Eyepiece - Which next?

[Naemeth]

Hello everyone, as some of you may know I'm planning on adding an ED80 to my growing astronomy collection, and I thought about adding another eyepiece to my collection, one to possibly cover a gap in my current line-up and be useful in both the Heritage and ED80 (unfortunately, this means eyepieces have to be fairly light - around 160g and 1.25"). Currently, my eyepiece collection gives me (in the Heritage)

26mm = 25x / 5.2mm exit pupil

18mm = 36x / 3.6mm exit pupil

8mm = 81x / 1.6mm exit pupil

7mm = 93x / 1.4mm exit pupil

2.5mm = 260x / 0.5mm exit pupil

In the ED80:

26mm = 23x / 3.5mm exit pupil

18mm = 33x / 2.4mm exit pupil

8mm = 75x / 1.1mm exit pupil

7mm = 86x / 0.9mm exit pupil

2.5mm = 240x / 0.3mm exit pupil

By looking at this line up, it's obvious I have a big gap, the question is which gap is more important to get rid of? High Power or Medium-Low Power? I do find myself, even with my 8mm, wanting to take a small step in magnification back when the seeing conditions aren't quite at there best, but the 2.5mm certainly does perform a very useful function and is excellent when the seeing is there. I think a 9mm might be the right choice for a little less power on the Heritage, but I think it would have a little too much power for that purpose on the ED80.

I'm starting to think 1 eyepiece won't cover the gap(s), I may need 2.

Any suggestions as to focal length(s)?

[rowan46]

I might go a 12mm and a 5mm but it's hard to say as it's such a personal decision 5mm keeps both scopes under their theoretical maximum and within normal british seeing conditions leaving you with 2.5 when seeing is very good and the 12 is around the midpoint between the 8 and 18 giving you aprox 54x and 50 x. That's the logical answer but viewing is such a personal thing it's not just about logic. what do you like to look at most when touring?

[Naemeth]

I might go a 12mm and a 5mm but it's hard to say as it's such a personal decision 5mm keeps both scopes under their theoretical maximum and within normal british seeing conditions leaving you with 2.5 when seeing is very good and the 12 is around the midpoint between the 8 and 18 giving you aprox 54x and 50 x. That's the logical answer but viewing is such a personal thing it's not just about logic. what do you like to look at most when touring?

Planets, the Moon on occasion. I also particularly like clusters and other DSOs. Unfortunately, unless I get out to somewhere less light polluted, galaxies are often a no-go - yes I can sometimes detect they are there, but they serve more as a "found it, seen it, move on" because the lack of visible detail makes it a less interesting object to study.

[Moonshane]

I think a 5mm would suit your purpose well enough and on its own really. with short focal lengths differences between eyepieces are not as massive so with the 5mm you'd have 130x and 120x in the two scopes which is good for a wide range of objects.

the BST 5mm is pretty good.

[Moonshane]

of course the ideal scenario would be a 6-3mm Nagler zoom - quite a bit of saving up for that though......

[stevepeverall]

I'm not an experienced astronomer but I'd go with what Moonshane says; x120-130 is great for doubles and clusters, also planets when seeing isn't too great and is my most useful mag on my 80mm. You could buy a x2 barlow to give you 13 and 4mm capability (assuming your 26mm is 1.25"). If you use a compass to draw concentric circles on a piece of paper which show your TFOV through your EP's the gap from 18mm to 8mm isn't a massive as you might think but I've read the most useful EP in mm is twice the f number of your scope which I guess is 12mm as Rowan says. I'd get the 5mm first though.

[Naemeth]

of course the ideal scenario would be a 6-3mm Nagler zoom - quite a bit of saving up for that though......

I thought that, it's not out of the realms of possibility, but might have to wait until end of August / September (even 2nd hand).

I'm not an experienced astronomer but I'd go with what Moonshane says; x120-130 is great for doubles and clusters, also planets when seeing isn't too great and is my most useful mag on my 80mm. You could buy a x2 barlow to give you 13 and 4mm capability (assuming your 26mm is 1.25"). If you use a compass to draw concentric circles on a piece of paper which show your TFOV through your EP's the gap from 18mm to 8mm isn't a massive as you might think but I've read the most useful EP in mm is twice the f number of your scope which I guess is 12mm as Rowan says. I'd get the 5mm first though.

I've already got a barlow and dislike using them very much . Thanks for the help anyway .

I think the best balance would be a 5mm (probably LV) and perhaps a 11mm TV plossl or 15mm TV plossl. Either that or the 3-6mm Nagler Zoom and both TV plossls

Thanks for the help everyone, really helped me decide .

[Stargazer_00]

Hi Jonathan,

I would go with a 4.7mm ES 82 myself and possibly an 11mm ES 82 as well if you wanted to fill that lower end gap. These UWA's would provide really pleasing ultra wide views and make the most of the short focal lengths that you have. They are affordable and high performance compared to other UWAs and are both lightweight for your circumstances. You really can't go far wrong with these eyepieces, amazing value for money.

[Naemeth]

Hi Jonathan,

I would go with a 4.7mm ES 82 myself and possibly an 11mm ES 82 as well if you wanted to fill that lower end gap. These UWA's would provide really pleasing ultra wide views and make the most of the short focal lengths that you have. They are affordable and high performance compared to other UWAs and are both lightweight for your circumstances. You really can't go far wrong with these eyepieces, amazing value for money.

Graham, perhaps the 4.7mm would be okay at 212g, but perhaps the 283g of the 11mm might be a bit heavy. Perhaps I actually need to try a heavy eyepiece to see how the scope copes with it .

[michael.h.f.wilkinson]

The (N)LV 5 should fit nicely in your line up. Nice eye relief, I found my LV 9 and LV 7 near parfocal, which is handy. At the long end I would seriously consider the MaxVision 24 68 deg as a replacement for the 26mm. My kids 114mm Mini-Dob could handle that with just a slight increase in the counterweight.

A 9mm would be too close to the 8, so a 12-15mm would be nice.

[Naemeth]

The (N)LV 5 should fit nicely in your line up. Nice eye relief, I found my LV 9 and LV 7 near parfocal, which is handy. At the long end I would seriously consider the MaxVision 24 68 deg as a replacement for the 26mm. My kids 114mm Mini-Dob could handle that with just a slight increase in the counterweight.

A 9mm would be too close to the 8, so a 12-15mm would be nice.

I hadn't thought about a counterweight, not really sure how I would go about making one for it. I might go for the Maxvision to replace my current 26mm, I'm just not sure. I guess it would depend how well my focuser will cope with some more weight.

[michael.h.f.wilkinson]

I hadn't thought about a counterweight, not really sure how I would go about making one for it. I might go for the Maxvision to replace my current 26mm, I'm just not sure. I guess it would depend how well my focuser will cope with some more weight.

Don't wait too long, the supply is limited

[Naemeth]

Just done some testing with improvised weights, the plastic that supports the focuser has a tendency to sag noticeably at 500 gms, and sag slightly at about 260g. This would mean collimation would be different for heavy and light eyepieces. I think it's a no-go on that basis!

Perhaps my initial guess of 150g - 160g was about right.

[Moonshane]

just the weight of the Nagler zoom I think

[Naemeth]

just the weight of the Nagler zoom I think

I saw that too

[alan potts]

Naemeth,

Get a 12mm Delos you know you want to..

Alan

[Stargazer_00]

The TV zoom is a cracking eyepiece for sure. I didn't realise the ES's were that heavy, sorry. They feel very light and small in the hand.

Most good quality eyepieces have a number of glass elements in them so will be reasonably heavy. I'd expect SWAs to be in the same sort of areas as UWAs in terms of weight.

that leaves you with BSTs (which I must say I didn't think were much lighter than the ES82s in the hand either) or Plossls.

Maybe look for TV plossls if a TV zoom itself is a bit too much?

[michael.h.f.wilkinson]

Naemeth,

Get a 12mm Delos you know you want to..

Alan

Or XF12 if weight is an issue (and cost too!)

[Stargazer_00]

XFs is a good call actually

[Naemeth]

Naemeth,

Get a 12mm Delos you know you want to..

Alan

I do, unfortunately it's 0.9lbs, or 408g (causing major slop with the focuser), so it's out of the question. That unfortunately rules out the XWs, Type 4/5 Naglers and Ethos too.

The TV zoom is a cracking eyepiece for sure. I didn't realise the ES's were that heavy, sorry. They feel very light and small in the hand.

Most good quality eyepieces have a number of glass elements in them so will be reasonably heavy. I'd expect SWAs to be in the same sort of areas as UWAs in terms of weight.

that leaves you with BSTs (which I must say I didn't think were much lighter than the ES82s in the hand either) or Plossls.

Maybe look for TV plossls if a TV zoom itself is a bit too much?

I was thinking TV plossls, and they cover quite a few of the longer FLs, but at the higher power end it's really either the Nagler Zoom (I'm not averse to spending that much on one eyepiece) or (N)LVs which are always comfortable and very very close in performance to the TV plossls.

Haven't used a BST, not sure how it would compare to a TV plossl to be honest, or how it would fare at F/4 as I'm planning on having a collection that I don't really need to upgrade.

Or XF12 if weight is an issue (and cost too!)

I've heard mixed things about the 12mm XF, but much better things about the 8.5mm XF, would the 12mm (N)LV be equal do you think (not in FOV obviously)?

[michael.h.f.wilkinson]

The (N)LV12 is bound to be as good as the others in that series. As you seem to like them, why not try the 12?

[Naemeth]

The (N)LV12 is bound to be as good as the others in that series. As you seem to like them, why not try the 12?

I do like them, I'm not sure though if I'd miss something if I got one over the other. I can't seem to find any reviews comparing the XF 12mm and the LV 12mm, although one review I just read implied the XF 12mm was better than the Radian in most ways (http://www.cloudynights.com/item.php?item_id=1438).

Hmm... I may as well wait and see if one of either turns up 2nd hand, and whichever is first I will get.

I think the perfect complement to the 12mm, whichever I get, will be the Nagler Zoom (3-6mm), I'll just have to save up a little longer for it .

Thanks everyone .

[Dunkster]

Not that there haven't been some fine suggestions so far, but it looks to me that by limiting yourself to options where the heritage focuser doesn't buckle under the strain is doing your observing eye a disservice... time to upgrade to something a little more robust perhaps

Just a thought...

[Naemeth]

Not that there haven't been some fine suggestions so far, but it looks to me that by limiting yourself to options where the heritage focuser doesn't buckle under the strain is doing your observing eye a disservice... time to upgrade to something a little more robust perhaps

Just a thought...

I'm already getting an ED80 .

[Moonshane]

As far as I am concerned, if you can use the 8mm plossl (in terms of eye relief) then the best option for what you want is the nagler zoom. I think everyone should have one (if your focal length is under or between 1.5 - 2m) it's that good.