Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

MK91

This topic has been archived. This means that you cannot reply to this topic.
12 replies to this topic

#1 john-AZ

john-AZ

    Vostok 1

  • -----
  • topic starter
  • Posts: 111
  • Joined: 06 Nov 2003

Posted 30 March 2004 - 10:54 PM

Has anyone used one of these (newer model) or know how they perform? The review on this site is outdated as the newer models have less central obstruction (now 27%) and improved thermal properties.
John

#2 John P

John P

    Messenger

  • *****
  • Posts: 443
  • Joined: 27 Jan 2004

Posted 31 March 2004 - 06:01 AM

The review section of Cloudy Nights has some information you might find interesting. I have a call into Mike at ITE right now to inquire about the MK91. I currently use a NexStar 11GPS and a 6" Russian Maksutov-Cassegrain on a GM-8 mount. The 6" offers outstanding high contrast images with pinpoints for stars and a very dark background. Since I'm fortunate enough to have aquired an AP900 mount (not a go-to) years ago, I'm considering selling a bunch of stuff to finance the MK91 and construct a permanent observatory.

#3 John P

John P

    Messenger

  • *****
  • Posts: 443
  • Joined: 27 Jan 2004

Posted 31 March 2004 - 06:47 AM

You're right, the review on this site is interesting but not real current. There's a very short review in MakScopes, and I recall seeing several other reviews including one by Mike at ITE and I'm trying to relocate them. As believe the biggest negatives were the cool down time and the narrow field of view. The pluses included great optics and the system favoring less expensive eyepieces. The MK91 would also probably appreciate an excellent mounting.

#4 john-AZ

john-AZ

    Vostok 1

  • -----
  • topic starter
  • Posts: 111
  • Joined: 06 Nov 2003

Posted 31 March 2004 - 12:01 PM

The issue of cooldown time is no longer and issue with the g-tube version Mike (ITE) offers. Also, Mike's lab and field test (done several years ago) was of the older MK91 (like Allister reviewed) with 33% CO instead of the now 27%, and now optics are said to be better...this is what I was hoping to verify.
I believe there is a device that Intes sells that allow you to operate at f/10 or even f/7...a reducer that would allow wider field of view. In addition, the g-tube version weights only 27lbs! This was the clincher for me.
The improvements have been so significant in addressing the "issues" that this scope (I would think) would be vastly improved over the one in Allister's review.
John

#5 John P

John P

    Messenger

  • *****
  • Posts: 443
  • Joined: 27 Jan 2004

Posted 01 April 2004 - 02:02 PM

I was hoping to talk to Mike at the upcoming Rockland show is Suffern, NY. His company is listed as one planning on being there but apparently Mike won't. I'm seriously interested in the MK91 and find your comments very positive but I wonder what the carbon fiber tube etc. mean for the costs. The ITE website shows a real substantial increase. I'm also concerned about the limited focus travel of the focuser but am somewhat used to using extension tubes, etc...because of the 6" Maksutov I'm used to. I understand the rear cell of the MK91 is threaded for standard Schmidt-Cassegrain accessories...do you know?

#6 john-AZ

john-AZ

    Vostok 1

  • -----
  • topic starter
  • Posts: 111
  • Joined: 06 Nov 2003

Posted 01 April 2004 - 06:09 PM

The MK-91 has a lot of backfocus. If you get the g-tube "kit" it is very easy to assemble and you choose the focuser you want (mine will come with a 1.5" draw Feathertouch). You should talk to Mike, I think he can get you into the g-tube version for about $4200. and you can put whatever focuser on that you want (and choose the draw length).
My question is how it will perform as an all-around scope. I know the f/ratio will limit FOV but I don't know to what extent this will limit deep sky work?!
John

#7 John P

John P

    Messenger

  • *****
  • Posts: 443
  • Joined: 27 Jan 2004

Posted 02 April 2004 - 06:59 AM

Thanks John, I'll be talking to Mike in the very near future. I gather you've ordered your MK91. (?) You'll have to let me know how it goes please. My skies seem to favor lunar and planetary work and the MK91 is well suited for this. Deep sky...you might consider a focal reducer for the larger objects. I would guess that the great contrast offered by this optical type would be a plus for most deep sky objects, especially CCD work. What do you plan to mount it on?

#8 john-AZ

john-AZ

    Vostok 1

  • -----
  • topic starter
  • Posts: 111
  • Joined: 06 Nov 2003

Posted 02 April 2004 - 12:04 PM

Yes, I went ahead and ordered one! I plan to mount it on a Losmandy G-11 with a 12" pier extender (for height).
Mike said for DSO, I can obtain a one degree field with a 32mm 80 degree ep. This should be adequate for all but a handful (pleides, M31, NA Nebulae, etc), and I'm hoping the scope has more contrast than my f/5 newtonian for objects like M57 and M51. Also hoping starclusters will be more pleasing. One would have to think it would provide these benifits but I've been fooled before. Your comments were positive with respect to contrast and star fields...how does you scope compare with a good 6" Newt.? How about a 5" refractor for contrast?
The scope comes at the end of April (we are waiting for optic set from Moscow). Exciting!
John

#9 John P

John P

    Messenger

  • *****
  • Posts: 443
  • Joined: 27 Jan 2004

Posted 03 April 2004 - 09:41 AM

I've only made a direct comparison between my 6" Mak and a 4" APO and I feel the images were identical, if not a bit better in the Mak. On almost all nights a fair comparison between anything is more a function of the atmospheric conditions than anything else, plus real dark skies are very rare. Although it sounds impossible, I often like the images visually through the 6" Mak more than the 11" SCT. I find the images with the SCT to often appear "soft" despite tweeking the collimation. On a rare, really good night I suspect the SCT will easily outperform the 6" MAK, but as I said...rare.

I wonder if it's my age (62) and if somehow my eyes favor the Mak. The contrast and dark background through the Mak are very obvious to me....very crisp. You'll have to let me know how everything goes as I expect I'll be ordering one in the near future.

#10 john-AZ

john-AZ

    Vostok 1

  • -----
  • topic starter
  • Posts: 111
  • Joined: 06 Nov 2003

Posted 03 April 2004 - 11:40 PM

I'll let you know John. I expect to get the scope in about 3 weeks. Mike has already installed the focuser and mounting brackets for my Losmany dovetail. If I forget, sent me a "private message" in about 3 weeks for the scoop.
John

#11 John P

John P

    Messenger

  • *****
  • Posts: 443
  • Joined: 27 Jan 2004

Posted 07 April 2004 - 05:49 AM

I'll do that John. I've noticed you have some previous experience with Maks, including both Mak-Cas and Mak-Nwt's. I'll be very interested in what you think of the MK91. One last question...do you have any experience selling used equipment? My stuff is in great condition and I'm considering selling it for the MK91 but have never done it before. Have you ever utilized Astromart for example?

#12 Gary BEAL

Gary BEAL

    Surveyor 1

  • *****
  • Posts: 1566
  • Joined: 10 May 2003

Posted 07 April 2004 - 04:23 PM

John P.
just sent you a PM.
Gary

#13 John P

John P

    Messenger

  • *****
  • Posts: 443
  • Joined: 27 Jan 2004

Posted 09 April 2004 - 01:29 PM

Sorry Gary, I probably nuked it because I didn't recognize the sender. Having virus problems in the states. Please re-send


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics