Jump to content


Photo

What Field of View for Your Eyepieces

  • Please log in to reply
65 replies to this topic

#51 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16717
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 08 January 2013 - 03:41 PM

David,

Well, I'll have to keep that in mind when I upgrade to a 14" Dob! :grin:

So far, though, I've haven't seen any advantage to using a super wide field - and I have two of them - to a good optical finder that's closely aligned to whatever decent eyepiece I have in the focuser of the main scope. If you have a good Zoom eyepiece, it's even better since you can dial in the optimum magnification and contrast to bag faint fuzzies or see structure in the brighter ones.

Mike

#52 David Knisely

David Knisely

    Hubble

  • *****
  • Posts: 15549
  • Joined: 19 Apr 2004
  • Loc: southeastern Nebraska

Posted 08 January 2013 - 03:54 PM

"Obviate"? Not when you are hunting (and more importantly, trying to identify) 15th magnitude and fainter galaxies that are *all* less than two arc minutes across inside a large rich galaxy cluster! Then, the finder is not all that relevant. I can easily use my Telrad alone to get the scope on such a group, but for tracking down individual galaxies inside, well, that is quite a bit different. With the big Hercules galaxy cluster (Abell 2151) for example, using the 14mm ES100 eyepiece, I have the power I need (135x) to get the scale up to begin to see them, but I also have the field I need to get more than a handful in the field at any one time (along with the rather widely-spaced field stars I need for reference in identifying all of them). In fact, with my ES100 eyepiece, I can see around 50 galaxies in that cluster within the 44.7 arc minute field that the eyepiece provides. There are several sub-groups of galaxies within that big but spread-out galaxy cluster which I made notes on, and the wide field meant that with my un-driven 14 inch Dob, there would be time enough to take a look and examine the plot of them in Megastar without them getting lost due to drift as I went back and forth between my charts and the eyepiece. To each his own, but for me, I am darn glad I got that wide-field eyepiece! Clear skies to you.

--------------------
David W. Knisely . . . . . . "If you aren't having fun in this hobby, you aren't doing it right."


That's awesome David! :jump:

How long do you dark adapt before checking that kind of stuff out? ...and what is the limiting mag of the skies you saw that in?

Cheers,


I generally don't start going after the really faint stuff until about 45 minutes after I got into the dark. I use that time interval to tweak things like collimation or to do a little "sight seeing" on some brighter and more familiar favorites in the night sky. My regular dark sky site has a typical zenith limiting magnitude of between 6.4 and 6.8, so it is fairly dark. Once I got my 14 inch, galaxy clusters started to get a lot more attention from me, even if they aren't exactly spectacular. The challenge is to ID a lot of the really tiny faint ones that are impossible to see at lower powers and are still a challenge even when you kick the power up a bit. I really like viewing the small "halo" of tiny faint galaxies that swarm around the two giant elliptical galaxies (NGC's 4889 and 4874) in Abell 1656 in Coma Berenices. It makes you really appreciate how big space really is. Clear skies to you.

#53 John F

John F

    Viking 1

  • *****
  • Posts: 625
  • Joined: 16 Feb 2004
  • Loc: Washington State

Posted 09 January 2013 - 03:21 AM

For most wife field/deep sky observing I find a 65 to 70 degree apparent field to be both very comfortable to observe with an more than sufficient for many if not most objects I might be viewing.

That said, I now mostly use 100-degree eyepieces for deep sky monoviewing. There are several reasons for that. First, I find the image quality of the Ethos eyepieces to be superb. Second, I don't wear glasses when observing and the 15mm of eye relief of the Ethos series is ideal for me. Third, even if I'm looking at an object/field that doesn't require really ultra wide true/apparent field to encompass and nicely frame it, I just ignore the outer parts of the field and concentrate on the center where the object it. It doesn't bother me to "waste" field in this way.

Fourth and most important. For certain objects and/or wide rich field targets in the Milky Way, a 100-degree can provide breathtaking views which a 70 (or even 80-degree) field eyepiece can't match. So it is nice to have an eyepiece that can provide those views when they're aimed at the right targets as well as perform very well for most other functions I need to use an eyepiece for. About the only object I don't like using Ethos eyepieces on is the Moon at higher powers (i.e., 100x & above).

For binoviewing I have tried using pairs of 13mm & 10mm Ethos eyepieces and found them spectacular in some respects but physically uncomfortable at least for me to observe with on the other so I don't use them for that. Another reason I prefer the Panoptics and T5/T6 Naglers for binoviewing is their much smaller size and lighter weights.

John Finnan

#54 Shneor

Shneor

    Viking 1

  • *****
  • Posts: 859
  • Joined: 01 Mar 2005
  • Loc: Northern California

Posted 09 January 2013 - 04:23 PM

Shneor,

Why do you keep both the ES 100 9 and ES 120 9? Is it just that the ES 100 9 is lighter and more convenient for your smaller scopes?

Mike

Exactly - the 120° is too heavy for my 6" Meade f/5!

Clears,

#55 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16717
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 09 January 2013 - 06:03 PM

Makes sense to me. :shrug:

:grin:
Mike

#56 GeneT

GeneT

    Ely Kid

  • *****
  • Posts: 12702
  • Joined: 07 Nov 2008
  • Loc: South Texas

Posted 09 January 2013 - 06:40 PM

I spent some time with a friend's 13mm Ethos and compared the views in my 12 Nagler. I just liked the Nagler better. Moving to mid and short focal length eyepieces, I am pleased with my Delos eyepieces. I own the 14, 10, 8 and 6 Delos. I kept my 4mm Radian for the once in a great while time I need that much magnification.

#57 Starman81

Starman81

    Surveyor 1

  • *****
  • Moderators
  • Posts: 1991
  • Joined: 06 Mar 2008
  • Loc: Metro Detroit, MI, USA

Posted 09 January 2013 - 07:19 PM

I spent some time with a friend's 13mm Ethos and compared the views in my 12 Nagler. I just liked the Nagler better. Moving to mid and short focal length eyepieces, I am pleased with my Delos eyepieces. I own the 14, 10, 8 and 6 Delos. I kept my 4mm Radian for the once in a great while time I need that much magnification.


Gene, I cannot fault you; the views both provide are pretty awesome. I love the ER of the Type 4's.

#58 Knygathin

Knygathin

    Lift Off

  • -----
  • Posts: 16
  • Joined: 31 Dec 2009

Posted 28 January 2013 - 06:37 PM

Tele Vue keep topping themselves with ever more spectacular eyepieces. Do you think there eventually will be a 180 degree AFOV eyepiece, perhaps with a concave shaped lens that you dip your eye into?

#59 faackanders2

faackanders2

    Vanguard

  • -----
  • Posts: 2255
  • Joined: 28 Mar 2011

Posted 28 January 2013 - 09:37 PM

David,

Well, I'll have to keep that in mind when I upgrade to a 14" Dob! :grin:

So far, though, I've haven't seen any advantage to using a super wide field - and I have two of them - to a good optical finder that's closely aligned to whatever decent eyepiece I have in the focuser of the main scope. If you have a good Zoom eyepiece, it's even better since you can dial in the optimum magnification and contrast to bag faint fuzzies or see structure in the brighter ones.

Mike


Multiple objects are when wide TFOV pays off. Able to see more objects in same FOV (Markarians Chain, M31/M32/M110, Leo's Triplet, More of Viel or North American, or M45, or M44, etc) and mor time when you can see multiple planets or moving obects )comets, asteroids) within same FOV of each other and or other DSOs.

Even with a camera I often find the wide angle lens more useful than the higher power ones.

#60 faackanders2

faackanders2

    Vanguard

  • -----
  • Posts: 2255
  • Joined: 28 Mar 2011

Posted 28 January 2013 - 09:47 PM

So I take it then that those who prefer the 'smaller' AFoVs clap on a pair of blinders when naked eye gazing... If not, how is a 100 degree field too expansive, when the eye's inherent field approaches 180 degrees?


:lol: Good one! However, naked eye, when I move my eyeball to the right to look on-axis at what was off-axis a second ago, my vision does not black-out or have a good amount of lateral color now on-axis until I get my head repositioned just right for the lateral viewing. And when I naked eye gaze to the right, the far left of my peripheral vision does not go away. Plus, when I gaze naked eye to the far right, I am not greeted with ubber-pincushion. All these are common traits in ultra-wides. Some people do not experience many of these, but many many do. Our eye's physiology is different from person to person. At any rate, its a very "unnatural" experience just gazing right in an ultra-wide. Takes some getting used to. For many, not worth the effort as just feels too unnatural. Plus, as said before, noticing unique asterisms in the FOV is much more difficult when one has to gaze around...they just are not as obvious. 70 degree eyepieces seem to tame all the devils much better than wider FOVs, plus still provide a very engaging space-walk like experience as well. Best of all worlds. If others don't have these issues...more power to them. But for me...70 is best and I feel I am missing absolutely nothing since I sold all my 82s...I actually feel things have improved quite a bit :cool:

I still do have 2 82s in the stall, but consider them "novelty" eyepieces, like the 28RKE. Great for once in a while because they give a different perspective, but not good as an every day thing.


with my 10mm 100 AFOV Ethos in my 17.5 f4.1 dob they make a full moon look like 7 ft tall an arm's reach in front of you with very little margin all around. Everyone who looks normall has they jaw hit the ground. That is what 100 AFOV can do! :jump: :lol: :roflmao:

What impresses everyone the most (biginners and experienced alike) is everyone know how large the moon is, so they know how much it is blown up. Keeping the entire sphere makes it look more natural/uncropped.

#61 faackanders2

faackanders2

    Vanguard

  • -----
  • Posts: 2255
  • Joined: 28 Mar 2011

Posted 28 January 2013 - 09:52 PM

I have Possils, Panoptics, Naglers, Ethos (all the other equivalent generic names) and by far the 100 AFOV get most use, followed by my maximum FFOV eyepieces for larger/multiple objects.

Before 100 AFOV came out my 14mm 84AFOV eyepiece got the most use, now it rarley gets used.

I tend to use lower powers more than higher ones.

24mm pamoptic gets used most in my binoviewers.

#62 faackanders2

faackanders2

    Vanguard

  • -----
  • Posts: 2255
  • Joined: 28 Mar 2011

Posted 28 January 2013 - 10:21 PM

The vast majority of the eyepieces I use have apparent fields of at least 100° - ES and Ethos. But the eyepiece that stays in my focuser the most - since I received it - is my 9mm ES "120°" which actually has an apparent field of around 140°. The apparent field is practically the same as the 13mm Ethos, and I've been using it as a finder eyepiece in my 22" f/4. But at 250X it's also great for viewing objects. When seeing is above average, I'll use Ethoi up to 3.7mm for appropriate objects. The more I use the 9mm, the greater the field I can see without having to move my head. There are two minor drawbacks: the eyepiece is heavy (about 2lb 14oz) and eye relief is 6mm, maybe a bit less.

Clears,


hOPE es COMES UP WITH A 5-5.5 100-120afov (120 PREFERRED!)

#63 faackanders2

faackanders2

    Vanguard

  • -----
  • Posts: 2255
  • Joined: 28 Mar 2011

Posted 28 January 2013 - 10:55 PM

The vast majority of the eyepieces I use have apparent fields of at least 100° - ES and Ethos. But the eyepiece that stays in my focuser the most - since I received it - is my 9mm ES "120°" which actually has an apparent field of around 140°. The apparent field is practically the same as the 13mm Ethos, and I've been using it as a finder eyepiece in my 22" f/4. But at 250X it's also great for viewing objects. When seeing is above average, I'll use Ethoi up to 3.7mm for appropriate objects. The more I use the 9mm, the greater the field I can see without having to move my head. There are two minor drawbacks: the eyepiece is heavy (about 2lb 14oz) and eye relief is 6mm, maybe a bit less.

Clears,


tHE ONLY THING i FIND 3.7MM eTHOS APPROPRIATE FOR IS GLOBULAR CLUSTERS. eVERYTHING ELSE IS WAY TOO MUCH POWER IN 17.5" F4.1

#64 faackanders2

faackanders2

    Vanguard

  • -----
  • Posts: 2255
  • Joined: 28 Mar 2011

Posted 28 January 2013 - 11:04 PM

For most wife field/deep sky observing I find a 65 to 70 degree apparent field to be both very comfortable to observe with an more than sufficient for many if not most objects I might be viewing.

That said, I now mostly use 100-degree eyepieces for deep sky monoviewing. There are several reasons for that. First, I find the image quality of the Ethos eyepieces to be superb. Second, I don't wear glasses when observing and the 15mm of eye relief of the Ethos series is ideal for me. Third, even if I'm looking at an object/field that doesn't require really ultra wide true/apparent field to encompass and nicely frame it, I just ignore the outer parts of the field and concentrate on the center where the object it. It doesn't bother me to "waste" field in this way.

Fourth and most important. For certain objects and/or wide rich field targets in the Milky Way, a 100-degree can provide breathtaking views which a 70 (or even 80-degree) field eyepiece can't match. So it is nice to have an eyepiece that can provide those views when they're aimed at the right targets as well as perform very well for most other functions I need to use an eyepiece for. About the only object I don't like using Ethos eyepieces on is the Moon at higher powers (i.e., 100x & above).

For binoviewing I have tried using pairs of 13mm & 10mm Ethos eyepieces and found them spectacular in some respects but physically uncomfortable at least for me to observe with on the other so I don't use them for that. Another reason I prefer the Panoptics and T5/T6 Naglers for binoviewing is their much smaller size and lighter weights.

John Finnan


i BRIEFLY HAD TWO 10MM ETHOS EYEPIECES FOR BINOVIEWING BUT THE DID NOT WORK WELL IN THE LOWEST (LL) POWER MODE WITH BRIGHT OBJECTS LIKE jUPITER (MANY RAYS ALL AROUND IT). aFTER SEVERAL NIGHTS, i RETURNED ONE. hENCE i ONLY VIEW MONO WITH 100 afov NOW. wISHED i WOULD HAVE BEEN ABLE TO GET THEM TO WORK IN ALL POWER SWITCH MODES.

#65 faackanders2

faackanders2

    Vanguard

  • -----
  • Posts: 2255
  • Joined: 28 Mar 2011

Posted 28 January 2013 - 11:10 PM

Tele Vue keep topping themselves with ever more spectacular eyepieces. Do you think there eventually will be a 180 degree AFOV eyepiece, perhaps with a concave shaped lens that you dip your eye into?


No. 180 TFOV camera fisheyes are very large. 180 AFOV eyepieces would also probably be very large, if possible.

#66 MRNUTTY

MRNUTTY

    Surveyor 1

  • *****
  • Posts: 1862
  • Joined: 22 Nov 2011
  • Loc: Mendon, MA

Posted 29 January 2013 - 09:59 AM

What do you mean by "power switch mode"?






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics