Planning your ideal eyepiece collection

[Timebandit]

 

 

The Dob Mob boys argue for DSO you only need 2 to 3 eyepieces, and possibility a power mate. Personally IMO I do not think they are far wrong with their thinking on this.

With planetary you do need IMO more eyepiece's, depending on planetary target and seeing conditions. As such 1mm intervals at the shorter focal lengths are a good idea. Personally as you already have a 5, 6mm BGO which you are happy with. I do not consider getting a nag zoom best for your money, better going for a dedicated 4mm similar to BGO.

From my own personal use on DSO. The two main eyepiece's that stay in the scope is the 20mm nagler and the Pentax 10XW. These sometimes are the only eyepiece's I take on a grab and go dark site trip. As they spend so much time in the scope. I think you are better off for DSO going for a few quality eyepiece's rather than quantity from my experience.

 

 

 

 

[Moonshane]

Here's my logic from a while back:

I since got into binoviewers and changed around quite dramatically:

 I think what you end up with depends on so many factors that it's not possible to remain with the same thing for long periods unless you have one scope and tend to stick with a smaller range of targets as well as maintaining your income / free spends position. That's my view anyway. 

 

 

[Littleguy80]

9 minutes ago, Piero said:

 

 

Hi Neil, as said by other members the 20 HDC is very good both optically and ergonomically. Also, the eyecup is an improvement against TV eyepieces in my opinion. I had the 30 ES which was sold because the 20 HDC was used more, is optically better (the 30 ES is a good eyepiece don't get me wrong), and is considerably lighter. This was with an F6 dobson. With a F4.7 dobson I would go straight with the 20 HDC, as Mark suggested. 

Again, as Mark suggested, I'd also advise to get the 20 HDC first. With a F4.7 dobson, I would get a 9 HDC afterwards (assuming that you like 100 deg views) rather than the 13mm, simply because the latter will give you almost 2mm exit pupil. With these eyepieces, I would forget a 2" barlow / powermate.  

Anyway, the 20 HDC is really a great eyepiece. It's also a pleasure to use in my refractor, showing nearly the whole Orion's belt in the FOV. The background sky in both my dob and refractor is neutrally dark (like TV eps), not grey as some eyepiece I have tried. The edge is also clean, allowing you to see the telescope coma (a bit noticeable at the edge in <=F6 scopes, but not disturbing). I am not obsessed with 100 deg views, but this is a very fine eyepiece. If I didn't have the Docter and the Zeiss zoom to play with, I would probably get some other focal length.. 

Thank you, Piero! The 20mm HDC certainly looks to be the clear favourite as first purchase. I've found that my 8mm BST is getting a lot of use as it gives fairly higher magnification but with a wider TFOV compared to the BGOs. This is why I was leaning towards the 9mm as an early purchase. I've not had a lot of sessions with the dob so I'll give it some time to decided whether the 13mm or the 9mm is a sensible follow up to the 20mm

[jetstream]

2 hours ago, Littleguy80 said:

Thanks Gerry. Even at secondhand prices, the Ethos is a fair bit more expensive than the Lunt. I don't get the impression that the difference is in performance is as great as the difference in price. Would you say that was fair?

I would say there is no difference in performance - actually I like the Lunt better on most objects. I use the 12.5mm Docter in my scopes, 10" f4.8 dob included and find it more flexible on many objects than my former 10mm Ethos, which was an excellent EP. For galaxies alone the 9mm Lunt might be a bit better than the 13mm supporting what Piero mentioned. In my comparison of the 12.5mm Docter to the 10E there were minimal differences on most galaxies and if searching out very faint galaxy core the 10mm BCO/9mm Circle T/7mm KK orthos go in which have better performance on extremely faint objects than the widefields. Just my opinion here...

[Littleguy80]

9 minutes ago, Moonshane said:

Here's my logic from a while back:

I since got into binoviewers and changed around quite dramatically:

 I think what you end up with depends on so many factors that it's not possible to remain with the same thing for long periods unless you have one scope and tend to stick with a smaller range of targets as well as maintaining your income / free spends position. That's my view anyway. 

 

 

I like the grouping system! Good way to organise your thinking on what you need. I'm still in the I'll just have one scope phase. I wonder how long until I have a collection like yours  

[Piero]

17 minutes ago, Littleguy80 said:

Thank you, Piero! The 20mm HDC certainly looks to be the clear favourite as first purchase. I've found that my 8mm BST is getting a lot of use as it gives fairly higher magnification but with a wider TFOV compared to the BGOs. This is why I was leaning towards the 9mm as an early purchase. I've not had a lot of sessions with the dob so I'll give it some time to decided whether the 13mm or the 9mm is a sensible follow up to the 20mm

Yes, sure, take your time. Most people like 100 deg eps, but not everyone. 

Regarding the comparison against the BST, I believe the Lunt is better. My 20 Lunt is certainly on par with the last offers by TV regarding contrast on axis, and I have nothing to complain with its off axis performance. The eyecup is a dream. I wish many other eyepieces had an eyecup like that. 

I placed a magnetic bar on the bottom side of the tube. No balancing issue.

Compared to the other 20mm 100 deg, the 20 Lunt is a feather, which is also a great advantage.

 

 

 

I will take a pic of the Lunt with the refractor at some point ...  

[Littleguy80]

2 minutes ago, jetstream said:

I would say there is no difference in performance - actually I like the Lunt better on most objects. I use the 12.5mm Docter in my scopes, 10" f4.8 dob included and find it more flexible on many objects than my former 10mm Ethos, which was an excellent EP. For galaxies alone the 9mm Lunt might be a bit better than the 13mm supporting what Piero mentioned. In my comparison of the 12.5mm Docter to the 10E there were minimal differences on most galaxies and if searching out very faint galaxy core the 10mm BCO/7mm KK orthos go in which both have better performance on extremely faint objects than the widefields. Just my opinion here...

The Lunt's seem like incredibly good value for money with that in mind. I just missed out on a 9mm BGO last week  I've read a few times that orthos are favoured for the extremely faint objects

[Littleguy80]

20 minutes ago, Piero said:

Yes, sure, take your time. Most people like 100 deg eps, but not everyone. 

Regarding the comparison against the BST, I believe the Lunt is better. My 20 Lunt is certainly on par with the last offers by TV regarding contrast on axis, and I have nothing to complain with its off axis performance. The eyecup is a dream. I wish many other eyepieces had an eyecup like that. 

I placed a magnetic bar on the bottom side of the tube. No balancing issue.

Compared to the other 20mm 100 deg, the 20 Lunt is a feather, which is also a great advantage.

 

 

 

I will take a pic of the Lunt with the refractor at some point ...  

I’m sure the Lunt will be a major upgrade on the BST. It was more a consideration of which focal length to buy after the 20mm. I’m use the 8mm a fair bit so the 9mm seems like a natural choice to buy after the 20mm. Thank you for the picture. Looks good in the dob  

[Piero]

2 hours ago, Littleguy80 said:

The Lunt's seem like incredibly good value for money with that in mind. I just missed out on a 9mm BGO last week  I've read a few times that orthos are favoured for the extremely faint objects

Those targets require dark skies. These are more important than any eyepiece as far as faint light catching concerns. Personally, I'd start with something that I use most of the time, and with time it will appear clear if more dedicated eyepieces are needed. 

Gerry lives in one of the darkest place on the planet, is very experienced on a multitude of targets, and observes with top-notch equipment. 

 

[Littleguy80]

8 minutes ago, Piero said:

Those targets requires dark skies. These are more important than any eyepiece as far as faint light catching concerns. Personally, I'd start with something that I use most of the time, and with time it will appear clear if something more dedicated is needed. 

Gerry lives in one of the darkest place on the planet, is very experienced on a large multitude of targets, and observes with top-notch equipment. 

 

Fair point, Piero. I suspect the observer is the limiting factor in my case  Still one day I hope to have honed my skills sufficiently to try for some of those targets under truly dark skies  

[25585]

Might be better buying a good Barlow for higher powers, but otherwise staying with lower to mid-range for ep choice. 

Do you want exact magnifications? 

Generally I would say 30, 20, 10 & a Barlow 2x for your dob. So you would have 30, 20, 15 & 5 effectively. 

Also to consider, will you be using a coma corrector? Wider field eps need them more to give good whole field stars. With up to (say) 65 deg AFOV, correctors may not be so needed. A factor to consider when researching reviews etc. 

[jetstream]

1 hour ago, Littleguy80 said:

The Lunt's seem like incredibly good value for money with that in mind. I just missed out on a 9mm BGO last week  I've read a few times that orthos are favoured for the extremely faint objects

I agree with Piero- get the EP that will get the most use. I'll give you an example of the widefield vs ortho on faint (for me) galaxies. In UMa there is a nice little group of galaxies, a few easy and one tough one. These are NGC 3972,NGC 3982,NGC 3990, NGC 3998 and the hard NGC 3977. The 12.5 Docter shows the first 4 easily, with the last one popping in and out of averted vision. The 10mm BCO will hold NGC 3977 in direct vision mostly.

Now some might jump up and down citing the magnification difference between the 12.5mm and the 10mm- well my 12.5mm Tak ortho doesn't see it and the 12.5mm Tak LE is not even in the running.  The cheap as chips 9mm Circle T holds it well, at least as good as the 10mm BCO, here the mag might be at play.

I don't enjoy staring for hours straining my eye for these little faint glows popping in and out but observe these in short bursts. The majority of my observing is with eyepieces I enjoy and on objects that are pleasing, brighter ones really.  You might want to base your eyepieces on the latter type of objects, but that depends on what you like and what your goals are.

 

ps- I bought many used orthos and sorted through them finding the best ones...

[Littleguy80]

18 hours ago, Floater said:

... No, but I’m going to fetch the metaphorical popcorn, sit back and watch this thread run.

I mean, ‘fantasy’, ‘eyepiece’ and ‘thoughts’ all in the same sentence? ?

At this point I feel I should stop and ask if you’re enjoying your popcorn, Gordon?!?  

[Littleguy80]

7 minutes ago, jetstream said:

I agree with Piero- get the EP that will get the most use. I'll give you an example of the widefield vs ortho on faint (for me) galaxies. In UMa there is a nice little group of galaxies, a few easy and one tough one. These are NGC 3972,NGC 3982,NGC 3990, NGC 3998 and the hard NGC 3977. The 12.5 Docter shows the first 4 easily, with the last one popping in and out of averted vision. The 10mm BCO will hold NGC 3977 in direct vision mostly.

Now some might jump up and down citing the magnification difference between the 12.5mm and the 10mm- well my 12.5mm Tak ortho doesn't see it and the 12.5mm Tak LE is not even in the running.  The cheap as chips 9mm Circle T holds it well, at least as good as the 10mm BCO, here the mag might be at play.

I don't enjoy staring for hours straining my eye for these little faint glows popping in and out but observe these in short bursts. The majority of my observing is with eyepieces I enjoy and on objects that are pleasing, brighter ones really.  You might want to base your eyepieces on the latter type of objects, but that depends on what you like and what your goals are.

 

ps- I bought many used orthos and sorted through them finding the best ones...

Good example/explanation, Gerry. I really like my BGOs so I do tend to keep an eye out for them on the for sale boards as a result. They’re such good value for money. I’d really like to try one of the longer focal lengths even if it’s not an eyepiece that gets used every session.

[Littleguy80]

1 hour ago, 25585 said:

Might be better buying a good Barlow for higher powers, but otherwise staying with lower to mid-range for ep choice. 

Do you want exact magnifications? 

Generally I would say 30, 20, 10 & a Barlow 2x for your dob. So you would have 30, 20, 15 & 5 effectively. 

Also to consider, will you be using a coma corrector? Wider field eps need them more to give good whole field stars. With up to (say) 65 deg AFOV, correctors may not be so needed. A factor to consider when researching reviews etc. 

Interesting. Hadn’t thought about a coma corrector. Not something I have any experience of

[25585]

53 minutes ago, Littleguy80 said:

Interesting. Hadn’t thought about a coma corrector. Not something I have any experience of

What if the focal ratio or focal length of your dob?

[Stu]

3 minutes ago, 25585 said:

What if the focal ratio or focal length of your dob?

Pretty sure it’s the f4.7. With 100 degree afov eyepieces then a coma corrector may well be needed to tighten up the edges.

Not sure if they all do, but the Paracorr adds a mild barlow (x1.15 I think) to ensure focus can still be reached. That will obviously change the mag/Exit Pupil calculations a little.

[25585]

If I was just starting in visual astronomy, I would be overwhelmed for eye pieces. 

My first scope would be an 8 inch F6 I am sure. Something capable but not too gargantuan. And good value for money. 

So possibly a Baader Morpheus or Vixen SLV. And a Barlow from one or the other. A parfocal range is not to be sneezed at. (Isn't Morpheus the ancient Greek god of sleep?)

[Floater]

1 hour ago, Littleguy80 said:

At this point I feel I should stop and ask if you’re enjoying your popcorn, Gordon?!?  

Yes, Neil, I am. ?

Always love to see the different input and how it helps to focus (couldn’t resist) the mind. Although, sometimes the choice and the suggestions are so diverse they can have a frying effect! ?? 

As before, with those powerful keywords in your first post I knew this one had legs ...

[25585]

3 minutes ago, Stu said:

Pretty sure it’s the f4.7. With 100 degree afov eyepieces then a coma corrector may well be needed to tighten up the edges.

Not sure if they all do, but the Paracorr adds a mild barlow (x1.15 I think) to ensure focus can still be reached. That will obviously change the mag/Exit Pupil calculations a little.

My F5 benefits from a Paracorr with the Panoptics, they are only 68 deg FOV. Vixen LVW at 65 deg are not quite so in need, until the 30 & 42mm. Probably a general need for all 2 inch fit eps. 

Plossls (apart from TV 55mm which would have too large an exit pupil) don't need a CC. 

I have no experience of ES FOV ranges, except the 34 & 40 Maxvision eps, which do both need coma correction. 

To @Littleguy80 start with 31.7mm first. The 2 inch ep world is great but probably not step #1 for a collection from scratch. YMMV of course

[Stu]

2 minutes ago, 25585 said:

My F5 benefits from a Paracorr with the Panoptics, they are only 68 deg FOV. Vixen LVW at 65 deg are not quite so in need, until the 30 & 42mm. Probably a general need for all 2 inch fit eps. 

Plossls (apart from TV 55mm which would have too large an exit pupil) don't need a CC. 

I have no experience of ES FOV ranges, except the 34 & 40 Maxvision eps, which do both need coma correction. 

To @Littleguy80 start with 31.7mm first. The 2 inch ep world is great but probably not step #1 for a collection from scratch. YMMV of course

If Neil wants to maximise fov the 2” is the way to go so it depends upon priorities. The 20mm Lunt is a nice option, and for nebulae etc coma is far less of an issue so a CC could follow if needed.

[25585]

20mm 2 inch eps are a class by themselves as not too heavy (but fairly) yet perform well. The Celestron Ultima LX 22mm & Orion Lanthanum 20mm (still to be star tested) do not have the counter balance need of longer FL 2 inchers. 

Lunt seems similar to the ES 20mm 100 deg. APM & WO also. 

[scarp15]

Great topic Neil, debating contemporary options, particularly as Ethos have become prohibitively expensive at retail in UK sterling terms . Clearly decisively, as advocated, the Lunt 20mm as a priority eyepiece and good optimum, at low power 4.25mm exit pupil.  

[25585]

1 minute ago, scarp15 said:

Great topic Neil, debating contemporary options, particularly as Ethos have become prohibitively expensive at retail in UK sterling terms . Clearly decisively, as advocated, the Lunt 20mm as a priority eyepiece and good optimum, at low power 4.25mm exit pupil.  

Horrible thought. What if EU increases tariffs on TV eps as imports from the US

[Piero]

11 minutes ago, 25585 said:

My F5 benefits from a Paracorr with the Panoptics, they are only 68 deg FOV. Vixen LVW at 65 deg are not quite so in need, until the 30 & 42mm. Probably a general need for all 2 inch fit eps. 

Plossls (apart from TV 55mm which would have too large an exit pupil) don't need a CC. 

I have no experience of ES FOV ranges, except the 34 & 40 Maxvision eps, which do both need coma correction. 

To @Littleguy80 start with 31.7mm first. The 2 inch ep world is great but probably not step #1 for a collection from scratch. YMMV of course

 

From your post, it seems that you are suggesting that coma depends on the AFOV and the barrel type, hence the field stop.

If so, the latter is incorrect. Take two 100 deg eyepieces with focal lengths of 20mm and 10mm. The FOV diameter in the 10mm is half the FOV diameter in the 20mm. Therefore, one would be tempted to say that it "shows" half coma. However, the magnification is double (and double is the coma aberration), therefore the amount of visible coma is exactly the same between the two eyepieces.