250px Dob' eyepiece advice please....

[Ande]

I'm looking at getting a couple of eyepieces that will work well with the 250px.  As I understand things it is a "fast" scope at f4.7.  I don't understand the science behind it, but everyone seems to be saying that fast scopes need good glass.  So, I guess the question is what is good glass?  I don't want to be spending silly money on Televue or similar, if I can get away with something more pocket friendly, but then I don't particularly want to end up buying twice either.  I inherited a 2nd-hand cheap Celestron kit that is so-so, and I also bought a new 8mm BST Starguider when I purchased the telescope.  However, I am completely underwhelmed by the BST ,as the views it offers seem no better than similarly powered, cheap Celestrons.  

Ideally, I would like something wide-field, say 32mm plus, and maybe an 18mm.  Decent eye-relief and a good fov would be nice too.  Any suggestions?

[Charic]

If your underwhelmed by the BST don't get a TeleVue Delos?
On my f/6 the BST gave just as good a view as the Delos, but you have an f/4 scope, the Delos may prove better, tested to f/4, 20mm eye relief and  72° afov.

Wont know unless you trial for yourself. Its a pity the BST did not come up to your expectation, you could buy 4 BST's for the price of a second Delos!

[Ande]

Thanks Charic.  I could do with attending a star party really, and grabbing a few peeks at other folks' stuff.  But the chances of work, weather, and star parties all coming in to alignment at the same time are close to zero, lol.  I've just been looking at the Baader Hyperion zoom lens (8-24mm)  seems to garner good reviews, and someone with the same scope as me has pledged it's goodness too.  Maybe go that route?

[Charic]

Just take what ever route you feel is the best or most adequate. Its not cheap buying the goods only to find their not up to your expectation.

I wanted to try several 'good' eyepieces and most probably they are, or at least have a good reputation, but my scope is easy to satisfy with only an f/6 ratio to consider. Plus my eyes might not be the best, conditions could be poor ( out of my control) scope not cooled enough or correctly collimated all go to make or break an eyepiece, or at least, the session just fails.

If I ever get a faster scope, I may consider Tele Vue De-Lites if my present lineup does not satisfy the needs, but I've  had some reputable eyepieces already, and sold them in favour of what remains. 

Your own eyes, the overall setup, and viewing conditions will decide whats best, but even the best can let you down. Find whats comfortable, affordable and available. you don't need the most expensive in order to achieve success.

You could probably have two 

[Whistlin Bob]

I've recently borrowed a Baader Hyperion for use in an f4.7 14incher and really enjoyed using it- being able to quickly change power and find the right balance between magnification & brightness is just brilliant. When the guy asks for it back I might be stretching this years astro budget a bit further...

[M Astronomy]

Hmm I wouldn't go with the zoom personally. Never tried it myself, but a zoom, whether it be a camera lens or an eyepiece, will never give as good a view as a fixed focal length. If you don't want to spend stupid amounts of money, I'd go for something more mid-range, like a explore scientific 68. Hope this helps.

[Ande]

Thanks each.  You've all given me something to consider.  Although it seems that anything that tempts me, Flo are awaiting stock of.  Maybe I'll play the waiting game and see if anything crops up in the classifieds.  It's this weather, it's making me go all retail therapy   @M Astronomy Explore Scientific is a new one on me.  I'll check them out

[pipnina]

1 hour ago, Ande said:

I'm looking at getting a couple of eyepieces that will work well with the 250px.  As I understand things it is a "fast" scope at f4.7.  I don't understand the science behind it, but everyone seems to be saying that fast scopes need good glass.  So, I guess the question is what is good glass?  I don't want to be spending silly money on Televue or similar, if I can get away with something more pocket friendly, but then I don't particularly want to end up buying twice either.  I inherited a 2nd-hand cheap Celestron kit that is so-so, and I also bought a new 8mm BST Starguider when I purchased the telescope.  However, I am completely underwhelmed by the BST ,as the views it offers seem no better than similarly powered, cheap Celestrons.  

Ideally, I would like something wide-field, say 32mm plus, and maybe an 18mm.  Decent eye-relief and a good fov would be nice too.  Any suggestions?

I have that exact scope and have loved my explore scientific 24mm-82deg "MaxVision" and my Vixen SLV 10mm. The 24mm hasn't got good enough eye relief for glasses but is very reasonable for the well-sighted. I chose the SLV partially because it touts a comfortable 20mm of eye relief while also having a decently large afov and a sensible magnification for the scope.

Based on my use of the 10mm I've found the eye relief to be the closest thing to comfort I've gotten while wearing glasses at the eyepiece. It also provided me some of the best views of jupiter I've had

I don't use the 24mm with glasses on most of the time because It's for observing big nebs and galaxies really. I find it good for that but if I wanted what the 24mm has to offer and a sharp view of it I'd get lasik...

 

Clear skies.

[Littleguy80]

I have the same scope and have also been considering eyepiece upgrades. My plan is to go for the Lunt/APM  HDC range starting with the 20mm and 9mm. Whilst they’re not Televue money, all the reports suggest that they’re very close to Televue Ethos performance. I believe the SkyWatcher Myriads are basically the same eyepiece but a bit cheaper and are well worth considering too. I started the thread below which discusses a few eyepiece options with people who are much more experienced than I and who have owned the mentioned eyepieces too.

The previous owner of my scope used Baader Hyperions I believe. I’m currently using BSTs among other eyepieces with the scope. 

Hope that helps  

[Ande]

Thanks all.  Although the more I learn, the less I understand, lol.  I'll have a careful pick through all of the suggestions, and compare price, specs and availability and see if I'm any the wiser

[Littleguy80]

33 minutes ago, Ande said:

Thanks all.  Although the more I learn, the less I understand, lol.  I'll have a careful pick through all of the suggestions, and compare price, specs and availability and see if I'm any the wiser

Haha take your time. Try and find a local astronomy club. You may well find people willing to let you try their eyepieces to help you find the right one for you. First Light Optics, who sponsor this site, are very good about letting you return equipment if you don’t get on with it, provided it’s not damaged etc. So even if you buy an eyepiece that doesn’t deliver what you were hoping then you can exchange it for something else. Well worth giving them a call or dropping them an email if you’re on the fence about a particular eyepiece 

[Ande]

Thanks Neil. I’ve yet to hook up with the local astronomy club, as their meet nights have so far coincided with my shifts. As soon as the opportunity arises then I shall surely do so.  In the meantime, I shall keep a keen eye on the classifieds ?

[Victor Boesen]

I use my explore scientific 82 degree eyepieces in the same scope as yours and I really like them.

[Ande]

Thanks Victor. They’re definitely on the shortlist ?

[niallk]

My minimalistic set for my 250px is:

24mm Panoptic

13mm Nagler T6

7mm Nagler T6

2.5x Powermate

I know you mentioned not TV - treat as an example of focal lengths & afov that I found to work very well across a wide range of targets in the same scope

[Ande]

Thanks Niallk.  I shall try to glean some titbits from your knowledge, setup and positive experience.  I actually managed a bit of a session last night, but found going to high magnifications really problematic, 8mm was just a real mess.  I suspect collimation, or lack of, could be a major factor.  I've got to bite the bullet and attempt to tackle this first, before I splash out.  Who knows, maybe the BST is good after all, lol.

[pipnina]

10 minutes ago, Ande said:

8mm was just a real mess.  I suspect collimation, or lack of, could be a major factor.

I would think either collimation or seeing. My 10mm can provide very good views so the magnification probably isn't to blame. (usually people say 1x mag per mm of aperture as an optimistic approach, which this scope is well below. I think 0.75x per mm is more like it but probably down to personal preference.)

We can rule collimation out entirely if you have a cheshire collimating eyepiece. If you have no collimation tools I strongly advise putting the cheshire at the top of your list! It's cheap and let's you collimate easily in minutes. At f4.7 collimation is more important than usual as well. If you have a cheshire try taking a photo through it and we can see if collimation is in error instantly

[Ricochet]

I would think atmospheric conditions are most likely to blame, not forgetting those inside the scope. A 10" mirror is a significant lump of glass to cool down. 

[Ande]

Possibly atmospheric conditions, but the scope itself had been outside about 5 hours by the time Jupiter presented itself.  The last time I looked at Jupiter, a couple of weeks ago, just before sunrise, it looked stunning.  But that was using my mak 127.  Lots of variables, but the truth is out there somewhere

[JOC]

If you have been trying to use your telescope since Christmas in the UK I would strongly suggest that it is probably atmospheric conditions that are to blame rather than your 'glass'.  I don't live in Kidderminster, but unless you've been living in some form of 'micro-climate' that is vastly different to the rest of the country I am amazed that you have found enough good conditions to make it worth even getting the scope out let alone form any opinions as to what is your best bit of glass.  The BST's generally get good press, I've got one for my 200P and find it works well (in what little time I myself have found to test it).  UK conditions have been really grim lately - have you really had it good enough to run a reasonable test?  If so lucky you!  LOL

[Ande]

40 minutes ago, JOC said:

If you have been trying to use your telescope since Christmas in the UK I would strongly suggest that it is probably atmospheric conditions that are to blame rather than your 'glass'.  I don't live in Kidderminster, but unless you've been living in some form of 'micro-climate' that is vastly different to the rest of the country I am amazed that you have found enough good conditions to make it worth even getting the scope out let alone form any opinions as to what is your best bit of glass.  The BST's generally get good press, I've got one for my 200P and find it works well (in what little time I myself have found to test it).  UK conditions have been really grim lately - have you really had it good enough to run a reasonable test?  If so lucky you!  LOL

Well, last night was the only the 2nd time I've been able to use the dob'.  It looked promising early on, so I put the scope outside, and then it went pretty clear at about 9pm, and I was able to stay out 'til 2.30am when it still looked pretty good, but I was whacked by then.  Regarding the BST, it could well be inexperience, or conditions, or both lol.  All I know, is that I get lovely views on the lower mags, and as soon as the 8mm BST goes in, things go pear shaped, so I then go the other way again.

[Ande]

1 hour ago, pipnina said:

I would think either collimation or seeing. My 10mm can provide very good views so the magnification probably isn't to blame. (usually people say 1x mag per mm of aperture as an optimistic approach, which this scope is well below. I think 0.75x per mm is more like it but probably down to personal preference.)

We can rule collimation out entirely if you have a cheshire collimating eyepiece. If you have no collimation tools I strongly advise putting the cheshire at the top of your list! It's cheap and let's you collimate easily in minutes. At f4.7 collimation is more important than usual as well. If you have a cheshire try taking a photo through it and we can see if collimation is in error instantly

I have got a Cheshire.  I bought it with the original order.  Just haven't plucked up the courage to attempt using it yet.  I was looking at AstroBaby's guide earlier.  May have a bash tomorrow.  Gulp

[pipnina]

2 minutes ago, Ande said:

I have got a Cheshire.  I bought it with the original order.  Just haven't plucked up the courage to attempt using it yet.  I was looking at AstroBaby's guide earlier.  May have a bash tomorrow.  Gulp

Cheshire eyepieces make the process incredibly easy thankfully Since the 250px has a small black ring on the primary you just have to get the black dot created by the cheshire directly in the middle of the black circle. The secondary mirror is more challenging I feel (mainly because of how tight the skywatcher screws are, I've wanted to adjust my secondary for a long time but I've not been brave enough to loosen the screws )

[JOC]

Astro baby's guide and a Cheshire is all you need, and allow yourself about 1.5 hrs the first time you try it.  

Another thing worth bearing in mind is not all the EP brands are parfocal.  Some require a considerably different adjustment on the focusser to others, one or two of mine are miles apart in perfect adjustment.  Also, as you up in magnification the amount of light will apparently diminish making the view seem 'dimmer'.  I have a 5mm Pentax XW an EP with a huge reputation, but I am having to get used to the image being less bright.  Consequently I find it is not the best EP unless the conditions are awesome, I don't think many peope have experienced awesome conditions yet this year, I certainly haven't.

[JOC]

There are many postings on SGL about SW secondary screws being tight as mine were.  The trick is to loosen the one in middle first.  It tensions the threads on the others.  Loosen it and the others shift easily.  I find the most tricky thing is that the secondary shifts slightly as you retighten the screws, so you have to play with it a little and in the finish tighten them taking account that the slight final movement will happen.   Do not forget to work on the scope with it laid horizontal length to the ground so things don't fall onto the mirror