Televue 8mm Plossl first Light

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"Televue 8mm Plossl first Light"
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I am afraid when reviewing Eyepieces (and telescopes for that matter) it is necessary to go through the technical specs before going onto the fun part, which of course is what you can see!

Televue is a company that is generally well regarded when it comes to astronomical eyepieces, they make all sorts from Super WIDE field monsters known as Ethos (I really badly want one of these but they carry a hefty £500 price tag) to little Plossls (the work horse of the Eyepiece world) these EP's are on the other end of the price scale at around £70 (although amongst Plossls, this would be considered mid to high price wise).

If you are new to astronomy (and in fact even if you're a seasoned vet) there are a few specifications that are vital for you to know whether this eyepiece is for you and YOUR telescope. For you see different EP's perform differently in different telescopes, what is the ultimate EP for one will be cast aside as useless by another. I will list the specifications at the end so that if you are just interested in hearing about what you can see you won't be bogged down by techy specs you don't wish to know about.

Another key thing to consider when choosing an EP is what are you going to use it for, do you lust after great lunar and planetary views or are you hunting more elusive fare, such as exploded stars or distant galaxies that are known to astronomers as faint fuzzies? This particular eyepiece is best used for planetary views, due to it's low focal length (lower focal lengths will yield more magnification) at 8mm focal length on my 1500mm focal length telescope I get a magnification of 187, but as I said I'll hold off with the boring stuff until near the end.

Right then, to the matter in hand...What can you see?

On Saturn (the jewel of the solar system) I was able to see extraordinarily defined cloud belts on the planets surface, with other EP's of similar focal length the belts were only ever hinted at. But there they were clear as day, a magical sight indeed.

After lingering over the body of the beautiful planet I turned my attention to her delicate ring system, because of Saturn's long 30 year journey around the sun and it's slow equatorial wobble the rings aren't in the best position at present to observe,they are for the time being edge on to us, in 3 or four years they will open up enough to show their complete beauty. Enough of the ring was visible to glimpse the Cassini division (a pronounced and even gap that goes right the way around the ring system). I have a feeling that when Saturn opens up to us this little EP is really going to shine. As well as the planet there are also it's amazing moons to consider including the orange hued disc (thats right it is actually resolvable as a disc not just a point of light) of Titan and it's sibling moonlets including enceladus, tethys, Dione and Rhea, all were perfectly beautiful using the TeleVue.

Lunar observations are wonderful with this TeleVue, you will see a world you thought you knew totally transformed, craters, rilles and jagged cliffs will explode out of the eyepiece, truly a wealth of detail. As there are no winds on the moon like there are here on earth, the cliffs are formed by collapsing crater edges rather than erosion and plate tectonics as they are on our own planet. I have to say though for lunar observations I have a much nicer EP that gives me a whopping 500X magnification when the atmosphere is steady enough to use it. But I would still put the Televue as a great Lunar eyepiece. False colour and aberrations (the bane of the planetary/lunar observer) are almost non existent right to the edges of the field.

On DSO's (deep space object, that is to say anything outside our solar system) the EP performs well, I toured the virgo super-cluster (an immense gravitationally bound filament of galaxies numbering in the thousands) and while with my telescope only a fraction of these faint fuzzies were attainable it was still an awing experience. Higher powers (shorter lower focal lengths) will often darken the sky when compared to EP's with lower powers, so in this respect it makes detecting elusive whisps of light that bit easier.

When used to view globular clusters (tightly bound balls containing a few thousand to a few million stars condensed into an area apparently the size of a quarter of the full moon, although in reality they are much bigger just much further away on the outskirts of our galaxy) the results were very pleasing, think of a large handful of diamonds scattered over a velvet black cloth.

Aspects of this EP make it ideal for planets and the moon, minimum chromatic aberrations and low internal reflections make it perfect for plucking details out of our closest neighbours, however nothing is perfect and the only gripe I have with the TV 8mm is that it has a tiny True field of view (the amount of sky you can see through the EP). As such it can be frustrating especially for owners of telescopes whose scopes cannot automatically track objects through the sky (most notably Dobsonian owners like yours truly).

Imagine centering a planet within your field of view only to have it flee at a terrific pace out of your line of sight (as the earths rotation causes things to appear as if they are racing quickly through the heavens), when your telescope is a little stiff the tiniest readjustment of orientation can cause your telescope to caterwaul about all over the place. In a nutshell small FOV'S (field of views) can offer a few brief seconds viewing only to be followed by a few frustrating minutes re-centering the planet. You do learn to get used to this process and as such it doesn't marr my enjoyment or reccomendation of this eyepiece significantly.

I would class the Televue 8mm as primarily a lunar/planetary EP although it will show planetary nebula and faint galaxies very nicely. If you want an EP that is first and foremost for DSO's then I would look elsewhere, with the ultimate example being the 13mm Ethos.

Strictly For The Geeks : )

These plossls are multi coated to lower internal refractions and they use only 4 elements to cut down on light interference (although I have a 3mm Williams Optics spl that has twice that amount which I actually prefer using overall). When used with my rather fast f5 dob the exit pupil is a rather nice 1.6mm, getting close to that 2mm sweet spot.

The TFOV is 0.3 degrees which is pretty paltry but as I said before you can't win them all. Eye Relief is 6mm so could be worse but again my WO SPL trumps this EP with a whopping 20mm which makes it so much more comfortable to view with. The TV has a field stop diameter of 6.5mm, while this is a little tight it's not the end of the world, my celestron 4mm omni plossl has a field stop of about half this which truly is uncomfortable to view through.

To Summarise

The tv 8mm plossl is a great addition to your planetary, lunar EP set and can even be used to bag those wispy gases, fiery balls and lanes of cosmic dust that make this hobby so diverse and rewarding, but again I will say that DSO's take a back seat where this EP is concerned. It will set you back around £70 but the views I've had of Saturn alone are worth every penny, when you throw in the other 7 planets in our solar system (and handful of planetoids) the moon and finally the DSO's, you have a fantastic eyepiece with only one flaw, its small field of view.

More about this author: Matt Kelly

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