Discovery 8" dobsonian reflector


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Brand and Model:Discovery 8" dobsonian reflector
Price ($USD):399
Type:Newtonian
Attributes: un-checked Go-To un-checked PEC
Aperture:203mm (8")
f Ratio:f/0
Focal Length:1200mm
Finder:6x30
Electric Power:
Mount:dobsonian
Tripod:
Weight (lbs):38 lbs.
Dimensions (w/h/d):48"
Description:

Vote Highlights Vote
Discovery 8" dobsonian reflector
This is my first scope, which I purchased
the 2nd week of Feb. 2002. Last night was actually the first time I used it, and
I'm totally satisifed with my decision to buy the Discovery 8' dob. Assembly was
easy, and the views of Jupiter and Saturn
were sharp. My only complaint would have to be the viewfinder, it was on the
fuzzy side. I'm a rookie to this hobby, but I'll highly recommend this scope to any first time buyer. With some patience,
more exposure, and practice I'm looking forward to some fun nights exploring the night sky!!

Overall Rating: 9
Optics:10 Mount:10 Ease of Use:9 Value:10
Weight: 10 (Trustworthy Vote)
Date:
By: ops56
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=66334


Discovery 8" dobsonian reflector
I got my 8" f/6 in 2000. It has the older base that looks like those supplied for recent Celestron Dobs. I understand an 8" f/7 is now available. If I bought it today, I think I would have gone for the f/7. I opted for the Pyrex mirror because of the enhanced coats with give a slight improvement in relectivity over the soda lime mirrors.

My ratings are based on a bell-curve against other commercial Dobs. The optics are made in America and each one is hand-tested. I have observed no optical flaws and especially no spherical abberations.

In my mind, the best optical test is high-power planetary detail. When properly collimated and cooled, images of the planets are razor sharp. Under good observing conditions, the optics easily support images of 240x. Using a TV Radian with a 60 deg. a.f.o.v., tracking is no problem. At lower magnifications, Plossls and orthos do just fine. Last winter I was able to observe Saturn's A, B and Crepe rings and both Cassini's and Eckne's divisions. Banding on the equator and the somewhat darker south pole region was also apparent as were five satelites. Much detail on Jupiter was evident including dark ovals, the GRS and festoons. Satelite shadows show up as tiny, black circles. Last winter I was using a UO 12.5mm ortho and Celestron Ultima Barlow. Now that I have a 10mm Radian, I hope to see a satelite transit. High-power views of the moon reveal tiny details including rilles.

On clear nights, two parts if the Veil are evident. From Cherry Springs, PA it was visible without a filter. The Rosette is also evident on clear nights. From a dark site M41 is intense. A nebula filter will reveal its full extent. To observe the brightest region under medium power, it is necessary to remove the filter to prevent the subtle details from being washed-out.

For an entry level commercial Dob, the mirrors on this scope are excellent. I do not give it a perfect score because under the bell-curve theory only the top 5% or so of mirrors get the 'A' grade. Since there are Zambuto mirrors and ones made of bizzare materials like Cervit, Discovery gets a respectable B+. The objective mirror is mounted with glue (no clips) on an aluminum cell with three spring-loaded wingnuts for collimation. The mirror comes center-marked from the factory. The secondary is mounted in a metal, 4-vane spider. Four Allen-head screws collimate the secondary. The 10" wide Sonotube is well ventilated. The focuser is a cast aluminum R&P 1.25" model. Sure, a 2" Crawford focuser is better, but the factory item is far superior to cheap, plastic focusers on many Meade or Celestron Newts. I have no intention of up-grading. With Pl. eyepieces, 32mm is about the practical limit due to barrel diameter. I also have a 40mm Pl., but its a.f.o.v. is narrower than a 32, so much of the benefits of its lower magnification are lost on a narrow image.

The mount is formica-covered particle board. It is strong and heavy enough to be stable. As with most Dobs, set-up consists of removing the dusk covers, plopping the base on the ground and putting the tube on the base. Balance is controlled by sliding altitude bearings. I found that the azimuth motion was sticky. I cured that by adding a washer made of a milk jug to the azimuth axis between the ground board and base plate. Now it is a lot better. Since getting a 22mm Panoptic, I have added a counterweight that goes on with Velcro so I do not need to adjust the balance for the unusually heavy eyepiece. The mount gets a 'six' because of the sticky azimuth and because it is particle board and not plywood (which is now available from the factory). Otherwise, it works well.

The whole thing is easy to use as is the case with almost all Dobs. It gets a 'six' as an average score when compared to other commercial Dobs of its size. The fact is that they are all pretty easy to use. Compared to an EQ mount which needs to be polar-aligned, the score would be much higher. Being an f/6, the focuser is never very high. I am 6' high, so I find a small folding chair makes observing easy while seated. Also, a unit finder like the Rigel Quick-finder makes finding objects far easier than using the supplied 6x30 finder. A small station wagon has ample room from transporting the scope to dark sites. With creative positioning, it will even fit into the back seat of a Chev. Cavalier coupe.

With the optical upgrade from the factory, the whole thing was $550 delivered. Considering that a four inch refractor can be $4000, I consider it one hell of a bargain.

Overall, the 8" f/6 is long enough for planetary observing and easy collimation. It is short enough for wide-field objects like the Rosette or the Leo trio. It has enough light grab for some good deep sky viewing, but is small enough to be easily portable. Plus the Dobsonian design lends itself to DIY improvements. I have lined much of the interior with black velveteen to surpress stray light. While this scope may not be the perfect first choice for any one kind of object, it is an excellent second choice for just about everything (except photography). This makes it extremely versatile.

Suggestions--
Discovery makes excellent reflector optics. Their eyepieces, however, are a different story. They work, but for a modest price, much better ones are available. For wide field viewing, I suggest the 32mm TV Plossl, the 30mm Ultima/Ultrascopic modified Plossl or a U.O. 32mm Konig. I have an Orion Sirius Pl. which does well, but I would like to upgrade to a Konig. If you don't mind spending $280, a 22mm TV Panoptic (the biggest they have in 1.25" format) is an excellent choice. Its 68 deg. a.f.o.v. gives about the same image scale as a 32 Pl., but much larger and in unbelievable clearity. For planets, you can go as low as a 12mm ortho or Pl. with a 2x Barlow and still track pretty easily. Again, for $260, the Teleview Radian 10mm provides tremendous high-power views. I find the Celestron Ultima [a.k.a. Orion Shorty-Plus] three-element Barlow works well with no chromatic abberrations. I also suggest getting a unit finder [so called because they magnify to 1x] which are much easier to use that the supplied 6x30 finder. Telrad and Rigel have models that appear to project concentric circles on the sky and other companies have units that appear to project a red dot. Metal gate handles can easily be attached to the sides of the base to make it easy to carry around. Also, a cheap, battery-powered fan helps cool the scope quickly on cold nights. Red dot laser collimators are handy and easy to use, especially at night, but only if your secondary is positioned properly. A Chesire line-of-sight collimator is best for that.

If you want an 8" Dobsonian telescope, the Discovery f/6 or f/7 is definitely the one to get. The objective mirror is the heart and soul of a reflecting telescope. For its size, you will not find a scope with better optics for under $1000.

Overall Rating: 9
Optics:8 Mount:6 Ease of Use:6 Value:9
Weight: 5 (Veritable Vote)
Date:
By: Anonymous (xxx.xxx.51.48)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=151500


Discovery 8" dobsonian reflector
Great scope. I purchased mine with the Pyrex upgrade. I reated a 9 because 10 is perfect. This scope might not be that, but it's close. After about 1/2 hr of cool down time I get great high contrast images of planets. Glob clusters show good detail. Open cluster are just beautiful.
I've only had to balance one time and haven't had any issues with that. Very easy to collimate. Stays collimated for long periods of time. I've only had to tweak it a few times in the 2 year+ that I've owned it. Highly recommended.

Overall Rating: 9
Optics:9 Mount:9 Ease of Use:10 Value:10
Weight: 5 (Veritable Vote)
Date:
By: jtpaoletti
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=142644


Discovery 8" dobsonian reflector
I have a 8" F/7 and I have enjoyed the view. The azimuth is extremely sticky though and I tried the milk jug washers and they did not help much (or enough). The viewfinder isn't all that great either. The optics seem to be superb, though this is my first scope and I have nothing to judge against. I have seen great details of Saturn, Jupiter, and the moon, as well as orion nebula, comet Neat and Andromeda galaxy. I feel as though I need more precise method of collimisation than by eye, as I have done it so far. I'm going to work on the azimuth with a little more engineering and I think that this telescope will be nearly perfect. Overall I highly recommend the Discovery dob.

Overall Rating: 9
Optics:10 Mount:6 Ease of Use:8 Value:9
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.146.195)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=395418


Discovery 8" dobsonian reflector
Excellent buy. This is my "quck look" scope and fills that role beautifully as well as makes a great planetary scope to compliment my VX120. I have the F7 version. Optics are incredible providing me with my best views of Jupiter to date. My only complaint is that the mount is a little stiff and I the sliding bearings are hard to adjust in the dark.

Overall Rating: 9
Optics:10 Mount:8 Ease of Use:9 Value:9
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.186.249)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=110724


Discovery 8" dobsonian reflector
This is a great scope for the money! Optics are excellent, and I use a telrad instead of the supplied finder.

Overall Rating: 9
Optics:10 Mount:9 Ease of Use:10 Value:10
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.201.202)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=79897


Discovery 8" dobsonian reflector
This is my first telescope and it performs like a dream. My first night out I was able to clearly see the bands of Jupiter's cloud tops. Collimating the mirror was a snap (I had never done it before), and on my second night out I was able to get the mirrors aligned well enough to clearly make out the Cassini Division in Saturn's belt with a 10mm eyepiece. The only problems I found are the same as what others have said; a fuzzy finderscope and the mount sticks slightly in azimuth rotation.

I did some looking around before I chose this scope, and I couldn't have picked a better one for a first scope.

Overall Rating: 9
Optics:9 Mount:7 Ease of Use:9 Value:9
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.31.73)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=50190


Discovery 8" dobsonian reflector
A great starter telescope, or second telescope, if you are moving up from a little refractor.

Overall Rating: 9
Optics:9 Mount:7 Ease of Use:10 Value:10
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.36.146)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=48069


Discovery 8" dobsonian reflector
I have one and love it.

Overall Rating: 9
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.43.118)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=39427


Discovery 8" dobsonian reflector
Great scope. Nice bright views.Very good contrast.Easy to collimate. Easy to track at high powers.

Overall Rating: 10
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.140.121)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=39426

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