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Tasco Galaxsee 114375
Submitted: Thursday, 21st December 2006 by Pete Moulton

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Tasco Galaxsee 114375

Optically it is an f500mm scope with a 4.5" (114mm) mirror, 3 "eyepieces" (MA 20mm, MA 10mm and SR 4mm and filters), 3 x Barlow, small Red Dot finder scope, Equatorial Mount, and comes with Tasco's SkyWatch software.

Astronomy is about having fun, yet reading some forums, beginners may get the impression that you need a zillion dollar Meade StiltScope telescope and a handful of TeleVue UltraCost eyepieces at $500 a shot to achieve this. The general advice is not to buy the cheap reflectors under $300, but save for a 6" or 8" dobson instead. I consider this sound advice for serious viewing, but this omits the fun factor! What if your budget IS only $250? Can you still have fun with a $250 scope? I believe that you can, so this review is aimed at those folk, especially parents, who want to get a telescope but have between $200 - $300 budget. You won't want to spend too much money in case little Johno or Kylie prefers playing with the box the scope came in rather than the scope itself. You also want to spend enough so that you don't need to instantly upgrade to something bigger if you (or the kids) like it.

Remember that there is a world of difference between the astronomers at Perth Observatory and the back yard telescope brigade. Somewhere between the two are the Astronomical Societies and Clubs. The difference is that whilst we back yardies are oohing and ahhing at the eye candy that the Southern Skies have to offer, the team at Perth Observatory are surrounded by calculations, formulae, theories trying to discover the what? why? where? and when? of our universe. Whilst I can sky hop to my heart's content around the sky, the observatory may have to watch the same single star or galaxy continuously over a period of days, months, even years. We will not get the same view through a 4.5" telescope that Perth Observatory get through their 24" telescope!  I mention this to help you form realistic expectations. (If you are in Perth, or visiting, I highly recommend a trip to Perth Observatory on one of their viewing nights.)

You will notice that I have deliberately included calculations and a bit of optical theory, since I believe that you should know the maths before you consider buying. I have also tried to make this review more generic so that it will apply to most budget reflectors in the $200-$350 price range, by showing you some of the pitfalls to watch out for.

If you have about $200 to spend, most astronomers will advise you to get a good pair of binoculars, a planisphere and a tripod with a bino mount. Binos are great, but if you want to see a planet as a disc of light rather than a bright dot, then you are going to need a telescope! You have to be aware that scopes at this price are not going to show you as much Deep Space stuff or high magnifications of planets, compared with more expensive scopes with larger apertures and longer focal lengths. Forget the photos of planets on the box! You will not see this through a scope at this price. These were taken by space probes during a flyby mission and have been enhanced from many composite images.

I already knew Tasco from my shouting days, as they made some great Red Dot sights that could be mounted on your "Dirty Harry" Magnum revolver or "Terminator" Desert Eagle semi automatic pistol. They are also a major player along with Simmonds and Bushnell making telescopic sights for air rifles. Midland Camera House (in Midland of all places!) were flogging a few Tasco scopes. I did a little research and went for the Tasco Galaxsee 114375, complete with "375 x Power" and photos of planets on the box all, for an amazing AUD $249!

Now whilst this may seem like one of those 'bargain basement' shaving mirrors inside a large baked beans tin masquerading as a Newtonian reflector, I happen to have fun with this little scope. I know its optical (and mechanical) limitations and compromises.  It's not a bad little scope, and can give you some good views as long as you don't push it beyond its limits.

Now lets break things down and show you where the $249 has gone. As is the case with ALL Equatorial mount scopes, a significant portion of the cost goes into the mount. The smaller the scope, the bigger the proportional cost of the Equatorial Mount. Today, a Medium duty Equatorial Mount will cost at least $150, a Red Dot finder scope will cost $30, but lets say that these both cost $125. That leaves only $125 for the eyepieces and telescope. Lets assume the eyepieces and 3 x Barlow cost $65, that only leaves $60 of the price for the actual scope tube itself. Only about a quarter of the original $249 has actually gone on the telescope bit. So now you see why $200-$300 "High Magnification" scopes have significant optical and mechanical compromises at this price. Corners must be cut in order to deliver a scope to market for a price.

First we need to understand a little about magnification. We need to know the magnification provided by an eyepiece, and, the magnification that the mirror (or objective lens in a refractor) can support.

To calculate the magnification of a certain eyepiece, simply divide the focal length of the telescope by the focal length of the eyepiece. The Tasco has a focal length of 500mm and using the MA20 20mm eyepiece will give the following magnification :

                       f (Scope) mm            500
   Magnification =     ------------       =   ------   =  25 x     
                      f (Eyepiece) mm           20

This is only half of the equation. We now know that the 20mm eyepiece will magnify images 25 x in the Galaxsee. We need to find out the maximum magnification that the primary mirror (or objective lens on a refractor) of the telescope can support. This is where the diameter/size of your mirror (on Reflectors) or objective lens (on Refractors and Catadioptcis) is required.

The common rule of thumb is that the maximum theoretical magnification that your scope can handle is 50 x magnification per inch of diameter on your mirror or objective lens. Remember that this figure is for PERFECT viewing conditions, that's those 5 cloudy nights of the year! PRACTICAL viewing conditions will not allow this magnification due to atmospheric conditions, weather, light pollution, etc. For normal viewing conditions I adopt a 30 x magnification per Inch of Aperture (mirror diameter) rule. This is just my preference, but I believe that it is more realistic than to rely on 50 x per inch figure often quoted.

Using a car for an analogy, we often we hear "350BHP!!" banded about, but this figure relates purely to the raw output of the engine when it is NOT connected to anything except a Dynometer (Brake)!! In reality, add in your transmission, rolling resistance of the tyres, air conditioning and other electrical hungry devices that sap charge power and the engine will not give a Brake Horse Power reading anywhere near the magical 350 BHP quoted in the latest Velocitus Vitus testostermobile sales brochure! Well the BHP figure for a car is like the "50 x per inch of aperture" figure often quoted for a scope. So I hope you now understand why I adopt a "30 x per inch of aperture" rule.

The 4.5" mirror in the Tasco allows the following magnifications:

  • Max Theoretical Magnification  = Diameter of mirror/lens in Inches x 50 =  4.5 x 50 = 225 x
  • Max Practical Magnification    = Diameter of mirror/lens in Inches x 30 =  4.5 x 30 = 135 x

So although the 4.5" scope can theoretically handle a maximum magnification of 225 x, for the vast majority of nights I expect no more than 135 x magnification tops.

What about Tasco's "375 x Power" claim on the box? Well the figure quoted is actually true! The Tasco eyepieces do indeed have the theoretical potential to magnify an image 375 times!! Using the 4mm eyepiece in the 500mm scope gives a magnification of 125 x. If you then add the 3 x Barlow, you then get the magical 375 x magnification. Unfortunately, in practice all you will see is a splodge because we've just proved mathematically that the Tasco's 4.5" mirror cannot collect enough light for this extreme magnification to be usable. Although the 4mm eyepiece plus the 3 x Barlow can give a staggering 375 x magnification, the mirror can only realistically support 135 x magnification.

From the maths, I know that the Tasco cannot realistically go much beyond 125 x magnification using the SR 4mm eyepiece. Knowing this also tells me that 4mm is the shortest focal length eyepiece I can use, so there's no point me splashing out $465 on a 3.5mm Naglar unless I want to put it in my wifes glassware display cabinet! Now you see why I deliberately gave you the maths lecture, so you have enough information to work out the limits on the scope you are looking at before you buy it. I also did this because the first accessories people buy are often eyepieces and Barlow lenses. There's no point buying one if it will create magnifications that your mirror cannot support!

Assembling the Galaxsee was not difficult, as Tasco included instructions on how to build the scope. Unfortunately Tasco failed to supply any information on how to setup the scope, so a new user would have had no idea how to setup the equatorial mount. There was nothing on Tasco's support web site either. This is difficult in the Southern Hemisphere since we do not have a pole star to align the mount with like Polaris (in Ursa Minor) in the Northern Hemisphere. Fortunately, I already had experience setting up the equatorial mount on my son-in-law's 4.5" reflector. For most of the time I set the Tasco mount up 'flat' to emulate an Alt/Azimuth scope as best as possible. There is quite a bit of flexion in the tripod, which is to be expected at this price.

The red dot finder scope is a neat affair, although is less than an inch in aperture at just 20mm. On balance it is more practical than a 6 x 30 or even 8 x 50 finder scope as the main usable magnifications of 25 x and 50 x make locating faint objects pointless. From my shooting days, I remembered the red dot allowed much faster target acquisition than the open sights, and I'm happy to report the same is true of the red dot finder scope included with the Galaxsee. To zero the finder scope, I selected Sirius near its zenith and centered it in the MA20mm eyepiece and then adjusted the elevation and azimuth on the red dot finder until the red dot was superimposed over Sirius.

The two slow motion controls that attach to the Right Ascension and Declination setting circles often come lose, so I was often having to tighten the thumb screws. The controls were dequate, but on dark nights, it was easy to clumsily grope about in the dark to find them only, to discover that you were turning the wrong one! They were not as sturdy as the ones on the Konus, but then that scope did have a heavy duty mount.

Looking at the Tasco's MA 20mm, MA 10mm and SR 4mm eyepieces (not even Plossls at this price), they have no discernible coatings and give magnifications of 25 x, 50 x and 125 x respectively. The MA20mm has the best eye relief. The 10mm requires your eye to be close to the lens. The SR4mm eyepiece has such a tiny view hole that it's almost unusable. A gnat's arse could see off the size of the view hole on the SR 4mm eyepiece. The SR4mm's eye relief is so bad, I've worn contact lenses with better eye relief!  The 3 x Barlow is a plastic toy telescope affair. The only eyepiece I can use the 3 x Barlow with is the 20mm since it's 25 x magnification will be trebled to 75 x, which makes the Barlow practically useless, so is best left in the snap lock plastic bag it came in! Whilst the eyepieces aren't bad, it is clearly here that Tasco have cut the most corners.

However, using the 20mm and 10mm lenses I get great panoramic views of the sky that are 'zoomed in' compared to my Optex 16x50 binos that I've used for the last 5 years. Jupiter resembles a star on steroids with 3 or 4 dots around it. Saturn resembles a cartoon type graphic like a fat star with a line through it, a bit like the Norwegian letter that combines an "O" with a "\".  The moon is great. I can make out the splodge of M42 in Orion's sword sheath, M45 (pleiades) is nicely framed, as are the Hyades in Taurus. In all, it gave me a better window into the treasures of the Southern skies than my binoculars ever could. I can just make out the Jewel box near Beta Crux. Mars and Venus were good, with Venus being the best. Mars was a red dot, so no views of the poles or grand canyons. This was when Mars and Venus were close to us.

The images were generally much sharper using the Konus Plossl 25mm and 9mm eyepieces that came with my son-in-law's Konus 910mm 4.5" reflector. The Tasco eyepieces were slightly brighter, but probably have fewer lens elements, maybe only 2 or 3 elements, than the 4 elements in the Konus Plossls. Saturn and Jupiter were clearly tiny balls of coloured light, a bit like the full stop created by a thick felt tip pen.

When I later bought the Optex 8" dobson, I used the Optex 25mm Plossl and Meade Super Plossl 12.4mm eyepieces that came with it for further comparisons. These eyepieces were generally better in sharpness and eye relief over the Konus offerings. I also acquired a GSO OPBAR 2 X Barlow which gave the Tasco MA 10mm 100 x magnification so I didn't need to use the dreaded SR 4mm contact lens masquerading as an eyepiece. The GSO Barlow was far superior optically as to make any comparisons with the Tasco 3 x futile.

The Tasco Skywatch software is actually very good, so you won't need to blow $115 on the Enthusiasts version of StarryNights. Unfortunately this software only runs on Windows machines, so Apple Mac or Linux users beware. When you consider that most Academic and Government observatories use Unix based systems, I consider Tasco's lack of software for Macs and Linux/Unix a glaring omission. If you use a Mac or Linux, like I also do, then I recommend getting Stellarium, as it is excellent, especially considering that it is free. If you use the KDE window manager in Linux then you can use the simple K-Stars program that often comes with most KDE based distros.

I still use the Tasco as well as my Optex 8" dobson and Optex 16x50 binos. The Tasco is great for wide panoramic views of the sky, whilst my Optex can reveal close up detail better. The two scopes actually complement each other and both are very portable. As for upgrades and extras, you can add an EQ1 motor to one of the setting circles. The best upgrade will be to get better quality eyepieces, as these will stay with you if you change telescope later.


Whilst I may appear to be harsh on the Tasco, all I am asking you to do is be aware of the limitations of these cheaper scopes. Provided you have realistic expectations, you can still have fun with the Galaxsee. I would recommend this scope if you only have $250 to spend and need a telescope. Otherwise, a 6" dobson can be bought for $350 from the likes of Andrews Telescopes, which would be a better buy as the extra $100 gets you a 6" mirror that collects almost twice the light of the Tasco's 4.5" mirror, and at least double the focal length.

Review by Pete Moulton (PeteMo). Discuss this review on the IceInSpace Forum.

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