Eyepiece upgrade

[Rich12389]

I have a skywatcher heritage 130p with stock eyepieces that I want to upgrade.

Not sure whether to opt for zoom eyepiece or single eyepieces, 8mm,15 and 30ish ,so would like recommendations for both please. 

I have a phone adapter which I would like to use with eyepieces if possible. 

[RT65CB-SWL]

Hi @Rich12389 and welcome to SGL. 

Highly recommended by several SGL'ers are these... https://www.firstlightoptics.com/bst-starguider-eyepieces.html 

If you are on a budget, then you may wish to consider these... https://www.firstlightoptics.com/vixen-eyepieces/vixen-npl-eyepieces.html - not sure how good they are, as I have not seen many reviews, here or other amateur astronomy forums/sites.

Whether they will be or are compatible with your 'phone adapter though, I do not know.

[EntropyTango]

Not sure what your budget is so i won't make any specific suggestions. 

The zooms always seem like a good solution as they cover a wide range of focal lengths

But the field of view is quite narrow at lower magnifications and this is usually where a wide field is needed the most.

I have 2 zooms but find I really don't use them for this reason, optically they are also a bit of a compromise like zoom camera lenses.

My suggestion is that you go for fixed focal length EP's of reasonable quality

There are plenty of choices out there

Perhaps consider joining an astronomy club (covid permitting)

Then you can look through a range of EP's and decide what works for you

Some ppl want eye relief, others field of view, others value and others just the best money can buy

It's a bit like food, some will love something others will hate.

The best solution is to try as many EP's before you spend your hard earned pennies

[Spile]

The zoom option with one wide angle lower power option works for me. I appreciate the additional cost but I worked out it would it would be a long term investment.

 

[Second Time Around]

I bought a similar 130mm f/5 reflector for a friend's daughter for Xmas, and so these suggestions are based on that experience.  

The eyepieces that come with these scopes are very basic starter ones, and can be improved at low cost.

I'd very much recommend a zoom eyepiece as your workhorse.  One zoom eyepiece will cover multiple focal lengths and so is really excellent value for money.  I have both the Svbony 7-21mm zoom at around £45 on eBay plus the Baader 8-24mm at £189. The Baader has a wider field of view and is sharper and more contrasty, but it's not 4x better.  I bought the Svbony zoom for my friend's daughter as that fitted her budget.

Despite having high quality fixed focal length eyepieces, I use my zooms a lot more often.  The zoom plus a Barlow lens and a low power, wide field eyepiece is often all I use the whole evening.  

Fixed focal length eyepieces may be slightly better corrected when compared with a zoom at the same magnification.   But that's not always a fair comparison as that magnification may not be the optimum for a given object.  This is because one of the many advantages of a zoom is to be able to dial in precisely the best focal length.  For instance, this may be 13mm or even 13.1mm, which may actually show more detail than shorter or longer fixed focal length eyepieces - even better quality ones.  

I particularly like the ability to increase the magnification to make use of brief moments of good seeing (a steady atmosphere).  It takes more time to swap out an eyepiece, and the opportunity may then be missed.  You can't see anything if you haven't got an eyepiece in the focusser!

Zooms also enable the field of view to be varied to frame an object to get the prettiest view.  For this reason I particularly like them for clusters.

Many of those who post here and advocate fixed focal lengths are experienced observers.  It's so easy to forget what it was like as a beginner!  A zoom eyepiece enables beginners to easily learn what difference a change of magnification makes on all the various classes of object.  It also shows them what focal lengths would be most useful to their eyes, their telescope, and their observing conditions.  They then have the option of buying/not buying the most appropriate fixed focal length eyepieces for them.  For these reasons I'd always recommend that beginners buy a zoom as their first eyepiece.

 

The downside of a zooms is their smaller field of view (FOV), so you'll still have use for a low power, wide FOV eyepiece to supplement it.   The maximum FOV of your scope is just over 2.5 degrees - it's determined by the 1.25 inch diameter of your focuser and the 650mm focal length.  This will be more than enough to show even all of the Pleiades cluster (M45) and leave space around to frame it nicely.  

There are various spec eyepieces that will get this maximum FOV.  I'd suggest a 32mm Plossl eyepiece, cost £29 from forum sponsors First Light Optics.  Go to https://www.firstlightoptics.com/astro-essentials-eyepieces/astro-essentials-super-plossl-eyepiece.html

I'd supplement the zoom with a Barlow lens.  Just in case you're not aware, a Barlow lens multiplies the magnification of any eyepiece it's used with.  It goes in the focuser before the eyepiece.  The multiplication factor varies but 2x is most common.  Some of these 2x Barlows can also be used at 1.5x, although it's not always mentioned in the blurb, and it's one of these I'd recommend.  These dual 1.5x/2x Barlows allow the black lens cell to be unscrewed from the body of the Barlow and then screwed into the filter thread at the bottom of an eyepiece to give approx 1.5x.   First Light Optics do one in their Astro Essentials range that even has a standard T thread at the top for attaching a camera.  It's just £25.  Go to https://www.firstlightoptics.com/barlows/astro-essentials-125-2x-barlow-with-t-thread.html

The exact amplification varies from eyepiece to eyepiece depending on where the field stop is located.  At 2x amplification with a 7-21mm zoom this will give you magnifications of approx 62-186x.  Most nights in the UK the seeing (atmospheric turbulence) won't be good enough to go as high as 186x and you'd get more use from the approx 46-139x that 1.5x amplification will give you.  Additionally, at a given magnification the field of view will be bigger with 1.5x amplification.  This is because the vast majority of zooms have a wider field of view at the high power end.

So the Svbony 7-21mm zoom, a 32mm Plossl and a 1.5x/2x Barlow lens will cost you about £100, and will be all you need for a long time.