Eyepiece for sw250 F4.7

[Louis D]

I have the 12mm Nagler T4 and 10mm Delos.  The Delos is sharp and flat to the edge.  It is also a bit sharper in the center than the Nagler.  The Nagler has a bit of exit pupil finickiness, probably due to some SAEP (Spherical Aberration of the Exit Pupil).  The Delos has a super stable exit pupil.  Both have adjustable eye guards, though the newer Delos version stays in place once locked down with the twist ring.  The Nagler's 20 year old "Instajust" version is not well liked in the astro community for multiple reasons.  The Delos is super easy to use with eyeglasses while the Nagler requires mashing your glasses into your eye socket to get close enough to take in the entire field.  If you don't wear eyeglasses, it's considered to have very comfortable eye relief.  There's also the 12.5mm Morpheus which isn't quite as sharp to the edge as the Delos, but is noticeably wider and also free of SAEP.  Instead of the Nagler, I'd probably try the new 12.5mm APM 84 degree which has been getting positive reports.

Below are my 9mm/10mm eyepieces and 12mm eyepieces for reference.  You can see that the Nagler wanted to kidney-bean due to SAEP with the wider and slower camera lens for the full view image.  The 12mm ES-92 is like a Delos on steroids.  Sharp center to edge, no SAEP, and enough eye relief for eyeglass users.  However, it lacks an adjustable eye guard which made it a no-go for @John recently since he doesn't wear eyeglasses when observing.  It's also huge and heavy.

Edited December 15, 2019 by Louis D
Added 12.5mm APM 84

[Adam Barnsley]

6 hours ago, Louis D said:

.  The 12mm ES-92 is like a Delos on steroids

You mean ES is better than Delos?

[John]

6 minutes ago, Adam Barnsley said:

You mean ES is better than Delos?

Much bigger, heavier and with a 92 degree field of view compared with the 72 degrees of the Delos. Optical performance is very similar. I've been comparing the ES 92's with my Ethos and Delos eyepieces. I didn't find the eye relief of the 12mm ES suited me so I've now sold that one. Still have the 17mm though. The ES 92's might not be quite as sharp to the edge in an F/4.7 scope as the Delos is though. My dob is F/5.3.

We are talking very large eyepieces here:

 

 

[Louis D]

7 hours ago, Adam Barnsley said:

You mean ES is better than Delos?

Just bigger in field, weight, and overall bulk.  Sharpness and clarity across the field appear the same at f/6 for me.  I can't speak to f/4.7 usage, though.

[Adam Barnsley]

N13T6 on way. Next one will be delos 17.3mm or DeLite 18.2. and Pentax XW 7mm.

[Adam Barnsley]

Once again, thank you all for your helping hand.

[John]

You have made some good choices there Adam

There is a sort of domino effect with eyepieces I've found. You get a nice one to see what they have to offer and then rather quickly get hooked and find yourself wanting to move the others to the same standard.

 

[Adam Barnsley]

Sorry for offtopic. I will be grateful if anyone could look. 

 

[niallk]

8 hours ago, Adam Barnsley said:

N13T6 on way. Next one will be delos 17.3mm or DeLite 18.2. and Pentax XW 7mm.

  - a remarkable little gem!

There's a lot to be said for minimizing faff in the dark like balance issues due to heavy EPs, and messing with 1.25" to 2" adapters when choosing a set, imho.

[Adam Barnsley]

Fresh delivery, I can't wait for the first light. There is only one problem, so far I'm bedridden.

[RT65CB-SWL]

Congratulations @Adam Barnsley.

Welcome to the TeleVue Nagler 13mm/Type 6 club.

You are going to 'love' it. 

[Louis D]

@Adam Barnsley Hope you're feeling better soon.  My daughter's come down with something as well.  Too much NYE partying, I think.

[Adam Barnsley]

1 hour ago, Louis D said:

@Adam Barnsley Hope you're feeling better soon.  My daughter's come down with something as well.  Too much NYE partying, I think.

Thanks You, but no party. New Year in bed as well.

[Adam Barnsley]

2 hours ago, Philip R said:

Congratulations @Adam Barnsley.

Welcome to the TeleVue Nagler 13mm/Type 6 club.

You are going to 'love' it. 

Thanks😊 I like green.

Edited January 2, 2020 by Adam Barnsley

[Guest]

I'm fairly new to this myself but I found that my laser collimator had to be collimated itself before I could use it to collimate the telescope.  On the laser there were 3 tiny rubber caps around the circumference. Take the rubber cap off and there was a tiny screw adjustment underneath. The way I did it was to make a cradle for the collimator so that I could rotate it while it shone on a wall. Then rotate the laser and adjust the screws so that the laser spot didn't move. It's a bit fiddly but not too difficult.

Steve

 

[John]

Sounds like you need to collimate your laser collimator as Steve says above. I'll split this thread so you get a new one on this topic otherwise the change of topic might get overlooked.

 

[John]

14 minutes ago, woodblock said:

I'm fairly new to this myself but I found that my laser collimator had to be collimated itself before I could use it to collimate the telescope.  On the laser there were 3 tiny rubber caps around the circumference. Take the rubber cap off and there was a tiny screw adjustment underneath. The way I did it was to make a cradle for the collimator so that I could rotate it while it shone on a wall. Then rotate the laser and adjust the screws so that the laser spot didn't move. It's a bit fiddly but not too difficult.

Steve

 

Steve - I've split Adams questions regarding collimation off into a new thread here:

I've copied a link to your comments into that new thread because I messed up the splitting process a bit

Hope thats OK.

One glass of wine too many for supper I fear

[Adam Barnsley]

I found, 3 holes silicone covered. I try sort it out today

[Adam Barnsley]

Hello again, I have another dilemma. Delos6mm appeared on the Market at a good price. Initially, I had to buy a Pentax XW 7mm , what is the difference between the two?

[RT65CB-SWL]

1mm...

Seriously, about the same eye relief. Pentax has 70deg / TeleVue has 72deg AFOV - Weight: Pentax 390g / TeleVue 454g.

The Delos is apparently is in the same parfocal group as the Nagler/Type 6 - the Delos has the 'Instajust' feature which I like.

Edited January 20, 2020 by Philip R

[John]

I agree with Phillip R. The differences between the XW's and the Delos (I have both) are practically zero in performance terms so the 1mm is the main one in this instance.

Delos are in the same par-focal group as the plossls, Panoptics and Nagler T6's etc apart from the 14mm and 17.3 which need about 8mm inwards focuser movement - close to where the XW's reach focus.

 

[Louis D]

7 hours ago, Adam Barnsley said:

Hello again, I have another dilemma. Delos6mm appeared on the Market at a good price. Initially, I had to buy a Pentax XW 7mm , what is the difference between the two?

I have a 7mm Pentax XW, and it has significant lateral color as you near the edge for such a premium eyepiece.  I've also experienced some difficulty holding the exit pupil compared the older 5.2mm XL which has a rock stable exit pupil and lacks any lateral color at all.  I also have the 10mm Delos, and despite reports from others to the contrary, I have had zero issues holding the exit pupil.  It is also quite sharp and color free to the edge.  I'd probably get the 6mm Delos without hesitation in your situation.  The 3.5mm XW by comparison has no exit pupil issues and no lateral color, so it would be a toss-up between it and the 3.5mm Delos.

[John]

I'll have to check this lateral colour issue with the XW 7mm tonight. I can't say that I have noticed it up to now despite owning the eyepiece for a couple of years

What would be a good test target Louis ?

 

 

[Timebandit]

 

 

 

I have a 7mm Pentax XW also for a number of years. Absolutely great eyepiece. I have had no lateral colour issues , and great sharpness to the edge in both my newt and frac . The 7mm pentax XW reminds me of a high quality Ortho , but without the drawbacks of narrow fov and tight eye relief. Love my Pentax 7mm XW and a real keeper.

 

 

 

[Louis D]

3 hours ago, John said:

I'll have to check this lateral colour issue with the XW 7mm tonight. I can't say that I have noticed it up to now despite owning the eyepiece for a couple of years

What would be a good test target Louis ?

 

 

As I recall, on bright stars, the 7mm XW would develop color smearing as the stars got to the last 15% of the field.  If I turned my head and eye just right to align everything perfectly, I could minimize it.  I'll have to get it out again and look for it to characterize what I saw in the past better.

The eyepiece was frustrating enough after having owned the 14mm and 5.2mm XLs for years, which did not exhibit such color issues, that I seriously considered returning it.  I've slowly warmed to it as long as I keep objects centered and not use the outer regions of the field.

I think I'm seeing something similar to what this CN reviewer saw in his 2004 comparison of the 10mm XW to the 10.5mm XL.  He consistently noted color issues farther in from the edge and of greater magnitude in the XW than in the XL.  Apparently, compromises were made to extend the field 5 degrees.