Which first?

[Naemeth]

Planning ahead again... but which would you get first?

Paracorr or 31mm T5 Nagler

I'm not sure how much coma will be present in the 10" dob with the 82 degree Nagler, and wouldn't want to spend all that money on the Terminagler only to want a Paracorr straight away, and I don't want to do it the other way around feeling that I don't actually need it.

Thoughts?

[alan potts]

I would say it depend on how much coma annoys you, it must be there in your other eyepieces. It would get to me with many wide field EP's so I would go for the Paracorr first, you know me well enough to know it would be the Televue one.

The Paracorr also can be used with you other eyepieces so it won't be lonely. I believe it also acts as a bit of a focal extender too, but by how much I don't know, I'm sure someone will tell us.

Alan. 

[Sam]

I would say it depend on how much coma annoys you, it must be there in your other eyepieces. It would get to me with many wide field EP's so I would go for the Paracorr first, you know me well enough to know it would be the Televue one.

The Paracorr also can be used with you other eyepieces so it won't be lonely. I believe it also acts as a bit of a focal extender too, but by how much I don't know, I'm sure someone will tell us.

Alan.

I agree with Alan and would go for the paracorr first, it'll help with all of your eyepieces. Having said that I think I should get one as well!

[Mr Spock]

I used a 22mm T4 in a 10" Newt and coma was annoying. I imagine the 31mm will be much worse.

[Moonshane]

if you are intent on getting both, buy whichever comes up first on the used market at a good price. it will probably be the nagler. if new, the paracorr for me. ideally try and borrow one. if you come to me you could try my 26mm Nagler and 13mm Ethos first with and without my paracorr.

[Moonshane]

three things to consider re paracorrs:

1) it acts like a barlow increasing focal length by a factor of 1.15. so your scope becomes an f5.4 and magnifications will be affected slightly.

2) weight - not that heavy but with a 31mm T5 consider balance

3) it takes your focus position in by approx. 18mm. so check your available focus on your most inward focusing eyepiece.

[Pig]

I would say it depend on how much coma annoys you, it must be there in your other eyepieces. It would get to me with many wide field EP's so I would go for the Paracorr first, you know me well enough to know it would be the Televue one.

The Paracorr also can be used with you other eyepieces so it won't be lonely. I believe it also acts as a bit of a focal extender too, but by how much I don't know, I'm sure someone will tell us.

Alan. 

I think its about 16 - 20% Alan

[Naemeth]

if you are intent on getting both, buy whichever comes up first on the used market at a good price. it will probably be the nagler. if new, the paracorr for me. ideally try and borrow one. if you come to me you could try my 26mm Nagler and 13mm Ethos first with and without my paracorr.

Thanks for the offer, I'm still training myself for cycling long distances, I have PM'ed you.

three things to consider re paracorrs:

1) it acts like a barlow increasing focal length by a factor of 1.15. so your scope becomes an f5.4 and magnifications will be affected slightly.

2) weight - not that heavy but with a 31mm T5 consider balance

3) it takes your focus position in by approx. 18mm. so check your available focus on your most inward focusing eyepiece.

I knew about the barlow - but it actually helps because it would make the exit pupil smaller for the Nagler

For weight issues, I'm not sure what I'll do yet, perhaps magnetic knife rack.

All my eyepieces focus quite far out, so I'm hoping that's not a problem.

It's decided, Paracorr first. The price isn't too bad new anymore, and you never see it 2nd hand, but I'll see if the 31T5 comes 2nd hand first .

[alan potts]

The magnetic knife rack is a fine addition to any scope just in case you need to cut a slice or two of Parma Ham while observing, just make sure the knife is nice and sharp.

Alan

[swamp thing]

Not sure I'd want the 31mm T5 in a 10" skyliner.

I have the 31mm T5, hardly ever use it in my 10" f/4.5. If I only had my 10" scope I'd sell it in favour of a cheaper option for how often it comes out of the case.

My 20mm T5 is by far my most used eyepiece at this aperture f/ratio by a considerable way.

If you have the money. Fine, but if it's expensive for you I'd look at the cheaper options If I were you.

[Naemeth]

Not sure I'd want the 31mm T5 in a 10" skyliner.

I have the 31mm T5, hardly ever use it in my 10" f/4.5. If I only had my 10" scope I'd sell it in favour of a cheaper option for how often it comes out of the case.

My 20mm T5 is by far my most used eyepiece at this aperture f/ratio by a considerable way.

If you have the money. Fine, but if it's expensive for you I'd look at the cheaper options If I were you.

Interesting thought Steve, but I use my 32mm TV plossl on the 10" dob all the time. I don't find the exit pupil a problem, even at 6.8mm .

[swamp thing]

That's my point. A 20mm T5 gives the same field of view as your 32mm plossl at a higher power and with better contrast. Very few objects need the extra giant FOV that the Terminagler gives, this plus loss of contrast means, it stays in the case.

Ask yourself how often you actually need a bigger FOV? Or would the same FOV at higher power and contrast be better?

I can count the objects on one hand that I use the big Nagler in my 10" f/4.5 exclusively for.

Pity you are so far away or we could meet up and I'd show you the difference.

I'm not saying the big Nagler isn't worth having. It's a fantastic eyepiece, but I seldom need its benefits in my 10". In big or slower scopes it's different the big Nagler comes into its own, here you really need the big FOV it gives you. Again though, in slower scopes does one really need the benefits in correction the big Nagler gives over cheaper alternatives.....probably not. For me the big Nagler is at home in big fast scopes where it's giant corrected field is well worth having. It gives me a degree field in my 20", and what I lose by the exit pupil is more than made up by what it gives me in FOV.

For how often it gets used in a fast 10" I would opt for one of the cheaper alternatives like the 28mm UWAN. These are superb eyepieces and considerably cheaper.

[Naemeth]

That's my point. A 20mm T5 gives the same field of view as your 32mm plossl at a higher power and with better contrast. Very few objects need the extra giant FOV that the Terminagler gives, this plus loss of contrast means, it stays in the case.

Ask yourself how often you actually need a bigger FOV? Or would the same FOV at higher power and contrast be better?

I can count the objects on one hand that I use the big Nagler in my 10" f/4.5 exclusively for.

Pity you are so far away or we could meet up and I'd show you the difference.

I'm not saying the big Nagler isn't worth having. It's a fantastic eyepiece, but I seldom need its benefits in my 10". In big or slower scopes it's different the big Nagler comes into its own, here you really need the big FOV it gives you. Again though, in slower scopes does one really need the benefits in correction the big Nagler gives over cheaper alternatives.....probably not. For me the big Nagler is at home in big fast scopes where it's giant corrected field is well worth having. It gives me a degree field in my 20", and what I lose by the exit pupil is more than made up by what it gives me in FOV.

For how often it gets used in a fast 10" I would opt for one of the cheaper alternatives like the 28mm UWAN. These are superb eyepieces and considerably cheaper.

It might sound odd, but it seems I almost exclusively use my longest FL eyepiece that I can most of the time, so that means reaching for the plossl. I also love having a wide field because I can never find anything . I know what you're trying to say, it's definitely appreciated, I guess I'm just not sure it would ever be left behind with the 10".

While it's a ridiculous example, in the travel scope it would give me 6.36 degrees, and an exit pupil of just over 5mm (coupled with slightly more magnification over the plossl), it is quite heavy so balance may be an issue but I'm sure the mount would be up to the job .

I really wish I could drive sometimes, then I'd actually be able to go and try these eyepieces...

[jetstream]

Not sure I'd want the 31mm T5 in a 10" skyliner.

I have the 31mm T5, hardly ever use it in my 10" f/4.5. If I only had my 10" scope I'd sell it in favour of a cheaper option for how often it comes out of the case.

My 20mm T5 is by far my most used eyepiece at this aperture f/ratio by a considerable way.

If you have the money. Fine, but if it's expensive for you I'd look at the cheaper options If I were you.

After reading posts like this from experienced Dob members I chose the 17mm Ethos-a bit more TFOV(not much)  and a bit more mag than the 20mm T5.This combo provides great contrast @ an exit pupil that works great with my OIII.I also considered the 20mmT5,but the Ethos came on sale for not much more.I would imagine other quality eyepiece brands with similar specs to perform well too.The 17 is my goto eyepiece already-awesome in my 90mm refractor as well.

[alan potts]

On the back of Swamp Things comment what about going for the middle ground and getting the 26mm Nagler. I agree with him the 20mm Nagler is a super piece of kit, you may find it hard to believe but it gets used about 10 times more than my 21mm Ethos. I don't know if it's just me being stupid but it was my first Televue and old habits seem difficult to break. In all honesty the amount of times the 21E has been in a scope, i could have saved myself 540 quid.

Alan

[BillP]

• I would go with the Paracorr first.  I have a 10" f/4.7 Dob and when I use a 40mm wide field I can still see the off-axis coma but it is tolerable because the image scale is so small.  With the greater magnification that a 31T5 would provide it becomes more obtrusive.  e.g., back when I had the 28mm UWAN I really did not like the off-axis coma when used without Paracorr.  And that eyepiece was so big and heavy that adding the Paracorr made it all rediculous.  So I eventually settled on the 40mm even though the exit pupil is over max because it is still quite nice without Paracorr - which does not matter much for me since I just use it for star fields and not DSO hunting.  Anyway, recommend you go with the Paracorr first.