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Pete66
newbie
Reged: 04/21/07
Posts: 3
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My wife has a 4.5 Orion dob and wants to go to a refractor as she prefers them over the dob.
Is the 100 mm EQ close to what she has?
As you can tell, I'm not into telescopes, although I do look through hers now and then,and she is not into computers, so here I am, kind of not knowing a lot,but this seems to be the place to get answers. 
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Patricko
professor emeritus
Reged: 01/30/07
Posts: 517
Loc: around the corner
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Welcome to CNs,
Yes, a 100mm refractor will give views of about equal brightness to her 4.5" dob; however, the refractor will have superior contrast and sharpness. The 100mm which you are talking about has a focal ration of 6. In other words 6X100mm=600mm focal length.
The drawback with this short tube refractor is that it will display false color (chromatic aberration) on bright objects, like the Moon, Jupiter, Venus, Sirius, etc.
If she likes Deep Space Objects and wide fields of view I would recommend the AstroView 100EQ. If she likes to observe the Moon and planets more I would recommend going with a 120mm f/8.3 achromat. These are all over the market and can be purchased used to save money. This scope is a 4.7" achromat refractor. It would do much better on the Moon, planets, and DSOs because of the increased aperture.
Once again I don't know how much you are willing to spend or what the observing goals are, but hopefully this is helpful to begin with.
Patrick
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PATRICK
 "Life is too short, go collect some photons!" - Me, myself, and I
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KWB
Postmaster
Reged: 09/30/06
Posts: 6615
Loc: Westminster,Co Elev.1646Meters
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Having owned both refractors and few 4.5 inch reflectors,my take is a little different. I would not use the term superior when comparing the 100mm F/6 and the Dob in terms of contrast or brightness of image. IMO the refractor might get an edge,slim at that, because of the noticeable CA to my eye in the refractor. The 120mm F/8.3 definately has an advantage over 100mm F/6 in terms of resolution,but CA is every bit as bothersome to me and usually was more so because of the considerably higher powers I used it at.
As far as useability,her present scope is far easier to get outside than the EQ mounted 120mm I had. I like the idea of the 4.5 inch Orion dob for smaller viewers in stature and the color free views these scopes deliver. IMO from an overall optical and ergonomic viewpoint,it gives up virtually nothing to the 100mm and very little to the 120mm.
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Kenny
"Everything which the enemy least expects will succeed the best."
Frederick the Great
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Patricko
professor emeritus
Reged: 01/30/07
Posts: 517
Loc: around the corner
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Hi KWB,
I agree with you that CA is a problem (especially on the Moon and bright planets), one that I don't like. I still think that aperture for aperture though a refractor shows pointer stars and more contrast. I would like to recommed the 120MM EON, but don't know how much they wanna spend.
I had a 4.5" StarBlast on a EQ-1 mount that I loved to use. Only draw back for me was that the f/3.9 was VERY picky about Exact collimation. Still it was a good scope. 
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PATRICK
"Life is too short, go collect some photons!" - Me, myself, and I
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KWB
Postmaster
Reged: 09/30/06
Posts: 6615
Loc: Westminster,Co Elev.1646Meters
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Hi Patrick
Maybe we aren't on the same page. My thinking is his scope is the F/8 Dob. BTW,welcome and call me Kenny.
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Kenny
"Everything which the enemy least expects will succeed the best."
Frederick the Great
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Patricko
professor emeritus
Reged: 01/30/07
Posts: 517
Loc: around the corner
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Oh, that is a good point. F/8 is a lot more forgiving that f/3.9. I liked my little dob quite a bit, the diffraction spikes were kind of annoying when trying to split tight doubles, but it was my only scope at the time.
I would like to see more unobstructed reflectors out there! That would be cool. No color, no spikes. Think Orion sells like a 3.6" one, wish they would go bigger.
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PATRICK
"Life is too short, go collect some photons!" - Me, myself, and I
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Raven911
Pooh-Bah
Reged: 03/12/05
Posts: 1356
Loc: New Mexico
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I have a 100mm F6 Astroview. It is a pretty good scope in my opinion. It gives a sharper view than the old Meade AR-6 I used to have. There is quite a bit of color on planets, but a good filter will stop most of that.
The good thing about these scopes is that they can be picked up for a song. I think I paid maybe $100 for my OTA, and tossed on a new crayford focuser. Spent no more than $200 in all for it.
ED junkies would hate it though.
I use mine for imaging too. It works pretty well for that also, but is no ED scope. I have found it has more light grasp than my 127mm Mak-Cass, and should beat a 4.5 inch scope in this regard. I think you would be shocked by what you can see with it under a good dark sky.
Go for it. Better yet, get a used one. I am sure if you posted a "looking for" ad in the Swap section you could find one. Though you might have to get the mount separately, or build one. If you decide you don't like it, you can always keep it for a super-finder, or later as a guide-scope if you get into imaging.
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http://smg.photobucket.com/albums/v287/Raven911/Astrophotos/
http://www.eye-of-the-raven.blogspot.com/
LXD-75 SN-10 UHTC/Moonlight CR1
IM M66 Mak-Newt
100mm F6/76mm F4.5/80mm F5/SV NHII 80mm F6 Achros
Canon 300D/DSI Pro Mono/Starshoot DSCI
8 inch F7 Newt on Edmund EQ
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Trondur
member
Reged: 03/09/07
Posts: 51
Loc: Cumberland County, Maine USA
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How would this scope work with inexpensive plossls and wide angles? I have the usual collection of GSO plossls (Orion Sirius, Meade 4000, Apogee, etc.) and Owl 6 & 9mm EWA and Garret 15 & 20mm SWA.
Everything I've read has led me to believe that f6 is too fast for these eyepieces. I can't afford anything better right now, so I haven't looked at these scopes.
Does anyone have any experience using these eyepieces in this scope?
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Terry
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60mm f11 Sears 2419 Refractor on Homemade Alt-Az Mount
80mm f11 Surplus Shed Refractor on Homemade Alt-Az Mount (Usable, but still Under Construction)
100mm f6 Orion Refractor on modified Majestic mount and tripod
114mm f9 Tasco Reflector on EQ-1 mount (Apparently, a rare Tasco, because it seems OK)
7x50 Swift Swiftfocus Binoculars
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AstroSteve
professor emeritus
Reged: 08/17/04
Posts: 629
Loc: Weston, Florida
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I have owned all these scopes one time or another. Get a Orion 120 F/8.3. It will be a much all around choice.
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AstroSteve
Orion Atlas GoTo Mount/Tripod GEM
William Optics Megrez 110ED Package III+Flattener
William Optics ZenithStar 70ED (Guidescope)
William Optics Guide Rings
SAC-10 3.3MP One-Shot Color CCD Camera
Meade DSI CCD (Guide Camera)
Canon Rebel XT 350D (DSLR Imager)
Nebulosity & PHD Guide(Stark Labs)Software
Shoestring GPUSB / Hap Griffin Cables
Energizer 120amp Hour Marine Battery (BIG POWER!)
Husky 400 Watt Power Inverter (THE JUICE!)
Dew-Not Dew Prevention System (Turn it up!)
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Patricko
professor emeritus
Reged: 01/30/07
Posts: 517
Loc: around the corner
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Hi Trondur,
I use plossls and kellners with a ST80. It is very fast at f/5. There is some field curvature with this design with fast scopes, but this doesn't stop me from using them. In fact a plossl performs better on the f/5 than do the "new" expensive wide field eyepieces do.
Have you ever considered orthos? Very cheap and very very sharp.
I would think that the Owl 6mm & 9mm$ would perform quite nicely on that scope. Those eyepieces have built-in barlows that effectively extend the focal length of the incoming light. Hope this helps.
Patrick
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PATRICK
"Life is too short, go collect some photons!" - Me, myself, and I
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CollinofAlabama
scholastic sledgehammer
Reged: 11/24/03
Posts: 892
Loc: Lubbock, Texas, USA
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Pete66, et alia,
I have owned the AV100 F/6 on the EQ-3 from Orion. I liked the scope very much. Having moved on to the ED refractor world, I don't think I could go back to this one again, but if you're wife prefers to not fiddle with a collimation-needing reflector, I understand. I have only recently overcome this fear, but it takes some time to get there, and her time may yet be waiting.
Her reflector has a spherical mirror, but this refractor is an achro, so both possess unpleasant optical problems, though in different measure. The refractor will, in my opinion, throw up crisper, nicer images overall, and be better. As mentioned, the refractor will have that pesky purple about all bright objects, so splitting Castor will be something of a challenge. The moon's limb will have a purplish tone bout it. Still, it will be sharper and crisper than the spherical reflector.
The mount is fantastic, and if she graduates to even an 80ED reflector, I think it's worth that.
Enjoy,
CDS
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Coelum Serendum
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Phil Frederick
professor emeritus
Reged: 12/19/05
Posts: 563
Loc: Seattle, WA & La Paz MX
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Hi Pete66,
Well, you've gotten a lot of advice here and I'll chip in my 2 cents.
I have the Orion 100f/6 at our place in Mexico and have had it for 4 years. Maybe I just have an excellent copy of this scope, but the CA is only a real problem on Jupiter, Mars and the Lunar limb. Other than that I find the views compare vary favorably with my 127Mak (except for FOV which is outstanding with the 100f/6)and only when you need to bump the power over 200x does it really fall behind the Mak. I did replace the R&P focuser with a Crayford which I highly recommend.
That said, I also have the SV102ED. If you want to spend $1100+/- than get the ED (or one of similar offerings from other manufacturers). You won't regret it for a second. However for $300 for an upgraded Orion 100f/6 you'll have a very nice, portable, easy to use scope that will show you a lot. I think it's a real value.
Plus, the fact that it's collimatable is a big plus in my mind. I initally thought the scope was ok but seriously messed with the collimation several years ago--wow, it was like a totally different instrument in terms of image sharpness. Didn't help the CA tho'  !
Don't you sometimes think there are as many opinions as scopes??? 
Good luck!
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Phil
Intes M603 6" Mak
Intes M500 5" Mak
SV102ED Osprey #0006
Astro-Tech 80LE CF
Orion 127 Mak
Orion ST120 f/5
Orion ST80 f/5
SV F50 Sparrowhawk
SV F60 Biggerhawk
Tak Teeguls, AT Voyager, SVP, Bogen475s, Oberwerk Jarrah, and a "Home-Grown" Tripod
...Naglers, Radians, LVWs, BO/TMBs, Stratus', and 32, 38 SWA's
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Pete66
newbie
Reged: 04/21/07
Posts: 3
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Wow!
Quite a response to my question.
Thanks to all for your replies and advice.
After talking to my wife it seems she is quite satisfied with the Orion SkyQuest but hates the hassle with the finder scope.
It is a nice size for her to handle in and out to the yard.
After checking out the Orion site I've found they make a right angle finder scope that I think will cure her problem.
I think I'll order one for her and maybe a Barlow to expand her choices.
I'll let you know how she likes it.
Thanks once again.
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KWB
Postmaster
Reged: 09/30/06
Posts: 6615
Loc: Westminster,Co Elev.1646Meters
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Welcome Pete
I think her choice is a good one as these are fun little scopes. A RA finder will make looking through the finder a lot easier. Despite the lack of parabolic optics,at F/8 these scope can deliver some fine images. My opinion is based on owning and viewing through them.
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Kenny
"Everything which the enemy least expects will succeed the best."
Frederick the Great
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darylf96
Pooh-Bah
Reged: 08/28/04
Posts: 1242
Loc: Danville, California
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Given the fact that the difference in aperture is not that great, you might want to consider a used 80ED and mount it on the Astroview mount. I would prefer a well-corrected refractor with a bit less aperture. Just a thought. The Astroview mount works nicely, and is much better since Orion
now fits it with a saddle.
Regards
Daryl
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KWB
Postmaster
Reged: 09/30/06
Posts: 6615
Loc: Westminster,Co Elev.1646Meters
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In own an 80ED and can say that a 114mm F/8 scope goes noticeably deeper as far as DSO'S and has better planetary resolution. The only optical advantage I see in the 80ED and it is a definate one,is it's ability to satisfy in the widefield mode. I much prefer the refractor on a light weigh alt/az mount.
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Kenny
"Everything which the enemy least expects will succeed the best."
Frederick the Great
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CollinofAlabama
scholastic sledgehammer
Reged: 11/24/03
Posts: 892
Loc: Lubbock, Texas, USA
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Pete,
From experience, get her a 0X finder to compliment her RA finder. Given the relatively light weight of her scope, I'd go with the Rigel QuickFinder. You'll have to drill a hole in the tube for the screw (which you should at least sharpie pen color black if it isn't a black screw to begin with to minimize internal stray light). This 0x finder is light weight. The telrad is the king of 0x finders, but it's pretty heavy and might upset the balance of the scope, and that wouldn't be worth it.
Good luck,
CDS
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Coelum Serendum
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Pete66
newbie
Reged: 04/21/07
Posts: 3
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Just to update, the RA finder arrived and she used it for the first time the other night and she loves it.
No more twisting to find objects.
Thanks again for all the help and responses.
If she is happy, I'm happy!
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