Pentax XW 5mm

[johninderby]

Having sold some more bits can afford a new planetary eyepiece so am lookig at something up to max £250.00. As this will be used in a dob or scope on a manual Alt-Az  mount quite often a decent fov is important  

Had also looked st the Vixen HR 3.4mm but just a bit too narrow fov and would prefer something in the 5mm range. Great eyepiece though. 👍🏻

Already have a Nagler 3-6 zoom but would like a wider fov.

Suggestions. 🤔🤔🤔

Edited July 1, 2020 by johninderby

[Geoff Barnes]

Hi @johninderby, have you considered the Baader Morpheus 4.5mm? If it is anything like the 6.5mm that I have it would be a great one to try. I've been hovering over the "Buy" button for months now, just waiting for the exchange rate to improve in my favour.  

[johninderby]

Had one of the Morpheus 4.5mm once and it was a fine eyepiece.👍🏻

Just realised the Morpheus has the same thread on the top as a hyperion so could use the TS smartphone adapter that screws onto the eyepiece. Hmmmmm 🤔🤔🤔

Edited June 26, 2020 by johninderby

[johninderby]

Re: the Pentax XW. The specs say there is an M43 thread under the eyepiece cup. Can anyone confirm  this.? 

Edit:

Have just confirmed that the Baader M43 to T2 adapter will fit the Pentax XW. Bit of lunar photography with the smartphone should be interesting. 🙂

Edited June 26, 2020 by johninderby

[johninderby]

Pentax XW 5mm ordered. 🙂🙂🙂

[Louis D]

I have had the older Pentax XL 5.2mm for 22 years and love it.  I know at least one user reports eye interfacing issues with the XW 5mm and replaced it with a used XL 5.2mm and has had no issues since.  I've had similar issues with the XW 7mm, but not the XW 3.5mm.  The Morpheus 9mm is a real keeper.  I've read that the Morpheus 4.5mm has some EOFB, but is otherwise very good.  There is no M43 thread on the XL line, so there is that.  There's also the TV Delos line if your budget stretches that far.  If you don't need to wear eyeglasses at the eyepiece, I'd check out the APM XWA 5 mm 110°.

[Timebandit]

21 minutes ago, johninderby said:

Pentax XW 5mm ordered. 🙂🙂🙂

 

 

Good decision on ordering a XW 5mm. I have had mine many years and a great quality eyepiece, you will not go far wrong with it IMO. The only problem is you may then want the 3.5mm XW  ,7mm XW and 10XW.  All cracking eyepiece's and IMO "Keepers"

 

 

 

 

[John]

Congratulations on the 5mm XW John. Like @Timebandit I have owned one for many years and find it an extremely well made and high performing eyepiece. It is my favourite lunar eyepiece with my 12 inch dob

I too have ended up with a "short set" of XW's

 

[johninderby]

Will be interesting to see how it works with the smartphone. 🤔

Althugh that’s not the main reason for buying it. 🙂

Edited June 26, 2020 by johninderby

[johninderby]

Eyepiece arriving tomorrow. 🙂

Came across this bit of info on the XW eyepieces that may be of interest if you haven’t seen them before. 

[Alan White]

I think you will like it John.
I found the one I had a bit tall in my then shorter scope, would work well now though.
The 10 mm was a peach, have no idea other than grass is greener, why I sold that one.

Looking forward to your reaction on it, the bolt case is a bit of a monster.

 

[Louis D]

And these:

Where the DS line indicates sagittal field curvature and the DM line indicates meridional field curvature.  The origin is on axis performance and the vertical axis indicates performance trending toward the edge at the top.  As the two lines diverge, it indicates increasing levels of astigmatism.  The 5mm should have almost none with field curvature canceling that of most telescopes.

[markse68]

4 minutes ago, Louis D said:

And these:

Where the DS line indicates sagittal field curvature and the DM line indicates meridional field curvature.  The origin is on axis performance and the vertical axis indicates performance trending toward the edge at the top.  As the two lines diverge, it indicates increasing levels of astigmatism.  The 5mm should have almost none with field curvature canceling that of most telescopes.

any idea where to get a higher res version of that first image Louis? I’ve seen it posted a few times but not found a higher res version- checked ricoh japan site too. 

Mark

[Louis D]

5 minutes ago, markse68 said:

any idea where to get a higher res version of that first image Louis? I’ve seen it posted a few times but not found a higher res version- checked ricoh japan site too. 

Mark

No, and I just checked the brochure tucked in with my XW 7mm, and there's no lens diagrams included on it either. 😟

[Louis D]

I dug around Pentax Japan with the Wayback Machine archives and located this eyepiece PDF that seems to have vector diagrams of the lenses that can be increased in size at will.

[markse68]

52 minutes ago, Louis D said:

I dug around Pentax Japan with the Wayback Machine archives and located this eyepiece PDF that seems to have vector diagrams of the lenses that can be increased in size at will.

That one's on the current Ricoh website too: http://www.ricoh-imaging.co.jp/japan/products/catalog/pdf/xo-xw.pdf#page=2

Ever seen an XL brochure? I guess there must have been one...

I tried to get the ZAO brochure from Company 7 lol. funny company

Edited June 29, 2020 by markse68

[MetroiD]

John, in this range of focal length I've gone for a 5.5mm and a 4mm eyepiece, in preparation for 2022 when planetary observation opportunities should hopefully be at their peak. I'm chuffed that I managed to track down a Meade 5k UWA 5.5m a while ago - I've even gone as far as to try it on DSOs - that's how much I enjoy this EP. The 4mm is the venerable UWAN of many names - regardless whether you know it as a Williams Optics, or a Helios, Skywatcher, OVL or Nirvana eyepiece, it is quite a sweet tool.

At 218x and 300x, these two give me the perfect amount of magnification for planetary observation and are quite delightful when pointed at the moon. I've heard the UWAN mentioned in the same breath as Naglers (on whose design I believe UWANs are based), however at a much more manageable pricepoint - I actually purchased a 16mm UWAN as well which I'm also rather fond of - while the Meade 5k UWA 5.5mm is a legend in its own right.

Actually, as part of these purchases, the utterly wonderful chap who sold me the UWAN also included a 2.3mm Celestron X-Cel - for those nights when the skies are extra clear. Stargazers are absolutely amazing folk

P.S.: Forgot to say - the above EPs should be available on the second-hand market (albeit after some digging around) for a combined amount below your intended budget.

Edited June 30, 2020 by MetroiD

[Louis D]

On 29/06/2020 at 15:08, markse68 said:

Ever seen an XL brochure? I guess there must have been one...

Yes, there were equivalent XL diagrams and specs, but I can't locate them online anywhere.

[JeremyS]

5 minutes ago, Louis D said:

Yes, there were equivalent XL diagrams and specs, but I can't locate them online anywhere.

How did you rate the XLs, Louis, relative to the XWs (Apart from the narrower fov of the XLs)? I presume the newer ones are generally better?

[Louis D]

4 hours ago, JeremyS said:

How did you rate the XLs, Louis, relative to the XWs (Apart from the narrower fov of the XLs)? I presume the newer ones are generally better?

The XLs have slightly brighter background skies than the XWs.  Perhaps improved coatings, scatter control, and stray light control are the reason?  Sharpness wise, the XLs are more consistent across their smaller fields.  The XWs tend to have more chromatic aberration in the last 15% of the field and more precise eye positioning is required to avoid seeing it.  That is, if you tilt your head and realign your eye with the edge, most of the chromatism goes away in the XWs.  This is just a non-issue in the XLs.  Both lines are equally sharp in the central 60 degrees or so.  There is variation from focal length to focal length, but it seems as if Pentax was pushing the limits of their design to gain that extra 5 degrees of field at the expense of flawless correction.  Field curvature wise, the two lines track pretty closely.  There wasn't any real improvement there.  I think the Delos made real improvements over the XWs in terms of field flatness and edge chromatism.

[JeremyS]

5 hours ago, Louis D said:

The XLs have slightly brighter background skies than the XWs.  Perhaps improved coatings, scatter control, and stray light control are the reason?  Sharpness wise, the XLs are more consistent across their smaller fields.  The XWs tend to have more chromatic aberration in the last 15% of the field and more precise eye positioning is required to avoid seeing it.  That is, if you tilt your head and realign your eye with the edge, most of the chromatism goes away in the XWs.  This is just a non-issue in the XLs.  Both lines are equally sharp in the central 60 degrees or so.  There is variation from focal length to focal length, but it seems as if Pentax was pushing the limits of their design to gain that extra 5 degrees of field at the expense of flawless correction.  Field curvature wise, the two lines track pretty closely.  There wasn't any real improvement there.  I think the Delos made real improvements over the XWs in terms of field flatness and edge chromatism.

Thanks Louis. I've got the complete set of Pentax XL's, which I've owned from new. This includes the rare, but narrower afoev, 28mm. I've never used an XW, so there is always the nagging suspicion that they must be much better..... 

[markse68]

10 hours ago, Louis D said:

Yes, there were equivalent XL diagrams and specs, but I can't locate them online anywhere.

strange that isn’t it🤷‍♂️ like they’ve been erased from history. Do you know what year they were released?

[markse68]

21 minutes ago, JeremyS said:

Thanks Louis. I've got the complete set of Pentax XL's, which I've owned from new. This includes the rare, but narrower afoev, 28mm. I've never used an XW, so there is always the nagging suspicion that they must be much better..... 

I have the 40 as my finder ep- it’s very light weight for its size- seems to have much less glass than an XW- i guess a much simpler design? Would be really interesting to find optical diagrams of the XLs to see how they differ internally

[John]

1 hour ago, markse68 said:

strange that isn’t it🤷‍♂️ like they’ve been erased from history. Do you know what year they were released?

https://www.sciencecenter.net/hutech/pentax/ep.htm

[johninderby]

Interesting 🤔

https://astromart.com/reviews-and-articles/reviews/eyepieces/other/show/understanding-pentax-xl-and-xw-eyepieces

Edited July 1, 2020 by johninderby