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30mm+ Eyepiece Question...

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#1 Dave Bush

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Posted 10 August 2022 - 10:43 AM

I'm thinking of using a 2" 30mm or longer eyepiece as a wide finder for my 10" Dob.   I'm not interested in those that are highly corrected like the TV or ES class optics as I'm not going to be "observing" through it but rather just using it to acquire an object and then move onto using my better eyepieces.  I just want a wide field with good eye-relief that allows me to use my glasses.  

 

 

So, having said that, among all the options, which would be some of the best performing for my f/5.4 system?



#2 bmcclana

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Posted 10 August 2022 - 10:50 AM

I really like my APM 30mm UFF. 

 

Wide, but not the widest. well corrected, Relatively light weight. Good eye relief for glasses.


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#3 YeloSub

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Posted 10 August 2022 - 11:05 AM

I'll second the 30mm UFF (from APM, Celestron, Meade, and others... all the same)

For glasses, that's the one to get IMO. And you wouldn't be settling, it's an excellent eyepiece.

Edited by YeloSub, 10 August 2022 - 04:42 PM.

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#4 russell23

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Posted 10 August 2022 - 11:16 AM

I'm thinking of using a 2" 30mm or longer eyepiece as a wide finder for my 10" Dob.   I'm not interested in those that are highly corrected like the TV or ES class optics as I'm not going to be "observing" through it but rather just using it to acquire an object and then move onto using my better eyepieces.  I just want a wide field with good eye-relief that allows me to use my glasses.  

 

 

So, having said that, among all the options, which would be some of the best performing for my f/5.4 system?

The 30mm APM UFF would probably be the best performing but also getting pricey at $249.  But for $95 you could consider the 32mm Agena SWA if the eyepiece is only being used as a finder.  The eyepiece is listed as having 24mm of eye relief, but the eye lens is recessed so it would be close.  It has been a long time since I looked through one but if I remember right glasses were possible with it, but it was tighter than the 38mm version.  If you wanted to be absolutely sure the eye relief would be sufficient you could go with the 38mm and not worry about the large exit pupil.  If it is only being used as a finder it probably won’t matter that much.


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#5 Dave Mitsky

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Posted 10 August 2022 - 11:25 AM

Based on everything that I've heard about it, I also recommend the 30mm APM UFF.

https://www.eyepiece..._p/17102030.htm


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#6 Dave Mitsky

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Posted 10 August 2022 - 11:28 AM

The 30mm APM UFF would probably be the best performing but also getting pricey at $249.  But for $95 you could consider the 32mm Agena SWA if the eyepiece is only being used as a finder.  The eyepiece is listed as having 24mm of eye relief, but the eye lens is recessed so it would be close.  It has been a long time since I looked through one but if I remember right glasses were possible with it, but it was tighter than the 38mm version.  If you wanted to be absolutely sure the eye relief would be sufficient you could go with the 38mm and not worry about the large exit pupil.  If it is only being used as a finder it probably won’t matter that much.

One caveat: if the OP's 10" Dob has a focal ratio of f/4.7, a 32mm Agena SWA will probably exhibit quite a bit of astigmatism.  


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#7 Blacksmith

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Posted 10 August 2022 - 11:38 AM

I used a svbony 34mm 72 degree eyepiece for a couple years.. While I wasnt well corrected on the edge it was pretty nice in the center 75%-80%.. I paid $59 when I bought it, though I think they are up to about $90 now.. The Omegon 32mm 70 degree is supposed to be pretty decent too.. Now Im talking sub $100 eyepieces here..
Just to mention it, I bought a AT 28mm 82 degree and its in a whole other league. Holds its own with ES and TV in my opinion. Its $200 new


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#8 Thomas Marshall

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Posted 10 August 2022 - 11:38 AM

Orion 2" Q 70 degree 32mm would be very good at resonable price. I love my Q 70/26mm.


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#9 Dave Bush

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Posted 10 August 2022 - 11:41 AM

One caveat: if the OP's 10" Dob has a focal ratio of f/4.7, a 32mm Agena SWA will probably exhibit quite a bit of astigmatism.  

Quoting from my original post...

 

"...which would be some of the best performing for my f/5.4 system?"



#10 BradFran

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Posted 10 August 2022 - 12:22 PM

The 30 APM UFF works great in my f/5 Dob. I wouldn't go much cheaper at this f/ratio. Having it for use with nebula filters is really nice. The only down side is that you will then want a coma corrector. I found a used GSO for 50 euro that completes it well. The pairing hardly wants to leave the focuser on a dark night.

 

Barring that, a 1.25" 32mm Plössl also makes a good finder and works well at f/5. The Celestron OMNIs can be had ridiculously cheap at the moment.


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#11 Ihtegla Sar

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Posted 10 August 2022 - 12:34 PM

The 30 APM 70 UFF is a great eyepiece but the AT 28mm 82 (closer to 84) will give a wider field of view and is in the same price range as the 30 APM 70. That's the one I would get for a "cheap" finder eyepiece, although the AT 28 is very well corrected so its not "cheap" in terms of performance.

EDTI: just noticed the "with glasses" part of the question. In that case you may want to go with the 30 APM 70 since it has more eye relief.

Edited by Ihtegla Sar, 10 August 2022 - 01:05 PM.


#12 Starman1

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Posted 10 August 2022 - 05:27 PM

30mm APM Ultra Flat Field, 70°, 36.4mm field stop.

Easy to use with glasses, and stars at the edge will not look like planetary nebulae.

At f/5.4, exit pupil of 5.56mm, so not so large you would have a problem with a too-large exit pupil.


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#13 Chad7531

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Posted 10 August 2022 - 05:30 PM

If you aren’t concerned with the view then get the largest 1.25 afov available. Using a 2” 30mm as a finder is no fun, and too much hassle for me to ever think about with my 10” dob. A 14mm 70* will work fine for me in that scope. I have a 30mm xw, I don’t use it. Only when I run out of targets on my observing list and sweep through the Milky Way.

Edited by Chad7531, 10 August 2022 - 05:32 PM.


#14 Starman1

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Posted 10 August 2022 - 06:25 PM

30mm objects in your 6" f/5 at 25x:

The Veil nebula

The North America Nebula

The California nebula

The Perseus Double cluster

M45

M44

M31/32/110

Cr 399          

Stock  1        
IC  5070        
Stock  2        
IC  1805        
Cr 140          
Tr 24           
Cr  69          
NGC  598        
Sh2-264         
vdB  20         
NGC 2238        
NGC 2237        
Cr 132          
NGC 6475        
IC  1396        
Blanco 1        
IC   434        
NGC 1976        
NGC 2632        
IC  4715        
Mel  22         
Cr 316          
Cr 464          
Cr  70          
Kemble 1        
Mel  20         
Abell  426      
NGC 6281        
Cr  65          
Mel 186         
Mel 111         
Mel  25         
Cr 302          
Sh2-276         
Cr 285


Edited by Starman1, 10 August 2022 - 06:27 PM.

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#15 RyanAstroMan

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Posted 10 August 2022 - 09:29 PM

The 30mm APM UFF is killer in my f/4.5 dob, it's given me some of my best views of the Veil Nebula with an OIII filter.
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#16 cimar

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Posted 11 August 2022 - 01:57 AM

I use two 31mm Baader Aspheric eyepieces as goto and filter usage eyepieces. Not perfect, but I like these. To have two samples simplifies filter switching.


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#17 eblanken

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Posted 11 August 2022 - 03:45 AM

Hi Dave & All,

 

I'm thinking of using a 2" 30mm or longer eyepiece as a wide finder for my 10" Dob.   I'm not interested in those that are highly corrected like the TV or ES class optics as I'm not going to be "observing" through it but rather just using it to acquire an object and then move onto using my better eyepieces.  I just want a wide field with good eye-relief that allows me to use my glasses.  

 

 

So, having said that, among all the options, which would be some of the best performing for my f/5.4 system?

 

 

I really like my APM 30mm UFF. 

 

Wide, but not the widest. well corrected, Relatively light weight. Good eye relief for glasses.

 

I'm not a Newt/Dob guy, but I am a fan of the Pentax XW series (I have a friend who uses these {and is happy} on a 24.5 inch {622 mm} x 118 inch {3,000 mm}, f/4.8 Newt on a GEM). Comfortable and generous eye relief are attributes of the Pentax 40 mm XW and 30 mm XW. There are lots of people  saying APM 30mm UFF, which I have zero experience using. I have the Baader Apheric 31 mm & 36 mm. I can say that the 30mm XW and 40 mm XW should be considered for 2 inch if they aren't above your price range. The Baader Apherics might be fine for your stated purposes and are less expensive {if bought used}, Dave. You might also consider the Vixen 42mm LVW (if you can find one these days). If you are a fan of LONG EYE Relief, then consider a 55 mm Televue Plossl, if you can find one used.

 

Ed (aka eblanken) Blankenship


Edited by eblanken, 11 August 2022 - 04:09 AM.

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#18 Jon Isaacs

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Posted 11 August 2022 - 05:36 AM

Quoting from my original post...

 

"...which would be some of the best performing for my f/5.4 system?"

 

Your entire first post:

 

"I'm thinking of using a 2" 30mm or longer eyepiece as a wide finder for my 10" Dob.   I'm not interested in those that are highly corrected like the TV or ES class optics as I'm not going to be "observing" through it but rather just using it to acquire an object and then move onto using my better eyepieces.  I just want a wide field with good eye-relief that allows me to use my glasses. 

 

So, having said that, among all the options, which would be some of the best performing for my f/5.4 system?"

 

 

So which is it?  The way I read your first post, you are not interested in well corrected eyepieces,. I have the 30mm APM 70 degree UFF.  It is a highly corrected eyepiece like the 31mm Nagler and the 35mm Panoptic, which I also have. 

 

If you are not interested in eyepieces like that, what does best performing mean?  Best performing with your eye glasses? or are you actually interested in well corrected eyepieces?

 

How much are you hoping to spend?

 

In terms of cost, $100 buys an entry level eyepiece like the 32mm 70 degree Q70 and clones, the 34 mm 72 degree Svbony which I believe is actually a 32mm Q70.  These eyepieces have decent eye relief and a lot of off-axis astigmatism at F/5.4. $200 buys the 28mm Astro-tech UWA, a bit short on eye relief for glasses wears but a well corrected view at F/5.4.  $250 buys the 30mm APM UFF, generous eye relief, well corrected. 

 

Between these two groups, there are very few, if any choicies.

 

Jon


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#19 Starman1

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Posted 11 August 2022 - 09:18 AM

Hi Dave & All,

 

 

 

 

I'm not a Newt/Dob guy, but I am a fan of the Pentax XW series (I have a friend who uses these {and is happy} on a 24.5 inch {622 mm} x 118 inch {3,000 mm}, f/4.8 Newt on a GEM). Comfortable and generous eye relief are attributes of the Pentax 40 mm XW and 30 mm XW. There are lots of people  saying APM 30mm UFF, which I have zero experience using. I have the Baader Apheric 31 mm & 36 mm. I can say that the 30mm XW and 40 mm XW should be considered for 2 inch if they aren't above your price range. The Baader Apherics might be fine for your stated purposes and are less expensive {if bought used}, Dave. You might also consider the Vixen 42mm LVW (if you can find one these days). If you are a fan of LONG EYE Relief, then consider a 55 mm Televue Plossl, if you can find one used.

 

Ed (aka eblanken) Blankenship

The op mentioned the eyepiece was for his 10" dob, likely f/5.

So The 31mm Baader Hyperion Aspheric would be a poor choice due to the f/ratio, as would be a 55mm Plössl and 42mm LVW.

The 30mm Pentax XW would be a nice eyepiece, but it's $150 more than the APM UFF 30mm and no better corrected.

 

If it's for merely acquiring a target, the under $100 class would be fine, but I tried to point out for Chad7531, and also applicable to the OP, that there are a lot of objects for which

you would want to use a 30mm for actually observing objects, and that means something well-corrected and relatively free of astigmatism caused by the fast f/ratio.

The APM UFF qualifies for correction and eyeglasses use, but the under $100 class does not.


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#20 russell23

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Posted 11 August 2022 - 09:54 AM

The op mentioned the eyepiece was for his 10" dob, likely f/5.

So The 31mm Baader Hyperion Aspheric would be a poor choice due to the f/ratio, as would be a 55mm Plössl and 42mm LVW.

The 30mm Pentax XW would be a nice eyepiece, but it's $150 more than the APM UFF 30mm and no better corrected.

 

If it's for merely acquiring a target, the under $100 class would be fine, but I tried to point out for Chad7531, and also applicable to the OP, that there are a lot of objects for which

you would want to use a 30mm for actually observing objects, and that means something well-corrected and relatively free of astigmatism caused by the fast f/ratio.

The APM UFF qualifies for correction and eyeglasses use, but the under $100 class does not.

I rarely recommend the Orion Q70/Agena SWA because of the horrible edge performance.  In this case, since the OP specifically said he was not planning to observe with the eyepiece, then the 32mm or 38mm SWA makes the most sense from a budget point of view.

 

But you are correct, there are lots of targets that can be observed with the 30mm FL so the 30mm APM UFF would be the best choice if you are looking for an affordable, but still excellent performing option.

 

Dave


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#21 Dave Bush

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Posted 11 August 2022 - 10:45 AM

Your entire first post:

 

 

So which is it?  The way I read your first post, you are not interested in well corrected eyepieces,. I have the 30mm APM 70 degree UFF.  It is a highly corrected eyepiece like the 31mm Nagler and the 35mm Panoptic, which I also have. 

 

If you are not interested in eyepieces like that, what does best performing mean?  Best performing with your eye glasses? or are you actually interested in well corrected eyepieces?

 

How much are you hoping to spend?

 

In terms of cost, $100 buys an entry level eyepiece like the 32mm 70 degree Q70 and clones, the 34 mm 72 degree Svbony which I believe is actually a 32mm Q70.  These eyepieces have decent eye relief and a lot of off-axis astigmatism at F/5.4. $200 buys the 28mm Astro-tech UWA, a bit short on eye relief for glasses wears but a well corrected view at F/5.4.  $250 buys the 30mm APM UFF, generous eye relief, well corrected. 

 

Between these two groups, there are very few, if any choicies.

 

Jon

In the context of what I said (you underlined), I asked...  

 

"...which would be some of the best performing for my f/5.4 system?"

 

and...

 

"I just want a wide field with good eye-relief that allows me to use my glasses."

 

 

So, if that's not clear, I'll try another way...

 

Since I'm only using this possible eyepiece as a finder, I don't need, nor do I want to pay for, highly corrected optics such as those suggested in many of the replies (Pentax XW, Baader Aspheric, even the UFF).  I know there are a lot of "cheap", simple designs out there and I'm just asking of all of those, which seems to be the best.



#22 Dave Bush

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Posted 11 August 2022 - 10:50 AM

 

If it's for merely acquiring a target, the under $100 class would be fine,

This is the key to this whole discussion.  I am only going to be using this eyepiece to acquire a target and then switch to a well corrected "observing" eyepiece.  I hate using my glasses for observing as for me, it takes away from the purity of the view (hard to explain my feeling on this).  So I'm willing to use my glasses in the finding of an object (I do so with a Telrad right?) but for any real observing, it's glasses off.

 

What I'm thinking is that using the main scope with it's greater light gathering ability, I might go better at finding, star-hopping, to an object than using a 50 or 60mm finder scope.   The only problem that I can foresee is that the field of view will be likely around 2º and perhaps that's not sufficient.  


Edited by Dave Bush, 11 August 2022 - 10:52 AM.

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#23 Dave Mitsky

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Posted 11 August 2022 - 11:01 AM

Quoting from my original post...

 

"...which would be some of the best performing for my f/5.4 system?"

I would venture that field edge astigmatism is still going to be considerable at f/5.4.



#24 eblanken

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Posted 11 August 2022 - 11:12 AM

Hi Dave Bush,

 

Thanks for clarifying. Please set us a ceiling on how much you are willing to spend for "cheap" "finder" eyepiece. $25 ???, $50 ???, $100 ???, $150 ???

 

Are you looking at 2 inch only ??? Or 1.25 inch as well ???

 

What eye relief do you want ??? 20mm ??? 30 mm ??? 40 mm ???

 

How wide a field do you want your "Cheap" "Finder" to see ? 0.5 Deg ??? 1.0 Deg ??? 1.5 Deg ??? 2.0 Deg ??? 3.0 Deg ??? 4.0 Deg ???

 

Answers to these will help us to get at what you really want to know. This is, after all, your post.

 

Best regards,

 

Ed (aka eblanken) Blankenship

 

Hi again: Your post (#22) came in while I was posting this (#24).

 

How about this as an alternative: Get a used < $100 ST-80 refractor (80 mm x 400 mm, f/5) and a used < $40, 40 mm Plossl in 1.25 inch format and make yourself a 10x finder for your 10 inch Dob/Newt. Keep the TELRAD. Maybe use a 32 mm Plossl or 24mm Plossl instead to get 400 mm / 32 mm = 12.5x finder or 400 mm / 24 mm = 17x Finder ???

 

Your first post on this thread assumes: 10 inch, f/5.4 Dob/Newt with a 30 mm "Cheap" "Finder Eyepiece" ===> 10 * 25.4 * 5.4 = 1,372 mm / 30mm =  45.72x "Finder" whereas your TELRAD has circles at 0.5 Deg, 1 Deg & 2 Deg at 1x. Do you really need something in between 1x and 45x ??? A 55 mm Plossl yields 1,372 mm / 55 mm = 25x, just saying . . .


Edited by eblanken, 11 August 2022 - 12:04 PM.

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#25 Dave Bush

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Posted 11 August 2022 - 12:10 PM

OK, so apparently my original post wasn't clear enough for some so let me try again.  

 

  • I have a 10" f/5.4 Dob.
  • It's equipped with a zero power finder and a 50mm optical finder
  • The optical finder provides about a 3.7º actual field of view 
  • That optical finder is used at 22x.  I can't go much lower in power due to my astigmatism
  • I don't use glasses when I observe.  When I observe (take note of that)

Problem:   Some objects are a bit too faint in that optical finder making it difficult to be sure that I've found them.  

 

Solution?...

 

I'm thinking that since my main scope pulls in much more light than the optical finder, maybe I can use it as a finder.  

The requirements for this to work for me would be...

  1. I need an eyepiece that gives me the widest field possible (so 2")
  2. Large enough eye-relief so that I can use my glasses.  

"Wait", you say.  "You said you don't use glasses when you observe"

 

Correct.  Observing means (to me at least) spending a long time at the eyepiece studying an object.  For finder purposes it's only a minute or less.  Further, I know that an eyepiece that would give me the wide actual field that I need, would have an exit pupil well beyond the point where my astigmatism kicks in.   I don't want to spend the $$ for another Dioptrx and the $$ for the eyepiece that it is compatible with just for the brief time I'll be using this "finder", thus my desire for an eyepiece that I can see the whole field through when using my glasses.

 

I know there are a lot of cheaper, simpler design, 2" eyepieces, 30mm or longer, that would fit my requirements.  All I'm asking is, of all of these, has anyone found one that seems to be better than the others in terms of correction.  

 

Now read this next part carefully...

 

I don't expect great correction near the edges.  Given my fast focal ratio and the level of optics that I'm asking about, I'm OK with that.  After all, I don't need pinpoint stars but rather just the ability to see stars and to distinguish between stars and DSOs.  But some  eyepieces may be better than others.

 

So, again, of all the options out there, does anyone have an opinion (based on first hand use) of which might be the best.  


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