recommend some eyepieces

[sejanus (Gavin)]

So the 16" LB is now pretty much working. I still need to collimate it properly but that problem is for another thread.

I'm a real eyepiece dummy and apart from reading the odd review on the 13mm Ethos which sounds great I am really quite clueless with what to buy.

My current eyepieces are ;

Televue 1.25" 32mm
Televue 1.25" 20mm
Televue 1.25" 11mm
Hyperion 1.25" 8mm - it says modular so I think this may fit into a 2" but am unsure and am not at home as I write this
Celestron junk 1.25" 40mm - I use it to locate alignment stars before switching to a higher power eyepiece
Meade 26mm 2" - came with the lightbridge, havent used yet.

So basically, what eyepieces would you recommend if you had a 16" 1800 odd mm scope and the above eyepieces already?

Out of the above, the only one I found that is really crisp is the 32mm. All the televues i bought from bintel a year ago and were all fairly cheap.

I don't mind spending a bit of cash to get really good ones - as long as they last. i.e. better to buy good to start with.

I'm a big fan of the planets so would like at least one real high power eyepiece for the planets, but other than that it's dso's. I have not looked through an Ethos but from what I read I do like the idea of having decent mag power whilst having a wide field.

btw I have nfi regarding barlows either

thanks heaps for any help

[Geoff45 (Geoff)]

Originally Posted by sejanus

So the 16" LB is now pretty much working. I still need to collimate it properly but that problem is for another thread.

I'm a real eyepiece dummy and apart from reading the odd review on the 13mm Ethos which sounds great I am really quite clueless with what to buy.

My current eyepieces are ;

Televue 1.25" 32mm
Televue 1.25" 20mm
Televue 1.25" 11mm
Hyperion 1.25" 8mm - it says modular so I think this may fit into a 2" but am unsure and am not at home as I write this
Celestron junk 1.25" 40mm - I use it to locate alignment stars before switching to a higher power eyepiece
Meade 26mm 2" - came with the lightbridge, havent used yet.

So basically, what eyepieces would you recommend if you had a 16" 1800 odd mm scope and the above eyepieces already?

Out of the above, the only one I found that is really crisp is the 32mm. All the televues i bought from bintel a year ago and were all fairly cheap.

I would go for a 6mm Televue Radian to give you 300 power, which would be high enough for all but the most excellent seeing conditions. You could use a 2x Barlow to get 600 power.

Your comment about things not being crisp could be due to:
1. Faulty eyepiece---highly unlikely with Televue
2. Faulty mirror--possible, but unlikely
3. Poor collimation--This is the most likely. With an f4.5 scope you are never going to get crisp images unless your collimation is spot on, or you are using a low power

[sejanus (Gavin)]

yeah the collimation is a point, with the 6mm though - wouldn't 300x be a tad higher than you could normally use in typical conditions?

previously I have restricted myself to 240'ish.

cheers

Gav

[Geoff45 (Geoff)]

In good conditions, 300x shouldn't be a problem. You have the Hyperion for 225x. If you are into planets, you need to have some power in reserve for when the seeing justifies it.
Geoff

[sejanus (Gavin)]

thanks for the info geoff

just for curiosity sake - assuming i don't have the 8mm.

If you had the 6mm radian, and the 7mm nagler - apart from the 1mm - is the only difference between them the wider FOV of the nagler? i.e. in terms of optical quality is there a difference?

hope that makes sense!

[Geoff45 (Geoff)]

I'm not sure. You would probably have to go to the Televue website to check this out.
Geoff

[OneOfOne (Trevor)]

There wouldn't be a huge difference in image size, but the wider field will keep the object in view for longer, especially with a fairly high magnification. The central area would have much the same "sharpness" in either, although I would expect the Nagler may be a bit sharper (?) but nothing mind blowing

[casstony]

The Naglers and Ethos are obviously desirable in your scope for their wide apparent field of view, but only some of them have long eye relief. How do you feel about the eye relief/comfort of your current eyepieces? If you like long eye relief your choices might lean towards the type 4 Naglers and Pentax XW's. If you find shorter eye relief ok (10 to 12mm) there are a lot more Nagler eyepieces to choose from.

[sejanus (Gavin)]

thanks for the reply.

I'm definitely going to get the ethos and will order one for bintels next lot.

I think the ethos 13mm with it's very wide FOV should remove the need to get anything in the 10-17mm range at least for now.

The 6mm radian vs the 7mm nagler t6 is a bit more interesting though.

I don't wear glasses and am not real fussed about eye relief.

Regarding this don @ bintel wrote this ;

Looking at the numbers I came to the following conclusion.

For lunar and Planetary observing a large field of view is not always necessary. In fact a larger FOV will give a smaller scale to the planets.

The Focal length of the 16" Lightbridge is 1829mm f/4.5

Using a 6mm Radian it would give you 304.8x and yield a 11.8' FOV. Jupiter fits 16x and Saturn fits 29x. A good scale size.
Using a 7mm Nagler it would give you 261.2x and yield a 18.83' FOV. Jupiter fits 26.9x and Saturn fits 45.8x. A smaller scale.

With this in mind I would be leaning more towards the 6mm Radian. With the 20mm of eye relief this is comfort all the way for planetary viewing.

So with that in mind the 6mm sounds the go however I a just a little concerned that the radian at 300x will be pushing it a bit (conditions wise) and also at 300x with a narrower FOV stuff will fly out of the eyepiece very quickly and will need constant 'tapping'

[casstony]

If you're getting the Ethos anyway, you might investigate how it performs in a high quality barlow. This way you'd have your 6.5mm eyepiece with a 100 degree FOV.

[sejanus (Gavin)]

well anyway, i ended up with both the 6mm and the 7mm and will be returning one of them as credit to the 13mm.

So first clear night I'll try both and keep the one I like more.

I have them in front of me - hefty little buggers!

[StarLane]

Now don't discount eye relief. Over long viewing sessions you will wish you had 20mm or so or ER, eg, Radians, Pentax XW's, Vixen LVW's etc. Eye strain is a problem after a while.

To me, ER is more important than FOV, IMO of course, and I don't wear glasses.

[davidpretorius]

I love the 6mm radian. I have looked at Jupiter in nice seeing through paul haese' 18"SDM and during star test with his 6mm............ it is a lovely eyepiece!!!

[rumples riot]

Yep the Radian is a star performer on a Newt. Best view of Jupiter ever was with that EP and the SDM at Wartook planetary camp this year. Very nice EP.

I can also recommend for your newt the 17mm Nagler and the 9mm Nagler. Both are excellent EP.

[ausastronomer (John Bambury)]

I currently have a 7mm Nagler T6 and a 7mm Pentax XW that I have compared extensively over the past 2 months on a large number of targets. I have also used the 5mm,6mm and 8mm Radians extensively. In focal lengths less than 10mm the Pentax XW's are slightly better performers than Nagler T6's or Radians IMO, from the widefield/ultrawidefield designs. The Pentax has fractionally better contrast, sharpness and light throughput. Importantly to me, it has a much cooler more neutral colour tone. ie. whites look white not coffee coloured.

That having been said, there isn't much between any of them. The Nagler has a larger TFOV and its coffee coloured tones help to accentuate some surface detail on Jupiter. The Pentax is more comfortable to use than the Nagler. While the Radian is clearly 3rd pick behind two exceptional eyepieces, it is an outstanding eyepiece in its own right and at the current selling price represents exceptional value for money. Like the Nagler, it has an inherent "coffee" tint and works well on Jupiter. You would certainly be very happy to own any of the three eyepieces. Over 50% of people would never pick a difference between any of them. I can also add that the 13mm Ethos is the first Televue eyepiece I have used that exhibits cool neutral colour tones. It does not have the warm coffee coloured tint inherent in the glass types/coatings used in the Plossls, Naglers and Radians. I may also add that the colour tone of an eyepiece is a personal thing and many people prefer the warmer tones of televue eyepieces. I don't.

As specialist planetary eyepieces Zeiss Orthos, Pentax SMC orthos, Nikon orthos and Brandons are all superior to the premium widefields. Unfortunately, the eye relief is short and the AFOV narrow.

As a mid focal length widefield I would also recommend the 17mm Nagler T4. It is an outstanding eyepiece.

Cheers

[sejanus (Gavin)]

thanks for that

Do you think the 17mm would be worth having, given the very wide FOV of the 13mm ethos?

[ausastronomer (John Bambury)]

Originally Posted by rumples riot

Yep the Radian is a star performer on a Newt. Best view of Jupiter ever was with that EP and the SDM at Wartook planetary camp this year. Very nice EP.

The outstanding view you got was the result of many factors all coming together at the same time.

1) A properly cooled telescope.
2) A properly collimated telescope.
3) A high quality large aperture mirror.
4) A target with good elevation hence the need to look through less turbulent air.
5) Excellent seeing conditions.

You would have got the same view with any one of 10 or more different eyepieces. The 6mm Radian is only one of many good ones and in fact inferior to many as a planetary eyepiece.

Cheers,
John B

[ausastronomer (John Bambury)]

Originally Posted by sejanus

thanks for that

Do you think the 17mm would be worth having, given the very wide FOV of the 13mm ethos?

If you can afford the Ethos that's what I would be buying. It has a marginally greater TFOV in your scope at 1.38 deg compared to 1.3 deg for the 17mm Nagler, yet at much greater magnification. 140X as opposed to 105X. This will give a darker sky background, improved contrast and greater detail due to the higher magnification, while still framing the target similarly. The only downside with the Ethos is that it has slightly less eye relief than the 17mm Nagler and is almost impossible to use with glasses on.

For people that don't wear glasses, the eye relief of the Ethos is perfect.

Cheers
John B

[casstony]

Since you're buying expensive wide field eyepieces you might also consider a paracorr. If you intend to purchase a paracorr this has an impact on which low/medium power eyepieces you select since it changes the effective focal ratio of the scope to 5.2(focal length 2100mm), thereby changing the magnification and exit pupil produced by each eyepiece. With a finder eyepiece for example, 30mm would be fine in the f/4.5 scope if it is used with the paracorr.

[ausastronomer (John Bambury)]

Tony raises a very good point. I was thinking that scope was F5 but I now realise it is F4.5. I have an 18"/F4.5 a 17mm Nagler, a 13mm Ethos and a TV Paracorr.

In my scope I feel a greater need to use the Paracorr with the 17mm Nagler than I do with the 13mm Ethos. In fact the 17mm Nagler really needs the Paracorr to deliver its best views in an F4.5 scope. The Ethos while improved slightly by a Paracorr in the F4.5 scope, still does very well without the Paracorr and the view without the Paracorr is still very good. You may want to try the Ethos and with any luck you won't need a Paracorr with it. If you go with the 17mm Nagler, in all likelihood you will also be buying a Paracorr.

Cheers,
John B