Unsure on Buying/upgrading eyepieces

[SmoothOperator]

So I’ve had my skyliner 200p dob For just over a year now and couldn’t be happier with it as my first scope. With the scope came a 10mm and 25mm eyepiece and I also purchased a cheap Barlow lense to go with it. On a good night with the 10mm and Barlow I have managed to get some stunning views of Saturn, making out the gap between the planet and ring clearly as well as seeing the coloured cloud stripes of Jupiter. Im now looking to expand my EP collection and have done some calculations. Based on my scope I believe the maximum magnification I can achieve is x403 and with a 6mm EP and Barlow would be able to achieve x400 magnification. Although this is within my maximum magnification can anyone offer an opinion on whether this means I’d be able to focus the image correctly or whether it’d just be a blurred image. Also by spending the extra money how much difference can be noticed with the same sized EP, for example would a £150 EP really offer much more than a £25 EP it terms of image quality. FLO sell a plossl EP set which comes with a 6,8,13,17 and 32mm EP as well as various filters and at first glance looks well worth  it but not entirely sure on whether it’ll offer more variety in my observing sessions. Guess I’m just looking for an opinion on where to go next as I’m a bit lost in the sheer number of different options.

https://www.firstlightoptics.com/eyepiece-sets/celestron-eyeopener-eyepiece-and-filter-kit.html

Edited July 22, 2020 by SmoothOperator
Spelling mistake

[Louis D]

Generally, about 30x per inch is what I figure for Newtonians, so about 240x max for your 8", which is where you are today.  The secondary obstruction and spider vanes tend to cut down on contrast at higher powers relative to an APO of equal aperture.

In particular, you'll be severely limited by UK seeing conditions, so 100x to 150x might be more realistic for Jupiter in particular.  Do you notice more detail in Jupiter at 240x than at 120x or are they simply bigger and more washed out?

Saturn's rings and Mars can take more power due to being of higher contrast.  On high contrast objects like double stars, you can try to push 300x or more.  If you want to go for 400x, I would recommend a 12" scope minimum and steady seeing conditions.

More expensive eyepieces have better lens polish leading to less scatter, better multicoatings, better stray light control, and wider and better corrected fields of view (especially in scopes faster than f/8 such as your own).  However, on axis, a well executed, cheap eyepiece can still perform very well.  Mainly, contrast and resolution on planets will suffer a bit.

[PaulM]

I started with a 200p as well and didnt regret getting a 2" wide angle EP just for M42 Orion Nebula and Pleidies which will impress as well as M81/82 and open star clusters. As for what I have I find the following covers how I want to observe a range of objects 4/8/15/24 and 32mm EPs and a 2x barlow.

[SmoothOperator]

59 minutes ago, Louis D said:

Generally, about 30x per inch is what I figure for Newtonians, so about 240x max for your 8", which is where you are today.  The secondary obstruction and spider vanes tend to cut down on contrast at higher powers relative to an APO of equal aperture.

In particular, you'll be severely limited by UK seeing conditions, so 100x to 150x might be more realistic for Jupiter in particular.  Do you notice more detail in Jupiter at 240x than at 120x or are they simply bigger and more washed out?

Saturn's rings and Mars can take more power due to being of higher contrast.  On high contrast objects like double stars, you can try to push 300x or more.  If you want to go for 400x, I would recommend a 12" scope minimum and steady seeing conditions.

More expensive eyepieces have better lens polish leading to less scatter, better multicoatings, better stray light control, and wider and better corrected fields of view (especially in scopes faster than f/8 such as your own).  However, on axis, a well executed, cheap eyepiece can still perform very well.  Mainly, contrast and resolution on planets will suffer a bit.

Oh okay my mistake, I’d read it was 50 x the aperture. So when viewing Jupiter I can definitely notice more detail when swapping to 240x just an adjustment of the focused. You’ll have to forgive me as I’m a bit of a novice and I don’t fully understand some of the language you’ve used like corrected field of view, what sort of effect does this have when looking through the eyepiece as opposed to an Uncorrected field of view?

thanks for the info on eyepieces also, much appreciated.

Edited July 22, 2020 by SmoothOperator

[SmoothOperator]

3 hours ago, Louis D said:

Generally, about 30x per inch is what I figure for Newtonians, so about 240x max for your 8", which is where you are today.  The secondary obstruction and spider vanes tend to cut down on contrast at higher powers relative to an APO of equal aperture.

In particular, you'll be severely limited by UK seeing conditions, so 100x to 150x might be more realistic for Jupiter in particular.  Do you notice more detail in Jupiter at 240x than at 120x or are they simply bigger and more washed out?

Saturn's rings and Mars can take more power due to being of higher contrast.  On high contrast objects like double stars, you can try to push 300x or more.  If you want to go for 400x, I would recommend a 12" scope minimum and steady seeing conditions.

More expensive eyepieces have better lens polish leading to less scatter, better multicoatings, better stray light control, and wider and better corrected fields of view (especially in scopes faster than f/8 such as your own).  However, on axis, a well executed, cheap eyepiece can still perform very well.  Mainly, contrast and resolution on planets will suffer a bit.

Also, based on what you’ve said would you suggest that instead of spending the money on the EP set in the URL I’ve copied or would it be better to spend it on a decent 8mm eyepiece which combined with the Barlow lens will give me my 300x mag?

[John]

4 hours ago, SmoothOperator said:

Oh okay my mistake, I’d read it was 50 x the aperture. So when viewing Jupiter I can definitely notice more detail when swapping to 240x just an adjustment of the focused. You’ll have to forgive me as I’m a bit of a novice and I don’t fully understand some of the language you’ve used like corrected field of view, what sort of effect does this have when looking through the eyepiece as opposed to an Uncorrected field of view?

thanks for the info on eyepieces also, much appreciated.

Jupiter does not really respond well to very high magnifications. The detail on it's surface is actually clearer at 130x - 170x than it would be at over 200x. Saturn and Mars are different - the higher magnifications are more useful on those.

It's not the scope so much as the seeing / atmospheric conditions that are the limiting factor. 200x and above needs really steady seeing conditions, a target that will benefit from such magnification and a properly cooled and collimated scope. Those things don't come together all that often !

Jupiter's surface details are subtle which is why lower magnifications do better.

Strongly consider the BST Starguiders as an upgrade path. Proven eyepieces with lots of members here who use scopes like yours !:

https://www.firstlightoptics.com/bst-starguider-eyepieces.html

 

 

 

 

[Barry-W-Fenner]

As an owner of a 200p myself I second @John comments regarding upgrading to the BST eye pieces. The 5,8,12 & 15 perform very well in the 200p with the 8mm being my go to. excellent value for money and a large viewing improvement over the stock eye pieces.

 

Regards

[Daf1983]

As Barry and John have already said, can't go wrong with the bst. I also have the 200p, and have brought the 8 and 12mm bst, and even for a newby like me, the step up of quality from the stock eyepieces is obvious. If you're looking for low power eyepiece, I can also recommend the vixen npl 30mm which is also available at a similar price to the bst.

Cheers

[Louis D]

12 hours ago, SmoothOperator said:

Oh okay my mistake, I’d read it was 50 x the aperture.

50x the aperture in inches for high contrast objects like double stars.  Low contrast objects like Jupiter don't respond as well to high powers.

12 hours ago, SmoothOperator said:

You’ll have to forgive me as I’m a bit of a novice and I don’t fully understand some of the language you’ve used like corrected field of view, what sort of effect does this have when looking through the eyepiece as opposed to an Uncorrected field of view?

Corrected meaning lacking in aberrations such as outer field astigmatism and field curvature.  If you let an object drift through a poorly corrected wide field eyepiece, it will get blurry by about 50% out from center to edge, thus negating any advantage to the wider field for an undriven scope such as yours.

9 hours ago, SmoothOperator said:

Also, based on what you’ve said would you suggest that instead of spending the money on the EP set in the URL I’ve copied or would it be better to spend it on a decent 8mm eyepiece which combined with the Barlow lens will give me my 300x mag?

I would pick up the 5mm, 8mm, and 15mm Starguider BSTs as others have recommended as well as a 32mm Plossl similar to the one in the kit.  Later on as funds allow, I would add the 35mm Aero ED for widest field views.

[Kyle Allen]

Another option are the Nirvana eyepieces. They have a very wide apparent field of view and seem very well corrected. The 16mm and 7mm would be useful magnifications in your 200P Dobsonian, while the 4mm would only really work on the Moon and require very good seeing conditions. 

https://www.firstlightoptics.com/ovl-eyepieces/ovl-nirvana-es-uwa-82-ultrawide-eyepieces.html