Eyepiece question with an Astromaster 130 EQ

[andyno]

I've just received an Astromaster 130 EQ as a gift and i am keen to get started on what i hope is a long and fruitful hobby in astronomy. Having never owned a telescope before, i have a (what i imagine) simple question to ask...

I am able to see Jupiter and the 4 big moons quite clearly using the 20mm eyepiece, jupiter appears as a crisp disc, albeit too bright to see any details (which i guess my moon filter could help with).. my question is, when i try to use the 10mm eyepiece, it looks great too. But when i try to combine the 10mm eyepiece with the 2x barlow lens, jupiter always appears somewhat out of focus no matter how much i adjust, and never the crisp disc i see with the 10mm and 20mm. Does this mean the telescope requires collimation (Stars seem to look fine through the scope, and i can't see any blurring or visual artefacts.)?

[AstroTux]

I had just about the same experience when I took delivery of my 2nd hand AstroMaster 130 and what you're seeing could be down to one of many reasons.

1. Have you let the 'scope cool down sufficiently? If not air currents in the tube can cause viewing problems.
   
2. Are the viewing conditions good? If you are trying to view through thin high cloud ( which can easily be missed by the naked eye ) then most objects will appear slightly out of focus.
   
3. Are you sure that you have tried all you can to get good focus? Not as dumb a question as it looks - it can take some time to find the 'sweet spot' with a new 'scope.
   
4. How good are your eyepieces/barlow really? I found the 10mm eyepiece not too bad, but not as good as an inexpensive GSO ( or similar ) plossl. My first 2x unbranded barlow was a disaster, so I purchased a Revelation Astro 2.5x which I am more than happy with.
   
5. Is your 'scope collimated?
   
6. ....... and probably many more.
   

The main thing is not to worry too much to start with. Any new 'toy' takes time to learn and a 'scope is no different. Don't rush into anything until you are sure, but learn as you go along.

If you are worried about collimation, again don't rush it. There are a number of good threads on here and on the Internet about the subject. You will probably have to learn it someday but take it one step at a time.

One issue you will have with the AstroMaster 130 is that it has no centre spot on the primary mirror to help with the collimation, but again if you search for 'AstroMaster 130' in this forum you should find a number of posts explaining how you can do this.

Above all, have fun with your new 'scope and welcome to SGL.

Hope this helps........

[Stu]

It is often the case that the supplied eyepieces with scopes are not of the best quality. Using the Barlow, which again may not be the best quality may just be pushing the magnification too high for the eyepieces. Assuming a 650mm focal length, you would be at x130 with the Barlow and 10mm.

All the other advice in terms of cooling, seeing conditions and collimation are valid so get to know how it all works and then maybe look at some better eyepieces which should make a difference. Don't need to spend a fortune - not used them myself, but BST's get very good reviews and are relatively cheap.

Stu

[nicks90]

i have the same scope and had the same sort of view as you - until i took it apart and put a centre spot on the primary so i could collimate it.

sorry.... not the easiest thing in the world to do and quite daunting. But if you take your time and work in a clean ordered environment it is straightforward to take to bits and put back together after spotting the primary mirror. You can then collimate it to get the crispest views possible for your local conditions.

as for focussing, yep - at high mags i struggled to get the focus spot on. One tiny movement of the focus wheel is enough to go from too far in to too far out. I made a simple mod to mine to overcome this - blu-tacked a golden syrup tin lid to the left hand focus wheel. Its that much bigger, meaning a 2mm movement on the edge of the lid is like a 1/4mm movement on the focussing wheel. Made a HUGE difference. I can really understand why people invest in a dual speed crayford type affair now!

good luck, once sorted it will give some epic views! On a clear night before Christmas i was able to see 4 distinct cloud bands on jupiter and got some cracking views of saturns rings the following morning!

[andyno]

Thanks for the replies! Really encouraging.

I've got a (stupid) question to ask, spotting the middle of the primary mirror..would this affect viewing - or do you wipe off the dot afterwards?

[pel]

I had that telescope when I started.

Using the x2 barlow and the 10mm eye piece together will put you near the very limit of the 130eq, mine was perfectly collimated and I had the same sought of view when using that combination.

Most of the time you will get semi-blurry views of the planets due to turbulance in the atmosphere. The images people produce of the planets are produced from 1000's of images, where the best ones are combined to produce one decent image.

Personally I would never intentionally mark my primary mirror and you may damage it in the process. You'll never be able to sell it down the line.

[AstroTux]

I've got a (stupid) question to ask, spotting the middle of the primary mirror..would this affect viewing - or do you wipe off the dot afterwards?

Not a stupid question.

Applying the centre-spot will not affect your viewing as it is in the area of 'shadow' caused by the secondary mirror.

I would suggest quite the opposite to Pel in that a properly marked mirror means that the user has taken time to learn about collimating their 'scope and have therefore looked after it better. The only thing I would say is make sure you have read everything you can and prepared yourself thoroughly before you even think about going through with this process. It does have the potential to damage your mirror if you don't do it properly.

Hope this helps.........

[Siriusmeg]

I've marked my mirror after following advice on this forum (sorry can't remember the exact thread but search astromaster collimation). It was a case of plucking up the courage to do it when the collimation got seriously bad It was pretty straightforward & has made a massive difference.

The focus point with barlow is very small - take your time and make tiny movements. Sometimes when the seeing is bad the barlow is just a step too far & focus can't be found.

In terms of better eyepieces, BSTs work well in my opinion.

[dag123]

For what it is worth I only use a barlow on my Astromaster 130EQ when using the web cam. For normal jupiter viewing, once located with my 32mm EP (with such a large field of view, I don't have to worry about the inaccuracy of the red-dot-fider), switch to my X-Cel eye-pieces.

The 10mm probably gives the best view of Jupiter as it is easy to focus, albeit a small image. The 5mm does gives a bigger image but it much harder to focus and the planet starts to show a bright halo, plus it is getting to the limit of the scope.

Another trick is to put on the tube cover after removing the small cut-out cap. This greatly reduces the light entering the scope, thus resulting in a less-bright image, but it removes the halo glare and gives an image with diffrent contrast.

Hope this helps

dag123