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First Light on a 150 Mak

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#1 fcathell

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Posted 14 August 2019 - 11:26 PM

I couldn't resist and bought an Orion 150mm Mak from the CN classifieds.  Collimation was dead on using indoor artificial star.  Took it out this evening and did some testing.  Star tests indicate some residual SA, but very nice airy disks of stars.  Images of Jupiter and Saturn were pretty good despite the local turbulence (94* outside - everything is hot from a high of 106 today).  Clean, excellent splits of both components of Epsilon Lyra. After Saturn got a little higher I pushed it up to 300X and it took the magnification fine. Cassini division all the way around. Was able to see the 4 brighter moons and pretty sure I caught traces of Hyperion. The focus is pretty "snappy" which is a good thing.  There is a small amount of image shift, somewhere around 20 arc seconds max which doesn't seem too bad. Focus is smooth with no backlash. Thinking about flocking the inside of the primary baffle tube. Any comments and/or comparisons with any of you other 150 Mak users would be appreciated.

 

Frank

Tucson


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#2 jeremiah2229

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Posted 15 August 2019 - 12:12 AM

I have the Orion 150 here and am completely satisfied with it. When the focus shift starts creeping larger I do a quick complete rack in/out and that brings it back to just barely any movement and I have to do this about every 5th or 6th outing with it (summer time only), depending on how much I use the focuser. I've been able to get some observing in this season on Jove at 300x (Ethos 6) and couldn't be happier. Nice little scope and I can go all night with just a dew shield. When these guys are collimated proper they are a double star pleasure, at least this sample is. I didn't really chase doubles until this scope arrived and I had my first view of Porrima with it then I became a double star addict lol. This season is the first time in my life I have seen the companion of Antares and this 150 at 225x makes it look good with steady air. I had no idea the component looked like a dim Uranus and now that I know what to look for I've been blessed to see it in all scopes here and every night I go out for Jove, Antares gets hit too.

 

Bottom line is I wouldn't want to be without this little 150, just so useful. I do wish it was an eight inch at the 1800mm haha.

 

Go out and enjoy your new toy every chance you get.  waytogo.gif

 

 

Peace...

 

Edit:

It's fun on globulars too, lol it's fun on everything.  ;)


Edited by jeremiah2229, 15 August 2019 - 12:18 AM.

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#3 elwaine

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Posted 15 August 2019 - 03:23 PM

Glad you're happy with the new Mak, Frank. How does it compare with your 5" Mak?

 

As far as flocking the OTA... you'll get different opinions on the effectiveness of doing that. Some swear by it, but I saw no difference when I flocked an ETX 125. However, I did notice an improvement when I added a longish dew shield (approximately 4 times the diameter of the OTA). The dew shield blocked stray light from street lamps and lights from neighbor's houses.

 

When Yuri first made his TEC 6" Maks, he used a series of baffle rings inside the OTA. But after he did some testing, he concluded that, in small Maks, baffles added nothing but weight. So the last few 6" TEC Maks were made without baffles. Years later, when he made a few 7" Maks, no baffles were used. (I have no problems with stray light in my 7" Mak, which is neither flocked or baffled, but it does have a short dew shield.)

 

The reason I mentioned baffles is because baffles and flocking are supposedly used for the same purpose. Judging by the number of refractors that come with baffles vs flocking, I think baffles do a superior job is reducing stray and reflected light; but that's only a guess.

 

If you decide to flock the OTA I'd like to know how it worked for you.



#4 fcathell

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Posted 15 August 2019 - 04:17 PM

Great comment Larry. I looked at the oblique angle glare/reflections off of the inner baffle tube while pointing the scope to an open window during the daytime and it doesn't look that bad. I found some thin felt sheets for flocking from an art store that holds it shape but may postpone using it.  It did make a difference on my old 127 Mak which did seem to have a more shiny inner baffle surface than do the later versions of the same scope. I need to get another good observing night with less turbulence and cooler temps!  It is 109F right now at 2:15 PM MST!

 

Frank



#5 spongebob@55

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Posted 17 August 2019 - 10:56 AM

Hi Frank,

I've been seriously thinking of getting a 150 in addition to my 127 Mak.   How do you feel about the increase in visual capabilities over the 127?   I'm hoping to be able to mount it to my Evolution mount.  Any input you can give me would be great.

I'll be following this post.  Thanks for posting.

Bob



#6 ictus

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Posted 17 August 2019 - 11:32 AM

Hello 

          I,am looking to get the orion 6''mak/cass with the starseeker IV mount.

          This is the same scope OTA? the  collimation it,s just the main mirror?

          I would like to use this for mainly the planets and brighter DSO,s.

          Basically for a grab and go, my 10'' dob is getting harder to get out. 

                                                                                                                         Thanks Anthony



#7 SeattleScott

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Posted 17 August 2019 - 11:59 AM

The 6” will provide roughly 50% brighter views, which is a very noticeable but not dramatic difference.

I think the star seeker is basically the same but may not have the 2” visual back and wider baffle for 2” eyepieces.

Scott

#8 fcathell

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Posted 17 August 2019 - 02:27 PM

I need to get the 150 Mak out beside the 127 and compare when we get another decent night here.  It's been monsoon clouds or hot nights with heavy turbulence lately. Of course as you all know, the minute you get another scope you want to try out, the weather goes to h*ll. The 127 is going to be hard to beat because it had excellent optics when I got it, and I flocked the primary baffle internally, and the secondary mirror baffle has been reduced such that the secondary obstruction is down to 33%.  I also sanded the inside of the secondary baffle to reduce any glare. There is no question the planetary images are brighter in the 150 as expected, but the question is - am I seeing more detail.  There is no question that Saturn's Tethys and Dione are easier to see. We shall see and I will update this discussion with time.

 

One interesting thing I have meant to comment on is that the reverse of "cooling down" in a Mak doesn't seem to affect the performance when it is reversed. My Maks almost invariably have cooler air inside of them when I take them out in the summer or early fall to observe.  The focus may change slightly over a half an hour, but there is no optical aberration "plume" when defocused as is the case when the internal air is warmer than the outside air. 

 

Frank

Tucson  


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#9 Auburn80

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Posted 17 August 2019 - 08:00 PM

Lol, this time of year here in the South, I'd get instant dew. Gotta let my closed OTA warm up slowly.
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#10 fcathell

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Posted 17 August 2019 - 10:22 PM

What is dew (ha, ha)?

 

Frank

Tucson


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#11 Asbytec

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Posted 18 August 2019 - 07:49 AM

Took it out this evening and did some testing.  Star tests indicate some residual SA, but very nice airy disks of stars. 

 

Frank

Tucson

Frank, I just came off a wonderful 8 years of observing with my Orion 150 MCT. The older version. I picked it up for a steal on closeout and it's been my longest owned and most used scope ever for a variety of reasons. One if which was the fact it worked very well. The other two reasons are retirement and excellent tropical seeing. I have not seen a heat plume in years (in our modest tropical climate) by cooling the OTA with a frozen medical gel pack. Perfect star images straight out the door. 

 

Well, not perfect. Some folks may differ, but I am convinced you will see some residual spherical aberration. It may look a bit over corrected. That is perfectly normal and by design (presumably without an aspheric primary). The reason is, well, you are not star testing a parabola. The MCT is a complex design, after all, so we cannot rely on Suiter's simulations of obstructed lower order spherical to guide us because that is not what we will see.

 

By design, the meniscus throws out a lot of higher order spherical and the primary's lower order spherical cannot correct for it completely. So, the wavefront will have some residual higher order spherical and this will show up in the star test making star testing a little less intuitive and a little more difficult to evaluate. Residual higher order can be quite high without affecting diffraction limited performance, something like 0.4 waves PV. You'll see some of that in the star test and likely with a low enough RMS to put you into the 90's Strehl, regardless.

 

Rest assured, it's very likely a good scope by design and it's an example where the view in focus is what matters. I am confident you will find sharp and high contrast in focus diffraction, that's what matters. So, don't rely on simulated images of lower order spherical to tell you much about how this scope is performing. That's not the design waveform of a Mak, it's more complicated than that. The star test can be deceiving. 

 

If you want to read more: https://www.telescop...k_spherical.htm

 

"An interesting aspect of the commercial Maksutov-Cassegrain is the question of its star test. There is a notion that its optics has special properties, making it sort of exception in that its intra and extra focal pattern are not supposed to be identical, even when it is near perfectly corrected. Or, put somewhat differently, that it doesn't need to have near-perfect star test for near-perfect performance.

 

The answer to this special status is in its higher order spherical aberration. Due to its steeply curved optical surfaces, especially those of the meniscus corrector, Maksutov-Cassegrain systems generate 6th-order spherical aberration that can't be cancelled (w/o aspheric surface terms), only minimized by balancing it with the 4th-order aberration. While roughly as much noticeable in the star test as the lower-order spherical aberration for given P-V wavefront error (FIG. 189), the balanced form is considerably less detrimental to image quality."


Edited by Asbytec, 18 August 2019 - 07:58 AM.

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#12 dweller25

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Posted 18 August 2019 - 07:58 AM

I need to get the 150 Mak out beside the 127 and compare when we get another decent night here.  It's been monsoon clouds or hot nights with heavy turbulence lately. Of course as you all know, the minute you get another scope you want to try out, the weather goes to h*ll. The 127 is going to be hard to beat because it had excellent optics when I got it, and I flocked the primary baffle internally, and the secondary mirror baffle has been reduced such that the secondary obstruction is down to 33%.  I also sanded the inside of the secondary baffle to reduce any glare. There is no question the planetary images are brighter in the 150 as expected, but the question is - am I seeing more detail.  There is no question that Saturn's Tethys and Dione are easier to see. We shall see and I will update this discussion with time.

 

One interesting thing I have meant to comment on is that the reverse of "cooling down" in a Mak doesn't seem to affect the performance when it is reversed. My Maks almost invariably have cooler air inside of them when I take them out in the summer or early fall to observe.  The focus may change slightly over a half an hour, but there is no optical aberration "plume" when defocused as is the case when the internal air is warmer than the outside air. 

 

Frank

Tucson  

Looking forward to your comparison......



#13 fcathell

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Posted 18 August 2019 - 01:36 PM

Thanks for the info Norme (Asbytec), and I am somewhat familiar with the higher order SA based on previous posts and discussions by you and others who are familiar with optical design. I have noticed one thing about this larger Mak in my initial tests. It actually shows a slightly different I/O focus diffraction pattern after I've let the scope acclimate for about 20 minutes. I get this very slightly with my 127 Mak but not at all with the 102 Mak and never noticed it with the 90 Maks. It doesn't seem to affect the images, however, for the most part. Keep in mind that at my location, the temperature is usually about the same outside as inside or actually warmer outside during the summer. As I posted previously, I never seem to have the temperature differential issue degrading the initial viewing when the outside air is warmer than the air inside the tube.

 

Frank


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#14 fcathell

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Posted 19 August 2019 - 12:05 AM

It was a superb evening here in Tucson.  I was able to compare my old "trusty" 127 Orion Mak to the new Orion 150 Mak. Transparency was excellent and I was surprised how minimal the turbulence was despite the afternoon temp reaching about 104 here. When I came in from observing it was 85. This was a tougher comparison that I had figured. I mostly used about 225X on both scopes and observed Jupiter and Saturn and later put the 150 Mak on M22. The 127 Mak easily handles 250X on the planets and I found that the 150 has no problem with 300X. Views were very sharp in both scopes and I can't say that I really saw anything more in the 150, HOWEVER, the extra brightness did noticeably enhance the small festoons in the NEB and the Red Spot Hollow. The RS was on the central meridian of Jupiter about 8:30 PM local MST. I think the RS appeared a little more red in the 127 Mak for some reason. Saturn was excellent in both scopes but again, the increased brightness certainly enhanced the view in the 150 Mak and Saturn's pale atmospheric bands were more evident. I could not detect any "softness" of the images in either scope even when pushed to 250X on the 127 and 300X on the 150. The 150 is definitely impressive and if my memory serves me well, I can't say that any of the 8" SCTs I've owned in the past ever quite exhibited the contrast on Jupiter as this 6" Mak does.  As you may have seen in an earlier post topic today, I put a handle on the 150 Mak and it is much easier to carry. Am I going to keep it - YES, but the comparison also made me appreciate how good the 127 performs also. For me the 150 is more of a "home" scope and is marginal for me as a "grab-and-go" scope.  The 127 fits that bill with the noticeably lighter weight. Will I move on to the 180mm Mak? Very unlikely because of its weight and size and the fact that my old Astroview mount would be very marginal. One other thing - the view of M22 in the 150 with a 25mm wide-field eyepiece was fantastic.

 

Frank    


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#15 spongebob@55

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Posted 19 August 2019 - 09:15 AM

It was a superb evening here in Tucson.  I was able to compare my old "trusty" 127 Orion Mak to the new Orion 150 Mak. Transparency was excellent and I was surprised how minimal the turbulence was despite the afternoon temp reaching about 104 here. When I came in from observing it was 85. This was a tougher comparison that I had figured. I mostly used about 225X on both scopes and observed Jupiter and Saturn and later put the 150 Mak on M22. The 127 Mak easily handles 250X on the planets and I found that the 150 has no problem with 300X. Views were very sharp in both scopes and I can't say that I really saw anything more in the 150, HOWEVER, the extra brightness did noticeably enhance the small festoons in the NEB and the Red Spot Hollow. The RS was on the central meridian of Jupiter about 8:30 PM local MST. I think the RS appeared a little more red in the 127 Mak for some reason. Saturn was excellent in both scopes but again, the increased brightness certainly enhanced the view in the 150 Mak and Saturn's pale atmospheric bands were more evident. I could not detect any "softness" of the images in either scope even when pushed to 250X on the 127 and 300X on the 150. The 150 is definitely impressive and if my memory serves me well, I can't say that any of the 8" SCTs I've owned in the past ever quite exhibited the contrast on Jupiter as this 6" Mak does.  As you may have seen in an earlier post topic today, I put a handle on the 150 Mak and it is much easier to carry. Am I going to keep it - YES, but the comparison also made me appreciate how good the 127 performs also. For me the 150 is more of a "home" scope and is marginal for me as a "grab-and-go" scope.  The 127 fits that bill with the noticeably lighter weight. Will I move on to the 180mm Mak? Very unlikely because of its weight and size and the fact that my old Astroview mount would be very marginal. One other thing - the view of M22 in the 150 with a 25mm wide-field eyepiece was fantastic.

 

Frank    

Thanks for the observational info Frank.

I have a 127 too and have been impressed by what it 'sees' for its aperture.  (Jupiters red spot also looks more intense in it to me.)   Its nice and light and my Evolution with the OE legs handles it w/o a vibration even in gusty winds. 

We hardly EVER have good seeing or steady skies here or for that fact, even good transparency (NJ).   I wonder how these two would compare on a night of below or average seeing?   I've often read that smaller apertures do better........whether or not that would apply to only an inch is open to discussion.

And our horrible light pollution!  Ug.

Could you tell us about how you installed a handle and what you used please?   

Also tell us about the 25mm.   I usually don't use anything other than a 24mm ES 68* in my 127.   

Thanks for posting

Bob


Edited by spongebob@55, 19 August 2019 - 09:19 AM.


#16 fcathell

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Posted 19 August 2019 - 10:09 AM

Bob - here's the link for the handle: https://www.cloudyni...le-for-150-mak/

 

It's in this same Cats and Casses section.  I also put one on my 127 years ago.  

 

You can definitely see the difference caused by atmospheric turbulence effects with small changes in aperture. I commented on this a little over a year ago on one of these forums.  I think that is one reason I find myself using my 102 Mak quite often, particularly during the hot months here in Tucson. 

 

Frank

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#17 Cometman

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Posted 19 August 2019 - 03:06 PM

I have been using my new 150 Explore Scientific Mak-Cass and I love it! The planetary views are  spectacular!


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#18 Chris Y

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Posted 23 August 2019 - 01:34 PM

I have been using my new 150 Explore Scientific Mak-Cass and I love it! The planetary views are  spectacular!

I'll throw in another big "HOORAH!" for the ES 152 M-C.  I love mine, and my neighbor is getting interested after seeing Jupiter through it a few weeks ago.


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#19 JimFR

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Posted 25 August 2019 - 07:52 PM

I have been using my new 150 Explore Scientific Mak-Cass and I love it! The planetary views are  spectacular!

This is a scope not many hear about.



#20 elwaine

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Posted 25 August 2019 - 08:51 PM

You can definitely see the difference caused by atmospheric turbulence effects with small changes in aperture. I commented on this a little over a year ago on one of these forums.  I think that is one reason I find myself using my 102 Mak quite often, particularly during the hot months here in Tucson. 

 

Frank

Frank, try wrapping the 150mm Mak in one of two layers of Reflectix and you won't be bothered with turbulence, nor will you have to wait until the 150 acclimates. It's like magic. I've given up trying tp explain (or understand) why the insulation works. All I know is that it works. It worked for my 150 Mak and it's working for my 180. 



#21 fcathell

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Posted 26 August 2019 - 10:42 PM

Larry - internal air acclimation is not an issue here in Tucson.  In fact, at this time of year the outside air is actually warmer than inside the air conditioned house.  My problem is truly atmospheric turbulance, particularly to the south because I have to view the planets (Jup and Sat) over a neighbor's house that has roofing tiles that heat up during the day and cause convection at night. The dry air here in Tucson also has high altitude convective cells that further aggravate the problem. The smaller Mak sometimes wins out because of the aperture relationship with the convective air cells.

 

Frank




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