Choice of EP power spacing for 200p Dobsonian

[sockgoblin]

hello there

I have decided on the Celestron XCel LX EPs for my Xmas pressie from Mrs W.

Id like some advice please on the spacing between EPs.

All are to be used with 200p Skyliner Dobsonian

Im working my way through the Messiers at the mo and I am in light polluted Cheshire ( especially after the arrival of a new neighbour who is trying to attract the second coming ,set up a helicopter pad, or land ET by the lights she has installed in her garden...)

My usual workflow is . setting circle or Telrad --> Finder scope--> 30mm--> and then  drop a 12mm plossl to inspect the DSO. I also have a nice Baader classic Q 2.25 barlow and I sometimes use this with the 30mm.

At present I own a 30mm Vixen NPL which I am very happy with, a 25mm plossl (hardly used but I do like it) , 12mm Revelation plossl and 9mm Revelation plossl.

With poor seeing and tight eye relief the 9mm is never used . The 12mm is used but eye relief is short . As noted above I tend to go straight from 30mm to 12mm . (I may well be missing the potential of 18mm ish ??)

I would like to buy two new EP below my 30mm.

Appreciate your thoughts please?

[ronin]

Going to say no rule that is really applicable. You might get the 5mm X-Cel and it may work 1 in 2 nights, whereas the 7mm would work every night. As DSO's are of assorted size m1 is a bit small M31 is a bit big.

My suggestion is if you like the X-Cel LX's (make sure they are the LX) then collect the lot. If I recall they do not have one around the 18mm to 20mm area so in a way that suits DSO viewing, the remainder will get used at some time or other. Ignore the 2.3mm, not sure what the purpose of that is.

At the lower end it is generally a case of tryng for the most magnification and when it drops off you go to the next longer eyepiece to maintain the view at the reduction of magnification. I do not have the 200P but I can find an eyepiece from 3.2mm, 4mm then 1mm increments up to 13mm - and in the collection I may have a 13mm just need to check all the eyepiece cases.

[Putaendo Patrick]

You seem to have your needs regarding magnification quite well covered.

30mm - x40

25mm - x48

30mm +Barlow - x90

12mm - x100

25mm +Barlow - x108

9mm - x133

12mm +Barlow - x225

The X Cel LX series is good optically and good value for money. However I'm not certain that they would fit an obvious gap in your range or strengthen a weak area.

If you're interested in DSOs I might be very tempted by a wider field of view 2" eyepiece. An 82 degree 18mm eyepiece would actually give the same field of view as your Vixen 30mm, but at a magnification of about x67. More expensive, yes - so I guess you'd just get the one. https://www.firstlightoptics.com/explore-scientific-eyepieces/explore-scientific-82-degree-series-eyepieces.html

 

[Saganite]

A few years back I had  a 200P, lovely, really lovely scope, and I  used  several BST eyepieces. The 18mm  was particularly superb.

[sockgoblin]

1 hour ago, Putaendo Patrick said:

 

1 hour ago, Putaendo Patrick said:

 

If you're interested in DSOs I might be very tempted by a wider field of view 2" eyepiece. An 82 degree 18mm eyepiece would actually give the same field of view as your Vixen 30mm, but at a magnification of about x67. More expensive, yes - so I guess you'd just get the one. https://www.firstlightoptics.com/explore-scientific-eyepieces/explore-scientific-82-degree-series-eyepieces.html

im still quite new to this game. I hadnt even considered 2 inch EPs

[rockystar]

The two I would buy are the 18 and the 9. I've got the same scope as you and feel that i'm missing a 9mm (got a 6.5 & 14 Morpheus), which is why i chose that size. And the 18 because I wouldn't go lower for now (my 6.5 rarely gets used, but it does get used so I won't part with it) and i think the 18 will be a good galaxy size. That's my opinion, for what it's worth

If I was to start again though, the ES 82 range is what I would go with.

[sockgoblin]

5 minutes ago, rockystar said:

The two I would buy are the 18 and the 9. I've got the same scope as you and feel that i'm missing a 9mm (got a 6.5 & 14 Morpheus), which is why i chose that size. And the 18 because I wouldn't go lower for now (my 6.5 rarely gets used, but it does get used so I won't part with it) and i think the 18 will be a good galaxy size. That's my opinion, for what it's worth

 

i notice that you have an 82 degree 24mm , is that a 2 inch? whats your opinions of a 2 inch in the 200p

[rockystar]

3 minutes ago, sockgoblin said:

i notice that you have an 82 degree 24mm , is that a 2 inch? whats your opinions of a 2 inch in the 200p

Yes, it's 2", it's a great eyepiece, works really well in the skyliner - It gets a lot of eye-time. you can keep things in the FOV for ages without having to nudge.

The only thing is, it's a bit of a faff swapping in an adapter when going back to 1.25, but it's ok.

 

[Charic]

It's worked out that I have used my  telescopes data plate to construct my EP collection.

I have a 6mm  to match the focal ratio of the scope (f/6) giving 200x power.
At twice the focal ratio a  12mm hits the 'sweet-spot' and the larger 2" Panaview  32mm  with its 70°afov 2" format provides my wide views through the scope.
The  Revelations have become my favourite Plössl.

No matter what the brand,  any  6mm gives me 200x  and an 8mm gives me 150x thats a fact,  but when it comes to comfort with regards to  eyerelief, fov ect you need to choose carefully.
The BST Starguiders suit my needs very well, they are my favoured EP collection,  but I have just noticed this week ( conditions allowed me to venture out with the scope -  Hoorah! ) that the fov on my Delos is  quite impressive, but that's it,  the actual image of the target appears the same, same details,  same brightness, same everything  with regards to my BST's except  the field of view is bigger.
 

As for choice of power spacing, should there be any ruling? A  set of 3, High, Medium and Low can be seen as adequate, but having  more EPs between those three, with varying fov's will allow you to better frame your target, also by having a gapless focal length  say 6mm to 32mm (26 eyepieces ?)  is not only expensive, impressive, overkill but very  time consuming when it comes to swapping out  each EP to get the best view,   but sometimes the effort is well worth it. I use  every BST during a session, one of them will fulfill my need on the night.

 

[sockgoblin]

12 hours ago, Putaendo Patrick said:

 

so i am now thinking

A new 2" 24mm ES 82 as my finding Ep (and a 2 to 1.25 adaptor)

and  new 9mm and 12mms they would be  either BST or xcel lx. I would keep the 30mm to use in a barlow to fill in the gap

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