Updating EP collection - help requested

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OzEclipse Australia
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Re: Updating EP collection - help requested

#21

Post by OzEclipse »


notFritzArgelander wrote: Sat Apr 24, 2021 8:06 pm All the advice so far is good but there are some factors that haven't been accounted for yet. So there are questions to be asked.

Do you need to wear glasses when observing? Do you have astigmatism? I don't have astigmatism so I can take my glasses off for observing and use the telescope to do my corrections for my eyes.

If the answer to both those questions is "no" and you already have a coma corrector, Plössls are an economical way to fill out an eyepiece collection. "The Evolution of Eyepieces" has Plössls as good down to f4. You don't have to get fancy shmancy with them. The Vixen NPLs are just fine and break no banks.

I wonder about the glasses and astigmatism also since you are interested in a 3x Barlow? Such a barlow would make eye relief and wearing glasses less of a problem too.
nFA,
I have a small amount of astigmatism - I think it's about 1 dioptre in each eye and I have to say that I don't notice much difference in star shapes when looking through a telescope. The slight improvement in optical correction is more than offset by the extra glass, reflections, and the annoyance of wearing glasses while observing. I always leave my glasses off. The astigmatism seems to affect close focus more eg noticeable difference reading fine print with a set of magnifying readers and my astigmatism corrected prescription glasses with the same overall diopter magnification.

Joe
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Amateur astronomer since 1978...................Web site : http://joe-cali.com/
Scopes: ATM 18" Dob, Vixen VC200L, ATM 6"f7, Stellarvue 102ED, Saxon ED80, WO M70 ED, Orion 102 Maksutov, ST80.
Mounts: Takahashi EM-200, iOptron iEQ45, Push dobsonian with Nexus DSC, three homemade EQ's.
Eyepieces: TV Naglers 31, 17, 12, 7; Denkmeier D21 & D14; Pentax XW10, XW5, Unitron 40mm Kellner, Meade Or 25,12
Cameras : Pentax K1, K5, K01, K10D / VIDEO CAMS : TacosBD, Lihmsec.
Cam/guider/controllers: Lacerta MGEN 3, SW Synguider, Simulation Curriculum SkyFi 3+Sky safari
Memberships Astronomical Association of Queensland; RASNZ Occultations Section; Single Exposure Milky Way Facebook Group (Moderator) (12k members)
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Re: Updating EP collection - help requested

#22

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Hi @turboscrew,
When you ask for this sort of advice, you will get a wide range of opinions. I don't disagree with the advice on medium priced eyepieces presented by others. I read in your OP that you seem to be interested in going down the premium route. So my advice is about premium eyepieces.

turboscrew wrote: Sat Apr 24, 2021 1:27 pm Now that it's time to plan updates to my eyepiece collection, I need help from more experienced people.

Firs step would be getting a better Barlow. I think that a cheap Meade Barlow 3x 1.25" just cancels the quality of those intimidatingly high priced eyepieces.
I've been thinking about TeleVue 3x 1.25" Barlow lens. Thoughts?
I have an old Meade (1970's) 3x non ed barlow. It is better than a Televue 2x ED barlow I purchased thinking it would be an upgrade. I have now removed the barlow lens from the TV and use the barrel as an extension tube. :lol: Televue make some lovely optics, but they also make some very mediocre stuff. I have seen some very ordinary examples of TV Plossls. In general, barlows are not a practical solution. The focal point shifts a lot when you insert a negative lens into the optical path.
turboscrew wrote: Sat Apr 24, 2021 1:27 pm I'm also thinking of getting ~20 mm wide angle eyepiece, but I've learned that not any such is good for my 300 mm F/4. Have to be careful with the selection. I think I'd like a 2" wide angle here.
Suggestions?
I've been thinking of Nagler T4 22 mm and ES 20 mm UWA (100°)
I have an 18" f5.5. At f5.5, the Naglers and many other eyepieces work well without a coma corrector. Even at f4, I think that your coma corrector should negate the need to have eyepieces designed/corrected for fast newts.

I am a fan of the Naglers. I have the 31mm and the 17mm. Both beautiful eyepieces in my 18" f5.5. I have tried the 22mm T4 and decided not to acquire one. It's just not quite in the same class as the 31mm and 17mm. Many of my visual observing posse seem to agree with this assessment in a wide variety of scopes. Friends who have a fuller range of Naglers use their 22mm least of all. I have the Denkmeier D21 (21mm 65 deg). Beautiful sharp eyepiece. The Pentax 20mm 68 deg is just as good. I would have been happy with either. I found a second hand D21 listed for USD90 - too good to resist. There is currently a Pentax XW20 for sale here in Australia for USD270.

The ES eyepieces are not bad but they are not the equivalent of Naglers, Pentax or Denks.
turboscrew wrote: Sat Apr 24, 2021 1:27 pm I'm also planning to replace a 10 mm cheap Kellner with some better 9 mm eyepiece. Suggestions? I'd probably prefer 1.25"

I'm also planning to get a 5 mm eyepiece (x240). That would be about the highest power eyepiece that has real use here. The weather is seldom good enough for x300. Suggestions?
I've been thinking of TV Nagler T6 and DeLite, and Pentax SMC XW.

The manufacturers don't generally indicate if an eyepiece is suitable for F4. Only sometimes. I remember seeing that Baader Hyperions are good for F/6 and forward, and that's why I never went for the zoom. Today, that note is gone.
The Pentax XW5 is excellent. I have a Hyperion 5mm and even in my 6" f7 it is really not great, dark low transmission and not clear. The Hyperion 5mm is a 22mm eyepiece with a 5x barlow nosepiece. You can screw off the nosepiece and have a 22mm. However it is not well corrected and focus falls off well before the edge.

On a night of good seeing, if you put the Pentax XW5 in after the Hyperion, it looks like you have swapped to a much bigger telescope - image is noticeably brighter and much much sharper. Have not tried the Nagler or the Delite. I have a Nagler T6 7mm that is excellent.
turboscrew wrote: Sat Apr 24, 2021 1:27 pm I tried to go through the "Evolution of Eyepieces", but it doesn't seem to be that helpful for me in this situation. I guess the Naglers described there are older designs replaced by the newer type 4, 5 and 6? And I didn't find anything about fitness for different F-numbers.

And the manufacturers seem reluctant to give out the "design class" of their eyepieces.

This is to be carried out within a longer time period, to avoid total bankruptcy.
You say this is a long term upgrade. That is ideal for looking for second hand bargains. I don't know what 2nd hand markets you might have access to over there but it's worth keeping your eyes open especially if you are patient enough to wait. The Australian market is small but I have acquired my entire premium collection over about 6 years from reasonably priced 2nd hand sources.

31mm Nagler T5, 21mm Denkmeier D21, 17mm Nagler T4, 14mm Denkmeier D14, 12mm Nagler T1, 10mm Pentax XW10, 7mm Nagler T6, 5mm Pentax XW5

Good luck

Joe
Image
Amateur astronomer since 1978...................Web site : http://joe-cali.com/
Scopes: ATM 18" Dob, Vixen VC200L, ATM 6"f7, Stellarvue 102ED, Saxon ED80, WO M70 ED, Orion 102 Maksutov, ST80.
Mounts: Takahashi EM-200, iOptron iEQ45, Push dobsonian with Nexus DSC, three homemade EQ's.
Eyepieces: TV Naglers 31, 17, 12, 7; Denkmeier D21 & D14; Pentax XW10, XW5, Unitron 40mm Kellner, Meade Or 25,12
Cameras : Pentax K1, K5, K01, K10D / VIDEO CAMS : TacosBD, Lihmsec.
Cam/guider/controllers: Lacerta MGEN 3, SW Synguider, Simulation Curriculum SkyFi 3+Sky safari
Memberships Astronomical Association of Queensland; RASNZ Occultations Section; Single Exposure Milky Way Facebook Group (Moderator) (12k members)
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