Eyepiece decisions

[Stu]

Hi

For some time I've been mulling over whether to change my eyepieces at the longer focal lengths but keep struggling to decide what to do.

Much of my observing is with a 106mm triplet, 690mm f/l and I do love the widefield views available with it. I also have an old SX250 in rehab at the moment so should consider this too. The mak is not really relevant for these discussions. I also use a WO SD 66mm which may get swapped at some point for an 80mm apo of some sort as my grab and go.

I currently have....

13mm Ethos

17t4 Nagler

22t4 Nagler

31t5 Nagler

41mm Panoptic

I have pretty much decided to sell the 41mm Panoptic, and am also probably/definitely going to keep the 31t5 as my widest field ep, it gives a lovely 3.6 degree field in the apo.

My thoughts had been around selling the 17 and 22mm naglers (eeeek) as well as the Panoptic and getting either a 17 or 21mm ethos. I know the 21mm ethos is a lovely ep, but I am thinking that the 31t5 has that end covered so a 17mm ethos would cover both the naglers, whilst giving some benefits in terms of contrast over the 22t4. If I got the 21 ethos, would the 31t5 be redundant?

Any thoughts and experiences would be appreciated.

Cheers,

Stu

[swamp thing]

I would lose the 41mm pan, get an 8mm ethos...job done.

[alan potts]

I would get the Panoptic 41mm out of the way, I believe these only come into their own on my type of scope with it's 3048mm F/L.

If you went for the 21mm Ethos and I just have, though I will not see until I come to England, whether you still keep the 31mm is to me down to the person. Myself I would keep it but if you don't want it PM me, I do.

The 17mm Ethos I can't speak too highly of, it's excellent, If you were to get 21mm Ethos I would keep the 17mm Nagler, likewise if you got the 17mm Ethos's then I would keep the 22mm. I think the later would be my choice.

Having said this I still think Steve has a very strong point in his short statement and one would pay for the other, so it would be cost free.

Alan.

[Moonshane]

hi Stu

I really can't comment as such on your suggestions but I think this sort of thought process (in me at least) is a result of not doing enough observing - due to recent weather in the UK. I think you could safely sell the 41mm Pan and then you have money sitting in the Bank ready for you to make your decision; personally, I'd leave this until after a decent period of observing - swapping out now might be like going shopping when you are starving hungry - not a good idea in my experience!

One option alongside Steve's comment is to buy an 8mm Radian if you can find a used one. This would not give the field of the Ethos of course but would confirm that 8mm is a useful magnification and whether it's one you will use a lot. If not then you can sell at no loss and think again. If you've done nothing by October, you could try mine at PSP.

I'd be interested to hear your comments on the comparison between 13mm Ethos and 17mm Nagler which have the same field approx of course. I really like the field and eye relief of the 26mm Nagler I have and feel the T4s might be a similar experience and one I prefer to the Ethos (I like to see the field stop).

I have been mulling myself for ages to decide if a 17mm T4 would be a better option for me than a 13mm E. You have both and I'd be interested if you think I'd benefit from both or if the 17mm T4 could replace the Ethos? Again, perhaps I could loan your 17mm T4 for an hour if you still have it in October?

It's never an easy choice but at least your choice is 'excellent quality' or 'excellent quality'?

[Stargazer_00]

I dont want to derail this at all, but having recently gotten into 82 degree eyepieces I find that the full 82 degree view is never visible all at the same time, i can't see the entire field stop all around - although the view is still circular.

I assume therefore that 100 degree eyepieces are the same and that the maximum field of view you can see (physically) is around 70-75 degrees but they have better viewing angles and you simply move your head to track objects edge to edge.

Is that a correct deduction? Once I have had my 82s for a while I'll no doubt want to get the odd 100 degree in my favorite magnficiations.

Do any eyepieces give the effect where your entire view is simply stars? As if you are looking at the sky. You can't see anything at all in all your periphial vision, no eyecup, no circular shape to the view, no anything but expanse of sky and stars.

[Stu]

Thanks all for the comments. I'll try to reply logically and in some form of order as there are lots of points made.

Regarding the 8mm ethos suggestion, I am not disagreeing with this, but at the moment am just trying to focus on sorting out from my 13mm Ethos upwards and then will deal with the shorter focal lengths. In trying to keep things simple, I didn't mention other eps I have. These include a 3-6 nag zoom and 7mm/9mm/18mm BGOs. In this area, I think when funds allow I will look at some Delos EPs as I personally feel the eye relief/afov combination seems more suitable at higher powers but have yet to try one.

The 41mm was used in my mak, infrequently, but this will definitely go. I think it is a lovely ep for someone with dark skies but that's not me on a regular basis unfortunately. The 31 gives nearly the same fov so this is sorted.

Shane, you are totally right of course. I haven't had the chance to spend a few hours switching between say the 13e and the 17t4 to see which I prefer. I suppose the gist of my question is around that mentioned in the last post. Does a shorter focal length ep with 100 degree afov, match or better a longer one with narrower 82 degree afov but giving a similar fov? Eg 17e vs 22t4 etc. I am fine with the eye relief of the ethos as I don't wear glasses when observing. I had assumed that smaller exit pupil would give darker sky background and better perceived contrast, plus the naturally slightly better performance of the ethos. Is this correct in people's experience? Surely a 17e would make a 22t4 redundant? Or not?

Shane, along these lines, why are you considering going the opposite way? Is it because you can't see the entire fieldstop at one time on an ethos so prefer more eye relief and narrower afov?

I think for the moment I will hang fire until I've got some observing in (what's observing?) and do some comparisons to see what I prefer.

Please do add any further thoughts on this though, all opinions welcome.

Cheers,

Stu

[Stu]

I forgot to add, of course you are welcome to try the 17t4 at PSP Shane

Stu

[Moonshane]

Hi mate

Don't get me wrong, I think that the 13mmE is a quite superb eyepiece. It's sharp and full of contrast. I see the 'point' of the 100 degree field as giving the no field stop view and it does this amazingly well although you can see the stop if you look around the corner.

My doubt is raised by the 26mm Nagler I think. The field just feels 'right' to me and I put this down to seeing the field stop. The 17mm Nagler will offer the same field as the 13mmE and slightly larger exit pupil (3.8mm vs 2.9mm in the 13mmE) but I have concluded that the 17mm will 'feel' better based on the 26mm Nagler. This is all a bit tenuous as I have never even looked through a T4 eyepiece of any kind so I may change my opinion then.

I'd compare the above to the comparison between a 11mm TV Plossl and a 9mm BGO. The 11mm TVP is fab and I am delighted to have rebought it but the eye relief whilst technically more than the 9mm BGO makes it 'more difficult' to use than the BGO. I find the 9mm BGO more comfortable to use given the smaller field and the fact that the field stop is more easily seen. Maybe I'm weird but my eyes suggest to me what I like

I'll certainly not be selling the 13mm Ethos until I have managed to do a side by side (thanks for the offer) and I'd be intending to also get a 12mm T4 as well if I did sell it and move to T4s for this range. One thing's for sure, the 26mm Nagler is always going to be in my case.

[Moonshane]

BTW, none of this will be short term (unless I sell the Ethos) and I'll be doing some serious saving in the meantime!

[Naemeth]

One thing is sure:

Any of those eyepieces you sell won't be around on the 2nd hand market long.

It's certainly a difficult choice - one I wouldn't want to make, they are all probably fantastic eyepieces. I suppose the only thing to do is directly compare a 17mm T4 Nagler and 17mm Ethos side by side, and see which one you prefer. Not many people have the cash for both, so a star party / local observatory is probably the best answer.

That probably didn't help much, but I hope it gives you something to think about .

[Stu]

Thanks Naemeth :-)

I know the T4's would not hang around and I am loath to sell them. I might be able to stretch to a 17e at the same time and see where I go from there after doing side by side comparisons.

Whilst something in me really 'wants' a 21e, I can't see it being more useful/ better than the 31 Nagler , particularly if I've got a 17e too.

Will have a think.

Stu

[alan potts]

Stu,

I can't see it being more useful etc:

I CAN see it being better than the 31mm from the point of sharpness, general control of light and FOV, however I do not believe it would be more useful. Don't forget there has been advances in coatings and optic design like nothing ever seen in the last 10 years.

Damo had both and off loaded his 31mm I believe because of the superior quality of the Ethos.

I would still keep both.

Alan.

[Stu]

Thanks Alan, I was worried someone would say that!

Am going to sit tight for a while probably and consider carefully. I'll probably end up with either 17e or 21e. I really can't afford both!!!

Stu

[nightfisher]

I cant and wont comment as i just dont get televue ep`s, but good luck working to the ideal focal lenghts

[alan potts]

Stu,

The 17mm is brilliant, I can't give you an opinion on the 21mm as I will not see it for a few weeks. In any case the 17E will be about 100 quid less than the 21mm . In my honest opinion I prefer the lower magnifcation that the 31mm would offer, that would be my reason for it staying in the box, if I had one (30mm UWA Meade). I tend to buy eyepieces based solely on the magnifcation they give not the FOV.

Alan.

[Stu]

Therein lies the rub. I'm a little different in that at low magnifications, field of view is important to me, as is sky darkness and contrast. At high mags I care about fov less which is why I think the Delos are a good option here (or BGO's)

In my 106mm....

A 17mm ethos gives

x41, 2.6mm exit pupil and 2.46 deg fov

A 22mm t4 Nagler gives

x31, 3.4mm exit pupil and 2.61 deg fov

So, virtually the same amount of sky, with higher magnification, presumably darker sky background and all the contrast/light control benefits of an ethos. With the same magnification as the 17t4 it SHOULD have them both covered.....

With 21mm it is less clear

21mm ethos gives

x33, 3.2mm exit pupil and 3.04 deg fov

31mm t5 Nagler gives

x22, 4.8mm exit pupil and 3.68 deg fov

I know from experience that pretty much the whole of the Veil will fit in the 31t5 and I love being able to do that, plus other widefield targets.

Logic says that 17e, 21e and 31t5 would cover everything but it really depends, as Shane says, whether the type 4's offer anything that I would miss.

The answer will be to either pick up a 17e or at least try one and see where I go from there. The nags aren't going anywhere for a while yet :-)

Stu

[Stu]

Btw, there is a 17e and 21e on eBay currently but they seem over priced to me, £499 and £599. Would you agree?

Stu

[Naemeth]

Btw, there is a 17e and 21e on eBay currently but they seem over priced to me, £499 and £599. Would you agree?

Stu

The 17e is about 80% of new price (£504 is 80%), 21e is over 80% of new price (£576 is 80%), so they better be with all original caps and boxes and paperwork .

[Stu]

They have caps and boxes, still seems a bit strong to me!

[Naemeth]

They have caps and boxes, still seems a bit strong to me!

Agreed. I think 70% is fairer.

[alan potts]

Stu,

Far too much maybe 60-70 pounds on each one, don't touch. I paid 445 for the 17mm before Christmas and 540 for the 21mm and that was only yesterday.

If you lived a bit closer I would lend you mine.

alan.

[Stu]

Thanks Alan, as I expected. Will wait for a better deal if I decide to get one

[Damo636]

Stu

As Alan has stated, I have recently sold my 31 Nagler. For me, although the Nagler showed slightly more sky, it didn't offer enough extra to convince me to keep it. I opted to move it on and reinvest the funds in a quality binocular. I figured if I wanted a truly wide-field fix I had two options, a short tube refractor or the bins. Is there a case to be made for owning both? I would say yes if you want, need, & can justify the cost of that little extra tfov. The 21 Ethos is the finest eyepiece I have ever owned & ever likely to own, I couldn't recommend it highly enough. Personally I feel the 17 Ethos would be too close to the 13 Ethos. I find the progression from the 21 Ethos to the 13 Ethos perfect. In your shoes, and bear in mind I have never used a T4 Nagler, I would keep the 31 Nagler, sell the 41 Pan along with both T4's & add the 21 Ethos.

[Stu]

Thanks Damo, much appreciated. More food for thought. I guess is thought the gap from 13 to 21 would be too much but what you say makes sense. As Alan suggests, I could always keep the 17t4.

I've got widefield covered with my WO SD 66mm which gives over 6.5 degrees with the 31 Nagler if needed.

Many thanks all for your input. I shall go ponder and keep an eye out for expensive bargains on ABS!!

Cheers

Stu