 you should be able to get an astroimaging refractor setup that works.

Especially now our dollar is so strong.

I would suggest cruising Astromart and wait for the right gear to be advertised from someone who has proof of imaging with that exact gear.


08-03-2011, 07:20 AM
For example this Stellarvue 102ED for USD$800:


Its under the $1000 GST threshold and you would be able to get a flattener from Stellarvue most likely far more easily than WO and have more confidence in them.

Stellarvue has a good reputation generally.


10-03-2011, 06:47 AM
No M90 was F6.9. The first versions were badged incorrectly. S&T discovered this back in '07 when the reviewed the first series. There is a heap of threads on this on CN forums if you want to research it further.

I recently bought an M90 from Astro Optical and at the time their prices were considerably better than Andrews so keep them in mind also.

Greg, the 102ed from Stellarvue uses FPL-51 glass so it shouldn't be as well corrected as the Megrez.

10-03-2011, 04:58 PM
The lens cell on mine says F6.9 f:621mm, but I have just measured it and it is indeed F6.2