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Tanglebones

Tele Vue Eyepieces for Mak 180

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Hi all.  I've been into astronomy for about a year and a half now and for all that time I've used either the stock 28mm LET 2" eyepiece that Sky-Watcher seems to love giving away with every scope, as well as a Baader 8-24mm zoom.  While I like using both of these, I have been saving my pennies for the day when I can get better quality ones.  I've never owned a Tele Vue, so that is what I'm going for first.  The two scopes I use the most are a 12" Newtonian (on an EQ mount) and a new Sky-Watcher Mak 180.  It is for this new scope that I am focusing on at the moment, though of course anything I do buy can be used in both.  

I used the 'Eyepiece Calculator' on the Tele Vue website and entered my parameters (2700mm FL, 180mm aperture, f/15, 2" eyepieces can be used) and viewed the resulting table.  I am pretty sure I've settled on the high power (DeLite 11mm) and medium power (DeLite 18.2mm) eyepieces, but would like to ask for some assistance with the low power selection.

I'm a bit confused by all the parameters I need to take into account so that I select an ep that will give me the best possible view with the limited FoV this specialized scope can offer.  I measured the opening in the visual back of the Mak 180 to be 30mm (I didn't use anything more accurate than a tape measure and my 54-year old eyes, but this is reasonably accurate.  

Q: Using the formula TFOV = Field Stop / Focal Length * 57.3, that works out to 0.64° maximum true field of view possible with this scope.  Is that correct?  And, therefore, I should be looking for an eyepiece that equals that TFOV, or smaller...

Q: If I assume that this 30mm is the narrowest opening light will have to pass through on the way to my eye (i.e. the 'field stop' of the telescope), is it true that if I select an eyepiece with a larger field stop, such as the Panoptic 35, then I will get vignetting?  I think this must be the case.  The field stop of this eyepiece is 38.7mm, so I reason that 30mm of that diameter will be fully illuminated and the remaining 8.7mm will suffer from some degree of vignetting.  Do I understand that correctly?

I'm also a bit puzzled by exit pupil.  I've read that 0.5mm exit pupil is the recommended minimum and that, in general, larger is better up to the pupil width of your eye.  That 35mm Panoptic has an exit pupil of 2.3mm in my scope, according to the fine folks at TeleVue.  So if I compare that to a 27mm Panoptic, which has a 30.5mm field stop and a 1.8mm exit pupil, which one will give the brighter views?  I'm really torn by this, because the 27mm won't have vignetting (by my earlier supposition), but it will have a smaller exit pupil.  Does one compensate for the other?

Using this 'logic', I've narrowed my choices down to the following, in order of greater to smaller TFOV:

Nagler 22mm (0.66° TFOV)

Panoptic 27mm (0.65° TFOV)

Ethos 17mm (0.63° TFOV)

If I'm reading this crazy mumbo-jumbo right, the Nagler 22mm will give me the larger TFOV (by a tiny amount over the P27), with the Ethos falling third.  What role does AFOV have in all this?  Would you guys recommend a 100° AFOV even if it meant a smaller TFOV?  Or would you take the larger TFOV over a smaller 82° (Nagler) or 68° (Panoptic) AFOV?

So many choices and I don't want to buy the wrong one!

If I haven't put you to sleep by all this, thanks in advance.

- Stu

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The 35mm Panoptic is the limit on this scope, the 41mm Panoptic vignettes a fair bit but this was never intended to be a wide field scope so I guess I can't complain.

It is a very good scope though and mine should see more light than it does, still not really many planets in the evening sky at the moment.

Alan

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the 27 pan has a great fanbase,personally....try an ethos first. If you can borrow one for a night it might save you an awful lot of money...eg....if you love them then you wont trawl through endless ep's ...or if you hate the widefield then this will save you money!.....ps the naglers are superb also....I don't think I'm helping much!

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The 35mm Panoptic is the limit on this scope, the 41mm Panoptic vignettes a fair bit but this was never intended to be a wide field scope so I guess I can't complain.

It is a very good scope though and mine should see more light than it does, still not really many planets in the evening sky at the moment.

Alan

Alan - does the 35 Panoptic vignette with this scope?  I don't see how it can't be vignetting, though I admit I'm not certain what causes that.

- Stu

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the 27 pan has a great fanbase,personally....try an ethos first. If you can borrow one for a night it might save you an awful lot of money...eg....if you love them then you wont trawl through endless ep's ...or if you hate the widefield then this will save you money!.....ps the naglers are superb also....I don't think I'm helping much!

Good advice, thank you.  I will ask in our local astronomy club if anyone has any of these eyepieces.

- Stu

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Stu,

Although the Ethos would give you cavernous AFOV, it wouldn't give you the low power option you are seeking to go alongside the two Delites (which sound like excellent choices with your scope.)

The best and most used wider field EP with my Mak and SCT is the Panoptic 24, but I am sure the 27mm would also be just as good a choice. They are fabulous eyepieces that seem to shine in all telescopes.

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Alan - does the 35 Panoptic vignette with this scope?  I don't see how it can't be vignetting, though I admit I'm not certain what causes that.

- Stu

No the 35mm Panoptic is fine with a TV diagonal and is one of my most used eyepieces, it is sort of a finder. The 41mm is not so good as it vignettes, it does a bit on my 12inch SC Meade as well but very slight.

Another thing I tried was a .63 focal reducer which for me was a waste of time, I read somewhere they could be used but I beg to differ.

I have a fair selection of TV eyepieces and they all work well on the Mak, with it being driven I also use orthoscopics as well but I find that 12.5mm is about as far as you need to go most of the time but I can recall using 9mm on Mars to give a nice round X300.

Alan.

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I've heard a lot of good things about the 24mm and now have it firmly in the possibility camp, replacing the 27mm which I've just given the heave ho.  I think a 35 Panoptic/24 Panoptic/18.2 DeLite/11 DeLite will be what I'm aiming for, along with the 2" and 1.25" Everbrite diagonals.  All in due course, of course, and these will work well with my other scope also.  (12" Newtonian).

Thank you for all the responses, much appreciated.

- Stu

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Sounds great Stu :icon_biggrin:

Out of interest, why do you feel you need 1.25" and 2" diagonals ?

Sorry if I've missed the answer elsewhere in the thread !

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To get maximum field of view with the Mak 180 I acquired just before Xmas, I bought a 38mm Panaview as I noticed that a number of people seemd to use these as their preferred (or maybe cheapest) wide field EP (thank you also John for the advice).

To my surprise it performs rather well (particularly when the eye cup is rotated out to the correct position!) as there were some accounts of vignetting and coma towards the outer part of the field. The field is reasonably sharp from edge to edge and is wide enough to fit in both M81 and M82 with some to spare (note the scope is the modern spec, with a 2" focuser and diagonal). Certainly, for the price I am impressed.

Chris

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If the aperture in the back plate leading to the 2" diagonal is 30mm my guess anything longer or wider than a 24mm Pan and your going to gain no significant FOV. There is supposedly an advantage to using 2" EP's but again no point going ultra wide beyond 24mm.

Edited by spaceboy

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If the aperture in the back plate leading to the 2" diagonal is 30mm my guess anything wider than a 24mm Pan and your going to gain no significant FOV.

That's the odd thing: the back plate connector has a tube which is (by eye) 1 1/4", however the FoV appears to be larger than I'd calculated, hence my point about M81 + M82. With a 24mm Pan, I think you'd only get about 44 arcmin FoV and yet to get M81 + M82 with a bit of space, you need nigh on 60 arcmin??

Chris

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No the 35mm Panoptic is fine with a TV diagonal and is one of my most used eyepieces, it is sort of a finder. The 41mm is not so good as it vignettes, it does a bit on my 12inch SC Meade as well but very slight.

That is consistent with my experience with an ES68 34mm. I doesn't vignette despite the visual back of the Mak 180 being only 30mm wide.

I'm not going to repeat what I just explained on CN but Tanglebones will find this reassuring :)

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I've heard a lot of good things about the 24mm and now have it firmly in the possibility camp, replacing the 27mm which I've just given the heave ho.  I think a 35 Panoptic/24 Panoptic/18.2 DeLite/11 DeLite will be what I'm aiming for, along with the 2" and 1.25" Everbrite diagonals.  All in due course, of course, and these will work well with my other scope also.  (12" Newtonian).

Thank you for all the responses, much appreciated.

- Stu

They sound like four fine, complementary eyepieces.

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I'm 54 years old, so how come I still feel like a 6 year-old on Christmas morning?  My new eyepieces arrived today and I'm frantically doing my best to appease the weather gods so I can check them out.  I ended up getting the Panoptic 35mm, the DeLite 18.2mm and the DeLite 11mm for the Mak 180.  I also picked up the Everbrite 2" diagonal.  Eyepieces to last many, many years I hope.

Thanks to everyone for your assistance and advice, whether followed or not it is always much appreciated.

- Stu

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Sounds great Stu :icon_biggrin:

Out of interest, why do you feel you need 1.25" and 2" diagonals ?

Sorry if I've missed the answer elsewhere in the thread !

Sorry, I missed this earlier.  I think I was assuming I would need both, but I guess I only need the 2" and can just step-down to use 1.25" eyepieces, correct?

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I noticed you were talking TeleVue, just be aware the TeleVue 2 inch diagonal does not come with the reducer allowing you to use 1.25 inch eyepieces, I had to buy these extra, 3 of them, though any brand will fit it is still going to cost 20 quid I would think.

I'm sad and had to have the real deal.

Alan

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Congratulations on your new eyepieces and the diagonal :icon_biggrin:

Sorry, I missed this earlier.  I think I was assuming I would need both, but I guess I only need the 2" and can just step-down to use 1.25" eyepieces, correct?

Correct but as Alan says, thay don't come as standard with Tele Vue Everbright 2" diagonals, despite their price.

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We had clear skies tonight so I had the Mak 180 out for an hour or so watching the Moon chasing Aldebaran around the sky.  I tested all three new eyepieces and I am very, very happy with them. On that scope, the 11mm will be the high power choice for most viewing nights, and both it and the 18.2 are sharp from edge to edge.  It is with the Panoptic 35 that I am most impressed, however.  I was just blown away by how much detail I could see, and how bright and clear everything was.  My attention was mainly focused on Sinus Iridum tonight and couldn't drag my eyes away from all the wrinkle ridges and tiniest of craters evident.  I was also looking at where Montes Jura descended into the 'bay', noting all the dark shadows and the glassy smoothness of the 'water'.  Lovely, lovely views.

If there is vignetting, I couldn't see it.  The FoV is larger than the Moon so if there was subtle darkening of the fringes it didn't catch my attention.  I'm hoping to get a look at M42 tomorrow night so I can compare it to my other eyepieces.

Again, many thanks.

- Stu

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Nice little report there Stu, good to hear that you got out, I had a beauiful sky but way too much snow around. As much as I love Televue eyepieces, it is worth considering others because at F15 the scope is very kind to all eyepieces. Meade and ExSc as well as Vixen's (though I have never used them) will give a very similar performance in the Mak.

If however you suddenly buy an F4 Dobsonian then the first alternatives I mention will not be as good but will still turn in a reasonable performance, I don't know how the Vixen ranges are at these speeds.

I started off with Meades, most of there better eyepieces from the 5000 Series and then moved over to TeleVue, this is where I wish now I had started, as I would have saved money in the long run.

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Glad its all looking good with the EPs.  The 180 is a cracking scope which makes almost any EP work pretty well.  I have found with mine that some ultra wides can be badly...... behaved the worst I have seen with mine was the ES 30mm 82' which produces vignetting but also a 'ring of fire' round the edge of the EP which is very distracting.  From memory the exit portal on mine is 25mm.  I rarely use widefields on it and prefer orthos in the main.  I have never tried the Pentax XW30 in it so cant say how that would perform.

Sounds like you are having great success with the scope though which is good to hear.

If the weather and my availability were to ever to come together again I could tell you how a great many EPs sat here gathering dust perform on it :)

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Nice little report there Stu, good to hear that you got out, I had a beauiful sky but way too much snow around. As much as I love Televue eyepieces, it is worth considering others because at F15 the scope is very kind to all eyepieces. Meade and ExSc as well as Vixen's (though I have never used them) will give a very similar performance in the Mak.

If however you suddenly buy an F4 Dobsonian then the first alternatives I mention will not be as good but will still turn in a reasonable performance, I don't know how the Vixen ranges are at these speeds.

I started off with Meades, most of there better eyepieces from the 5000 Series and then moved over to TeleVue, this is where I wish now I had started, as I would have saved money in the long run.

Alan - I also have a Sky-Watcher 300PDS, so selected quality eyepieces up front so that I would maximize the views in both scopes.  I wanted a set that was versatile enough for current and (potentially) future scopes and put a fair amount of time into picking what focal lengths I wanted.  Of course, all the plans of mice and men will come to nowt as soon as something new and shiny is released.  :-).

- Stu

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Glad its all looking good with the EPs.  The 180 is a cracking scope which makes almost any EP work pretty well.  I have found with mine that some ultra wides can be badly...... behaved the worst I have seen with mine was the ES 30mm 82' which produces vignetting but also a 'ring of fire' round the edge of the EP which is very distracting.  From memory the exit portal on mine is 25mm.  I rarely use widefields on it and prefer orthos in the main.  I have never tried the Pentax XW30 in it so cant say how that would perform.

Sounds like you are having great success with the scope though which is good to hear.

If the weather and my availability were to ever to come together again I could tell you how a great many EPs sat here gathering dust perform on it :)

Thank you, Astro_Baby.  I have to say - you are one of the primary reasons I now have a Mak 180.  When I was initially scope shopping I didn't give them a second thought and went ahead with a 300PDS.  Later, as I was looking to complement that scope with something more geared to planetary/lunar/double star work, it was your review that really made me take a hard look at them.   Even with the Newt, your collimation advice was printed off and in front of me the first time I nervously reattached my secondary after flocking the tube.  

When you are new to something, and searching about in the darkness for the first toe-hold on to what seems like an impossibly high mountain to climb, websites such as yours (and Dion's videos come to mind also) are invaluable.  The effort of taking the time to start and finish the writeup, and to shoot/edit/add the images, all for the benefit of others, is much appreciated.  In gratitude, I'll talk to Environment Canada and see if we can send some cloud-free skies your way in a couple of days.  :-)

- Stu

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Sorry to flog a dead horse here, but I just wanted to give an update on my choice of eyepieces to use with the Mak 180.  To recap, and save anyone from having to re-read, I received a lot of good advice in this thread, some of which I didn't follow...  In the end, I bought a Tele View Panoptic 35 to use as my low-power EP, an 18.2 DeLite as my medium-power EP, and an 11mm DeLite as my high-power EP.  I also bought the 2" Everbrite diagonal and a 2" to 1/25" adapter.

In one of my last posts I mentioned wanting to try the Panoptic 35 (P35) on M42 and I had my chance a few weeks ago out at a darkish-sky site.  First though, here is an entry from my observing log taken on the 27th of September 2014, which is the first time my eyes ever looked at M42 through a telescope - "I have to say, M42 was a bit underwhelming and I’m not sure why.”  Contrast this with my entry on Friday, 11th of March 2016, which is when I went out to the dark sky site::

Tonight, there is only one word I can use to describe M42.  Two words.  Absolutely stunning.  Oh, how my comment of  2014-270/21 comes back to haunt me ("I have to say, M42 was a bit underwhelming and I’m not sure why.”).  I have never seen M42 looking so beautiful and I think I am just a little bit in love.  And not just with M42, the TV35P was pretty much my only eyepiece for the majority of the evening.  Using it, I saw the Trapezium as clearly as if I was there.  Pin-sharp and very bright, surrounded by fold after fold of billowing nebulosity.  That nebulosity seemed to take on a 3D perspective, even though I knew I wasn’t seeing it as such.  It looked like it had depth to it, though, like it would look as I approached it.  
 
The fish mouth was dark, far darker than I think I’ve seen before in other scopes.  As too was the dark nebulosity that separates M42 from M43.  I also saw the swept-back ‘wings’ for the first time, matching what I see in people’s images.  And those three distinct stars all lined up underneath the starboard wing.    And all this was before trying the UHC and OIII filters.  Under the UHC filter, the Trapezium stars were a bit harder to see but I attribute this to the extra nebulosity I was observing, which only enhanced the 3D-like experience.  The stars all had a blue-green tint to them, but strangely this didn’t detract from the view.  It gave it an unearthly, surreal perspective.  I then switched to the OIII filter and there were less stars again and I noted the nebulosity had a different shape to it.
 
It amazes me that this hauntingly beautiful sight was right there for me to view my entire life, and until just over a year ago I never took the time.  I’m so glad I finally did.

The views through the two DeLites are *almost* as good, but not quite, which I attribute to illumination of field.  They are just as sharp and clear as the P35, but not quite as well lit.  That Panoptic 35 is now my go-to eyepiece and it is always the first one I reach for.  I haven't noticed any vignetting at all.  If it is present then it is very subtle.  So if any others find themselves wondering which eyepiece will give them the widest possible field of view in a Sky-Watcher Mak 180, with a minimum of distraction, then I highly recommend they look at Tele Vue's Panoptic 35.  In this particular telescope it gives some lovely, lovely views.

Just wanted to close the loop on this, in appreciation for all the help given.

- Stu

PS - I've subsequently purchased a Tele Vue 2x Powermate and am now considering selling the cats in order to afford a 4x one.  ("C'mon, get in the cage you two, and stop meowing.  Your new owners are clearly animal lovers, they have a dozen dogs...")

 

 
 
Edited by Tanglebones
Made it family friendly. Sorry!

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