What upgrade next?

[Langy]

I've got the Astromaster 130EQ and very happy with what it can do so far. Since buying this only a month ago I've already bought the MD and replaced the RDF with the Rigel, both of these have been serious value for money on how the basic scope was. I also bought what I'm told was a reasonable 2x Barlows and adaptor to use my DSLR which mainly gets used for Lunar as it's not really appropriate for much else, which I don;t mind as piggy backing the scope with a 300mm lens has a lot of life left in it before I even think about anything greater.

So now I have a dilemma of what I should buy next to get the most out of the scope.

For EP, the 20mm I really do enjoy that came with the scope. It's bright, clear and wearing glasses is a joy to look through. It's ideal for the moon and pleiades (a bit wider on the second may be better). The 10mm I'm not very keen on, it goes in briefly for when I look at smaller objects like Jupiter, Orion Nebula and Andromeda but soon gets swapped back. I think the main issue is the glasses and very narrow FOV when looking in caused by the small opening in the EP. I know the spec says it has a highest useful magnification of 307 but compared to what I've got that just seems silly going anywhere near there even if it would work.

My second thing is on culmination. I don't know too much about this but have watched the series of videos on YouTube from Astonomy Shed and a few others. Now last night when I packed up I thought I'd take a look to see which parts were getting damp inside the scope. It mainly looked like the stem on the secondary mirror, checking the primary I could see there is already a gathering of dust of something on it. However with shining the torch inside I couldn't see any center spot marking on the primary. So I guess I would have to culminate it by checking for the three clamps holding the mirror.

I'm certainly intending on keeping the scope for some time as I'm sure that even though it's a beginner scope it should be capable of a lot more that as when bought.

Thoughts please?

[itmo]

if you google with "collimation" you will get more hits than with "culmination" You should get a cheshire for collimating the scope if you dont already have one and google for "center spotting the primary" or something to find instructions on how to attach a center spot mark. Also dont worry about dust. 

[Squagnut]

Hi Paul - I'm also in Carlisle

You may benefit from long eye relief EPs, which are more comfortable when wearing glasses. It would certainly not be getting the best from your kit never to go below 20mm! Stock EPs supplied with telescopes are usually usable but mediocre.

[Langy]

if you google with "collimation" you will get more hits than with "culmination" You should get a cheshire for collimating the scope if you dont already have one and google for "center spotting the primary" or something to find instructions on how to attach a center spot mark. Also dont worry about dust. 

It's been one of those weeks with my typing  , I spend all day at a keyboard and most of my spare time, so touch typing has come on well, but for some reason this last week I feel I have typed twice as much with all the mistakes.

Now give me a laptop, desktop PC, mobile phone and even my DSLR and I will take it all apart to attempt most repairs. As precise as you have to be if you don't put things back with a torque wrench it really doesn't matter. Now I've had the scope for a month now and as easy as it may be to do the center spotting, it frightens me in that what may work now won't work when I put it back or I'll cause some damage to the mirror. Think I will leave that to someone who can do it or at least have them beside me when it done to help when I make the mistakes.

Now the Cheshire I believe can still be used to collimate when I don't have a center spot as you should be able to see the brackets holding in the mirror (I think ).

In my world (live gadgets  ) a laser would be ideal, but from what I've seen and read they are far from accurate so I will look into a Cheshire especially when I get the next favorable comment for one.

Hi Paul - I'm also in Carlisle

You may benefit from long eye relief EPs, which are more comfortable when wearing glasses. It would certainly not be getting the best from your kit never to go below 20mm! Stock EPs supplied with telescopes are usually usable but mediocre.

With seeing recent posts of people viewing the moon and Jupiter at 150X plus my mere 20mm and 10mm are far from what I can get to. Is there a recommendation as to what I should be looking for? How is the eye relief measured and what is classed as a good eye relief? I've heard plossi being mentioned a lot but without reading all the posts about EP what are the recommendations for a good budget and mid range EP?

[John]

With seeing recent posts of people viewing the moon and Jupiter at 150X plus my mere 20mm and 10mm are far from what I can get to. Is there a recommendation as to what I should be looking for? How is the eye relief measured and what is classed as a good eye relief? I've heard plossi being mentioned a lot but without reading all the posts about EP what are the recommendations for a good budget and mid range EP?

Eye relief is the distance the eye needs to be from the centre of the top lens of the eyepiece to see the full field of view. It can vary from just a couple of mm to 20mm or more. If you wear glasses when observing (which I don't) I believe around 12mm-15mm at least of eye relief is considered necessary for a rewarding observing experience. If you don't wear glasses to observe you can cope with just a few mm but it takes some practice and it's not all that comfortable for many of us.

Plossl and orthoscopic design eyepieces have eye relief that is generally around 80% of their focal length so the shorter focal length ones (ie: 6mm, 5mm, 4mm etc) need the eye to be very close to the top lens. 

You will see many recommendations for budget, mid-range and expensive eyepieces and we all have our favorites. The BST Explorers / Starguiders get lots of good press on here, have comfortable eye relief and retail at around £48 each I believe. I guess it depends on your budget as to whether that is low cost or mid-range !

I've not used them myself but the feedback on here gives me confidence in recommending them as a really good step up from the low cost ones that come as standard with scopes.

[Langy]

Thanks John most appreciated for the EP.

I think that an EP around £50 is mid range from what I have seen, cheap / budget are the real cheap ones on eBay at around £20 which I dare say are the quality of my current 10mm, so I would get no benefit there.

I just taken a look at the STL website and there are no prices on there, but as an active seller on eBay found some on there. I'm drawn to the 1.25" 8mm BST Explorer Dual ED eyepiece Branded "Starguider" one as this will be a different magnification to my current 10mm, upping the magnification to x81.25. It may be later down the line that I have to have another Barlows if the one I have isn't good enough.

That will be the EP sorted out now for Collimation.

STL also have the Sky's the Limit Cheshire Collimator for Newtonian Telescopes - long on their list. Would this be used to do both mirrors? Also will I be able to make sure the primary is aligned properly with no center spot?

[Moox]

You won't go wrong with the 8mm BST, will be much nicer than your 10mm.

[inedible_hulk]

+1 for the 8mm BST

[Tiny Small]

Center spotting your scope and using a Cheshire or collimated laser will make your life easy, but you can do a rough collimation without any of it, especially if it's just for visual observing. Make a collimating cap by drilling a 3mm hole in the exact center of a covering cap for the EP holder. Put it in and look through to make sure that the secondary is in the center of the hole, then take it out and do a star test. For this, use your highest power EP (smallest number) and point it at a bright star then de-focus it. You should see concentric rings. If not, your primary needs adjusting on the rear of the scope. Simples If the seeing is poor, you won't be able to do a proper star test as the rings will be distorted, but even then, the distortion should have an overall even radius from the center so you can still get it roughly in the right place. Of course, I would always recommend using a Cheshire or laser in the first instance, but if they're not available, this works. Also, don't just assume that you need to collimate. Do a star test first and if that is out, then collimate. A guide to what you should be seeing can be found here right down at the bottom of the page; http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm

[Tiny Small]

Also, when doing the above, the secondary needs to be circular as well as central in the collimating cap.

[Langy]

Thanks, I did find that guide which has already been bookmarked.

It would be nice to have the center spot on the mirror (don't know why it's not there as standard) so at least if I got a cheshire I could see if it was out that way.

Will try the star test when we actually get some viewing though.

[Tiny Small]

Center spotting is easy and nothing to worry about. Take the radius of your primary, use a compass to draw the circle on plain paper and carefully cut it out then use a bit of rolled up tape to stick a coloured in sticky circle (hole reinforcer from a stationers) over the hole the compass made, then line your cut out circle over your primary and press down. Entire operation takes about 5 minutes.

[RikM]

I also wear glasses while observing and find that I need 15mm + of eyerelief to be comfortable. Similar to John, I have not actually used the BST Starguider eyepieces, but I don't recall hearing a bad word about them and there are many happy owners posting, so it should be a safe bet

Centre spotting a primary is not that difficult and does make life easier. If you don't want to get a fancy Cat's eye one, you can use one of those little punch-hole protectors. Most Cheshires these days are combined with a long sight tube. This makes it much easier to check if the secondary is centred properly but it does mean you probably won't be able rack the focusser out far enough to see all the mirror clips. A coli cap as described above would be to solution to that, together with a star test. When start testing, do make sure your test star is in the exact centre of the eyepiece. If it off to the side, coma can give you an asymmetric diffraction pattern that is easy to mistake for miscollimation. 

[Langy]

Just found this fro Celestron https://www.astronomics.com/documents/celestron/celestroncollimatingtool.pdf

I guess they are only expecting a not so precise job done as to why there is no center spot.

[Tiny Small]

Just found this fro Celestron https://www.astronomics.com/documents/celestron/celestroncollimatingtool.pdf

I guess they are only expecting a not so precise job done as to why there is no center spot.

To be perfectly honest, for purely visual, this is probably enough. A Cheshire or laser will get you almost perfect but all that is required for visual is a successful star test, and a successful star test will show concentricity a little way either side of perfect so actually covers quite a broad area. Your eyes won't notice if it is better than that (though a long exposure photograph would certainly highlight it), so I suppose, if this method gives you a decent star test, it's good enough.

[Langy]

Just ordered the 1.25" 8mm BST Explorer Dual ED eyepiece Branded "Starguider"  

​Now hopefully I will get some viewing time   when it arrives and all this cloud and wind   will go away!

[Langy]

Update!

After only ordering the EP yesterday morning it has been delivered in the post today, now what about that for service.

The first thing I've noticed is how heavy and big it actually is. This makes the stock lenses look so puny. I think now I may well find out how bad my 20mm EP is and that's the one I'm happy with. The 10mm stock could well become a paper weight.

Now when are those clear skies coming? 

[ardbeg74]

The first thing I've noticed is how heavy and big it actually is. This makes the stock lenses look so puny. 

Was going to add +1 for the BST 8mm but you have already bought it! Its a hefty bit of kit and worth every penny IMHO. You are going to have fun with that when the clouds break.

+1 for the cheshire, along with the 8mm BST this is another purchase i've felt was "worth its weight".

All the best

Mark 

[Squagnut]

Good choice! I've never used an 8mm BST, but yes, proper EPs very quickly show the shortcomings of stock EPs. Mind you, not all EPs that come with scopes are poor - my C9.25 came with an excellent Celestron 25mm plossl.

Since you say you're comfortable with it, it's possible that your stock 20mm is a long eye relief EP. Certainly the 25mm that came with my SkyMax is. It's not a great EP, but worth hanging on to for that reason alone.