The Perfect Number of Eypieces?

[John]

My set serves 3 scopes, my F/5.3 12" dob and my F/7.5 4.7" and F/6.5 5" refractors:

31mm, 21mm, 13mm, 8mm, 6mm, 5mm, 4mm, 3.5mm and 3mm.

With the 12" dob the core set are the 21mm through 5mm inclusive, most of the time. The others do get used from time to time though. With the refractors they all get used.

I also have a 2x 2" Powermate and a few plossls knocking around.

I do find having a more "crowded" set towards the shorter focal lengths useful so that I can find the most effective magnification for a given object under pertaining conditions.

[Floater]

That is a bit rich from the man who has enticed to buy more EPs us with all those brilliant designs of his

My set serves 3 scopes, my F/5.3 12" dob and my F/7.5 4.7" and F/6.5 5" refractors:

31mm, 21mm, 13mm, 8mm, 6mm, 5mm, 4mm, 3.5mm and 3mm.

With the 12" dob the core set are the 21mm through 5mm inclusive, most of the time. The others do get used from time to time though. With the refractors they all get used.

I also have a 2x 2" Powermate and a few plossls knocking around.

I do find having a more "crowded" set towards the shorter focal lengths useful so that I can find the most effective magnification for a given object under pertaining conditions.

I think you've hit the nail on the head, John.

Mr Nagler was probably referring to what is needed with one telescope. If you have more than one scope then a choice of EPs for each makes sense.

At least, that's how I try to justify my collection of more than three ...

[callisto]

At the mo I just use 4......6mm, 12mm, 16mm and 24mm 

[YKSE]

So what is the perfect number for a single scope?? I say 7. What do you think?

Paul

If zooms or barlows are allowed, I would say a  4 are enough for most of many-scope owners.

My last ten observings or so in dark site, with C8(f10), 80ED(f7.5) and 120ED(f7.5), only three eyepieces were used, 40mm, 31mm, and 17.8-9.8 zoom. Targets had been faint fuzzies,  large as the Veil, North America (over 2-3°) to small galaxies just over 1' in size. For planetary work, the zoom can be barlowed to 3.7mm, which should cover the best seeing conditions.

A pefect minimum number may be good to have, it's just that sometimes we'd like to have some fun too and some other viewing experiences, like binoviewing or UWA's pothole views, etc, also our have curiosity, all these can break that perfect number.

[michael.h.f.wilkinson]

Seven can't be perfect, it's prime

Sorry, I'll get me coat. The one with the number theory book in the pocket please

[estwing]

21 13 and an 8mm ep's plus a x2 powermate..and at the moment its one too many!...sorta goes...21mm...ah yes thats nice..(in with the 8mm)..HELLO!

[alan potts]

Feel it is all down to how many scopes one has. If I had only the one I reckon I could get by with 4 eyepieces or maybe only 3, in any one night, unless I am playing, I only really use this smallish number despite having many more. What is a high power on one of the shorter scopes, say 4.5mm F/L EP is unuseable on the 3048mm of the Meade as it would give a very large cricket score.

Alan

[Paul73]

Seven can't be perfect, it's prime

Sorry, I'll get me coat. The one with the number theory book in the pocket please

Good point.

I'll include my 20mm BCO 50° for Fuzzies closes to bright stars. That makes 8!

Or, loose the luxury of my ES 30mm 82° because the 24mm does the trick 90° of the time. That makes 6!

Paul

[John]

....I'll include my 20mm BCO 50° for Fuzzies closes to bright stars. That makes 8!

They are usefull to have. I have a 20mm TV plossl for the same purpose.

[michael.h.f.wilkinson]

They are usefull to have. I have a 20mm TV plossl for the same purpose.

Haven't felt the need for that. But I might try the Vixen Ortho 25mm I use for solar H-alpha in the Solar Spectrum set-up, or the TV Plossl 25mm I have lying around.

[John]

Haven't felt the need for that. But I might try the Vixen Ortho 25mm I use for solar H-alpha in the Solar Spectrum set-up, or the TV Plossl 25mm I have lying around.

The reason I have one is that all my other eyepieces longer than 5mm are either 100 or 82 degree AFoV ones. Most of the time they are great but occasionally (eg: the Horsehead) a narrower field can be advantageous and the 20mm fl gives an exit pupil that is effective for H-Beta filters with my 12" dob.

Or so I'm told - I've not seen the darn thing yet !

Your 25mm ortho and TV plossl will do the same job.

[michael.h.f.wilkinson]

I managed the Horse-Head Nebula with the LVW 42 and Nagler 31, but it was very, very hard

[Mr Spock]

Space pony? Never seen it - it's just a myth

[RikM]

I must admit that I have a 21mm TV plossl for horsehead hunting but I don't generally count that one. I haven't seen it yet either.

[bomberbaz]

I bought a 25mm vixen plossl for HH or similar viewing. That gives a good narrow FOV with the right exit pupil.

Must admit it has only been used a half dozen times but at a sub £40 price its worthwhile having at my disposal.

I am in the process of changing my collection (again) and soon will have just a TV 2x 2" powermate and 3 2" EP's as well as the afore mention plossl.

I may add a 2nd hand 6mm ep to that for high powered viewing but there is no rush.

Watch this space as they say ;-)

[ollypenrice]

I'm happy with three per scope and, in the big Dob, I really run 95% of the time with two because I don't use it for planetary. Give me two really good Ethi or Naglers over a much larger number of lesser ones.

Olly

[michael.h.f.wilkinson]

I'm happy with three per scope and, in the big Dob, I really run 95% of the time with two because I don't use it for planetary. Give me two really good Ethi or Naglers over a much larger number of lesser ones.

Olly

But a larger number of top EPs are even more fun

[Sonicfishcake42]

2 for me, 

8-24mm zoom + 40mm (Oh and a 2.25 barlow)

[estwing]

Come on Steve..fess up!!!

[bomberbaz]

Cant yet calvin, pictures speak a thousand words, haha.

[vlebo]

I have the Pentax XW 30 , 20 and 10 and I will be going for the 7mm and I think that will do me .

[Highburymark]

The answer is either one (the Leica zoom and a decent Barlow) or an infinite number. I'm somewhere in the middle.

[YKSE]

The answer is either one (the Leica zoom and a decent Barlow) or an infinite number. I'm somewhere in the middle.

Look like another Zoom junky to me

[SpaceWalker]

So what is the perfect number for a single scope?? I say 7. What do you think?

Basically, I agree with you and with Moonshane. Depends on the scope used, but 7-8 eyepieces max should be enough.

On my 90mm f/9 frac I mostly use 3, the 32mm TV Plossl, 20mm ES68 and 8.8mm Meade 5K UWA. Plus 2x Meade TeleXtender (it's not an eyepiece, right?  ).

For my 8" Dob I have way too many but only some are used at a permanent basis. I'm reworking my collection now toward 7-8. IMO, what Uncle Al advised  here, 3 wide angle eyepieces more or less  evenly spaced with jump of ~1.8-2x or 4 wide angle eyepieces also evenly spaced with jump of ~1.6x. For general observations or like Uncle Al says for a "Space Walk" that would be enough. Since I have interest in observing low contrast DSOs like galaxies, than a couple of extra eyepieces around 2mm exit pupil providing smaller jumps in magnification and exit pupil in this region for more flexibility. Plus 1-2 high power planetary eyepieces for exit pupil of 1-0.7mm.  I got a  good 7-20mm Russell Optics zoom in hope to replace  my medium and high power eyepieces,  but appreciate it less and less. I like expansive views, even 60*AFOV look claustrophobic to me after I got my first 82*AFOV eyepiece a couple years ago  .

[Erekose]

I find I need or want about 10. Reason for that is that at the lower focal lengths I would like a 4mm, 5mm and 6mm then a step to 8mm. Find that some nights and scope I can use a 5mm, others the lowest useable is 6mm and at times when the 5mm is good the 4mm will deliver.