|Entry: Astronomy:Equipment Reviews:Telescope Reviews:Meade ETX90-RA|
First the bad news. It's easy to get sucked in by the oh so cute appearance of this thing. But ergonomically, it has to be about the worst design around. For me, the easiest way (or least difficult, I should say) to use it is to set it on the ground and lay down sideways behind it. For comparison, the Orion shorttube 80 on the tabletop equatorial mount is a cinch to use just about anywhere.
Besides having a pitiful 21mm aperture, the finder scope on the 90RA is straight through, not right angle; so I must scoot up underneath it -- a lot like I am fixing to change the oil on the car -- to look up through it (recall, we're laying on the ground here). And since this is an 8 X 21 finder, you don't get near the field of view or light gathering that you would get on an 8 or 9 X 50 finder. But, it's good enough to find Saturn, Jupiter, the moon, or M42. However, given that the scope itself has a 1250mm, f13.8, focal length -- which ain't going to give you much of a field of view -- if you were figuring on scanning around to find things, you might want to do a little more figuring. Scan around with the shorttube 80? Sure! Scan around with the 90RA? Well .... hmmmmm. Actually, the shorttube 80 with a 32mm eyepiece essentially IS a finder scope; so I usually don't bother putting a finder on the shorttube 80.
Again, comparing the 90RA and the shorttube 80: The mostly plastic base of the 90RA makes for a real case of shivers and shakes every time you touch the focuser or any other knob. The tabletop equatorial mount with the shorttube 80 is reasonably steady.
The 90RA drive takes three AA cells. I use NiMH without any problems. But, you have to remove three screws to remove the base to install and remove the AA cells. As long as we indulging in bad physical design, let's go whole hog eh? Now, here the shorttube 80 isn't much better: You must take apart the shorttube 80's drive to install a 9V battery (again a NiMH in my case), and in some positions, the counter weight on the tabletop equatorial mount bumps into the drive motor; so you have to move the weight out to a position that unbalances things.
The location of the RA and DEC manual adjustment knobs on the 90RA is such that it is a bit inconvenient to get to them when your head is blocking access to them because you are doing something stupid like looking in the eyepiece.
There are a number of dimwitted physical design details on the 90RA, and that is the reason for my rather low ease of use rating.
Now for the good news (Yes, there is some good news!).
After you get past all the aggravations and annoyances, the optics are pretty good. I would say they support magnifications at or near the 50X per inch Nirvana goal. I can't say you'll be blown away by any exquisite detail, but they ain't bad. Comparing it to my shorttube 80, I would have to give the 90RA a slight edge on detail. And, of course, the 90RA has absolutely no purple halo (which is in abundance on the shorttube 80) on anything. Now, let's be clear about this. When it comes to detailed views of something like Saturn, my Orion f8 6-inch dob, and Meade 8-inch UHTC LX10 will both trounce the 90RA into the ground, dig it back up, trounce it back into the ground, dig it back up, and then throw into a dumpster and spit on it. The 90RA offers decent, but not outstanding, 90mm planetary views and nothing more. This scope isn't about to put Televue out of business any time soon. It's use on deep space objects is very limited (as is the case for most non-premium 90mm scopes). You might be able to grab a few open clusters, but I wouldn't count on much of anything else.
The 90RA does provide a simple, but actually quite accurate way to set the angle for polar alignment. After I have it polar aligned, mine does a good job of tracking. So give it pat on the back for that. The RA setting circle is big enough to be semi-useful. The DEC setting circle might get you into the general neighborhood, but will probably leave you to do some groping around after that.
I know I have razzed the 90RA a wee bit here, but I actually do give mine some use. I got mine for $149 with the 26mm deluxe Plossl eyepiece when Meade (via Astronomics) was running a special on these things. For the money, it's good value. It's main strength is that it is very convenient to pick up and take outside for casual planetary use. After you get used to the boneheaded physical design (assuming you do get used to it), the optics deliver good enough performance to fix you up for those times when you don't need the ultimate in exquisite planetary views.
And you do have to admit ... These things are soooooo cute.
Overall Rating: 6
Optics:7 Mount:5 Ease of Use:4 Value:9
Date: 03/23/2004 10:50:46 pm PST
Entry: Astronomy:Equipment Reviews:Telescope Reviews:Orion StarMax 127mm Mak-Cass
I've had this for over a year now and have done some comparisons with my Celestron CR-150HD (6-inch Chinese refractor) and XT 6 Dob. I use it on a Celestron CG5 mount.
The Starmax does a decent split of the double-double with a small diffraction ring around each star except where the rings intersect. The Celestron does it better. Planetary detail on Jupiter and Saturn is substantially better with the Celestron. However, Starmax has no purple halo as with the Celestron (most of which can be removed with a v-block filter). I should add that I was lucky and got what has proven to be one of the better CR150's that have come off the assembly line. Planetary detail on the Starmax is sharpest at about 120 - 140 power while the Celestron can usually go to about 170 - 200 power before no further improvement is seen and detail starts to soften up. On double stars, the Starmax will support up to about 250 power yielding a decent image encircled by a small diffraction ring. The inside / outside focus images are comparable.
My general impression of the Starmax is that optics are OK, but nothing remarkable.
Starmax focuser is smooth with negligible (if any) image shift. The knob is located upper left on the back -- not the ideal place I think. The dinky finder scope is of limited usefulness.
The mediocre overall light transmission combined with the 5-inch aperture limit its usefulness for deep space objects. Every time I try it for this purpose, It seems that it is always starving for light.
One must exercise some care when collimating the Starmax because there is a rubber band that will easily fall out -- the work of a mentally retarded designer. I originally thought this was a defect in the scope. When I contacted Orion about this, I found their customer service to be almost hostile.
In comparison with Celestron CR150 refractor, the Starmax is soundly beaten on all points but chromatic aberration. It is fairly close to the XT 6 for showing detail, but the XT 6 wins out on deep space objects. For what it's worth, The Starmax beats the pants off an ETX90 (as one would expect).
The Starmax is an OK, but not outstanding, scope and represents a reasonable value for the money. If we are to call the likes of TMB, Televue, etc. a 10, then I think a rating of 6 is fair for this scope. It does a decent job of providing a portable and modestly priced scope for planets and double stars. I find it unsatisfactory for deep space objects. If nothing else, it will give you something to put on your CG5 mount after you buy a GOOD mount for your Celestron CR150.
Overall Rating: 6
Date: 06/16/2003 10:36:17 am PST
Entry: Astronomy:Equipment Reviews:Telescope Reviews:Orion SkyQuest XT6 (Intelliscope) Dobsonian
Out of the box, with just a simple, quick collimation, optics provide good resolution. The XT6 does a good job on double stars, but getting any significant detail out of the larger globular clusters with the XT6 is a bit dicey under "typical" city observing conditions. In a semi-dark location, clusters such as M13 and M22 yield a decent number of resolved stars with typical conditions. Smaller clusters such as M92, M15, and M2 are not so generous and require excellent conditions to show any detail. The XT6 splits the double-double with Orion's 15mm Ultrscopic combined with their Ultrascopic barlow. And in the moments of clear viewing, it can be seen that the split is quite clean. A star test looks good. I think the optics on this scope will make it a good planetary and double star scope, but I can't verify its planetary abilities at this time since the only view I've had of Saturn has been low in the sky on a so-so night.
After owning it for about three weeks, I decided to give it the full-blown optical alignment and collimation. In order to square the focuser with the secondary, I had to remove two of factory screws and use #8 half-inch screws so there would be sufficient length to permit shimming one side of the focuser with two #8 washers on each screw (i.e. four washers total). After the deluxe alignment and collimation, the detail visible through the scope was excellent. Even on nights of mediocre viewing, powers of 200X - 250X are supported with no problems, and close doubles are easily split. It seems like these f/8 six-inchers, when they have been carefully aligned and collimated, are tough to beat when it comes to splitting close doubles and showing detail.
I do have some complaints about the mechanical qualities of the scope.
The mount is rather stiff, probably because the spring tension supplies a little too much tension. When adjusting altitude, there is a tendency of the bearings to initially resist movement then suddenly break loose causing you to go past your target (I think this is called "stiction".). I haven't gotten around to it yet, but I intend to move the teflon base pads a bit closer in to the center to make azimuth movements a little easier; either that or do the milk carton thing.
The focuser is terrible: Being plagued by a ridiculous amount of slop, it's easily the worst I have ever used on a scope (worse than those plastic Meade jobs). There is so much slop in the fit that objects shift considerably when adjusting the focuser in and out. Tightening the tensioner just makes things worse because this presses a plastic bar against the eyepiece tube, and the plastic grabs the drawtube and makes it rock back and forth even more as you turn the adjuster knob back and forth. This also effects one's ability to collimate. With a laser collimator, the red dot will move at least an inch on the main mirror when the focuser knob is turned back and forth. And, as already mentioned, it required a hefty amount of shimming to square the focuser with the secondary. I found that collimating with a Cheshire eyepiece gave the best results. The primary mirror comes with the center already marked -- a nice feature.
I was able to solve the slop by shimming the focuser drawtube with the "vel" part of velcro strip with adhesive backing. I cut two narrow strips from a larger strip and stuck these narrow strips inside the focuser body. After I did that, it occurred to me that sticking a single strip to the tensioner bar might work too. I also cleaned out some chrome chips that had flaked off in the gear mechanism. The shimming and the clean out (mostly the shimming) made a world of difference. I'm wondering if there should have been some additional teflon shims that the manufacturer "forgot" to insert. It's possible that all shimming I had to do to the drawtube is partially responsible for extra shimming of the focuser body in order to get it squared with the telescope.
The instructions mention a 2mm hex key for the smaller adjusting screws on the secondary mirror. On the scope I received, the fit of a 2mm hex key (not supplied with the scope) was so loose as to make me doubtful that these were hex screws. After some experimentation, I found the fit of a 5/64 inch hex key to be correct.
The dinky finder scope is essentially worthless (why do they make these things?). If you don't have one of those red dot finders, get one (and figure the cost of one into your total investment in scope). I'll never understand why dealers don't sell the telescope at a reduced price without options and offer some option packages, at special pricing, for eyepieces and finder scopes so you can decide on the quality and price of the accessories you want instead requiring you to pay for lame accessories and eyepieces you don't want. If they only knew how many scopes I have NOT purchased because I didn't want to pay for the junk accessories. (end of editorial)
Stray light seems to be more of problem with the XT6 than with my 10-inch Dob. My house is located close to an expressway where overhead viewing runs about mag 2.5 give or take a bit. My viewing location is only slightly worse than a Wal-Mart parking lot; so I have LOTS of stray light! I've always read that the smaller Dob should be less affected by city light than the larger Dob; but my experience has been just the opposite. When trying to resolve globular clusters, the stray light does pose a real problem.
For those debating if a 6-inch scope is big enough, some thoughts:
My 10-inch Dob is an excellent Synta-made unit from Oceanside (www.optcorp.com) (essentially, the same thing as the XT10). I have looked through a fair number of 8-inch Dobs and SCT's; and, for deep space observing, the larger scopes do pull in more stuff and resolve more deep space detail. In a crapola viewing location (such as my house), all the extra light negates much of the advantage of the larger scope. But when I go to darker locations, I find that I spend A LOT more time with the 10 than with the 6. So part of your decision should be based on the conditions under which you will use the scope.
I have split the double-double with the 10 only under exceptional conditions. However I, and those who have looked through it, think it shows very good, sharp, images in general. It's relatively short focal ratio (f/5) makes it much touchier about alignment and collimation, and the aperture probably makes it more sensitive to atmospheric turbulence. The 6 is very forgiving of less-than-perfect collimation and routinely splits close doubles with no problems. But in a dark location, the 10 can reveal detail in those deep space objects that the 6 cannot. Also, the two-inch focuser on the 8- and 10-inch scopes is a BIG advantage. Looking through a big, wide-angle eyepiece like the University Optics 40mm Konig MK-70 gives a huge "portal into space" that the 6 can never do (in its stock form). So part of your decision should be based on what you want to spend most of your time looking at -- a case of "the right tool for the job."
Then there is the issue of size and portability. The 10-incher is not much smaller than a 30-gallon hot water heater (non energy efficient model). With the XT6, I can stuff a couple of eyepieces and a barlow in my pockets, grab a stool in one hand (Harbor Freight sells a good pneumatic adjusting stool for about $20), and grab the scope in the other hand. I can grab everything in one trip out of the house.
If one is going to have only one scope and is debating about the size, even though I don't have an 8-inch scoe, I think an 8-inch scope seems like a good compromise between the portability, ease of collimating at least "close enough for government work", sufficient aperture to show some deep space detail, and the ability to give big, rich-field views. For example, the Orion XT8 weighs only about four pounds more than the XT6 (if Orion's published specs are correct), so you have only a little less portability. One thing I do miss with the XT6 are those big, rich-field views that a 2-inch focuser allows when using big, wide-angle eyepieces. Besides providing lovely views of the Milky Way that the XT6 can't come close to matching, those wide views make things a lot easier to find (DEFINITELY an important consideration for somebody learning to navigate the sky). If all you ever did was planetary or double star viewing, then the lack of a 2-inch focuser would probably never be missed. But you WILL eventually want to do some deep sky viewing; and the first time you ever get an eye-full of what a big, 2-inch, wide-angle eyepiece provides, you'll wonder how you ever got along without it.
Optically, the XT6 is excellent, especially after you give it the deluxe alignment and collimation treatment. Detail is fine, but I find the aperture and overall light gathering to be just under what is required to show any significant detail in glubular clusters or for reeling in a nebula (at least to satisfy my tastes). In this aspect, the 10-inch beats the XT6; but the XT6 can split close doubles that the 10 cannot (usually). Mechanically, the XT6 has some rough spots; most notably, a sorry excuse for a focuser on the one I received. And you are paying for a rinky-dink finder scope that you will end up replacing.
Overall, this is a fine scope for when you want something portable, for splitting doubles, and (I suspect) for planetary work. On deep space stuff, the 6-inch aperture is somewhat limiting if you have easy access to a dark viewing location, but you can still see quite a bit with it. If you are forever stuck in a piss-poor viewing location, then the XT6 will probably be just about as good as the larger scopes.
Overall Rating: 7
Optics:8 Mount:6 Ease of Use:8 Value:8
Date: 10/16/2002 06:39:33 am PST
Entry: Astronomy:Equipment Reviews:Eyepiece Reviews:GTO Proxima 31mm
First Proxima arrived with loose elements, and retainer ring was bound up so tight (possibly from paint) that it would not budge. So had to go through hassle of returning it for replacement. Deduct a point for quality control.
Compared with University Optics 40mm Konig Mk-70 in Synta-made 10-inch dob from Oceanside (www.optcorp.com). Lense coating on UO is better; light reflection on Proxima is fairly noticable. If you want that big window on space view, UO is much better -- but much of that is certainly due to 40mm for UO versus 31mm for Proxima.
Tried Proxima in Orion 2-inch barlow on M22. View was very sharp over entire field. Definitely must give Proxima high rating for sharp image.
Proxima accepts Orion filters; UO does not.
I got Proxima primarily to use when I wanted higher power than what UO 40mm provides and to use Orion filters. For my purposes, the Proxima is proven to do exactly what I intended for it to do. It compliments the UO 40mm quite well.
Overall Rating: 7
Date: 08/15/2002 10:57:30 am PST