Celestron 8 SE accessory advice

[Mack Truck]

I just bought a Celstron 8 SE along with a Baader Hyperion 8-24 zoom eyepiece. Even though 5 focal length in 1 eyepiece is pretty convenient, the image lacks definition using 8 and 12 mm focal length. So any advice for a short focal length eyepiece ? I was thinking something like TeleVue, but does it worth the price ?

Besides what accessories would you recommend ? I was also wondering about a Barlow and a couple of filters, so any advice would be appreciated.

[rwilkey]

Welcome to SGL Mack and congratulations on your new telescope. My first recommendation would be a dew shield as the glass at the front will dew up in minutes otherwise, you can get one here: http://www.firstlightoptics.com/dew-prevention/astrozap-flexible-dew-shield.html

or you can make your own from camping mat material.

Certainly TV eyepieces will be exceptional in your scope, but well out of my budget and I am not sure the cost would justify the benefits. I think an 8mm Vixen LVW would work nicely in your telescope, the LVW's are robust eyepieces and have good contrast and pin-sharp views here: http://www.firstlightoptics.com/vixen-eyepieces/vixen-lvw-eyepieces.html

Another alternative to consider would be the Explore Scientific 80 degree series, similar to the TV's but without the heavy price tag. Your telescope has a focal length of 2032mm and a focal ratio of f/10, and in this instance I would NOT consider it worth your while getting a Barlow, it will be too much.

As regards filters, if you are likely to be into deep sky objects (DSO's) you will most likely need a low power ep which will possibly be a 2" ep, assuming you have a 2" focuser I would recommend the 32mm SW PanaView, or the 30mm SW Aero ED for widefield studies. This creates a dilemma if you are then thinking about filters, do you get 2" or 1.25" filters? First of all, the filters I recommend are the SW UHC filter and a SW OIII filter for viewing nebulae, assuming you want to get into DSO's. Some people also prefer using a Moon filter, I do, and I would recommend an ND96 (0.9) which gives 13% light transmission, or alternatively, a Baader Neodymium filter, which can also be effective when viewing planets here: http://www.firstlightoptics.com/light-pollution-reduction/baader-neodymium-filter.html

Good luck with your choices but choose carefully, also see what others have to say.

[John]

Hi and welcome to the forum !

For what it's worth, I had my best ever views of Saturn a few years ago with a Celestron 8" SCT (like yours) and 8mm Tele Vue Plossl (250x). These can be picked up used for around £50 or they are £78 new, which is quite a lot for a plossl, albeit a very nice one.

There are plenty of other options for your scope though that will work well as Robin describes above. I put a 2" diagonal on my C8 and used a 38mm super wide eyepiece for nice low power, wide angle (relatively speaking !) views.

I agree with Robin that barlow lenses are not much use with scopes with a focal length of 2000mm.

PS: Do you have a dew shield for the scope yet ? - if not you will need one as the SCT design does attract dew to the front corrector plate.

[DoctorD]

Before you dive in and buy more eyepieces - did you give your scope time to cool, this can affect the sharpness of the view. An 8" SCT can take an hour or more to cool.

The Hyperion zooms get good reviews and should be great with your C8.

At the higher power end I assume you are looking at planets & the moon - at 8mm you are looking at x250 which will need a well cooled scope and good seeing. Even at the 12mm and x167 you will need the scope to be cooled.

A 2" diagonal and a wide field eye pieces might be a good complement to your zoom EP.

Hope this helps

Paul

[scarp15]

Yes I use an 8mm TV plossl and when conditions allow it cant be beaten in this scope at high power. However I also use an 11mm (185x) plossl and 13mm (156x) 82 degree field, each 1.25" EPs, both receive considerably more use at high power.

[Mack Truck]

Welcome to SGL Mack and congratulations on your new telescope. My first recommendation would be a dew shield as the glass at the front will dew up in minutes otherwise, you can get one here: http://www.firstligh...dew-shield.html

or you can make your own from camping mat material.

Certainly TV eyepieces will be exceptional in your scope, but well out of my budget and I am not sure the cost would justify the benefits. I think an 8mm Vixen LVW would work nicely in your telescope, the LVW's are robust eyepieces and have good contrast and pin-sharp views here: http://www.firstligh...-eyepieces.html

Another alternative to consider would be the Explore Scientific 80 degree series, similar to the TV's but without the heavy price tag. Your telescope has a focal length of 2032mm and a focal ratio of f/10, and in this instance I would NOT consider it worth your while getting a Barlow, it will be too much.

As regards filters, if you are likely to be into deep sky objects (DSO's) you will most likely need a low power ep which will possibly be a 2" ep, assuming you have a 2" focuser I would recommend the 32mm SW PanaView, or the 30mm SW Aero ED for widefield studies. This creates a dilemma if you are then thinking about filters, do you get 2" or 1.25" filters? First of all, the filters I recommend are the SW UHC filter and a SW OIII filter for viewing nebulae, assuming you want to get into DSO's. Some people also prefer using a Moon filter, I do, and I would recommend an ND96 (0.9) which gives 13% light transmission, or alternatively, a Baader Neodymium filter, which can also be effective when viewing planets here: http://www.firstligh...ium-filter.html

Good luck with your choices but choose carefully, also see what others have to say.

Sorry for the beginner question, but what would be the benefit of 2" filters over 1.25" ? And what do you need to adapt 2" filters on a Nexstar 8 SE ? Thanks.

[Mack Truck]

Hi and welcome to the forum !

For what it's worth, I had my best ever views of Saturn a few years ago with a Celestron 8" SCT (like yours) and 8mm Tele Vue Plossl (250x). These can be picked up used for around £50 or they are £78 new, which is quite a lot for a plossl, albeit a very nice one.

There are plenty of other options for your scope though that will work well as Robin describes above. I put a 2" diagonal on my C8 and used a 38mm super wide eyepiece for nice low power, wide angle (relatively speaking !) views.

I agree with Robin that barlow lenses are not much use with scopes with a focal length of 2000mm.

PS: Do you have a dew shield for the scope yet ? - if not you will need one as the SCT design does attract dew to the front corrector plate.

What's a 2" diagonal ? Thanks for clarifying what is obvious for you

[John]

Sorry for the use of jargon

A 2" diagonal replaces the 1.25" diagonal that comes with the scope. You need it to be able to use 2" eyepieces but you can also use 1.25" eyepieces by using an adapter (usually supplied). Here is a link to one:

http://www.firstligh...ct-adaptor.html

[rwilkey]

Hi Mack, no need to apologise, we all started at the same spot, a 2" (or 1.25") diagonal (often called a 'star diagonal') is a right-angled part with a mirror that goes in the back of the telescope focuser to make viewing easier. As I don't have the same scope as you, I am not sure whether you have a 2" or 1.25" focuser to allow the fitting of either, perhaps someone else will be able to answer this, although I think John has answered this in part above (you need to add one). Using 1.25" or 2" filters will be dependant on whether you are using them with a 1.25" or 2" eyepiece, although you can use 2" filters with 1.25" eyepieces providing a 2" diagonal has a thread for filters. Another alternative is to use a precision centering adaptor 2"-1.25" in a 2" diagonal (as I do) so that 2" filters can be used with both 2" and 1.25" eyepieces.

John, you type quicker than me, and also explain it better!

[Dunkster]

Welcome to SGL!

Dew shield is probably the first thing to get

As you have the Hyperion Zoom, you're OK for around 100x upwards. I find at the 24mm end the FOV is narrow, so a nice 2" wide field EP would work nicely, assuming you don't suffer too much light pollution at your observing location. You would also need the 2" diagonal to hold the 2" eyepieces. Baader also include a 2" adapter for the zoom to use directly in a 2" diagonal - as the zoom is heavy it should provide some additional stability and reassurance. Personally I find the Explore Scientific 82 degree series a good balance of performance and price, but there are other excellent eyepieces out there at a variety of prices.

Hope you enjoy your 8SE - it's a great scope IMO!

[Mack Truck]

Hi Mack, no need to apologise, we all started at the same spot, a 2" (or 1.25") diagonal (often called a 'star diagonal') is a right-angled part with a mirror that goes in the back of the telescope focuser to make viewing easier. As I don't have the same scope as you, I am not sure whether you have a 2" or 1.25" focuser to allow the fitting of either, perhaps someone else will be able to answer this, although I think John has answered this in part above (you need to add one). Using 1.25" or 2" filters will be dependant on whether you are using them with a 1.25" or 2" eyepiece, although you can use 2" filters with 1.25" eyepieces providing a 2" diagonal has a thread for filters. Another alternative is to use a precision centering adaptor 2"-1.25" in a 2" diagonal (as I do) so that 2" filters can be used with both 2" and 1.25" eyepieces.

John, you type quicker than me, and also explain it better!

Thanks for clarifying that. But what would be the benefit of using 2" eye piece and filters with my 8SE ? Is there any improvement in terms of viewing ? Thanks again.

[Sobel]

My dad and I bought an 8SE before Christmas so still got loads to learn, but I'm under the impression a 2" eyepiece will potentially give wider fields of view. Not 100% sure on the mathematics or how the optics achieve this, but from what I've read, 2" EPs are very useful for low magnification, wide FOV.

But I'd wait for a more informed person to explain

[Sobel]

As an additional point, if I'm OK to ask in this thread, to achieve wider FOV I'm under the impression I can do one of two things :

1) Buy a 2" diagonal to use larger 2" EPs (30 - 40mm) (requires a 2" diagonal and new EPs)

or

2) Buy a focal reducer to attach to the telescope, converting from an f/10 to something like an f/6.3 which in conjunction with existing 1.25" EPs will achieve something similar in terms of FOV (using existing 32mm plossl)?

[John]

A 2" eyepiece can give a wider field of view because it's barrel is wider. It's as simple as that. The edge of the field of view of an eyepiece is defined by a ring inside the eyepiece called a field stop - thats what creates the sharp black edge to the view you see. The size of the field stop is ultimately limited by the physical internal size of the eyepiece barrel.

So, for the 2000mm focal length C8 a 32mm eyepiece in the 1.25" size with the maximum size field stop will show a true field of view of approx .83 of a degree of sky which just a little more than 1.5x the diameter of the full moon. A 32mm eyepiece in the 2" size can have a larger field stop and can therefore show a true field of view of approx 1.28 degrees or 2.5x the full moon. Thats over 50% more sky.

A focal reducer, such as the one Sobel mentions reduces the focal length of the scope to around 1260mm so the same eyepieces will show a wider view. There is a catch I believe in that I think 2" eyepieces won't work well when a focal reducer is used due to light loss around the edges of the view but I'm not 100% sure of that.

The majority of deep sky objects will fit into a 1 degree field of view though but there are a few "biggies" out there such as M31 (the Andromeda Galaxy) and companions, the Veil Nebula etc which need much wider fields of view to fit them in. You can still see bits of them with a narrower field of view but there is something lovely about a wide, low power field on a dark night which is why many folks own more than one scope of course !

[jonathan]

Some of the best views I ever got of the Great Nebula in Orion were through a Skywatcher PanaView 38mm, which is a 2" eyepiece. I have a Williams Optics 2" Diagonal which is very solid and great to use, it is permanently attached to a Baader SteelTrack focuser. I do not use the original focuser anymore as I found it a bit inaccurate and caused too much vibration - the feather touch required on the Baader SteelTrack means that I don't see any vibration, although I do not use the original Celestron Goto mount either which was a vibration machine itself; with the focuser, 2" diagonal, and a 9x50 finder scope my 8SE is now too bulky and heavy for it anyway.

I had to ask FLO to order in the Celestron 9x50 finder scope specially, though the Baader 40mm Super Sky Surfer V looks pretty nifty. I just find that the red dot finder is not enough by itself for those smaller objects, both can be fitted at the same time and both are useful to have. Sometimes I do wish that I had a 90 degree erecting prism finder scope though, as it can be a real neck-twister!

I have 1.25" and 2" moon filters, not purchased at the same time I might add. I use the 2" if I am using the 38mm PanaView to view the moon, which is nice sometimes.

The 1.25" is useful for cutting out some of the glare from the brighter planets, or for using my 1.25" eyepieces on the moon.

I also have invested quite a bit in dew heater systems - multiple tapes and a controller; I have a tape on the finder, a large one on the end of the scope, one for the eyepiece. Also have an Astrozap dew shield. Even with all of this lot running, dew does sometimes get the better of me, on some nights nothing will stop it.

Consider a Maplins flight case for your eyepieces, diagonals, power cables etc. Here's mine:

That's the original diagonal on the right, the much larger 2" on the left next to it. Above them is the 2" 38mm, it's a heavy beast! Some people don't like the PanaView eyepieces, but then they may have different scopes to mine or be willing to spend more. Then 10mm X-Cel and 25mm Celestron Plossl. Bottom left is the dew controller but the electronics in that broke, it will be replaced with a new one I purchased recently. Main power cable is in red and black - this is a Sky Tron ST-002 for the Celestron SCT; this is a very nice cable, plenty of thick copper core. Skywatcher red / white LED torch on the right there, just above a 1.25" moon filter. Top left is actually a 12v charger / adaptor for USB devices but I haven't used it at all - I suppose it would come in handy out in the field for an iPad or something.

As for fuzzy views, I find that 10mm is often fuzzed out by poor atmospheric conditions, 12mm might be the best you could use on those occasions. My next eyepiece is 25mm, I could probably upgrade mine to a better eyepiece but I may not notice much difference through the 8SE, I would upgrade it mostly for use in my 150P reflector. I would not expect to see much through my X-Cel LX 5mm eyepiece in the 8SE, as it is an eyepiece I purchased for the much faster f5 150P. You may find that your Celestron 25mm Plossl eyepiece will give sharper or brighter views than the zoom eyepiece, worth doing a direct comparison.

[Mack Truck]

Thanks everyone for your input, I appreciate the feedback

I think I am definitely in for a Tele Vue eye piece. If I understand the benefits of a 2" diagonal, I am a bit confused about high power EP since they seem to come only in 1.25" (Nagle and Delos). So I guess 1.25" is the way to go for planetary observation ?

[rwilkey]

Thanks for clarifying that. But what would be the benefit of using 2" eye piece and filters with my 8SE ? Is there any improvement in terms of viewing ? Thanks again.

2" eyepieces more often than not are used for low power deep sky observing, the advantage of the 2" ep is that it can give you a slightly wider view of the sky because the field stop will be larger, many people use ep's with ultra-wide views, like the naglers and others - 82 degree ep's, but a 70 degree ep can give good views and so on. There is no actual difference in using a 2" filter over a 1.25" filter, they both do the same job, they are the same multi-coated glass. There are, in my view however, some benefits of using a 2" filter...

the first is that as they darken the sky, the light transmission through a 2" filter and ep is better and more evenly spread.

The second advantage is that the 2" filter can be used easily in combination with 1.25" eps by using an adaptor inserted into the 2" part of the focuser, or attach the 2" filter to the star diagonal, in this way you can use either 2" or 1.25" eps without having to swap over the filter to a different ep (filters are usually screwed directly into the bottom of the ep by the way, in the nosepiece).

A third point is that this can save you money, although 2" ep's are more expensive, it does save you buying both 1.25" and 2" filters for your various ep's. I did it the long way round as I did not have the benefit of this knowledge, I bought 1.25" filters, only to buy 2" filters later once I realized the benefits of wider field studies with 2" ep's.

I hope this does not sound too complicated but it's the way I now view things with hindsight!

[Mack Truck]

Thanks again for the tips

One more thing: I have noticed the stock diagonal of the Nexstar 8 SE hits the base mount when you point toward zenith. Any advice on a 2"diagonal that would work ?

[John]

Thanks again for the tips

One more thing: I have noticed the stock diagonal of the Nexstar 8 SE hits the base mount when you point toward zenith. Any advice on a 2"diagonal that would work ?

This could be an issue. You can get 2" diagonals that screw directly onto the threaded port on the back of the scope, like the 1.25" visual back (as it's known - it's the adapter you push the 1.25" diagonal into) does now. That might allow clearance for the 2" diagonal as it's closer to the back of the scope.

[Mack Truck]

This could be an issue. You can get 2" diagonals that screw directly onto the threaded port on the back of the scope, like the 1.25" visual back (as it's known - it's the adapter you push the 1.25" diagonal into) does now. That might allow clearance for the 2" diagonal as it's closer to the back of the scope.

Any brand/model in mind ?

[John]

Any brand/model in mind ?

This one will screw straight onto an SCT port:

http://www.telescopehouse.com/acatalog/Diagonal_Dielectric_99__Quartz_LX.html

Whether the clearance will be enough when the scope is pointing towards the zenith I'm not 100% sure though. I think it would be OK but maybe another member of the forum has the 8SE and uses it with a 2" diagonal and could comment ?

[Dunkster]

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Thanks again for the tips

One more thing: I have noticed the stock diagonal of the Nexstar 8 SE hits the base mount when you point toward zenith. Any advice on a 2"diagonal that would work ?

You can slide the dovetail through the clamp a little so that the diagonal will clear the base - at least, with a 1.25" diagonal - it is designed to be sufficiently balanced as such, so it sounds like your OTA is a little low anyhow. With a 2" diagonal it's a little more challenging ... I tend to avoid the zenith itself and draw the line at about 80 degrees and this prevents the 2" diagonal running aground.

I use a GSO/Revelation 2" SCT diagonal and it's fine, were I to do it all over again I'd probably go for the William Optics diagonal John linked to earlier in the thread...it's just got more of a quality feel about it, fewer rough edges

[jonathan]

I always found it difficult to know when the 8SE was properly balanced in the Celestron mount, I do recall it would hit the base at the zenith though which was a little disconcerting when it swung around and up and down trying to find something.

[cplee42]

A little late to the discussion but I also have the 8SE and over the last few years have made a few observations on accessories... Firstly I WISH i had gone straight for a 2 "diagonal and started a collection of eyepieces and filters at this size rather than starting with 1.25” kit. I now use the 2 " and it offers much better Imaging 'experience'. II also have the baader zoom (which fortunately comes with 2" attachment) but find (like you) the 8mm is underwhelming. However I have tried 8mm single EPs and frankly you need good seeing to exploit 8mm or smaller on an 8SE. I would agree a good wide field EP is a MUST, such as a Williams Optics range.

personally i never liked the red dot finder so initially upgraded to a baader sky surfer. However I quickly realised a 9x50 RACI is a great addition to the scope and lets you star hop for fun! Also good for general appreciation of the region you are observing. I also recommend a heated dewshield which has served me very well. I have found filters to be OK but not stunning to use except a variable polariser for moon and UHC for occasional nebula. Coloured filters are not very significant in what you can observe. I also find the Celestron vibration suppression pads for the tripod legs to be of limited use. Barlows have not been very useful. For focussing get a clothes peg and clip it to your focusser to improve fine tuning of the image.

I also highly value an adjustable observing chair so that you observe at a comfortable position and you can 'relax' to concentrate on the view!

[LukeSkywatcher]

I have an 8SE and an 8-24mm Hyperion zoom. I also find that the 8mm is lacking in sharpness. I use a Vixen 8mm NPL ep to overcome this. Personally i think the 8SE used in conjunction with an 8mm EP gives me the best views of planets.

8mm Vixen NPL costs about £30. Great EP's and really covers that 8mm "blind spot" that the Hyperion zoom loses.

http://www.firstlightoptics.com/vixen-eyepieces/vixen-npl-eyepieces.html

The views with the NPL's are sharp to the edge of the FOV and offer brilliant contrast.