XW or DeLite?

[Don Pensack]

On 26/06/2022 at 14:53, Highburymark said:

Optically, you can’t go wrong with Delites, Delos or XWs. I’ve used all three extensively and it’s incredibly difficult to split them. That’s why in the many forum threads dedicated to examining their various merits, most comments are about ergonomics and personal preferences.
If AFOV is important, go Pentax. If weight is important, go Delite. They are both about as good as modern medium-wide eyepieces get.

The average AF in the Delite line is a hair under 62°

The average AF in the XW line is 69°

The average AF in the Delos line is 72°.

 

[Highburymark]

21 hours ago, Don Pensack said:

The average AF in the Delite line is a hair under 62°

The average AF in the XW line is 69°

The average AF in the Delos line is 72°.

 

I’d class them all as medium-wides, perhaps allowing myself a little bit of poetic licence with the Delites. They certainly feel like more than 62 degrees in a binoviewer.

[Louis D]

4 hours ago, Highburymark said:

I’d class them all as medium-wides, perhaps allowing myself a little bit of poetic licence with the Delites. They certainly feel like more than 62 degrees in a binoviewer.

50 degree Plossls used to be considered wide angle when Huygens, Ramsdens, and Kellners ruled astro catalogs; thus 65 to 70 degrees were Super Wide Angle (SWA).  Then came Ultra Wide Angles (UWAs) around 80 degrees and Hyper Wide Angles (HWAs) around 100 degrees.  I don't know what to classify the 9mm ES-120 as, however.  Ludicrous Wide Angle (LWA)?  The first 10 that came off the line were missing their internal field stop and actually have a 140 degree AFOV.  Would that be Plaid Wide Angle (PWA)?

[Highburymark]

Mega? Though not sure that suggests anything greater than ‘hyper’, which already sounds painful. 
Thankfully the Delites were a return to lighter and smaller eyepieces after several decades of increasing size and weight. Doubtless it’s one of the reasons why the T6 Naglers have endured so long. 

[Louis D]

4 hours ago, Highburymark said:

Mega? Though not sure that suggests anything greater than ‘hyper’, which already sounds painful. 

Meade had their MWA line which I assume stood for Mega Wide Angle.  They claimed 100 degrees, but delivered somewhere between 80 and 90 degrees, depending on the focal length.  The eAFOV was around 90 degrees due to barrel distortion.

[TheycallmeRiver]

I'm still learning about eyepieces and I don't own a DeLite yet, but my take on the only XW I own (the 10mm) is that eye placement seemed pretty fussy.  I've tried with the eyecup flat, extended all the way out, and at various steps in between. 

It's probably more inexperience on my part than anything else because i'm aware that this is a much loved eyepiece, but my first and second impressions of the XW weren't brilliant.

I have my eye on a Morpheus 9mm that might eventually replace it, but until then i'll keep persevering.

[Louis D]

1 hour ago, TheycallmeRiver said:

I'm still learning about eyepieces and I don't own a DeLite yet, but my take on the only XW I own (the 10mm) is that eye placement seemed pretty fussy.  I've tried with the eyecup flat, extended all the way out, and at various steps in between. 

It's probably more inexperience on my part than anything else because i'm aware that this is a much loved eyepiece, but my first and second impressions of the XW weren't brilliant.

I have my eye on a Morpheus 9mm that might eventually replace it, but until then i'll keep persevering.

Try a 12mm Nagler Type 4.  It is extremely fussy to take in the entire field of view.  The moment the field stop pops into view, blackouts start raging around the field of view.  The 12mm ES-92 is much better behaved in this respect.

I've not noticed that the 7mm and 3.5mm Pentax XWs are any fussier than my 5.2mm and 14mm Pentax XLs, 9mm and 14mm Morpheus or 10mm Delos.  I do wear glasses at the eyepiece, so I always have a reference distance thanks to them.  That may help with eye placement stability.

[vagk]

1 hour ago, TheycallmeRiver said:

I'm still learning about eyepieces and I don't own a DeLite yet, but my take on the only XW I own (the 10mm) is that eye placement seemed pretty fussy.  I've tried with the eyecup flat, extended all the way out, and at various steps in between. 

It's probably more inexperience on my part than anything else because i'm aware that this is a much loved eyepiece, but my first and second impressions of the XW weren't brilliant.

I have my eye on a Morpheus 9mm that might eventually replace it, but until then i'll keep persevering.

Pentax XW 10mm eyepiece is one of the best of all time. Perfectly corrected. Never leave it, you may regret it.

[TheycallmeRiver]

28 minutes ago, vagk said:

Pentax XW 10mm eyepiece is one of the best of all time. Perfectly corrected. Never leave it, you may regret it.

You aren't the first to say that to me in response to my pretty basic level criticism of the eyepiece.  I do still fancy the Morpheus 9mm because I love the 12.5,  Maybe I'll keep both and learn to use the 10XW a bit better.

[Voyager 3]

On 25/06/2022 at 00:19, great_bear said:

Now that is a VERY astute point. 

I am in the same boat as the OP - same FL for the same scope weirdly enough - and whilst I was set on a Delite, this thread had me considering the Pentax. 

But parfocality? Darn good point there.

It bugs me already that the Delos 17.3 isn’t parfocal with the other Delos, but having to refocus whilst at the other end of the focal range - whilst chasing a target at high magnification? Hmmm yeah, that’s possibly a dealbreaker for against the XW for me. 

So did you get either of these eyepieces?

[great_bear]

14 hours ago, Voyager 3 said:

So did you get either of these eyepieces?

Due to my mirror disaster I'm delaying further eyepieces purchases until later in the year - will report back at that time though...

[Voyager 3]

24 minutes ago, great_bear said:

Due to my mirror disaster I'm delaying further eyepieces purchases until later in the year - will report back at that time though...

OMG

[great_bear]

OK - I found my solution! 

As an experiment, I screwed my WO Binoviewer OCA lens onto my 6mm Delos (via an unwanted filter with the glass removed to help with the fussy 1.25” threads). The results were more than impressive - startlingly good in fact. So, I’ve effectively built my own 5mm Delos! 😁

Problem solved! - for me at least…