Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Superfluous oculars?

  • Please log in to reply
12 replies to this topic

#1 wrvond

wrvond

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1641
  • Joined: 25 Sep 2014
  • Loc: West Virginia

Posted 12 October 2019 - 02:06 PM

Using the astronomy tool, I plugged in each of my eyepieces for each of my telescopes. The results seem to indicate I’ve got a couple EPs I don’t really need, but I want a second (or more) opinion.

 

Sky-Watcher 120 ED FOV
XT10g FOV
C8 FOV

It looks to me like the Nagler 16mm and Panoptic 19mm are too close and the Panoptic 24 and 32mm Plossl are too.

I’m thinking the Pan 19 and 32 Plossl should be tossed.

 



#2 Eddgie

Eddgie

    ISS

  • *****
  • Posts: 24624
  • Joined: 01 Feb 2006

Posted 12 October 2019 - 02:27 PM

It is highly personal. 

 

I have always thought that there was such a thing as being too granular. While exit pupil sometimes plays a role in eyepiece selection, the primary reason for different eyepieces is to allow better framing of the subject under observation.

 

Now, how much room do you need around the subject you are observing before you find it "pleasing?"

 

For me, it was "enough to more than enough and not a bit less."  LOL.  

 

Seriously.. As an example  I found little value in going from a 27mm Panoptic in my C14 to a 22mm Panoptic in my C14, I grew to make my basic step a double double the field size (not a 50% increase that you recommend if you are in the business of selling eyepieces).

 

But the end of my conventional eyepiece observing I was doing 90% deep sky of my observing with just three eyepieces: Wide field-low power, medium field-medium power, and smaller field-high power.  I found that the tiny incremental changes in field size were not at all missed, and I found that I did a lot more observing and a lot less eyepiece changing.  Heck, I was using a binoviewer with a power switch and I stopped changing eyepieces at all, relying on the power switch to make all of my field size changes.  

 

So, it is really a very personal and subjective call.  

 

I did some of the most productive observing of my life though when I ditched the eyepiece case and went to three simple powers. 

 

I think you are waaaay to granular though, but I will be in the minority I am sure.


  • dryfly, russell23, wrvond and 1 other like this

#3 sg6

sg6

    Fly Me to the Moon

  • *****
  • Posts: 5910
  • Joined: 14 Feb 2010
  • Loc: Norfolk, UK.

Posted 12 October 2019 - 02:40 PM

Just keep them.

Things will change and you may find one day what you like switches.

 

Never listen to software.

Also how often do you look at M31, is the result the same for M33, M13, M1, C14 and the countless other objects.


  • wrvond likes this

#4 TOMDEY

TOMDEY

    Aurora

  • *****
  • Posts: 4665
  • Joined: 10 Feb 2014
  • Loc: Springwater, NY

Posted 12 October 2019 - 03:22 PM

There's more involved than just object-space field. And when your stable of favorite telescopes changes... favorite/appropriate eyepieces will also morph. And as your eyes get older, etc. A lot of friends have re-bought eyepieces that they thought they didn't want anymore. Yeah... some people I know...

 

On the other hand, if starts to get creepy obsessive-compulsive... sell off some just to get your feet back on the ground, and post this sobering picture on the wall of your eyepiece vault. >>>

 

Warning Signs:

>Taking pictures of your epiece collection

>Taking them out; admiring them; putting them away, without even using them

>Crafting endless spreadsheets of your collection; noting "still need" ones    Tom

Attached Thumbnails

  • 126 imelda marcos shoe museum 2018 3000 pair.jpg

  • rowdy388 and wrvond like this

#5 astro744

astro744

    Viking 1

  • -----
  • Posts: 627
  • Joined: 22 Sep 2007

Posted 12 October 2019 - 03:28 PM

The astronomy tool is likely generating the graphic based on field stop diameters which you can also get from Tele Vue for their eyepieces.  See http://www.televue.c...page.asp?id=214

 

Any eyepiece with the same field stop diameter will give the same true field.

 

As you can see from the Teke Vue data there are a three eyepieces with around 27mm FSD:

40mm Plossl

32mm Plossl

24mm Panoptic

20mm Nagler 5 (disc)

20mm Nagler 2 (disc)

 

 

There are also a few eyepieces within a mm or two around 21mm/22mm FSD:

25mm Plossl

19mm Panoptic

17.3mm Delos

16mm Nagler 5

13mm Ethos

26mm Plossl (disc)

16mm Nagler 2 (disc)

 

Although the FSD and therefore the true fields are equal for a given telescope, the apparent fields, eye relief, magnification and exit pupil are different giving a different viewing experience.

 

In the case of 32mm Plossl vs 24mm Panoptic; the former gives a larger exit pupil and is good for slow instruments (say f10) to give a brighter image often required for better performance with some interference filters and greater eye relief for eyeglass wearers.  The latter has that wonderfull 68 deg field which is about what most people can comfortably take in without having to look around (if that's what they prefer).

 

In the case of your 19mm Panoptic and 16mm Nagler 5 you get very similar small physically sized eyepieces with the former giving a little less power, a little greater exit pupil and a little greater eye relief.  I use one or the other on my Stellarvue 80mm finder as well as my Tele Vue 60 telescope for low power sweeping at slightly darker sky backgrounds than the 24mm Panoptic or 32mm Plossl give me.


  • Jon Isaacs and wrvond like this

#6 SeattleScott

SeattleScott

    Fly Me to the Moon

  • *****
  • Posts: 5852
  • Joined: 14 Oct 2011

Posted 12 October 2019 - 09:02 PM

The only practical reasons to have different FL eyepieces with the same FOV would be for matching magnification to seeing, or viewing preference like hyperwide versus LE, etc. At 19mm FL you probably won’t need that for matching magnification to seeing unless you have like a 12” SCT. So yeah not much point in keeping the 19 Pan unless you prefer the viewing ergonomics, or maybe keep it for a second string outreach set, although that’s fairly fancy for outreach.

Scott
  • wrvond likes this

#7 russell23

russell23

    Cosmos

  • *****
  • Posts: 9891
  • Joined: 31 May 2009
  • Loc: Upstate NY

Posted 12 October 2019 - 09:28 PM

It is highly personal. 

 

I have always thought that there was such a thing as being too granular. While exit pupil sometimes plays a role in eyepiece selection, the primary reason for different eyepieces is to allow better framing of the subject under observation.

 

Now, how much room do you need around the subject you are observing before you find it "pleasing?"

 

For me, it was "enough to more than enough and not a bit less."  LOL.  

 

Seriously.. As an example  I found little value in going from a 27mm Panoptic in my C14 to a 22mm Panoptic in my C14, I grew to make my basic step a double double the field size (not a 50% increase that you recommend if you are in the business of selling eyepieces).

 

But the end of my conventional eyepiece observing I was doing 90% deep sky of my observing with just three eyepieces: Wide field-low power, medium field-medium power, and smaller field-high power.  I found that the tiny incremental changes in field size were not at all missed, and I found that I did a lot more observing and a lot less eyepiece changing.  Heck, I was using a binoviewer with a power switch and I stopped changing eyepieces at all, relying on the power switch to make all of my field size changes.  

 

So, it is really a very personal and subjective call.  

 

I did some of the most productive observing of my life though when I ditched the eyepiece case and went to three simple powers. 

 

I think you are waaaay to granular though, but I will be in the minority I am sure.

I completely agree with this.  Lately my observing has been extremely relaxing because I've limited my eyepiece case to three eyepieces:  30mm APM UFF, 14mm Delos, and 6.5mm Morpheus.

 

In the SV and AT102mm ED's those give:  24x w/3.0 deg field, 51x, and 110x. 

 

In the SW120ED those give: 30x, 64x, 138x. 

 

I've really found I don't need anything else.   I don't think a jump from 50x to 75x (for example) really does much.  In general, I see those three magnifications as: 

 

24x --> widest field viewing and great for framing really large clusters, nebula, and starfields.

 

51x --> nice magnification for balancing resolution and framing for larger DSO.

 

110x -->  best magnification for pulling out the most resolution without the image becoming too dim due to a small exit pupil.    Also in my location this is about as high a magnification as I can count on almost every night. 

 

I do not see the jump from 51x to 110x as being a "gap".  If I was to make a jump from 51x to 75x, the view at 71x would lack the nice framing I get at 51x, but would not provide the resolution I get at 110x.  So even though I have eyepieces that give ~75x with my 102mm scopes I just blow on by and go straight to the 6.5mm Morpheus. 

 

So by taking out just the three eyepieces I eliminate the temptation of trying those other magnifications out.  Less swapping of eyepieces means more observing. 


  • wrvond likes this

#8 SeattleScott

SeattleScott

    Fly Me to the Moon

  • *****
  • Posts: 5852
  • Joined: 14 Oct 2011

Posted 12 October 2019 - 10:47 PM

You guys are really talking me out of picking up a 10mm to slot between my 8 & 13. I was kind of thinking that while it would be nice to frame any target nicely, if I get the gaps too tight, I might end up using more time swapping eyepieces to try and frame a target perfectly. Right now it is fairly straight forward, at least with DSO. I do have tighter gaps on the high power side for matching magnification to seeing. I will play around more to get the perfect view of the Moon and planets. But it would be time consuming to do that for DSO also. Interesting to hear from those who have been there, and then reversed course.

Personally three eyepieces isn’t quite enough for me, if for no other reason I like tighter gaps at high power. I have seven in my GNG kit, largely because there are seven holes in the case, so they must all be filled! A couple are redundant in terms of FOV they provide, with one eyepiece providing more magnification (ultrawide) and the redundant one (Vixen LV) providing more ER for glasses and convenience in terms of being parfocal with my LVWS. So really six to choose from in terms of framing objects. Even with my full set, I have just seven options for framing targets. Bigger gaps at low power, smaller gaps at high power. So I guess I am in the middle. Not a minimalist, but not dragging out two Pelican cases of glass either. I’m kind of thinking if I want to spend another $300 on an eyepiece, rather than filling a not particularly large gap, I might be better off getting an eyepiece that will give me a different experience. Like maybe my first hyperwide. So rather than a guessing game of which eyepiece will best frame a target, I just decide whether I want long ER or 100 degrees AFOV. Something to think about.

Scott
  • russell23, wrvond and 25585 like this

#9 wrvond

wrvond

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1641
  • Joined: 25 Sep 2014
  • Loc: West Virginia

Posted 12 October 2019 - 11:25 PM

For the most part I am a “fill the viewfinder” kind of guy. I use the maximum magnification seeing will allow. I do find, however, there are items I simply don’t use that are in my case - the 2x and 3x Barlows being two of them. 
I don’t think the 32 Plossl really brings enough to the table that would cause me to consistently choose it over the 24 Panoptic.

Likewise, the 19 Pan isn’t as comfortable as the 16mm Nagler if the object size in the EPs are comparable.

My eyes are already fairly old and damaged by diabetes so less sensitive than most to nuances in brightness I think.

I’m going to have to start paying attention and see which ones I actually use most. Instead of starting with the Plossl as my lowest magnification wide field I think I’ll start with the Panoptic instead and see how that feels.



#10 Deep13

Deep13

    Skylab

  • *****
  • Posts: 4426
  • Joined: 25 Jan 2005
  • Loc: NE Ohio

Posted 14 October 2019 - 07:57 AM

Agree with the OP's original assessment. The 16 and 24 are frankly better than the other two.

#11 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 78951
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted Yesterday, 04:50 AM

Using the astronomy tool, I plugged in each of my eyepieces for each of my telescopes. The results seem to indicate I’ve got a couple EPs I don’t really need, but I want a second (or more) opinion.

 

 
 
 

It looks to me like the Nagler 16mm and Panoptic 19mm are too close and the Panoptic 24 and 32mm Plossl are too.

I’m thinking the Pan 19 and 32 Plossl should be tossed.

 

There's far more to an eyepiece than the field of view.  Exit pupil is an important factor and determines the brightness of an extended object. A 32 mm Plossl is 78% brighter than a 24 mm SWA, this can be helpful in a slower scope or when viewing dim objects, particularly with a aggressive deep space filter.

 

I use closely spaced eyepieces. Scott mentioned the 10 mm fitting between the 13 mm and the 8mm. When I'm hunting down, tiny faint galaxies in a good sized scope operating about F/5, this is a critical region and teasing out a faint galaxy usually is in this range. For me, very often the 11 mm is optimal but it depends on the galaxy and the conditions.

 

For me, a relaxed attitude comes from having a relaxed attitude, not feeling pressured for time or some expectations. I like to have the eyepieces I might want close at hand.

 

Jon


  • SeattleScott, wrvond, bbqediguana and 1 other like this

#12 jaraxx

jaraxx

    Ranger 4

  • *****
  • Posts: 382
  • Joined: 14 Sep 2017

Posted Yesterday, 08:54 AM

I look at eyepieces as “windows” to look thru, and the windows sometimes have differences even if they provide the same FOV. There are big differences in brightness and magnification and smaller differences in tint and tone - maybe the term for it would be “eye feel”.
Not too long ago I was gifted with some old TV Plossls my sister found in a box of stuff she bought at an auction: 40,17.5 and 10.5mm. I have a 32mm Plossl, more mag and the same (or maybe even a bit more) FOV than the 40, but the 40 is brighter and that difference is important sometimes. I have good eyepieces that are nearly the same magnification as the other TVs, but they are still useful and sometimes preferable. I’ve a 17.5 Morpheus that I think highly of and yet I was looking at the moon the other night and the window provided by the Plossl was preferable to the Morpheus. I’m uncertain why - it didn’t seem to be a difference in clarity (Plossls are often cited as having great clarity) - maybe because the moon filled more of the window, or maybe because the tint was a bit different. I can’t really qualify it, but I’m keeping both of these eyepieces around for now.
I also have different scopes, and eyepieces that work fine in a 127 Mak don’t necessarily work as the same in an f/5 refractor.


  • wrvond likes this

#13 SeattleScott

SeattleScott

    Fly Me to the Moon

  • *****
  • Posts: 5852
  • Joined: 14 Oct 2011

Posted Yesterday, 11:24 AM

Plossls are great budget planetary eyepieces. Since they only have four lenses there is less opportunity for light scatter. Your Morpheus probably has eight lenses. The Morpheus gives more eye relief and a wider FOV, and possibly better edge correction in fast scopes. But it takes a lot of glass to do that. The TV Plossl isn’t trying to do as much, so it doesn’t need as much glass, and has less light scatter. I had a TV 8mm Plossl that I felt edged out my 7T1 and 8LVW on planets. But the eye relief was too short for my liking and I sold it. Now I have an excellent Tak 18LE, very sharp planetary eyepiece. But the 17lvw and 15 Panoptic can go just as wide with more magnification, and a bit better edge correction in fast scopes. The Tak 18 would be an excellent planetary eyepiece for say a 9”-12” SCT, or a 7” F15 Mak. But alas I have no such scope to do justice to it, so I will probably sell it. So yeah, different eyepieces can do different things well and match better with different scopes.

Planetary eyepieces, to me, are kind of the equivalent of a NFL kicker. As they say, you’ve only got one job,...so you ought to be good at it, or else you won’t be sticking around. More complex designs can keep a spot in my case in different ways. Ok you have 50 AFOV but you are well corrected and have long ER so I will use you sometimes. This other one isn’t well corrected but it has wide AFOV and works well in slow scopes so it can stay. But planetary eyepieces are usually narrow with tight ER, so they better have great contrast, or there is no reason to keep them around.

Scott

Edited by SeattleScott, Yesterday, 11:31 AM.



CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics