Aces High Bulletin Board
General Forums => The O' Club => Topic started by: OIO on February 08, 2003, 11:04:48 AM
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Speak up geeks! Im enlisting in the ranks!
Im looking to buy a telescope under $600 that would let me see planets & deep sky objects.
Problem is, I know as much about telescopes as I know about cars. I turn the key, put gas and take it to its oil changes and thats all I know (to give you an idea).
I know there's 3 kinds of scopes, reflectors,refractors and those Casselgrain (sp?) ones.
Reviews online seem to be written for people who know WTF all those terms of optics and mathmumbojumbo mean, even the "newbie guides" are full of it. None of them puts things in laymans terms.. they shall burn in hell :D
Ive read many recomendations: get a 6" or better aperture (so far I think more aperture means they gather more light which means better image quality... or something like that), then I see that the Casselgrains are better for novices since they dont require much maintainance on their optics+ they dont have color-aberration or image screwing-up things that the other 2 scopes are prone to... and such.
but ive heard the reflectors end up having much better images. So right now im torn between a reflector and a casselgrain. Too bad the casselgrains seem to be only 5" or smaller.
In any case, here's what is a MUST for me:
1) GO-TO feature.
2) See planets in good detail (ive read that if a scope can see several rings in saturn its got good detail, those that see only the rings as a single-blur around the planet aint good).
3) $600 or less
4) Ability to mount a camera on it & have it track the "target"
Nice bonuses:
1) Would be neat if you could see the image on the scope in your PC.. dont know if thats possible.
2) Require little maintainance... my ignorance on this subject scares the heck out of having to take the thing apart to..oil it or something ;)
3) Ability to get decent detail in deep-sky viewing. Im a nutcase for the hubble pics of galaxies and nebulas, but im well aware they are color enchanced pics, so I dont expect to see that stuff on the scope.
So far the scopes ive been looking at are:
SkyView Pro 8 EQ
Optical Specifications
Type Reflector
Diameter (Mirror or Lens) 203mm
Light Grasp 50.1 sq. in.
Focal Length/ F Ratio 1000mm, f/4.9
Magnification
(w/ included eyepieces) 40x, 100x
Highest theoretical magnification 480x
Accessories
Eyepieces Sirius Plössl 25.0mm, 10.0mm
Finder Scope 6x30
Focuser 2" Rack-and-pinion
Diagonal N/A
Other included items Collimation cap
Optional Electronic Drive TrueTrack single axis, dual ax
Other Features 2" Focuser
Physical Parameters
Mount type SkyView Pro
Tripod Steel
Weight, assembled 62 lbs. 0 oz.
Tube Length 38.0 in.
Also looking at:
Meade 6" f/5 (SN-6EC) LXD55 w/Electronic Control
Includes 6" f/5 schmidt-newtonian optical tube assembly with EMC super multi-coatings; quick attach cradle ring assembly with locks; 6x30 achromatic viewfinder; all-metal rack-and-pinion focuser with eyepiece holders for both 1.25" and 2" eyepieces; Super Plossl 26mm eyepiece. LXD55 equatorial mount with worm gear drives and electric slow-motion controls; micrometric controls; illuminated polar alignment finder with reticle; variable height field tripod with accessory shelf. Autostar dual-axis control system with 9-speed drive controls, 30,223-object database and GO TO locating; battery pack accepting eight (user-supplied) D-cells (optional power cords available separately); instructions.
Meade 8" f/4 (SN-8EC) LXD55 w/Electronic Control
Includes 8" f/4 schmidt-newtonian optical tube assembly with EMC super multi-coatings; quick attach cradle ring assembly with locks; 6x30 achromatic viewfinder; all-metal rack-and-pinion focuser with eyepiece holders for both 1.25" and 2" eyepieces; Super Plossl 26mm eyepiece. LXD55 equatorial mount with worm gear drives and electric slow-motion controls; micrometric controls; illuminated polar alignment finder with reticle; variable height field tripod with accessory shelf. Autostar dual-axis control system with 9-speed drive controls, 30,223-object database and GO TO locating; battery pack accepting eight (user-supplied) D-cells (optional power cords available separately); instructions
Meade DS-2114ATS
Supplied complete with Autostar #494 Computer Controller for observing 1,500 objects automatically (accepts 8AA user-supplied batteries), aluminized and multi-coated primary mirror and matching elliptical flat secondary mirror (D=114mm, F=1000mm f/8.8); aluminum tube assembly; giant rack-and-pinion focuser with sleeve lock and 1.25" and 2" eyepiece holders; altazimuth mount with variable-tension locks on both axis; cradle ring assembly; #492 Dual-Motor Electronic Control System with control motor and cord for each telescope axis, battery pack accepting ten AA-size (user-supplied) batteries, control panel, and 4-speed Electronic Controller; Meade StarNavigator PC-compatible astronomical software with database of over 10,000 celestial objects, full-length adjustable heavy-duty aluminum field tripod with accessory shelf; 6x30 viewfinder,; two eyepieces (1.25") - MA25mm, MH9mm; operating instructions.
So Geeks, Any suggestions? :D
(all the above scopes i can find priced below or just above $600 in reputable stores)
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About 10 years ago a buddy of mine from work had a cool telescope. Sucker was big, about 4' high or so with the thingy you look in down at the base. I have no idea if it was a reflecter or refractor or any of that mumbo jumbo. But I do know that he said it had an 8" lense. We were able to see Jupiter and 3 of it's moons with it. BUT :D Jupiter looked smaller than a marble and the moons where just points of light. It looked black and white too and I couldn't really make out any of the cloud shapes on the planet. And it moved off screen freakin fast, so if you get one make sure to get a motor on it.
The moon looked really cool with this though.
[edit]
Oh yeah I think they do have things so you can hook them up to your PC. That would be sweet. Set the thing up outside w/ the motor and object finder and go in to the PC and look :)
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ach please edit the post and cut all that empty space!
Oh wait.. I get it. :D :D ;)
(do edit it pls, my mouse dont have scroll thingy.. and i hate you btw hehe)
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Hi. I just received my new toy a couple of weeks ago.
My baby (http://www.astronomics.com/main/product.asp?n1=2&t1=1&myStype=Schmidt%2DCassegrains&styp=3&bURL=tMeade%2Easp&vid=1&product%5Ftype%5Fid=1&sku=12210GU&op=)
Of course I've had new scope owners curse. Cloudy weather for weeks after my scope arrived. I did get a breif respite from the clouds the other weekend and took the beast out to a great dark sky site. WOW. It was great. I had a little trouble initially with the GPS system but that was expected. The purpose of that trip was to break it in and work out the kinks. Once I actually read a little of the manual (always a last resort for me) it didn't taken to long to get it working. Now there will be some idiots that will try and tell you that using "goto" isn't "real" astronomy. Thats roadkill. I've had a lot of scopes over the years and I've done my share of star hopping. If you're in to that fine. But don't try and tell anyone else their not a real "man" if they don't spend 30 min trying to find some dim object with charts.
With "goto" you spend your time observing, not searching. I gauruntee you that they don't star hop with the hubble, they dial in the coordinates and go straight there. Duh!
There was another guy at the dark sky site when I was there with a large manual Dob. In the time it took him to 3 objects I had zipped through 20-30 Messier objects. I could point to any object in the universe I wanted within seconds, effortlessly. I some times enjoy star hopping. I can always do that by manually slewing if I choose. But it sure is nice just to go straight to what you're interested in if you want.
I gotta goto meet someone for lunch but I'll answer some more of your questions when I get back.
Wab
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Hmmm, while we're on the subject...is a Meade LX/50 any good?
SOB
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Hope you come back soon :D
While ye at it, here's some Q's ive wanted answered for a long time:
1) The focal ratio F/4 F/5 on the scopes..the lower the better for astrophotography right?
2) Whats the relation between the aperture, focal length and magnification (10X, 50X, etc) in the performance of the scope?
The casselgrains look really great, but I began looking into reflectors because almost every review said they got better images than the casselgrains.. yet most of said reviews did mention the casselgrains performed "equiivalent" to the reflectors in most areas. So ye see im very confused between the two. The reflectors are said to have issues with false colors or something like that.. well, I really dont care about that, im already color blind so getting the "right" colors is not really a factor for me :D :D :D
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OK. Back. ;)
Typing up some answers but here are some pics of my baby.
Some with the new video mounting I just got, and also some of my previous home made scope. And I mean HOME MADE! Ground and figured the mirror myself. But that was when I was younger and crazier. Now I just buy the damn thangs. ;)
http://66.169.128.146/telescope/smaller/
Wab
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Very Very nice Wabbit!!
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I think i hooked the biggest geek in the barrel! whoohoo!
Teach me meister! :D
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OK. Hmmm where to begin....
My first suggestion would be to see if there is an Astronomy club in your area. I would join it. This gives you a lot of people to talk to before making a buying decision. You can join even if you don't have a scope yet. Most clubs have some "loaner" scope s you can use and try out. Generally, other members will be glad to talk with you and let you look through their scopes. This lets you get lots of first hand experience with a broad range of brands and designs. A good telescope is a fairly signifigant investment and I'd suggest you take some time first to make sure you make the best choice for what you're interested in. There are a heck of a lot of different choices out there.
At the highest level, there are only really 2 main designs for optical telescopes. Refracter and Reflector. It depends on what they use for their primary optical element, a mirror or a lens. Even though Schmidt-Cassegrains have a corrector lens up front their primary optical element is still a mirror in the rear cell. Some people argue Schmidt-Cassegrains is a third hybrid because of the front corrector lens but I think their wrong. ;) The primary "light collecting" element is the primary mirror so its really a reflector.
I generally don't like to give direct advice but I'll go out on a limb. HOWEVER YOU SHOULD REALIZE EVERY THING I SAY IN ONLY MY SILLY OPINION.
The main factor you need to clarify to know what kind of scope you should go with depends on the type of astronomy you're interested in. You seem to be more oriented towards solar/lunar/planetary type observing. As opposed to hunting "dim fuzzies" like nebula's and galaxies. The price range you mentioned with the features you desire is a difficult equation to balance. Refractors are generally the best for planetary work. They provide the crispest image quality and are sealed systems that require little maintenence. However, they are usually signifigantly more expensive per inch of apeture. (PLEASE AVOID THE CHEESY DEPT STORE REFRACTORS!!!!)
Newtonian reflectors are your best bang for the buck, but they require periodic maintainence like aligning the optical elements. Not terriblely difficult, but not trivial. You have to keep the mirrors clean which is not easy with an open tube system. Occationally you have to take the mirror out of the tube, clean it and put the whole thing back together again. You get the most apeture for the buck, but they are higher maintainence.
"Goto" is sure nice but is going to require other sacrifices given your price range. Mainly you'll be sacrificing apeture.
I think you need to seriously think about your photography requirement. Most of the scopes you're talking about aren't all that useful for astrophotography. Although people are starting to get into astrophotography using modified webcams that might interest you in. (I'll post link later.)
If your main interest is solar/lunar/planetary you might can do without tracking and goto. The moon, sun, and planets are very easy to spot and not hard to follow manually. If you do your planetary photography with a webcam you don't tracking. There are comprimises you can make to gain additional benefit.
to be continued...
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Hmm.. well a 6" LDX55 from meade with the ultra-high-transmission-coating runs for $780.
the 8" LDX55 without UHTC runs for $839
the UHTC is said to increase the light gathering by 15%.. so I dunno which is better in the end, the 6" with the UHTC or the 8" without it. Somehow my logic says the 8".
both reflectors with the go-to.
The 8" one without the go-to is $699. So I dunno maybe I could get this one and later on get the go-to system. Decisions decisions....
http://www.optcorp.com/cart/ProductList.asp?SearchBy=PK_KWID&SearchFor=76&SearchRestrict=PR_CATID&SearchRestrictID=1
is where im looking them up.
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Unfortunately, like most things in life, it’s hard to have everything all at once.
Generally, scopes that are optimized for planetary work and less good for galaxies and nebulas and vica versa. You really can’t optimize for both. You can make various compromises but you have to give something up.
For solar/lunar/ and planetary work I think your most import variables are: closed tube, minimize central obstruction, long focal ratio, aperture. Roughly in that order of importance.
For deep sky work: aperture, aperture, and aperture, oh and maybe short focal ratio. ;)
For photography or visual the general rule is:
Solar/lunar/planetary – longer focal ratio is better. The objects are already pretty bright and the longer focal ratio gives you better image scale. Eyepieces have an easier time handling long focal ratios.
Deep sky – shorter focal ratio is better. Concentrate light on dim objects, shorten exposure time. Objects are usually pretty extended so the wide field of view of shorter focal ratios help out. However short focal ratios can start introducing artifacts and distortions around the edges of the field like “coma” and field curvature.
As far as the aperture/focal ratio/magnification go:
Magnitude = Main optical focal length/ eyepiece focal length
So a single eyepiece can give two different magnifications on two scopes with different focal lengths.
I have a 26mm eyepiece. My SMT has a focal length of 3048mm so that eyepiece gives me a mag of ~117x. But on my other scope, of focal length only 1400mm, that same eyepiece gives a mag of ~53x.
The only effect aperture has is to limit the reasonable amount of mag you can use. The general rule is ~50x/per inch of aperture with a max limit of 500x for most observing conditions.
So with my 12” SMT I can safely go up to the 500x limit if the weather permits.
But a 3” refractor won’t benefit from anything over 150x no matter how good the “seeing” is.
To be continued…
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Hmm.. well a 6" LDX55 from meade with the ultra-high-transmission-coating runs for $780.
Heh, well now is $600 a hard limit or a soft limit? It can make a big diff in what I would suggest. ;)
I know how you feel. You saw my monster 12"? Heh, I was originally only looking for an 8". :):):):):)
Questions:
1. IF you had to make trade offs give me a percentage of your interest in solar/lunar/planetary vs deep sky nebulas and galaxies. (i.e. 60%/40% 50%/50% , 90%/10%)
2. Do you have a laptop?
3. How intimidated would you be about doing optical alignments periodically and maybe once a year pulling the mirrors out for cleaning and reassembly? Would you be willing to give up some aperture for very low maintainence? Or is pure aperture more important and you're willing to open a book and roll up your sleeves?
4. Is $600 a hard limit? If you got a range, give me the range.
Wab
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1) planets 70% anything else 30%. For galaxy pics i go to the hubble website.. its my personal gazillion" scope you know ;)
2) no I dont. However I do live in the outskirts of the city and usually get very nice, dark nights..so traveling to viewing spots to get a better sky aint a problem for me. I was planning to wire my PC (close to window) to the scope outside.
3) Heck if its once a year or twice a year that aint a problem. If its once every month though, I got a problem with that. :)
4) well, $600 is the ballpark, but as im sure you can relate, if a 6" is 780 and the 8" is just ~$60 more.. and so far ive read that increasing aperture exponentially increases perfomance...well, you know how it goes. No movies or happy meals for 3 months to squeeze it in hehe.
So no its not a hard limit but I definetely dont want it over $800 (ok ok $839 geez ;) ).
I started looking at a scope that was $399 with the go-to feature, the DS2114ATS from meade (on list in first post). Then I read a lot more into it and saw people suggesting 6" or more for best viewing experience/longevity of the item and of course, photography.
Remember im just starting at this, if you look over the $399 one and think it can handle a camera and give me a nice image of stuff, that will probably be the one I take. However if you think the 6" one is so much better than the $399 one I got no problem going a couple hundred to get it. I can develop a distaste for personal spending for a few months for that scope ;) .
BTW, if you have YAHOO INSTANT MESSANGER, drop me a line.
daniel_londono_84160 <---YahooIM ID
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Well, here is my opinion, and please remember, its only that.
Given everything you've told me... I think (if I were you) I'd look very carefully at getting the Meade AR-5 with Autostar ~$695.
This is a 5" refractor. It has a nice long focal length. Decent aperture. Its a sealed system and will require almost no maintainence. There is no alignments to do or mirrors to take out and clean. Supposedly this model is fairly well corrected for chromatic abberation. You won't be able to beat it for solar/lunar/planetary stuff. For what you're interested in, the 5" refractor will beat the 6" Schmidt-Newtonian like a stick. Its an equatorial mount with autostar so it it will "goto" and track. The 5" aperture is not grand, but its fine for the planets and can still see some of the brighter deep sky stuff. For the other stuff there is always Hubble. ;) Also the refractor has no central obstruction like the Schmidt-Newtonian so you'll have a much cleaner, higher contract image. The most important thing for planetary stuff.
So for what you're interested in, given your price limit, that would be my best recomendation.
I have been very happy with my meade. I didn't go thru OPT but I've heard good things about them.
Hope it helps.
Wab
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Oh, one more thing, I don't care if you have to sell blood or dress up as a sheep and prostitute yourself....
Get the Meade eyepiece deal for the extra $99. Its simply the best deal I've seen in 10 years. They will also perform very well with the longer F9 focal ratio of the AR-5. You won't regret it.
Wab
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Hmmm, while we're on the subject...is a Meade LX/50 any good?
SOB,
Sorry bud, I'm not familiar with the LX50. Could you point me at a source?
Wab
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I thought refractors gave really crappy deep field views. Ach i am so confused now :p
Well, let me ask ye this evil wabbit:
If I had said 50% 50% on my interests of planets/stars, which would you have recommended?
Also, what is your opinion on the Meade DS-2114ATS? Im really looking at this one because where I work at we have a program where I might be able to get this one almost for free, but I would like to know what I can expect from that scope (there is other junk I can get for free with the same program hehehe).
SOB: Link to that LX50? I couldnt even find it in the MEADE products catalog on-line. They have LX10 LX90 and LX200's, but no 50's. :(
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"Look mom, nerds"
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I'm into Assphotography. Is any of that equipment useful for taking long distance pics of my hot neighbor?
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Well, now you didn't mention anything about free! Of course anything free is better. You can always use it for a while til you decide what you want to spend money on.
Now, your only talking 4.5" aperture inch there. And its a newtonian so it has a central obstruction. Prolly about a 1" diameter secondary. So it only has about 4" real aperture and because of the central obstruction won't have as clean and high contrast an image as a refractor.
That scope will certainly be worse on both the planets and deep sky stuff than the AR-5, but if you can get it almost free so what? You've lost nothing. Later when you feel you're ready to step up, you can spend some money then. Maybe by then, you'll be ready to step up to a 8" SCT which would really prolly be closest to what you're looking for. But that will cost money.
Sound like the free one is a good starter scope for ya.
FYI,
A longer focal ratio refractor will be better on planets than galaxies. A shorter focal ratio reflector will be better on galaxies than planets.
If you're mainly interested in deep sky stuff you prolly want a reflector because:
- You can get more aperture per dollar
- You can usually get shorter focal ratios in reflectors which is better for deep sky.
- Deep sky objects are usually already kinda fuzzy and low contrast like nebulas and galaxies so the loss of contrast from the central obstruction (secondary mirror) on a newtonian is not much of an issue.
If you're mainly interested in planetary stuff (and are going to stay below about 6") you prolly want a refractor:
- no central obstruction so the image is much sharper and higher contrast.
- longer focal ratios give you larger image scale and higher mag for a given eyepiece.
- its a sealed tube, easier to maintain and no tube currents.
There are no exact answers. Its all about priorities and trade-offs.
Hope this helps.
Wab
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It does help a lot thanks :)
Thing is, I probably wont be able to get the scope via my job before that wonderful $99 deal expires *grrr*. So perhaps ill just buy the refractor and get IT with the optics.. then get the DS one in my job, sell it and use its money to get the LXD55 6" :D :D
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hey wabbit, about those "hybrid" scopes (casselgrains)...
Whats the difference between their type?
There is Schmidt-Cas and matsukov-cas types.
There's this one: Meade ETX-125EC
Includes Maksutov-Cassegrain optical tube assembly (D = 127mm (5.0"), F = 1900mm, f/15) with MgF2 coatings on the correcting lens and standard aluminum coatings on the primary and secondary mirrors (Ultra-High Transmission Coatings, available optionally); internal flip-mirror system for either straight-through or 90° observing position; aluminum fork mount with electric slow-motion controls, setting circles and locks on both axes; electronic control panel; 4-speed (8x, 32x, 0.75°/sec, 5°/sec) dual-axis motor drive system with Electronic Controller; sidereal-rate tracking in equatorial mode with optional table tripod or deluxe field tripod; internal battery compartment accepting eight (user-supplied) AA-size batteries; 8x25mm right-angle viewfinder; Series 4000 Super Plössl 26mm eyepiece (1.25"); operating instructions.
and this one:
NexStar 5i Specifications:
* 127mm (5") Diameter Schmidt-Cassegrain
* Focal Length of 1250mm
* Focal Ratio of f/10
* 6° per second slew speed
* Fully enclosed high speed motors on both axes
* Integrated hand controller built into the side of the fork arm
* Schmidt-Cassegrain optics with Starbright coating
* Designated AutoGuider port
* Auxiliary Port for optional Accessories, including CN-16 GPS module
* Battery Compartment for 8 (user supplied) AA batteries
* Weight: 17.6 lbs
How would these 2 compare vs a refractor for planets and a reflector for deep-sky? And to each other, they seem to do be the same thing
:confused: :confused:
edit:
Just saw a 10" Reflector LXD-55 for less than $1000 WITH the Go-To and tripod :P .
aya yai...
Would a 10" reflector get better or just as good a view of the planets as the 5" refractor?
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There is Schmidt-Cas and matsukov-cas types.
They are very similar designs with similar performance. The main difference is the type of corrector lens plate up front. The cas used an almost flat plate. The matsukov uses a heavily curved corrector that traditionally has been considered difficult to shape well. But with computer controlled grinding now days I don't think its much of a problem.
I considered both those mentioned scopes before making my recommendation. They are both good scopes. I've heard good things about both. But there are a couple of reasons I leaned towards the AR-5:
- Although both the above mentioned scopes are "sealed" systems, they also both have secondaries that will need periodic adjustment. The refreactor requires none.
- Since both the above scopes have secondary mirrors, the area blocked by the secondary has to be subtracted from the total light gathering aperture of the main tube. So a 5" reflector with a secondary doesn't gather as much light as a 5" clear aperture refractor. Plain and simple.
- When ever you have a central obstruction (like a scondary), it causes light to be scattered as it enters the tube. This is called diffraction. It will cause you to get a slightly less crisp image and will slightly washout and reduce the contrast of the image. A refractor has no central obstruction. You can focus star into much more pinpoint like sharp dots. You get a much higher contrast image.
- Both those scopes had equal or longer F/ratios as the AR-5 with no more aperture so they'd do no better or worse on deep sky stuff versus the refractor.
On the other hand, both those other scopes are "folded" light path so they fit into a shorter tube which is easier to mount stablely.
Still, my personal rule of thumb would be: anything approaching equal aperture and equal electronics I'd always choose the refractor.
However, you generally can't get a refractor over 6" without paying a king's ransom. However reflectors over 6" aperture are common. Shear aperture can overcome alot of design defficiencies.
I'd take a 5" refractor over a 6" schmidt-newt any day. Now a 5" refractor vs a 8" schmidt-newt is a much harder decision. Would I take a 10" newtonian reflector over a 5" refractor? Hmmm probably (with some caveats). But now you're talking much more than the $600 you told me I had to work with. ;) Watch it! Its a slippery slope that leads to a 12" monster!
I'd need to think about it some more to give a clearer opinion. However the first thing to look at is the mounting. That is where most dealers try to recover the cost. When they put that 10" on the same tripod they use for 6" and 8" then its prolly way to heavy for the mount. You'll have bad problems with vibration and general wobblyness.
You're getting close to the dollar amount where I'd start recommending a well made 8" Schmidt-Cas rather than a 10" newt or schmidt-newt. It'll be less maintainence and will prolly have a more stable mounting because of its shorter tube.
You're starting to see why I recommended joining a club and get a chance to try out a lot of different designs and sizes before making a decision. There are a lot of variables to balance. :)
Wab
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Would the 10" reflector LXD-55 have comparable or better planetary views than a 5" refractor wabbit?
(you can see me digging my own greed-grave no? LOL) :D
Yeah, the 600 buck ballpark is getting to be a bit wobbly. The way I see it, anything over $400 is worth getting GOOD or not getting at all. Getting a 5" refractor for 600 bucks and then noticing i cant take decent pics of nebulas is something i'd curse myself for. But a 900 dollar 10" reflector, if it has as-good planet pics as the 5" reflector and i'd assume, darn good deep-sky views, then its a good tradeoff in my book.
The mount was something I was reading about in reviews.. some folks have guides on how to adapt the heavier scopes on those mounts without too much spending, so that wont be a problem i think. :)
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Would the 10" reflector LXD-55 have comparable or better planetary views than a 5" refractor wabbit?
Hmmmmm .... probably. But there are a couple of variables to consider (as always ;)):
- the scope you mentioned is a F/4 focal ratio. Short focal ratio scopes aren't optimal for planetary observing. They give wide field of view but small image scale. Short focal ratio scopes also introduce defects like "coma" and "field curvature" to the edges of the image. Eyepieces have a harder time performing well with short focal ratios because the light cone is so steep. You'll have to use very short focal length eyepieces to get a usable mag for planets which means they have little eye relief and are more uncomfortable to use. Also short focal ratio scopes have a secondary that is a larger percentage of the total aperture than the same diameter scope with a longer focal ratio. The larger percentage obstruction increases diffraction and loss of contract. Also short focal ratio scopes are more sensitive to missalignment than longer focal ratio scopes. You'd have to be very dilligent about keeping it perfectly collimated (collimation is the aligning of optical elements of a telescope). You have to check it often especially if you move the scope around. For an F/4 scope, it wouldn't take much missalignment to degrade the performance on planets below that of a 5" refractor (that requires no collimation).
- When doing planetary work you are usually working at relatively high mag. The effects of vibration are equally magnified as at hi mag. On a wobbly scope, at high mag, just touching the focusing knob or a slight breeze can cause the image to wobble unusablly for 10-15 seconds. I have grave doubts that you would be able to renforce the mount sufficiently. I'd almost rather see you get a 10" manual Dob which would be much cheaper and rock solid (although no tacking or goto).
I'd consider that scope more 70% deep sky/ 30% planetary.
At the money range you're now talking about, I'd lean more towards the LDX55 SC-8.
- Its F10 rather than F4
- Its on the same mount but 1/3 the weight and length so MUCH more stable. An order of magnitude more stable.
- its alot more compact and easy to more around, easier to store
- schmidt-cass's are easier to maintain than newts. There is only one optical element to adjust rather than two.
Its a little less aperture than the 10" newt but I think you'd be happier with it overall.
Wab
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Of course we've strayed pretty far from an "almost free" 4.5" reflector. ;)
You now officially have contracted "aperture fever"! Lol! ;)
There is an antidote, but it is usually very expensive.
Wab
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:D :D :D
Im getting the flu hehe.
K one last question (yeah right! haha)
This Ultra-High Transmission Coating thingy.. its said to improve the scope by about 20%.
Does that mean that, say, a 6" with that thing would perform like an 8" reflector without it? Or would the 8" without it still outperform the 6" with it?
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Heheh. After I wrote that last post I was looking at the scope add in Astronomy magazine and I said to myself "next he's going to ask about the coating..."
The straight answer to your question is........kinda/sorta. ;)
OK. Here's the deal. There are a couple of ways of measuring the performance of a given telescope. Quality or quantity.
1. You can talk about its "Resolving" power: Quality. It refers to how fine of detail can be teased out of an image. Like can you see that little 1km wide crater on the lunar surface or does it just blur into a dark smudge. Its mostly a function of aperture but can be effected by things like the size of the central obstruction, collimation, focal ratio, etc. The way they used to measure it was by looking at binary stars of a know distance of separation. By looking at different pairs that had different known separation distances you could find the pair that you could just barely "resolve" into two separate stars rather than a single elongated blob. That distance between the stars , usually measured in ArcSec's or ArcMin's, was the "resolving" power of the scope. This test was known as "splitting doubles". So if I could just split a double with a known separation of 2 ArcSec's then the scope was said to have "2 ArcASec resolving power".
2. The other measurement is pure "light gathering" power: Quantity. You don't really care about how sharp and focused it is you just want to know how dim an object you can see. This is usually measures in "Magnitude". Magnitude is a logarithmic measurement scale of light intensity. Wierd thing is its inverse. The lower the number, the brighter the object. The brightest star you see in the night sky is about -1mag. Distant galaxies may be 15mag. A person with good vision at a dark country site can see to about 6mag with the naked eye. Light gathering is purely a function of effective aperture. Basically, how many photons can you put on the eyeball.
The coating will increase your "light gathering" power, but it will do nothing to help your resolving power. The 20% increase, which I hear is REALLY more close to 12% is in AREA not diameter. So a 6" with coating will be more like a 6.5". You might see a slightly dimmer galaxy but it won't make Jupiter look any sharper.
For planetary stuff resolving power is much more important than pure light gathering power. Given your stated ratio of interest and the amount of cost, you could easily do without it. I certainly wouldn't trade the eyepiece deal for it. But if you had the money to throw around, it wouldn't hurt anything. ;)
Clear as mud?
Wab
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MUD :)
yeah thank a bunch. You should write a newbie guide wabbit. All your posts have been VERY layman's terms.
All the other newbie guides to this hobby have been quite heavy into terminology (you almost slipped into it "Also short focal ratio scopes have a secondary that is a larger percentage of the total aperture than the same diameter scope with a longer focal ratio. The larger percentage obstruction increases diffraction and loss of contract." heehee).
Astrophotography 4 Dummies
By Akwabbit
Has a nice ring to it. Maybe its sale could get you that 50" reflector you want... :D :D
Edit: What i'll do is hunt the net for pics to compare before I decide. If I see that a 5" refractor with X eyepiece pics look just a taaad different from the 10" reflector pic with same eyepiece i may go for the reflector. Im into both planets and deep sky, i just thought planets would be neater to picture. But now that ive been informed the nebulae pictures were not really color-enchanced, that the color does show on the film but not the naked eye.. well that changes things a LOT :)
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Here's a brief summary of telescopes by British astronomer Patrick Moore:-http://www.bbc.co.uk/science/space/myspace/nightsky/telescopes.shtml
Also these other sites:-
http://www.tass-survey.org/richmond/answers/telescope.html
http://www.perkins-observatory.org/FAQ.index.html
http://www.spinaweb.ie/showcase/2001/spin1124/spinaweb/astronomy/tbfaq.html
Also try downloading the program 'Skymap Pro' http://www.skymap.com/products.htm which is a very useful bit of software. You can download the demo version which has almost full features.
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Heh, just got off the phone with OPT ...
interesting stuff.
They say the LXD55's have a not-so-good mount for photography...actually no scope under $1000 has it hehehe. Of course, I work in sales so I dont know if the guy was being honest or just trying to upsell me =P
Will do some more research into the mounts too.
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I think you could get away with it on the SC-8 because its so compact the weight of the camera is very close to the axis.
The 10" on that same mount is almost not usable even for visual work. IMHO.
Wab
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Hmm...this is all I could find on it - http://bogeystar.50megs.com/scope.htm
SOB
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If you're interested in planetary photography, you should check these guys out. There are a lot of people get great planetary images from cheap modified web cams. If your computer is going to be within reach of a serial cable you might want to check it out.
qcuiag (http://www.qcuiag.co.uk/)
This would be very light to mount. Well within the LDX55 SC-8.
Can you believe this came from a $30 web cam???
(http://www.cometdust.demon.co.uk/QCUIAG/Choice%20Images/jupiter/Jupiter%2012-30-01.jpg)
Wab
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a webcam? geez!
hey wabbit, i found a site full of pics taken with the 10" SN from meade.
take a look, tell me how you see them in yer experten opinion :)
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All taken with the SN 10" as far as i can tell (thus why i try posting them when they have their ID'ing text on top).
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and..
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and...
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btw, wabbit, if ye avaliable, i'd like to e-mail ye.
what you think of these pics?