Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

stargazine_ep28_banner.thumb.jpg.b94278254f44dd38f3f7ee896fe45525.jpg

alan potts

Pentax 5mm XW and Delos 4.5mm

Recommended Posts

I have not had a chance to compare while they are side by side but that is something I could do in the future without costing me. I had the Delos 6mm, dropped it, replaced it with the 6mm Ethos and borrowed a Delos from a friend, but loaned him the Ethos. I can get the two together later in the year for a few weeks. I think the Delos has just that bit better transmission and control on bright objects but this could just be the difference in the FOV playing tricks on my mind. I wouldn't read too much into it, memory is not a way of making a comparison, maybe I should not have said it.

Alan.

Share this post


Link to post
Share on other sites

Interesting. Be good to see a Potts side by side special on these two :-)

Stu

Share this post


Link to post
Share on other sites

Excellent report Alan and I'm glad I finally got the time to read it :). Just one question though: Was the chromatic abberation around the Moon blue? I get that same blue "ring of fire" with the Vixen LVs, Moonshane reports it is the same with the Ethos, but it's not there with the TV plossls or the Delos as you have reported :).

I can't recall who it was but he had his head screwed on the right way in his choice but wallet emptied at the same time. He went for 8mm Delos 7mm XW 6mm Delos and 5mm Xw

That's Steve (bomberbaz):

:)

Share this post


Link to post
Share on other sites

I've never been in a position to compare the same focal length of Delos vs Ethos but have always assumed they are same quality with just the fov/eye relief differentiating them. Is there a view that the Delos may be better?

Stu

I've read reports that the Delos go just a little "deeper" on DSO's when used with very large (20" or more) scopes. The reviewer had previously judged the Ethos as the best they had used up until then (they seem to have access to every premium eyepiece you can imagine including Zeiss ZAO's !) so the Ethos is clearly no slouch in that department.

I always felt that the Delos was introduced to deliver Ethos qualities in a package with more eye relief and for those who did not want and did not want to pay for, a 100 degree field of view.

I'd really welcome Alan's thoughts on how the two compare though as his scopes are much more like the ones the rest of us have access too than the Cloudynights reviewer I mention above :smiley:

Share this post


Link to post
Share on other sites

That's interesting John, thanks! If they are only differentiated on monster scopes then I think we'll be comfortable in the knowledge that Ethoi are worth their asking price. Well, as much as we ever were :eek:

Alan, as you have most of the scope types at large, a discerning eye and developing career as a keyboard operator, I will really look forward to any future duel of these babies for sure, but could you also put an Ethos 13 in the ring with the Delos and XW 14s and see if any of them flinch? Your LX and Mak deserve the exercise ;)

Oh for clear skies and all the eyepieces we could wish for... :sigh:

  • Like 1

Share this post


Link to post
Share on other sites

The LX and Mak are not the sternest of tests, you need a fast Dobsonian or the like

This is true. Alan can only use the scopes he has though, unless we all club together to buy him a 20" dob :grin:

  • Like 1

Share this post


Link to post
Share on other sites

This is true. Alan can only use the scopes he has though, unless we all club together to buy him a 20" dob :grin:

The exact sort of thing kickstarter was made for :)

"£... buys you the secondary mirror and a picture of Alan's face when he first assembles it" :D

Alan, how does a Sumerian Optics dob sound?

  • Like 1

Share this post


Link to post
Share on other sites

This is true. Alan can only use the scopes he has though, unless we all club together to buy him a 20" dob :grin:

The Mak-Newt and the fracs he has give a good indication. I was wondering why a monster dob is best, when a first order approximation would suggest any fast Newtonian might do. The answer is that for a given focal ratio, the bigger Newtonians have the smaller central obstruction. The kids' 4.5" F/4.3 has a massive 44% central obstruction in order to prevent vignetting. The diffraction that causes might well mask some of the aberrations of the EP

Share this post


Link to post
Share on other sites

Yes I agree the LX is slow and the other even slower and no real test . The fastest scope i have is the F5.26 Mac/Newt which at a meter could use almost any eyepiece but at the 35mm end the exit is getting a bit large. The APO is F7 so the M/N is about as fast as I can go though I also have a 70mm ED at F6 but it is not that great. Maybe I will try to do a bit on all of them and I can use the 13mm Ethos as well. It will take me some time to put it together at the moment it seems to be thunder-storm season, 9 in three days, it don't look too cleaver for tonight at the moment either.

When you think about it I could have a 20 inch dob if I didn't have so many eyepieces, eyepieces are easy to hide from the trouble and strife, a 20 inch would need a new building making , which would be a must because I would be in with it.

The reason I made the suggestion of the LX and the Mak is beacsuse I use 12mm-14mm in them as high power planetary eyepieces . I am no expert but I just find it easier to judge eyepieces when they are close to the limit, on the other scopes they don't really push the title of midrange. I am game to have a go and write my findings, I wish some of you could come and join in, it's only 3 days drive, so I am told.

Alan

  • Like 1

Share this post


Link to post
Share on other sites

Superb report on these two eyepieces, Alan, and really interesting for me. I'm building an eyepiece collection around XWs or Delos' and it really seems as though there is barely anything between the two models optically.

I don't think there's anything wrong with either eyepiece, but the snags for me are, smaller range of focal lengths in the XW line-up, and lack of availability, especially Delos', in the second hand market. I buy S/H wherever possible, but if I don't find the ones I need by the time nighttime returns to Scotland, I'll buy new. Saying that, I picked up a 10mm Delos off eBay in perfect condition, and it exceeds my expectations. Absolutely stunning, at least to handle! The design and build are infallible, and of a standard I've not seen in any eyepiece I've owned, including my ZAO orthos. I'm especially glad TV have listened to the complaints and used a tapered recess on the barrel rather than the previous sharp edged design.

Is there any difference between the two in weight? I got the impression that the Delos are a touch heavier?

Andrew

Share this post


Link to post
Share on other sites

Andrew,

I will put them on the scales and let you know, I have never thought of doing that, something to include in the future. If you wish to read my thoughts on the 6mm and the 10mm Delos as well as the 4.5mm in depth there are reports of some length in members equipment.

In truth I think any of these Delos or Pentax XW ranges offering 20mm of ER will out gun most if not all eyepieces in this area, they are that good. As John pointed out back in the thread the Pentax was not even designed for astronomy market and it goes back a good few years.

I had to move the apples first. 4.5mm Delos 485g Pentax 5mm xw 390g, these are not exact scales and came from Argos about 20 years ago.

Alan.

Edited by alan potts

Share this post


Link to post
Share on other sites

I can't recall who it was but he had his head screwed on the right way in his choice but wallet emptied at the same time. He went for 8mm Delos 7mm XW 6mm Delos and 5mm Xw

What a line up these make from two of the best eyepiece manufacturers,

That was me and your right about the wallet Alan :grin:

ps just noted Naemeth fiound it, cheers

Edited by bomberbaz
  • Like 1

Share this post


Link to post
Share on other sites

Great report btw Alan, love this kinda stuff but then it always starts you wondering about, well maybe I do have space for something else in my box, no stoppit :evil:

Share this post


Link to post
Share on other sites

Steve,

Yes I agree dangerous words. It was Johns report on the BGO's that made me go for them, though the 3 BGO's 1 Hutech and the Kasai only cost a little more than one of the eyepieces we are talking about here. I truely mean the comments about what a line up of quality 70 degree eyepieces. Look after them they will serve you well for years.

Alan.

  • Like 1

Share this post


Link to post
Share on other sites

Digging up another worthy old thread.... ?️?️

Compared to Pentax XW 7mm & 10mm, I have found their XW 5mm unsuitable for me due to Radian-like cut-offs if eye placement is not exact.

Eye relief on the XW was fine, no problem, but I have had to return the XW 5mm due to lack of comfort from required positioning exactness. My 10mm will get Barlowed or Vixen LVW used instead.

 

Edited by 25585
  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.