great_bear

On 12/01/2023 at 11:23, Ricochet said:

I found that brushing the Musou straight onto the tube didn't leave a great looking finish and was still reasonably shiny under bright light at shallow angles.

Yes, I did the same with the baffle tube of my Mak 180.

It offered no improvement at all over the Sky-Watcher factory finish (although it wasn't any worse, either). Musou clearly offers no benefit at oblique angles although may be of some use when painted onto small parts which are too fiddly to be flocked.

14 hours ago, fullmoon said:

So a stargazer 5mm and 3.2 would be a recommendation?

Depends on whether you’re planning on being Barlow-free or not. 

I’m Barlow-free because:
1. It’s less hassle & confusion on a night
2. I don’t want excess glass in my “regular” top power (unless designed-in)
3. I don’t like figuring out the mathematical leapfrogging required to reach an effective Barlow strategy
4. Good Barlows are actually quite pricey compared to Starguiders
5. I don’t like some of the side effects of Barlows - many eyepieces don’t play well with them.

Of course, some people will undoubtedly disagree, but personally I’ve no regrets about being Barlow-free.

With regard to focal lengths, these days I’m reluctant to recommend specific eyepieces to those starting out, but I will say the following:

Highest Power:

• 3.2mm - The highest power that gets reasonably satisfying lunary/planetary views under good conditions with a 130p Explorer and a good-quality eyepiece. Most nights, this will be usable - just not every night.
• 4-5mm - A good fallback for when the sky steadiness is too poor for the 3.2mm

Lowest Power:

• 24mm - A nice wide eyepiece at around this length will show the maximum wide field that the 130p allows.

Others:
As to what might fit nicely between those two extremes of high and low, there's a huge range of options, all down to personal preference and budget.

Brands:
As for brands overall, well that’s a whole new conversation! But I will say, when it comes to being well-corrected off-axis at (i.e. stars etc. that are not in the middle of the view) at a focal ratio of F5 (like the 130 is), there are not many 'budget' eyepiece product lines that work well. The Starguiders certainly do - at least for 15mm and shorter focal lengths.

14 minutes ago, Don Pensack said:

That 18mm UFF is only £109 from FLO.

That is very inexpensive for such a well-corrected 65° eyepiece.

Is a 24mm UFF likely to be better corrected at F5 than a 24mm SWA (Meade 5k)?

The 10mm UFF didn’t work out well for me at F5 and I sent it back. 

Hi,

I’ve got a couple of really nice telescopes - a 150 with a custom mirror, and a Mak 180 on a big, sturdy HEQ5. 
 

BUT - I still regularly use my (wife’s) 130 Explorer like yours. It doesn’t really give up *that* much to its much more expensive, bigger siblings - especially when paired with an eyepiece like a Starguider 5mm or even a 3.2mm if the sky is steady. 
 

I remember when we first got the 130 Explorer thinking that we wouldn’t get to see great views, but we’ve since had some jaw-dropping views from it. 
 

The supplied 10mm and 25mm eyepieces are kind of “OK” for lower power views, but the 10mm + Barlow never got me very good planetary views. 
 

Nonetheless, the biggest factor in getting good planetary and lunar views is the not just a clear night, but a clear night PLUS a steady sky and for us not to happen to be right under the jet stream (which happens a lot) and to be outside and a few feet away from the house and not be trying to observe something that’s right above other people’s rooftops. 
 

Persevere and you’ll be rewarded in time with some very memorable experiences. It’s a good telescope. 
 

One thing that can help with focussing is to just put a large clip on the focused knob to give you some fine-focus control. 

2 hours ago, Louis D said:

The 18mm Meade HD-60 is similarly the weakest link in that line as well.

The problem is that all of these step-up 18mm eyepieces are positive-only designs with no negative Smyth lens group to improve correction in faster scopes.  The 18mm APM UFF and its brand-mates would probably be a good bet at that focal length since it is a negative-positive design.  Yes, it is considerably more expensive.

FLO do a StellaLyra version at £109

What's the concensus on how the StellaLyra Kitakaru's perform at these tricky 18mm and 25mm focal lengths with F5/F6 scopes Louis - do you know?

On 08/01/2023 at 15:19, mr_belowski said:

I got the 18mm and was pretty unimpressed with it.

When I asked about the Starguiders on CloudyNights, it was mentioned that the 18mm appears to be the weak point of both the Starguider and Celestron X-Cel LX lines, with neither being a clear winner.

I have a 12mm and 5mm Starguiders. Both are superb, although the 5mm needed an extra baffle fitting to improve lunar performance.

I now have a 3.2mm on the way. 

The Starguiders are for my (wife's) Sky-Watcher 130P Explorer, in which they work very well. In the Dob I use Tele Vue Delos instead.

The general consensus on CloudyNights was that fans should blow on to the mirror. It’s also how my 8” GSO Dob was made.  

On 18/01/2023 at 23:17, bosun21 said:

On heavy nights of dew I also use a dew band around my eyepieces.

Another tip is to not use the tripod eyepiece tray for eyepieces (nor a Dob eyepiece rack) on cold nights - keep them in a foam-lined case with the lid closed when not in the focuser. I also keep my bulb-blower handy for eyepiece de-misting. 

The eagle-eyed may have spotted that I’ve set the moon phase 180 degrees out. 
 

I can’t wrap my head around them making full moon black and new moon white - so I’m ignoring those labels - it will work fine setting the pointer in the opposite position. 

Very happy that a late Christmas present has just arrived. It was late because my wife had to work so hard to get one, and I’m delighted she did. 
 

Formerly sold by FLO, these are sadly no longer in production and stock of this exact configuration is not held anywhere. 
 

It’s a shame these are discontinued, but I’m of course delighted that I probably got the last one available anywhere:

I believe these eyepieces (in price order) will all work well in F5 scopes. Most other eyepieces not in this list will be somewhat out-of-focus or otherwise distorted at the edges at F5

• BST Explorer eyepieces (one of the best yet relatively inexpensive options - excellent performance although some moon glare at the shortest focal lengths)
• Celestron X-Cel LX eyepieces 
• Baader Morpheus
• Pentax XW
• Tele Vue Delos or Delites
• Nikon (the most expensive)

You might want to consider buying and selling second hand to discover what you like. For example I saved up for an 82-degree apparent-field-of-view eyepiece once and then discovered in-use that ultra-wide views are really not to my liking. I ideally prefer 60-70 degree views.

You may also discover that you get better views without glasses. Those that keep them on usually do so because they need them for sketching or basic mobility, or to eliminate strong astigmatism or other issues. For general, non-severe, short-or-long sightedness glasses are not needed at the eyepiece.

As much as I hate mingling with other human beings, going to an astronomy meet-up to get hands-on experience of what other people use can be valuable. 

Just purchased a 27mm Panoptic… If only just to get more use out of my Dioptrx! 😄

I use Meade S5000 “Plossls” of 20mm and 14mm in a Mak 180.  That gives me 162x and 231x (includes the 1.2x magnification caused by the binoviewer light path length in the Mak)

In the middle of the night - between 1am and 2am - there is occasionally a period when I can switch up to 286x for about 30mins by using the WO 2x binoviewer Barlow with the 20mm S5k’s (which causes a 2.12x magnification in the Mak)

18 hours ago, Second Time Around said:

 If you put a 42mm x 2mm o-ring or elastic band over the threads, not only is the Dioptrx held securely, but you can also rotate the Dioptrx to vary the angle.

Brilliant!

18 hours ago, Second Time Around said:

A final tip: put a tiny bit of glue or Blutac at the 12.00 position on the outer rim of the Dioptrx.  That way you can quickly and easily get the correct angle for the Dioptrx when changing altitude on a Dobsonian etc.

Also brilliant!

10 hours ago, Louis D said:

No, I haven't taken mine apart.  It's way too nice sharpness and contrast wise in the central part to do that to it and risk ruining it or getting dust in it.

I’m happy to. 

So I just took the 20mm apart, examined it closely and - whilst we can’t know for sure the curvature of the inner, cemented surfaces, it seems to be - as I said earlier - an Erfle II:

3 hours ago, Shimrod said:

My challenge now is that I need reading glasses when I have my contact lenses in!

I’m in the same boat - but a cheap pair of reading glasses from (literally) Sainsbury’s does the trick. As stated above I don’t use contacts during astronomy because I prefer the look of stars without them. 

4 hours ago, Don Pensack said:

Basically, any eyepiece with at least a 2mm long top section 41-43.9mm in diameter.

Perhaps, but without a lip similar to Tele Vue, you will lose the combination of free rotation with secure fitting. I wouldn’t want to knock the thing off the top of the eyepiece whilst clumsily adjusting it with cold hands.   

You could screw it tight and spin the whole eyepiece in the focuser I suppose - but that may be tricky when using eyepieces with screw up/down eyeguards, which is quite common in the longer focal length category. 

4 hours ago, Don Pensack said:

It can even be made to fit other eyepieces in various creative ways.

Yes - I have given serious thought to superglueing a Nagler Dioptrx adaptor onto the tops of my SWA and Aero ED eyepieces to do just that.

Contact lenses make the brightest stars look a bit of a mess. Instead of sharp pinpricks of light they bloat (at least with the brands I’ve used) into a bunch of fuzzy diffraction spikes. 

I use one. 

I was going to say I got it a couple of years ago, but I just checked and it was nearly eight years ago!

My one is 0.75

I got it for my 17.3mm Delos when used in my F6 Dob. It’s easy enough to use - just defocus on a star, rotate until the diffraction rings are circular not oval, and you’re done. 

There are a few annoyances:
- With a Newtonian, you need to rotate it (of course) as you raise the angle of the scope in order to keep it aligned
- The letters that are printed on the side to help with alignment are on the lower ring, not the upper one with the glass on, so if you remove and replace the Dioptrx then the lineup will have changed a little depending how tightly you’ve closed the mechanism
- When you remove it, chances are you’ll want to replace the eye guard before others use the eyepiece. This involves peeling it off the Dioptrx (easy) and stretching it back onto the eyepiece (hard - especially in the dark)

Now I’ve got it, I’ll keep it, but if I were to go back in time and reconsider - knowing what I know now - I probably wouldn’t buy one. Here’s why:

- For those like me, who need 0.75, it only makes a difference to eyepieces with a 3mm or greater exit pupil 
- You might not need it when using those eyepieces in a different (slower) scope
- It only fits Tele Vue eyepieces
- You only notice it on brighter stars
- Even if you have more than one eyepiece to apply it to, do you really want to keep unscrewing and refitting it every time you swap low-power eyepieces whilst observing?
- If not, would you buy one-per-eyepiece instead? (unlikely)

In my case, all it’s really done is make the Delos 17.3mm £100 more expensive for a marginal gain in sharpness - and even then, only on a scope that I don’t use at home (and rarely use elsewhere, for that matter).

Overall then, not my smartest purchase. 

It’s basic geometry isn’t it Don?

The maths dictates that a wide apparent field of view with enough of a gap to accommodate spectacles (or just personal preference) will result in big, expensive lenses being required. 

Do you think that one day it will be possible to mass produce high-quality plastic lenses that could match the performance of glass, and bring the cost down?

10 hours ago, Louis D said:

Add in the fact that sales tax isn't collected by FLO

Oh, it is for those of us in the UK - it's just that by law, UK web sites have to show prices with the sales tax ("VAT" at 20%) already baked in.
(typically, the final sales invoice will break out the tax separately to make it clear that qualifying businesses can claim it back)

I’d recommend this - the 24mm SWA  (£9 over budget, but close enough).

I have the old Meade version and I use it in all my scopes - it gets a LOT of use.

https://www.firstlightoptics.com/explore-scientific-eyepieces/explore-scientific-68-degree-series-eyepieces.html

23 hours ago, Louis D said:

The general consensus is that JOC reissued the Meade 5000 Plossl series as the ES-62 series since the specs and focal lengths are so similar.  If that is the case, I can speak to the 40mm focal length since I own the Meade 5000 Plossl version.  It is super sharp in the inner 50% at f/6 and then rapidly fuzzes out moving to the field stop due to astigmatism.  On the plus side, the moon doesn't distort much at all moved from center to edge.

The design is basically a variation on the Zeiss Astroplan opened up to 60/62 degrees.  Even if it had been limited to 50 degrees, their design would still have had edge issues since that would only eliminate the outer 17% or so.  Normally, these Astroplan variations are sharp to the edge at f/6 over a 50 degree AFOV as with the old Celestron Ultima, Parks Gold, Orion Ultrascopic, and Baader Eudiascopic "Plossls".

The view through the 40mm Meade 5000 Plossl in my field flattened 72ED is shown below relative to others.  Since it is a scaled design, all of the other focal lengths except for the 5.5mm, which has 6 elements, should perform similarly.

I took a S5000 Plossl apart (not the 40) and it wasn’t like that at all on the inside. Are you going by documentation or have you taken a look yourself? 
 

Mine was basically an Erfle variant. 
 

The 26mm would be a mess at F6. It wasn’t that great at F15 to be honest. 
 

However, apart from minor eye-glint, the 20mm and 14mm are essentially perfect in an F15 Mak - I wouldn’t swap them for anything. The glass has a breathtaking coolness to it. I’ve used mine in a WO Binoviewer for several years now, and nothing has beaten them. 
 

interesting to hear they’re back in production. I saw that range and wondered if those might be them redesigned. 

On 20/11/2022 at 03:52, Louis D said:

To allow for more downward/backward adjustment range, the rocker box side height might have to be increased to allow the tube to clear at the bottom.  They may have deemed the range enough for most users.

Perhaps - and it's certainly the case that the size and operation of the scope is - in its current configuration - perfect for outreach; the height of the rocker box is such that children old enough to look through a scope will find it the right height, and adults can use a regular stool and be able to bend down or straighten up and look through the eyepiece at all elevations without requiring the seat to be adjustable in any way.

It's the most physically-comfortable scope set-up that I've got.

The 5mm was well-worth the wait by the way.