what use for mid-power EPs?

[Ags]

I find I am either trying to get the maximum field of view or the maximum magnification (that the seeing will allow). so my mid-power EP, a 15mm plossl, almost never gets used, except when I want a big view of the whole moon. Am I missing something? Is there a good use for EPs in the 11mm - 17mm range? I understand that you can up the power to increase contrast, but my widest field view is already at 50x magnification, so I don't think that is relevant to me.

[Chris H]

On my scope my workhorse ep is 12mm it gives me x100 and I find it perfect for viewing DSO's. It is often a lower than the atmosphere will allow but a lower mag will let in more light so for extracting detail out of faint objects it is perfect.

What scope do you have?

[AWR]

I find my 15mm plossl (x100) is often useful for double star splitting when conditions do not favour the 9mm (x167). Some doubles just seem to split easier at this magnification.

Andrew

[NGC 1502]

If I could have only one eyepiece for my 10" Dob, it would be my 13mm LVW.

I find it's just right for many objects, larger open clusters, M35 & NGC457 spring

to mind, galaxies too, M51 for instance, the mid power darkens the sky background

and increases contrast. At Kelling in Sept, I could see the "S" shaped structure

of M33, and the main dust lane in M31, with my 13 giving the best view at 92x.

Of course I use higher and lower power as well, and would not want to be without

them, but the 13 is in the focuser the most. Can you hear "Ethos" calling gently ? !

But we all vary, what works for me, may not work for others.

Best regards, Ed.

[Ags]

Maybe this depends on aperture to some extent - I have a 102mm Mak so I have less light to work with (Ed and Chris, you seem to be using 10" scopes). If my optical understanding is right, then a nebula at 50x in my scope would have the same surface brightness as a nebula at 100x in a 200mm scope (i.e. 4 times the light spread over 4 times the area). Obviously this only applies to brightness of extended objects (and the sky background) but not stars, which are always the same brightness for a given aperture regardless of magnification.

I've tried getting better contrast by using my 15mm plossl, but I find the nebulous objects just get too faint. As for faint stars such as those in M13, I find I need to go up to 150x magnification to bring them out.

But I am thinking of getting a 13mm Hyperion, even if it is only for massive views of the whole Moon. Maybe I just like Hyperions and I want another... ;-)

[John]

It's no accident that the 1st Nagler released was a 13mm as was the 1st Ethos

[Moonshane]

good point John

I also have my fave EP and it's a 13mm Ethos; simply superb and it's not just the field. the magnification seems to be just right for a number of things in my scope and has been giving the sharpest views of Jupiter recently (at 123x).

On the subject mentioned, mid range is the area I am debating in my mind currently. I have the 13E and a 35mm (46x) Panoptic which give great views. it's the in between bit that I am really thrashing about in my mind as is Ags.

I have bought a 22mm (73x) Panoptic as this is the 'cheapest' of the mid range TV EPs and I may well stick to this as I can go readily from the 35 to the 13mm so I reckon at £140 (used) for the Panoptic it's 'better' than £200-300 (used) for the equivalent Nagler as it won't be used as often as either the 35mm Pan or the 13mm Ethos. BUT it will give me more contrast than the 35mm and if I think I have found something then I can swap to either the 22mm or the 13mm for more contrast/magnification. In short, I tend to agree with Ags!

[Nick P]

If you have truly dark skies to observe under, you would find that mid range EP's in the range you mention would be almost constantly in the scope! however if like most of us you have a certain level of light pollution to contend with, increasing magnification and therefore background contrast would be more beneficial.

I say this on the basis of my experiences under truly dark skies with a 90mm apo (fl C. 560mm), where the main EP I used was a 12mm nagler which I could resolve many globulars with, and gave great wide field views of the rich star fields available. because the mount was undriven and not too stable high mag was a little under 100x with a 6mm radian!

[Hypernova]

My most used eyepiece in my dob is a 14mm Antares Speers-Waler. It has a 82 degree AFOV and gives 85x witha 0.9 degree TFOV in my scope which I find is perfect for viewing most deep sky objects, as well as comets and some other solar system bodies.

I do long after a decent low power eyepiece though.

[Kef9]

Well my 13mm ethos give me a great view of the double cluster and other DSOs!

Its also great to powermate to a superb 6.5mm planetary eyepiece.

[brantuk]

Personal experience only - I have a variety of ep's of differing quality that give a full range of magnifications, field widths, and eye relief, accross 3 telescopes.

[pvaz]

My most used EP, used to be an Agena 15mm 70'. Now it's the 10mm Ethos (same FOV of a Nagler 13mm or my old 15mm Agena). As others pointed out, an EP in the 16 to 12mm range provides just the right FOV for most DSOs.

[Mr Spock]

If I could have only one eyepiece for my 10" Dob, it would be my 13mm LVW.

Same here. My 13mm LVW in my 10" is my most used eyepiece.

For my 10", the list is as follows:

22mm T4 Nagler + Baader MPCC for extra wide views

13mm LVW for all DSOs

9mm NLV for doubles

7mm T6 Nagler for globulars and smaller planetary nebulas

6mm TMB Planetary for moon/jupiter

4mm NLV for all planets

I wish I had gone the LVW route - 13mm, 8mm, 5mm, 3.5mm. But it's too late now, the cash is spent...

[michael.h.f.wilkinson]

I use the two "mid-rangers" for my F/10 scope (22mmT4 Nagler, and 14mm UWA) more than any other. only for extended nebulae (M31, M33) and large open clusters (h + chi Persei, Pleiades) do I use the 40mm Paragon. Especially in the case of planetary nebulae, they are best viewed at moderate magnification.