Eyepieces

[cyborg421]

Hi all,

i have a Delos 6mm and a Nagler 11mm. whilst out observing Jupiter last night I found that the 11mm was crystal but the Delos was pushing the mag a bit far. can anyone recommend a quality eyepiece between the two? Would an 8mm Ethos be any good or would the cost not justify with what I have already? How many eyepieces is sensible with that range?

Simon

[Tinker1947]

Low mm EP's some thing like what you mention or the Pentax XW 7mm , my 10mm was crystal clear the 5mm last night showed all the bands but wasn't pin sharp, there was a lot of mist in the air.....so max power is ok but it doesn't get used a lot.....

[cantharis]

LOL I can´t afford the eyepieces you already have. No way could I recommend an improvement.

[cyborg421]

I wasn't supposed to be bragging. I think it is partially about how many eyepieces you need to have. A lot of people seem to have a lot of eyepieces over what I would consider a small range. It will be partially about cost but also about seeing conditions as well.

Simon

[ronin]

Canot see why a 6mm Delos would not have worked. You would be at 200x and the Delos should handle the f/4.7 of the scope.

If the conditions were not good then perhaps but it seemed clear most of last night, and the temperature usually means pretty stable. Although not sure what the pressure charts were like.

The problem is that you mau find if the 6mm didn't quite do it then a 7mm might have. At the short end 1mm can make the difference. If anything then perhaps look at an 8mm but the one you try is up to you.

[John]

The variations in seeing conditions are why it's useful to have a range of high magnifications available. You can then find something that is the optimum match for the conditions and object being viewed at a particular time.

I would have thought a 6mm would work well enough on Jupiter with your scope quite often but your local conditions might just have prevented it. On cold nights the central heating plumes rising from the roofs of surrounding houses can play havoc with the steadiness of images even if the atmospheric conditions are otherwise good. You then have to back off the power to find what can be used, or wait for the object to move out of the plumes.

I have eyepieces in the focal lengths 8mm, 6mm, 5mm, 4mm and 3.5mm to allow flexibility at medium to high power with my scopes.

[rwilkey]

I would have thought an 8mm would be the best for your in-between range, I often use this one as my lowest reasonable value, gives me 125x in my 200P which I find ideal, having said that I also have a 7mm 82 degree as well (Axiom LX), which I find better in my C100ED, horses for courses I suppose. You might consider Explore Scientific worth a try, they get good reviews everywhere, though well out of my economic range. I get most of my quality ep's s/h.

[cyborg421]

Thanks for that. It's true that the 6mm can be fantastic when conditions allow and I've had some fantastic views through it. But as people have mentioned the local conditions do not always allow for it to be used, which I was the case last night. An 8mm seems to be a sensible value to go for but I wondered if a 7mm was too close to a 6mm to make much difference.

Simon

[rwilkey]

Thanks for that. It's true that the 6mm can be fantastic when conditions allow and I've had some fantastic views through it. But as people have mentioned the local conditions do not always allow for it to be used, which I was the case last night. An 8mm seems to be a sensible value to go for but I wondered if a 7mm was too close to a 6mm to make much difference.

Simon

Like the 6mm, the 7mm is good if conditions allow, but to be 'risk free' I would go for the 8mm from my experience with these focal lengths.

[brantuk]

I've found that 1mm between eypiece sizes doesn't make the view significantly better (or worse). It's just a personal preference but I like to have 2mm or 3mm or 4mm between eyepiece sizes. I think you'll enjoy an 8mm between the 6 and 11 Simon - it gets a lot of use in my scopes. I drop to 5mm when conditions allow. Alternatively I often double a 13mm with a Powermate depending on the object.

[Moonshane]

When I was deciding what my eyepieces should be I wanted a set that would cover all scopes that I might ever own. This is not as hard as it sounds, a fact proved by my having three scopes - a 16" f4, a 12" f4 and a 6" f11 - all dobs - which covers most of the aperture and focal length range of most scopes - I am not likely to buy an SCT.

Although I have one set of eyepieces, they are broadly in three mini sets. Thankfully I did all this when I had a lot more free income. If I were doing it now then I'd have a most restricted set of eyepieces and scopes.

16" f4

Main scope used for DSOs at home and dark sites and sometimes masked to 170mm for high contrast planetary, lunar and double star observing. Using the paracorr I have a focal length of 1840mm. Manual.

12" f4

Future dob project to be made into a suitcase dob for camping trips etc

Focal length 1200mm at f4, no paracorr. Manual.

6" f11

Manual dob but on a driven home made equatorial platform. Allows tracked high power views of planets and doubles / moon plus my main solar scope.

I have attached my eyepiece summary for each scope showing the most used eyepieces for the three scopes highlighted in blue. You will note the bunching at higher power with all but two being 13mm or less in focal length. When observing planets in particular, I find that a 1mm step can make a big difference, especially in the scopes with long focal lengths.

If I had to choose say four eyepieces then I would retain :

26mm Nagler

13mm Ethos

10mm Radian

6-3mm Nagler zoom

If I had a slower focal ratio in all scopes, I'd have no shame (or loss in image quality) in retaining

32mm TV Plossl

15mm TV Plossl

9mm BGO

7mm BGO

but in both cases I'd miss the others in between.

I suppose overall my point is to try and decide what sort of scopes you like and what observing you will be doing and go from there and build a set of eyepieces that will last a lifetime.

eyepieces and scopes.xls

[Mike73]

If you dont mind using barlows then how about getting a TV Powermate and get two EP's for the price of one?

Personally I dont like using barlows of any kind so I have 6 EP's - 7mm/8mm/10mm/14mm/17.3mm and 26mm.