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Equipment Discussions >> Cats & Casses

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pdxmoon
scholastic sledgehammer
*****

Reged: 06/27/13

Loc: Oregon
Attention all Star Max 90 Owners
      #5964823 - 07/10/13 10:12 PM

Hello Friends:

Neewb question:

For those of you who have or have owned an Orion Star Max mak 90, how often did you or do you do collimation? This is not a how to question, it's a how often question.

I've never had any sort of reflector or mak, and I'm trying to get a sense of how much tinkering one has to do with a scope like this.

Thank you!


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DaveG
sage
*****

Reged: 12/28/03

Loc: Ohio
Re: Attention all Star Max 90 Owners new [Re: pdxmoon]
      #5964866 - 07/10/13 10:28 PM

Most Maks, especially those with smaller aperture rarely if ever need collimated. I have owned several Maks and the optics have been perfect out of the box.

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pdxmoon
scholastic sledgehammer
*****

Reged: 06/27/13

Loc: Oregon
Re: Attention all Star Max 90 Owners new [Re: DaveG]
      #5964894 - 07/10/13 10:46 PM

Hmmm. That definitely lowers the anxiety level. Thanks!

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Binojunky
Carpal Tunnel
*****

Reged: 12/25/10

Re: Attention all Star Max 90 Owners new [Re: pdxmoon]
      #5965702 - 07/11/13 01:29 PM

Same here, over the years I owned two ETX 90,s, a Apex90, two of the latest version C90,s,one of the previous version C90 and a Apex127, all arrived in good shape with no collimation issues,DA.

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csrlice12
Postmaster
*****

Reged: 05/22/12

Loc: Denver, CO
Re: Attention all Star Max 90 Owners new [Re: Binojunky]
      #5965717 - 07/11/13 01:40 PM

While you may only need to adjust it occasionally, I'd check it each viewing session; escpecially if I've moved the scope or drove any distance.

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stevenf
sage


Reged: 10/11/09

Loc: Vancouver, BC
Re: Attention all Star Max 90 Owners new [Re: csrlice12]
      #5965722 - 07/11/13 01:43 PM

I have an ETX90, a Skywatcher 90 mak (same as the star max 90) and a 127 mak. None of them have ever needed collimation (at least to my eyes!).

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Eric63
scholastic sledgehammer


Reged: 06/16/12

Loc: Ottawa, Ontario
Re: Attention all Star Max 90 Owners new [Re: stevenf]
      #5966061 - 07/11/13 04:59 PM

I have a 127 Mak (1 year now)and drove many miles with it (and on dirt roads too). Have not yet had to touch collimation.

Eric


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Attention all Star Max 90 Owners new [Re: pdxmoon]
      #5966140 - 07/11/13 06:04 PM

Not often and generally only if mishandled. Small MCTs take the usual bumps and vibration from travel quite well. The internal components have little mass, and the mechanicals that hold them in place are overbuilt (i.e., more robust than necessary given the lightweight work they do). Unlike 8" an larger SCTs with hefty mirrors and comparatively less robust mechanicals for the work being done which require collimation often if traveled with, these little guys hold collimation well unless dropped or handled very roughly.

Though I know you're not asking "how to" I feel the answer to that question nonetheless has bearing on the underlying question implied by your post - "Because I've not ever done it, is collimation to be feared?" Unlike secondary collimator catadioptrics these Gregory Maksutovs are rear collimators. This is important because when you collimate a front collimator of any significant apeture, you so so by walking around, making an adjustment to the secondary, then going back to the eyepiece, recentering the defocused star and checking your work. This is a time consuming iterative process that is done in the dark. These little maks, though, are collimated indoors in daylight and you never need leave the rear of the scope. No star is needed. No re-centering between adjustments is required. Orion provides instructions in pdf format on its website, but basically there are 6 screws, 3 large and 3 small, inset into the rear casting of the scope. Three of them pull the primary to tilt it and three of the push the primary to tilt it. Whenever you collimate, you adjust all 6 screws, keeping the same tension as you started with on the mirror during the process. Heck, you don't even use an eyepiece. You just center your eye in the baffle (using a Cheshire or even collimation cap - $6.95 from Rigel Systems - will help, but isn't essential), note which way the reflection of the edge of the primary is "lunetted" and then pick your starting screw accordingly. The instructions are precise from there. It's hard to go badly wrong. I'd say you should have ZERO fear.

Regards,

Jim


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CollinofAlabama
Carpal Tunnel
*****

Reged: 11/24/03

Loc: Lubbock, Texas, USA
Re: Attention all Star Max 90 Owners new [Re: Eric63]
      #5966210 - 07/11/13 06:58 PM

I owned all three Orion Maks, way back, from 2002 to 2006. Never collimated any of them, nor needed to. See this for some basic collimation info. In particular, notice the chart a ways down. When you get to F/6, it starts to get mechanically very easy to keep an instrument collimated. As one moves farther out, say F/8, the "sweet spot" gets almost silly large, 11mm (closing in on 1/2 an inch). All Orion Maks are F/13.something, so they're "sweet spot" is gonna be HUGE. In practice, this means that being out of perfect collimation by even as much as 1/2" will not affect the device's diffraction limited performance. That may sound small, but I assure you, given the tolerances involved, it's HUGE.

So the truth is that unless you do something really stupid like drop it (in which case you will probably be more likely to smash the corrector plate, anyway), you're unlikely to ever need collimating any Mak-Cass F/13+, which all the Orion Maks are. There are problems with F/13 -- like terrible True Field of View, but collimation will NOT be one of them. People trying to correct a few millimeters off perfect collimation on F/13 Maks don't understand diffraction limited optics and how that is affected by the Focal ratio (F/Ratio). In short, you're highly unlikely to ever need collimating an Orion Mak-Cass. Just take care of it (duh!), and it will provide years of excellent performance. These exact same rules apply to refractors (which are more resistant to miscollimation and optical performance than reflectors). Newtonians are a special breed, and usually require collimation, but even this need is directly related to the F/ratio. F/8 scopes can probably get buy once a year. F/6, once a month, F/5 and below, better check every time you go out. Unfortunately, people can get so Newtonian focused they forget about other optical trains and their requirements, and tend to over-emphasize collimation. With standard, F/13+ Mak-Cass', it's just not relevant, at least not typically.

But I wouldn't look at the 90mm model. Given you have an 80mm ED scope coming, the 127mm is where I'd look at coming into this ballgame at. It would provide considerably better performance over the 80mm on smaller targets.

Bon la chance


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Attention all Star Max 90 Owners new [Re: CollinofAlabama]
      #5966224 - 07/11/13 07:10 PM

Problem is, like other folded catadioptric designs, the MCT uses fast mirrors to achieve a system focal ratio of f/13. Collimation criticality depends on the speed of the mirrors, not the final system in such a scope. These MCTs are every bit as dependent on perfect collimation for best results as an SCT I suspect (most of which have f/2(!) primaries; collimating an SCT is akin to collimating an f/2 Newtonian).

Regards,

Jim


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CollinofAlabama
Carpal Tunnel
*****

Reged: 11/24/03

Loc: Lubbock, Texas, USA
Re: Attention all Star Max 90 Owners new [Re: jrbarnett]
      #5966480 - 07/11/13 10:40 PM

Thom,

See the Wikipedia entry and this article to get a better understanding of the amazing Dmitri Maksutov and his telescope. Fascinating life and a truly ingenious design -- to take a fast, easier to produce spherical mirror, and eliminate the spherical aberration with an aspherical corrector plate that defocuses light outward to begin the optical train of this scope. What an optical master he was. To win awards under Stalin, while having fought with the White Russians, wow! You almost have to love this telescope because of its fantastic history.

Jim's right, of course. Mak-Cass' begin the optical path with an aspherical corrector striking something like an F/2.5 spherical primary mirror. However, the light bounces back to a secondary that slows the whole path down. Literally, the steep optical curve of the primary is thoroughly straightened out by the secondary. So the light that reaches the focuser (and consequently the eyepiece), is now so "un-steep" that it results in an F/13-ish style light cone. So that's the effective F/ratio. Doesn't matter what happens before, only what happens when it reaches the eyepiece.

Of course, it does matter what happens before, but like Jim pointed out earlier, these small Maks are overbuilt and designed to be relatively tough. Not that foolishness and carelessness can't ruin their collimation -- it certainly can --- but rather gentle respect for the optic will generally be all that's needed to keep it well collimated for years of pleasant operation.

The main drawback for this design is True Field of View. Couldn't get over that hurdle, myself. I really like a wide field, looking for a target. Also, some targets, like the Veil, the outer reaches of M42, M31, the Markarian Chain, M81/82 & NGC 3077, these can't be framed in a Maksutov the way newtonians with wide field eyepieces, and smaller refractors can. And if they're good optically, these other designs can often do well on high power.

Still, there's something nice about the Maksutov and it's long focal ratio. The skies are often extra dark, and the color of stars sometimes comes out better in them. A really nice scope, at least for 5" and below. The 5" is big enough. Larger models are made, but the thermal problems that the 5" has in abundance, larger models have exponentially worse. To say nothing of the weight. Still, if you just want a quick view, a 4" Mak sure is nice. And on a moon drenched night, when there are no conjunctions calling for a wide field view, a 5" Mak can satisfy like few other scopes.


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Attention all Star Max 90 Owners new [Re: CollinofAlabama]
      #5966654 - 07/12/13 12:31 AM

I was messing with mine, comparing it to an AT60EDT (60mm f/7 triplet) and SV80S (80mm f/6 triplet) last weekend. On centralized DSOs like globulars, I actually preferred the C90 to the others. The SV80S was the better star field scope, for sure, but at 1/9th the price of a used SV80S, the C90 is quite a nifty G&G option. I'm planning on taking mine along for this summer's dark sky adventure (to use as a spotter, as well as for a little small scope, dark sky astronomy).

The C90 is actually near and dear to my heart for another reason. When I was in graduate school longer ago than I care to remember, and my parents had moved and packed up all my stuff, including my 6" f/8 Newtonian was sent off to a storage facility...somewhere. I bought myself a Christmas present, wanting a telescope for "relaxation". I picked up a cheap-o Bausch & Lomb 3.1" MCT and put it on a $25 Velbon photo tripod. Starving, in-debt-up-to-my-rear student that I was, I made a dew shade out of a rolled up dark green hanging folder (thick paper). When the "big one", the Loma Prieta quake, rocked the Bay Area and shut off the power for 4 days, I enjoyed one of the finest observing sessions in my life with that little scope. I loaded the scope and mount into a backpack, hopped on my mountain bike, and rode 35 miles from my apartment in Santa Clara past my parent's old house in Cupertino and up into the foothills, illegally entering one of the open space preserves after close. Not a shred of light to be seen. Inky black transparent air. Totally quiet surroundings. Note that there were no traffic signals, no phone service, nada. I remember riding back to my apartment at the crack of dawn with a big smile on my face.

I'd love a repeat of that '89 session with the C90 under the dark, high desert skies of the Colorado Plateau this September.

Regards,

Jim


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CollinofAlabama
Carpal Tunnel
*****

Reged: 11/24/03

Loc: Lubbock, Texas, USA
Re: Attention all Star Max 90 Owners new [Re: jrbarnett]
      #5967272 - 07/12/13 11:49 AM

I still remember well how my favorite of the bunch, the Apex 102, framed the DumbBell so nicely. Just did one fantastic job for such a small scope. I also recall my 5" Mak's view of M31 with a 32mm Plossl. I think the latter target can look better in a big dob with a wide field, but I guess I hadn't looked thru that many back then. Just fantastic view.

However, romance is no substitute for the cold, hard facts. The Celestron C90 spotter is the same as the Orion Apex 90 (same Chinese OEM, Synta), and it costs $150 shipped from B&H Photo out of NY (and probably the same price from a lot of other places, too). I wouldn't get the Orion iteration of this scope. At $299, the Apex 102 is twice the money. It's certainly not twice the scope, but it is better. A little more light grasp, while not taking a hit in portability or thermal equilibrium issues (more important if you live in a cold climate -- but still important to me on the 33.5 parallel, deep in the continent and almost a kilometer above sea level). The 127mm is quite a bit heavier than the others, and can take a while to thermally equilibriate in the winter. Of course, it costs the most, new, at $400, but naturally delivers more photons at the eyepiece. They're all good, but I'd get the C90 over the Apex 90 for cost, then it's pretty much Orion's ballgame for the 102 and 127's, new at least. Every Apex I've had, btw, had a nice focuser without a lot of slop. I purchased all mine new. The C90 makes sense for über portability, the 102 is the best compromise of aperture, portability, and performance, and the 127 is the absolute best performance, in a very reasonable package compared to most 5" scopes.

Good luck


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pdxmoon
scholastic sledgehammer
*****

Reged: 06/27/13

Loc: Oregon
Re: Attention all Star Max 90 Owners new [Re: CollinofAlabama]
      #5969068 - 07/13/13 02:08 PM

Thank you Collin and Jim. My observation at present is limited to backyard urban viewing, mainly PDX (Portland, OR.) I concentrate on lunar and planetary. It sounds like for the narrow FOV of a mak, it might be a really fun scope for good detail on the moon, although without tracking at higher magnification and a narrow FOV it might be a chore?

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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Attention all Star Max 90 Owners new [Re: pdxmoon]
      #5969460 - 07/13/13 07:02 PM

Huzzah Portland!

<----------- Reedie here. PDX FTW!



- Jim


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pdxmoon
scholastic sledgehammer
*****

Reged: 06/27/13

Loc: Oregon
Re: Attention all Star Max 90 Owners new [Re: jrbarnett]
      #5969486 - 07/13/13 07:15 PM

Hi Jim:

Ah, a Reedie. That explains everything :-)

My best man is a Reedie, which is why, 25 years ago when we moved from LAX to PDX he turned us on to Eastmoreland. We lived there for 20 years until April, when we moved across the campus to our downsize home in Reedwood (off Steele). Better neighborhood for observing: no streetlights, and all single story mid century modern houses.

Now if I could only convince my backyard neighbor to cut down that apple tree, I'd have an absolutely unobscured view of the west!


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pdxmoon
scholastic sledgehammer
*****

Reged: 06/27/13

Loc: Oregon
Re: Attention all Star Max 90 Owners new [Re: pdxmoon]
      #5969493 - 07/13/13 07:19 PM

BTW gentlemen, what do we think of THIS?

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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Attention all Star Max 90 Owners new [Re: pdxmoon]
      #5969544 - 07/13/13 08:07 PM

Haven't heard much good about it, to be honest, which can't be a good thing.

If you have $300 to spend, stretch it to ~$400 and get a C5 SCT. Same focal length as the C90, but 127mm of aperture, which will make a noticeable difference. It even comes with a nice case. The C5 will ride on pretty much the same mount as the C90/Apex 90.

What's your buying timeline? Immediately or in the near future but not immediately. I may be able to hook you up with your pick of a C5 or a C6 for a price for either one that is "too good to refuse". But I won't be ready to do it for a few weeks because I'm using those two scopes to finish up the observations for an article I'm working on.

Regards,

Jim


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pdxmoon
scholastic sledgehammer
*****

Reged: 06/27/13

Loc: Oregon
Re: Attention all Star Max 90 Owners new [Re: jrbarnett]
      #5969611 - 07/13/13 08:55 PM

Not even sure I'm buying. I'm doing my research and learning. I'm going to a Rose City Star Party soon and hopefully will be able to look into many scopes to continue my education.

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rocketsteve
sage
*****

Reged: 04/17/11

Loc: Southeast Louisiana
Re: Attention all Star Max 90 Owners new [Re: pdxmoon]
      #5970268 - 07/14/13 11:56 AM Attachment (16 downloads)

I've owned a StarMax 90 since 2004 and have never needed to collimate it. I even brought my mak to the Grand Canyon when I took my family on vacation in 2005. It was one of my carry-on items, so it went through TSA scanning and inspection, jostling in and out of the overhead compartments, and it was perfectly fine after returning home. Even though the scope is small, it's quite robust in it's construction. It's my primary telescope when doing planetary observing.


Dropping the telescope, onto a hard surface, is probably the only thing that would wreck your collimation...


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