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Delos 3.5mm vs. Pentax XW 3.5mm?

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#1 sportsmed

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Posted 23 October 2021 - 07:33 AM

So I was looking at 3mm to 4mm eyepieces to push my refractors to higher mag on planets and was about to pull the trigger on the Delites but was thinking I would rather have a wider FOV then 62o. And I wasnt for sure if I wanted to buy a 3mm or a 4mm first so I thought splitting the difference could be a good option with a 3.5mm. So for those of you that have been able to view with the 3.5mm Delos or Pentax or have had both and was able to compare I was wondering your thoughts on the two. I would mainly be using them in my AT80ED but I do have a Orion 120ST on a manual mount hence the wider FOV would be nice, plus I will be buying another Astro-Tech refractor in the future. Would be interested in your thoughts, thanks!



#2 John Gauvreau

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Posted 23 October 2021 - 07:41 AM

The nutshell is both are superb and you won’t be making a mistake with either one.  

I have tried both and have the 3.5XW.  It is strictly personal preference as the view through the Delos was equally good.  Just my taste made me pick the Pentax XW. 
 

I totally get what you’re saying about the wider field, although it’s not crucial at high magnification planetary viewing.  My 3.5XW is used often for this purpose and I absolutely love it.  So comfortable and contrasty.  Others will tell you the same about the Delos and they are also correct.


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#3 RAKing

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Posted 23 October 2021 - 08:09 AM

I agree with John - both of these eyepieces are superb and you should be happy with either one.

 

I have both of these eyepieces and the reason is the Delos is parfocal with the other short Delos eyepieces and the Pentax is parfocal with the other Pentax eyepieces.  When you get up to very high magnification, the exit pupil is tiny and focusing can be a chore sometimes.  It might just be my eyes, but I find it better for me if I focus with a longer eyepiece, then move to a parfocal higher magnification eyepiece where a simple "twitch" of the fine focus knob keeps everything razor sharp.

 

So if I am using a Delos 6 or 4.5mm, I'll put the Delos 3.5 in the case; if I am using the Pentax 7 or 5, I will carry the Pentax.  And since there are more Delos with tighter "gaps", I have been using the Delos series most of this past year.

 

Cheers,

 

Ron


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#4 junomike

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Posted 23 October 2021 - 08:09 AM

As John stated, either are excellent and they are more similar than different.

I had both complete sets and kept the Delos (at the time) as I prerffered the warmer tone and Star saturation.

At times however on some objects I preferred the cooler tone of the XW's.

Can't go wrong with either.


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#5 f74265a

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Posted 23 October 2021 - 08:39 AM

Own both. Agree with above both are excellent. Subjectively prefer the 3.5 Delos. But if I’m using my xw set for the evening then I stick with 3.5 xw. Xw is less expensive, which is a plus.
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#6 GGK

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Posted 23 October 2021 - 09:19 AM

To show the difference between the Delite, XW and Delos---

 

Note that these are not the same focal length or the short focal length you're considering, so overall length will change accordingly.

 

IMG_2621.jpg

 

IMG_2620.jpg

 

They're all great optically and as others have said, "best" is simply personal preference. 

 

I prefer the Delos or XW vs. the Delite because of the larger diameter opening in the eyecup.  I view without glasses and extend the eyecup up high and put my face in contact with the rim.  The "tunnel" blocks much of the side ambient light.  Due to the Iris in the Delite, the opening is smaller and my eyelashes will hit the iris when used this way, so I must drop the eyecup a little and keep further away. This doesn't happen with the XW or Delos.   I use Delites in a binoviewer because they're smaller and with both eyes, I keep my face back a little anyway. The Delites are also much lighter.  Views in all three are sharp.


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#7 Tank

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Posted 23 October 2021 - 10:04 AM

Had both in a TEC 140
Both acted pretty much the same on Jupiter/saturn
Cant go wrong with either
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#8 csrlice12

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Posted 23 October 2021 - 10:41 AM

Have a mixed set of XWs and Delos....optically, flip a coin....ergonomically.....Al shudda hired the XW clothing designer.  A simple twist and the XW is adjusted.  I sometimes feel like I'm choking a Delos to death adjusting the eyecup.   JMHO....there's also the 3.7 Ethos to consider $$$$.


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#9 sportsmed

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Posted 23 October 2021 - 03:44 PM

Thank you all for your replies so far, I like to read others experiences with gear so its helpful. The main thing for me was to have a EP that is very well designed optically since it will be one of my highest mag eyepieces for planetary and of course having a wider FOV then the Delites. I'm leaning toward the 3.5mm Pentax, since everyone says its pretty comparable to the Delos and its cheaper as well as lighter. The only other option that interest me is the APM 100o but not sure optically how it holds up to the Delos or XW. 



#10 f74265a

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Posted 23 October 2021 - 03:58 PM

Above suggestion of 3.7 ethos is spot on. It is fantastic albeit expensive. Overall, the 3.7 is my favourite High power eyepiece. No comment on apm 100s.
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#11 SeattleScott

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Posted 23 October 2021 - 04:52 PM

I think a Hyperwide is a bit overkill for planetary use in an 80mm, unless you are trying to frame the Moon at high power or something. You just aren’t going to hit the 400x+ magnifications where you really want 110 AFOV to help with tracking. Makes more sense to go with smaller, lighter eyepiece with less glass and light scatter. Not that there is a big difference between 8 and 9, so if you really do want to frame the Moon, I suppose go for it.

Scott

#12 GGK

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Posted 23 October 2021 - 06:21 PM

Thank you all for your replies so far, I like to read others experiences with gear so its helpful. The main thing for me was to have a EP that is very well designed optically since it will be one of my highest mag eyepieces for planetary and of course having a wider FOV then the Delites. I'm leaning toward the 3.5mm Pentax, since everyone says its pretty comparable to the Delos and its cheaper as well as lighter. The only other option that interest me is the APM 100o but not sure optically how it holds up to the Delos or XW. 

It makes no difference to me what eyepiece you buy, but know that many of us can’t see the full field at 100 degrees in an Ethos or other ultra wide angle eyepiece. In addition, the eye pieces your discussing above have 20mm eye relief, but the Ethos and APM have a max of 15 mm. I just visited Skies Unlimited with the intent of buying some Ethos, but left with none. The eye relief for me was uncomfortably short, and I was not able to see past about 80 degrees without moving my head around a lot. If I could tolerate the shorter eye relief (like many can) and if I could actually see the full field of view (like many can), I believe it would be a fantastic eyepiece for DSOs. It just isn’t for me. I’m very happy in the 70 to 80 degree range though, and 17 mm minimum eye relief is an absolute must-have for me. Suggest you see if there’s a place to try one before laying down the $$, or figure the small loss selling it right away is the price of the trial if it doesn’t work out for you. 
 

edit<removed doubled word>


Edited by GGK, 23 October 2021 - 09:35 PM.

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#13 sportsmed

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Posted 23 October 2021 - 09:35 PM

I think a Hyperwide is a bit overkill for planetary use in an 80mm, unless you are trying to frame the Moon at high power or something. You just aren’t going to hit the 400x+ magnifications where you really want 110 AFOV to help with tracking. Makes more sense to go with smaller, lighter eyepiece with less glass and light scatter. Not that there is a big difference between 8 and 9, so if you really do want to frame the Moon, I suppose go for it.

Scott

Well the reason I was mainly thinking APM 100o was for drift time on a manual mount but framing the moon etc can also be a plus with a 100o . But I have never used a Hyperwide EP only up to 82o which I like and find 68-82o to be a sweet spot for me for framing objects and dealing with drift time when using manual mounts. And having less glass/ light scatter is a valid point and also a reason I'm looking at buying a 3.5mm in the first place. Because I have been using my ES82 6.7mm and X-Cel LX 9mm with a 2.5x barlow for high power viewing and have to deal with some light scatter at times.



#14 csrlice12

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Posted 23 October 2021 - 11:38 PM

To be truthful....seeing the entire moon in the fov of my 81mm refractor at 170X is quite a site.....


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#15 ausastronomer

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Posted 24 October 2021 - 03:54 AM

Have a mixed set of XWs and Delos....optically, flip a coin....ergonomically.....Al shudda hired the XW clothing designer.  A simple twist and the XW is adjusted.  I sometimes feel like I'm choking a Delos to death adjusting the eyecup.   JMHO....there's also the 3.7 Ethos to consider $$$$.

 

Why do you keep adjusting them ?

 

I can understand that if you lend them to people you might need to re adjust them, or if you're playing around, but if you're the only one using them you shouldn't need to adjust anything.

 

I haven't moved the eye cup on my Pentax XW's after setting them where they needed to be 20 years ago and I haven't moved the eye cup on my Delos after setting it where it needed to be 7 years ago.

 

Cheers  


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#16 csrlice12

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Posted 24 October 2021 - 10:05 AM

Why do you keep adjusting them ?

 

I can understand that if you lend them to people you might need to re adjust them, or if you're playing around, but if you're the only one using them you shouldn't need to adjust anything.

 

I haven't moved the eye cup on my Pentax XW's after setting them where they needed to be 20 years ago and I haven't moved the eye cup on my Delos after setting it where it needed to be 7 years ago.

 

Cheers  

It's my bad eyes, use in different scopes.  Sometimes my dominant eye is useless due to a detached fluid sack and floaters and I have to use my right eye, whose vision is not as good.  Eye doc says wait till I need cataract surgery before correcting the detached fluid sack.....it's also a bit detached on my right eye, but not near as bad.  I also find I adjust them based on if I'm doing lunar/planets versus nebulas and galaxies.


Edited by csrlice12, 24 October 2021 - 10:07 AM.


#17 cst4

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Posted 26 October 2021 - 11:08 AM

Thank you all for your replies so far, I like to read others experiences with gear so its helpful. The main thing for me was to have a EP that is very well designed optically since it will be one of my highest mag eyepieces for planetary and of course having a wider FOV then the Delites. I'm leaning toward the 3.5mm Pentax, since everyone says its pretty comparable to the Delos and its cheaper as well as lighter. The only other option that interest me is the APM 100o but not sure optically how it holds up to the Delos or XW. 

I have 3.5mm Delos, XW, and APM.  In my 4" F/7 apo 3.5mm provides the "theoretical max" of 50x/inch at 200x.  I use this magnification a good bit on planets so I've been battling it out with these 3 EP's for quite some time now.  The intention was to keep only one, but it's been a very tough decision as they are all 3 wonderful.  In my opinion the XW has the best light/scatter/glare control with perhaps the blackest background so it might get my vote optically.  However, the Delos is neck and neck and may be a bit sharper near the edges and with a more solid build.  The APM might be a smidge behind the others optically but not by much and provides awesome drift time at 200x on my manual mount.  You can't go wrong with any of them as long as you are ok with their weight and size.


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#18 iseegeorgesstar

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Posted 26 October 2021 - 07:14 PM

To show the difference between the Delite, XW and Delos---

Note that these are not the same focal length or the short focal length you're considering, so overall length will change accordingly.

IMG_2621.jpg

IMG_2620.jpg

They're all great optically and as others have said, "best" is simply personal preference.

I prefer the Delos or XW vs. the Delite because of the larger diameter opening in the eyecup. I view without glasses and extend the eyecup up high and put my face in contact with the rim. The "tunnel" blocks much of the side ambient light. Due to the Iris in the Delite, the opening is smaller and my eyelashes will hit the iris when used this way, so I must drop the eyecup a little and keep further away. This doesn't happen with the XW or Delos. I use Delites in a binoviewer because they're smaller and with both eyes, I keep my face back a little anyway. The Delites are also much lighter. Views in all three are sharp.

Oh wow. What a size difference. I just got a 4mm delite and found it "weighty". Boy would I have been shocked if I got a Delos. Lol.

Edited by iseegeorgesstar, 26 October 2021 - 07:14 PM.

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#19 sportsmed

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Posted 27 October 2021 - 03:40 AM

I have 3.5mm Delos, XW, and APM.  In my 4" F/7 apo 3.5mm provides the "theoretical max" of 50x/inch at 200x.  I use this magnification a good bit on planets so I've been battling it out with these 3 EP's for quite some time now.  The intention was to keep only one, but it's been a very tough decision as they are all 3 wonderful.  In my opinion the XW has the best light/scatter/glare control with perhaps the blackest background so it might get my vote optically.  However, the Delos is neck and neck and may be a bit sharper near the edges and with a more solid build.  The APM might be a smidge behind the others optically but not by much and provides awesome drift time at 200x on my manual mount.  You can't go wrong with any of them as long as you are ok with their weight and size.

Thanks for your reply, yea the optical quality is what I'm really after but of course with a wider FOV, that APM does interest me because of the drift time or framing the Moon etc. But if the XW is better optically then that would be a better option since it will be mainly used for planetary and 70o is still a fairly wide view. Its good to hear from someone that has all three eyepieces and can compare. So many options, I wish I could just try all 3 before I bought haha.



#20 rkelley8493

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Posted 27 October 2021 - 01:05 PM

I've got the 3.5 XW & 3.5 Delos, but I haven't had much time to compare them yet. I also have the 3.7 Ethos and was planning to do a shootout sometime in the near future.

So far, the differences I've seen between the XW & Delos are as follows [viewing with a 130 f/7 apo refractor].

The Pentax 3.5 XW has a slightly brighter image than the Delos, and the color tone is more neutral. Jupiter's Red Spot had a distinctly different shade of red than the nearby cloud bands, almost a 'salmon' color. I could also see tonal differences in each of the cloud bands, like an artist's palette of red, orange, and brown. With the Delos, the color tone was a bit warmer, but it gave richness to the cloud bands and made it feel more saturated in color. The tonal differences in the cloud bands weren't as visible, but the colors seemed richer overall.

When using an eyepiece with such a short focal length and long eye relief, the biggest problem is the exit pupil behavior. The XW was more prone to black-outs when your eye wasn't positioned correctly. However, the Delos was more prone to chromatic aberration of the exit pupil [aka Ring of Fire distortion].  Both have an adjustable eye guard to help position your eye correctly, but it takes some practice and you have to get familiar with the eyepiece[s] to get the best use out of it.


Edited by rkelley8493, 27 October 2021 - 01:08 PM.

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#21 Dave Mitsky

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Posted 27 October 2021 - 01:47 PM

I also own a mix of Pentax XWs and Tele Vue Delos eyepieces but none of those focal lengths.  I enjoy using both types, preferring the ergonomics of the XWs and the field of view of the Delos eyepieces.


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#22 Tom Dugan

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Posted 29 October 2021 - 10:09 AM

Thanks for starting and contributing to this thread, everyone! I have an ES 127ED, and I love the Pentax XW 5mm in it. I've noticed that even here at sea level I've still got a little bit of headroom, magnification-wise, and y'all have cemented my choice of the 3.5mm Pentax.


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#23 ausastronomer

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Posted 30 October 2021 - 04:40 PM

Thanks for starting and contributing to this thread, everyone! I have an ES 127ED, and I love the Pentax XW 5mm in it. I've noticed that even here at sea level I've still got a little bit of headroom, magnification-wise, and y'all have cemented my choice of the 3.5mm Pentax.

Hi Tom,

 

I'm sure you will be very happy with the 3.5mm Pentax XW.  I have had all of the 1.25" Pentax XW's for many years.  I put all of the 10mm and under Pentax XW's on pretty equal footing and absolutely superb.  They have no warts for mine. The 14mm and 20mm Pentax XW's work very well in my newtonians when combined with a paracorr, but show some field curvature without the paracorr.

 

Cheers


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