163 replies to this topic

[25585]

I thought the 24Delos has 22mm eye relief?  Still no go?

Its eye alignment that is the problem for me with Delos (& probably T7s too). Delites not affected, of those I tried (11mm & up). 

[Procyon]

Its eye alignment that is the problem for me with Delos (& probably T7s too). Delites not affected, of those I tried (11mm & up). 

Even when you roll down the eye guard and with that big Delos lens? Btw, do you know if the lens size will be the same as the other Delos (I believe they are abut 35mm in diameter) given that we know the eye relief and afov stats? I never understood how Don calculates these things, no matter how many times he tells me.

Edited by Procyon, 08 April 2025 - 06:40 PM.

[25585]

There is not much difference in TFOV between a 24mm Delos and 19T7, and only 16x magnification. But exit pupil is 1mm greater in the 24mm. I wonder if the Delos is a T7, but with a shrunk AFOV or the T7 is a maxed-out Delos in 2". If they are both from the same mysterious optical designer....

 

Lower price, weight, and longer eye relief might be the decider for some people between the two.

Attached Thumbnails

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Edited by 25585, 08 April 2025 - 06:53 PM.

[Scott99]

The notch in the accessory that the compression ring sits in is another "hangup point" when inserting the equipment.

That is true, I occasionally feel that.  I probably would like a nylon-tipped setscrew for my observing.  I don't need the clamp to exert a whole lot of force, just a tiny bit, with the eyepiece sitting in a star diagonal it's more like a "safety" in case something weird happens. 

[Scott99]

So the 24mm Delos looks more compact than the other Delos, and it looks like it doesn't have the twisting, rising body.  It's heavier than Panoptics but lighter than Naglers & Ethos. 

 

It is nearly twice the weight of my 20mm Masuyama 85'er.  Interesting competition there.  In my two f/9 scopes I doubt the 24mm could dislodge the Masuyama.  The 24mm would rule the shorter-focus world though.  This 24mm Delos with its smooth barrel and compact form is the most interesting TV ocular to me in many years.  

 

So a 30mm Delos would probably be similar in weight to the 30mm XW and 35mm Panoptic.  Hopefully a good response to the 24mm will bring on 30mm and 40mm Delos.

[CrazyPanda]

and it looks like it doesn't have the twisting, rising body

 

You mean the adjustable eye guard? It definitely has that.

 

See the second picture on Agena's listing: https://agenaastro.c...-tv-del24-2.jpg

Edited by CrazyPanda, 11 April 2025 - 10:13 AM.

[Phillip Creed]

So the 24mm Delos looks more compact than the other Delos, and it looks like it doesn't have the twisting, rising body.  It's heavier than Panoptics but lighter than Naglers & Ethos. 

 

It is nearly twice the weight of my 20mm Masuyama 85'er.  Interesting competition there.  In my two f/9 scopes I doubt the 24mm could dislodge the Masuyama.  The 24mm would rule the shorter-focus world though.  This 24mm Delos with its smooth barrel and compact form is the most interesting TV ocular to me in many years.  

 

So a 30mm Delos would probably be similar in weight to the 30mm XW and 35mm Panoptic.  Hopefully a good response to the 24mm will bring on 30mm and 40mm Delos.

I highly doubt a 40mm Delos is even possible.

 

In theory, a 72° eyepiece could be made up to ~21mm focal length in a 1.25" barrel but Tele Vue maxed it out at 17.3mm.   Based on that even a 30mm Delos is a stretch.

 

Clear Skies,

Phil

[Mike W]

I highly doubt a 40mm Delos is even possible.

 

In theory, a 72° eyepiece could be made up to ~21mm focal length in a 1.25" barrel but Tele Vue maxed it out at 17.3mm.   Based on that even a 30mm Delos is a stretch.

 

Clear Skies,

Phil

Gee, I wonder if Televue knows that! LOL

[25585]

No need for longer than 24mm FL Delos, as the 35 & 41 Panoptics theoretically have long enough eye relief already, and there is still currently the 22T4 Nagler as well.

[Phillip Creed]

No need for longer than 24mm FL Delos, as the 35 & 41 Panoptics theoretically have long enough eye relief already, and there is still currently the 22T4 Nagler as well.

Agreed, though to me the 35Pan become superfluous once the 31T5 came along since the latter has the smaller exit pupil and larger TFOV.  For those with refractors, SCTs or just don't care about exit pupil with their dobs, a 41Pan is the practical limit for TFOV with its 46mm field stop.

But it might get interesting if the Nagler Type 7 design was extended.

The Panoptic design has notable pincushion distortion.  You can clearly see that when you run the numbers.  Without distortion, a 68°-AFOV eyepiece should have a field stop 1.19X the focal length (68° / (180/pi)), or (68° / 57.3°).  But the Panoptic field stops run 1.11 - 1.13X, roughly 5% less.

Nagler Type 5's and Type 6's have similar distortion  An 82° eyepiece without distortion would have field stops ~1.43X focal length, but the T5s and T6's have field stops ~1.35X focal length.

What does get close to that 1.43X FS/FL ratio are the T7s:

https://www.televue....page.asp?id=214

**IF** Tele Vue could construct a 46mm field stop eyepiece whose field stop is 1.43X focal length that puts its focal length ~32mm.  Between the 41P and 31T5, the selection comes down to exit pupil for many observers.  But a 32T7 would essentially have the same exit pupil as the 31T5 but the maxed out FOV of the 41Pan.

Clear Skies,

Phil

[jrmacl]

Agreed, though to me the 35Pan become superfluous once the 31T5 came along since the latter has the smaller exit pupil and larger TFOV.  For those with refractors, SCTs or just don't care about exit pupil with their dobs, a 41Pan is the practical limit for TFOV with its 46mm field stop.

But it might get interesting if the Nagler Type 7 design was extended.

The Panoptic design has notable pincushion distortion.  You can clearly see that when you run the numbers.  Without distortion, a 68°-AFOV eyepiece should have a field stop 1.19X the focal length (68° / (180/pi)), or (68° / 57.3°).  But the Panoptic field stops run 1.11 - 1.13X, roughly 5% less.

Nagler Type 5's and Type 6's have similar distortion  An 82° eyepiece without distortion would have field stops ~1.43X focal length, but the T5s and T6's have field stops ~1.35X focal length.

What does get close to that 1.43X FS/FL ratio are the T7s:

https://www.televue....page.asp?id=214

**IF** Tele Vue could construct a 46mm field stop eyepiece whose field stop is 1.43X focal length that puts its focal length ~32mm.  Between the 41P and 31T5, the selection comes down to exit pupil for many observers.  But a 32T7 would essentially have the same exit pupil as the 31T5 but the maxed out FOV of the 41Pan.

Clear Skies,

Phil

I'm glad you posted this because I was playing around with astronomy tools with the relationship between the field of views of the Nager T5 16mm versus the Delos 17.3mm and that is what I guessed would be the maximum sized Delos.

 

It always plays with my mind a little when I do this because in my head I think well if they can make a 31mm T5 then why can't they make a 1.25" 19mm T5, or if 16mm was a large as they could make the T5 in 1.25" then how did they go larger than 25mm in 2"? (31 / 8 = 3.875, 3.875 x 5 = 19.375 and 16 / 5 = 3.2, 3.2 x 8 = 25.6). It seems to me that if the T5's are a scaled design then they should have been able to make a 19mm 1.25" but what do I know?

Edited by jrmacl, 12 April 2025 - 01:09 PM.

[Phillip Creed]

Regardless of what the MAXIMUM focal length of the Delos design turns out to be (Tele Vue probably knows), it's refreshing to see it expand enough to enter the 2"-realm.  It leaves all but the widest fields within reach of the Delos series, and there just isn't IMO a better eyepiece series out there.

Clear Skies,

Phil

[russell23]

Agreed, though to me the 35Pan become superfluous once the 31T5 came along since the latter has the smaller exit pupil and larger TFOV.  For those with refractors, SCTs or just don't care about exit pupil with their dobs, a 41Pan is the practical limit for TFOV with its 46mm field stop.

But it might get interesting if the Nagler Type 7 design was extended.

The Panoptic design has notable pincushion distortion.  You can clearly see that when you run the numbers.  Without distortion, a 68°-AFOV eyepiece should have a field stop 1.19X the focal length (68° / (180/pi)), or (68° / 57.3°).  But the Panoptic field stops run 1.11 - 1.13X, roughly 5% less.

Nagler Type 5's and Type 6's have similar distortion  An 82° eyepiece without distortion would have field stops ~1.43X focal length, but the T5s and T6's have field stops ~1.35X focal length.

What does get close to that 1.43X FS/FL ratio are the T7s:

https://www.televue....page.asp?id=214

**IF** Tele Vue could construct a 46mm field stop eyepiece whose field stop is 1.43X focal length that puts its focal length ~32mm.  Between the 41P and 31T5, the selection comes down to exit pupil for many observers.  But a 32T7 would essentially have the same exit pupil as the 31T5 but the maxed out FOV of the 41Pan.

Clear Skies,

Phil

I have not used the 31mm Nagler, but I have used the 35mm Pan.  I would say the 35mm is not superfluous for the following reasons:

 

~1.  Better eye relief for glasses wearers.  The 35mm Pan has 24mm of eye relief and is very comfortable with glasses.  Again, I have not used a 31mm Nagler, but reading numerous posts on this forum the 31mm Nagler seems to be a borderline eyepiece for glasses.

 

~2.  Lower weight.  The 31mm Nagler weighs almost 10 oz more than the 35mm Pan.  I do not think that would be an issue for any of my current focusers, but I have had refractors in the past where the 35mm Pan was as much weight as I felt it could handle. 

 

~3.  Lower cost.  The current prices are $734 for the 31mm Nagler and $451 for the 35mm Pan. That is a $280 difference which for some people would be a deal breaker difference. 

[Mike W]

Agreed, though to me the 35Pan become superfluous once the 31T5 came along since the latter has the smaller exit pupil and larger TFOV.  For those with refractors, SCTs or just don't care about exit pupil with their dobs, a 41Pan is the practical limit for TFOV with its 46mm field stop.

But it might get interesting if the Nagler Type 7 design was extended.

The Panoptic design has notable pincushion distortion.  You can clearly see that when you run the numbers.  Without distortion, a 68°-AFOV eyepiece should have a field stop 1.19X the focal length (68° / (180/pi)), or (68° / 57.3°).  But the Panoptic field stops run 1.11 - 1.13X, roughly 5% less.

Nagler Type 5's and Type 6's have similar distortion  An 82° eyepiece without distortion would have field stops ~1.43X focal length, but the T5s and T6's have field stops ~1.35X focal length.

What does get close to that 1.43X FS/FL ratio are the T7s:

https://www.televue....page.asp?id=214

**IF** Tele Vue could construct a 46mm field stop eyepiece whose field stop is 1.43X focal length that puts its focal length ~32mm.  Between the 41P and 31T5, the selection comes down to exit pupil for many observers.  But a 32T7 would essentially have the same exit pupil as the 31T5 but the maxed out FOV of the 41Pan.

Clear Skies,

Phil

Pincushion in the old pan design, not the 24pan that Paul D. designed.

[russell23]

Pincushion in the old pan design, not the 24pan that Paul D. designed.

The first time I tried a Pan - the 27mm - I was thrown off by the pincushion.  But after more years using different eyepieces I found it less objectionable.  I don't have a 35mm Pan right now, but I think it may be the best of the Pans currently offered.  I would guess the 24mm Delos will compete with the 27mm Pan more than the 24mm Pan just because of the 2" barrel.

[25585]

The 24 Pan does not have enough eye relief for glasses wearers. Its predecessor, the 24mm Wide Field only just had, and that was down to its old school form factor i.e. "smoothie".

Edited by 25585, 12 April 2025 - 05:39 PM.

[russell23]

The 24 Pan dies not have enough eye reluef for glasses wearers. Its predecessor, the 24mm Wide Field only just had, and that was down to its old school form factor i.e. "smoothie".

I'm guessing, but I suspect the 24mm Pan still has a market for those that want a max 1.25" and for those that want to use binoviewers.  The 24mm Delos will draw people like you and I that need enough eye relief for comfortable use with glasses.  The 24mm Delos is definitely on my radar.  I think it would be great with all of my refractors.  I was planning on the 9mm T7 Nagler, but if they become available at about the same time I might opt for the 24mm Delos first because I think it would get more use than the 9mm Nagler. 
 

[Mike W]

The 24 Pan dies not have enough eye reluef for glasses wearers. Its predecessor, the 24mm Wide Field only just had, and that was down to its old school form factor i.e. "smoothie".

Even my 19pan has plenty of E/R for me. Can't you use a Dioptrix or take your glasses off?

[25585]

Even my 19pan has plenty of E/R for me. Can't you use a Dioptrix or take your glasses off?

No. My glasses subscription and use need goes beyond what a Dioptrx can do. 

[russell23]

Even my 19pan has plenty of E/R for me. Can't you use a Dioptrix or take your glasses off?

Without glasses the 19mm Pan is great. I really wish I could use it without glasses. 

 

I really disliked the dioptrx.  Not to mention eyeglasses tend to correct fully for the individual eyes.  I never felt the dioptrx was as good as my glasses when I did have one.

[Mike W]

I get it but stop painting eyepieces as unusable for eyeglass wearers when it's not true for all but severe cases. My daughter wears glasses and she does fine with the 24 pan without them.

[russell23]

I get it but stop painting eyepieces as unusable for eyeglass wearers when it's not true for all but severe cases. My daughter wears glasses and she does fine with the 24 pan without them.

That is not what I said or have ever said.  A lot of hyperbole on this forum today.  If you have to wear glasses while observing to correct for astigmatism then the 24mm and 19mm Pan will not work because you cannot use them with glasses.  They are unusable for people in that situation.  Consider yourself fortunate that you do not have to wear glasses to correct for astigmatism.  When you have astigmatism the effects are worse at larger exit pupils - 19mm and 24mm eyepieces can be particularly unusable for people that need glasses. 

 

And what is "severe cases"?  Every person that has astigmatism will have an exit pupil size at which the effects of the astigmatism is noticeable.  And for many people astigmatism gets worse as you age making the astigmatism noticeable at smaller and smaller exit pupils. In addition, whatever astigmatism level your daytime glasses have, it is typically a 1/4 diopter worse at night with a larger exit pupil.

 

I used to be able to get away with taking off my glasses when the exit pupil was 1.4mm or smaller.  Now it has to be less than 1mm.  So unless I get an f/19 telescope I'm not going to be able to use the 19mm Pan without glasses.  And you cannot use a 19mm Pan with glasses - so that is the problem.

 

You severely underestimate what people with astigmatism, not an uncommon eye condition, deal with due what I assume is a complete lack of experience with the condition.  I'd say talk to someone you know that observes and has astigmatism, but all you have to do is pay attention on this forum to understand the problem.  It has been discussed in detail for years.  Given that you have been on this forum since 2006 it is quite unbelievable that you do don't understand this.

 

 

 

 

[TayM57]

I really disliked the dioptrx.  Not to mention eyeglasses tend to correct fully for the individual eyes.  I never felt the dioptrx was as good as my glasses when I did have one.

Agree.

[Mike W]

I get it but stop painting eyepieces as unusable for eyeglass wearers when it's not true for all but severe cases. My daughter wears glasses and she does fine with the 24 pan without them.

That was meant for 25585, not you. You must have been responding the same time as me. The same time stamp.

25585 said "The 24 pan does not have enough E/R for eyeglass wearers" My daughter does not have astigmatism so although she wears glasses not to look through the telescope or binoculars.

I wear reading glasses and am slightly nearsighted but my eyes still pass DMV. I do wear glasses for driving at night but never use them with my binocs or telescope.  

Edited by Mike W, 12 April 2025 - 09:35 PM.

[Dobs O Fun]

Let's knock off the back and forth and the who-said-what-to-who.

 

This thread is one point from being locked.