78 replies to this topic

[Procyon]

One eyepiece, one scope and a gadget like a field flattener or focal reducer, for a dark site trip for rich field views, which are you taking and why?

 

What is a better wide field view for you? 3º, 4º, 5º, 6º, 7º?

 

No cameras..

Edited by Procyon, 24 April 2025 - 08:11 PM.

[slavicek]

That looks like you will be looking at some wide field nebulas in which case I'd take:

 

 

 

 NV is the eyepiece, fast camera lens is the telescope, up to 8 deg FOV.

[weis14]

I'll take my Stowaway and 22mm Nagler.  This gives a 3º FOV, but without causing too much astigmatism in my eyes due to a large exit pupil.  

 

No gadget needed.

[TOMDEY]

Rich Field is defined as the exit pupil(s) matching (or exceeding) that of your dark-adapted eyes'. But Wide Apparent Field of View (AFOV) certainly contributes to the experience as well. Add to that two telescopes (one for each eye) and that doubles the pleasure. For myself... that pretty much leaves two choices, presuming that I would avail only one, and not the other >>>

 

The 152mm F/8 APO Refractor with the 30mm eyepiece shown in the picture below. The exit pupil is admittedly "only" a generous 3.75mm, AFOV 100^o, True Field of View (TFOV) is 2.46^o, magnification 40.5x. The 3-inch Star Diagonal allows the entire field to be seen from center to edge with no vignetting whatsoever.

 

But far more portable would be the ultrawide Nikon WX 10x50 "Astronomical Binocular" with 5mm exit pupil and gargantuan 9^o TFOV.

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[Procyon]

I should have added a budget of 3-5k lol. But that's cool, a 30mm ES 100 in a big refractor, nice man. Love the sound of that setup. I was wondering if a 3º TFOV was small with a 22mm T4 in my refractor, I guess it's alright. 

Edited by Procyon, 24 April 2025 - 09:21 PM.

[TayM57]

4º hits the sweet spot for me. N31T4 + 8 f/3" gives some very nice wide views, even with the CO being a bit of a problem.

[Jon Isaacs]

My two cents:

 

Scope: TeleVue NP-101 4 inch F/5.4 modified Petzval.. flat field.

 

Eyepiece:  31 mm Nagler. 4.45° at 17.5x with a 5.7 mm exit pupil.

 

To quote a little known amateur astronomer:

 

"That's the closest to heaven I ever expect to be."

 

 

Nearly all my scopes provide a Rich Field Experience.. the 22 inch is F/4.4, F/5.05 with the Paracorr 

 

With the 31 mm Nagler, that's 91x with a 6.1 mm exit pupil and a 0.85° field. Remove the Paracorr and it's 79x with a 0.98° field and a 7.0 mm exit pupil.

 

Stars are bright-bright.. the sky can look like one big open cluster.

 

Jon

[RalphMeisterTigerMan]

If you are on a budget, then try the following; 8-inch F/4 (or less) Richfield Doby plus a 2" ParaCorr Type 2, 21mm Ethos, or 22 Nagler type (4?) or 35 Panoptic. Or the widest field eyepiece of your choice. With the appropriate type of mount you can observe while sitting. Oh, and do not forget the 2-inch filter of your choice. Don't forget the Telrad with "riser" option and laser collimator. Sure, it's low tech but will always work and will not disappoint under dark skies. 

 

Also, you'll get observing "happy" during the appocalypse of your choice while the GPS satellites are screaming down from the skies and everone else can't get their Goto systems to work and also fighting off a hoard of Zombies. 

 

Clear skies and keep looking up!

RalphMeisterTigerMan

 

*** Available NOW for a limited time! RalphMeister "Anti-Zombie Sray", "Zombie-Be-Gone". Only $99.99 plus shipping and handling. Call now, operators are standing by - 202-456-6213 ! Call now and often!!!

Edited by RalphMeisterTigerMan, 24 April 2025 - 09:33 PM.

[TayM57]

 

Stars are bright-bright.. the sky can look like one big open cluster.

 

Jon

 

It sure can! Interesting tidbit: The other night I was observing M67 with the 24". In the focuser, I had the 12ES92. The cluster was rich and bright. In the 9" f/3 finderscope with the N31T5, the cluster was essentially invisible.

 

I thought that was fascinating. Similar to how the Double Cluster loses its magnificence when going too low in magnification.

[Procyon]

If you are on a budget, then try the following; 8-inch F/4 (or less) Richfield Doby plus a 2" ParaCorr Type 2, 21mm Ethos, or 22 Nagler type (4?) or 35 Panoptic. Or the widest field eyepiece of your choice. With the appropriate type of mount you can observe while sitting. Oh, and do not forget the 2-inch filter of your choice. Don't forget the Telrad with "riser" option and laser collimator. Sure, it's low tech but will always work and will not disappoint under dark skies. 

 

Also, you'll get observing "happy" during the appocalypse of your choice while the GPS satellites are screaming down from the skies and everone else can't get their Goto systems to work and also fighting off a hoard of Zombies. 

 

Clear skies and keep looking up!

RalphMeisterTigerMan

 

*** Available NOW for a limited time! RalphMeister "Anti-Zombie Sray", "Zombie-Be-Gone". Only $99.99 plus shipping and handling. Call now, operators are standing by - 202-456-6213 ! Call now and often!!!

lol, what's a good manual mount for that? cool setup.

 

I like sitting and drinking coffee though, I can't reverse the OTA upside down right, can I?

 

 

Edited by Procyon, 24 April 2025 - 09:50 PM.

[therealdmt]

From among the gear I already own, my first choice would probably be my 100ED with an ES68 34mm eyepiece. That would give me 2.6° TFOV and a 3.8mm exit pupil. Not the widest or richest of rich fields, but it would still be plenty fun, especially if complemented by my binoculars, including my 2x54mm constellation binocular. And naked eye. I’d be a happy camper.

 

Its funny, because this question is kind of coming up for me. My wife wants to take a trip just after the coming new moon (due to other commitments, we can’t be gone just before and during the new moon itself, unfortunately) that will include a visit specifically to an area with darker skies, and the question will soon come up of which telescope to bring on this 5 day only-partly-to-feature-astronomy car trip. I know my wife will want me to bring my 10" Dob, but I’m thinking the 100ED for convenience factor and more room in the car over those days. Meanwhile, I have a 72ED that I’ve never used under dark skies (the best conditions I’ve used it under have been suburban).

 

My SkyWatcher 72ED with the ES68° 34 mm yields a 5.5 degree tfov and a 6mm exit pupil. I’m tempted to bring that one, but I think I’d be left wanting more aperture

[Messyone]

Easy….100mm f5 achro with ES 40 68 or ST 120 with a 20mm 100.  Done both and prefer the 120 f5 20/100 combo.

 

 

 

 

[SeattleScott]

Previously I did some research and it sounded like the wide field junkies feel like life begins at 4 degrees wide. Personally I top out at 3.4 although I had a 4 degree option for awhile.

[Procyon]

Good read for a wide field noob like me  Where's Thomas to bring in the arguments lol.

 

https://www.ianmoris...ield-observing/

 

https://www.reddit.c...ctor/?rdt=42831

 

Edited by Procyon, 25 April 2025 - 09:18 AM.

[bobhen]

For rich field viewing, I use my 102mm F5 achromat. The scope can be reduced down to a very fast F3.5. I don't use eyepieces. I use my Image Intensifier. That is the scope I would take along with the intensifier.

 

The scope is portable enough for an airline overhead bin or to toss in a car at a moments notice.

 

Magnifications used are around 20x and 15x. Ha filters are used for nebulas and IR Pass filters are used for non-nebula objects. 

 

But with the intensifier, there is no pressing need to travel to an extremely dark sky! I can do rich field viewing right from home. As a matter of fact, the rich field views from my light-polluted home with the intensifier are much better than when I use the scope with eyepieces from an extremely dark site. Words cannot express just how much the intensifier improves rich field observing.

 

The image shows the refractor with the intensifier in the diagonal – a deep sky, rich field machine.

 

Bob

 

 

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[Procyon]

For rich field viewing, I use my 102mm F5 achromat. The scope can be reduced down to a very fast F3.5. I don't use eyepieces. I use my Image Intensifier. That is the scope I would take along with the intensifier.

 

 

 

Bob

The intensifier causes the reduction to f/3.5? Have their been improvements to remove static and that Gulf War green image? How do the views look like?

 

There's no way to add a focal reducer to a 100mm f/6 achro without causing vignetting in the eyepiece right? I keep reading a telocentric barlow would be best, but no screwable lenses exist. Or simply aren't possible to make?

 

PS> I was looking into if I can somehow barlow a 48mm Brandon since I like this eyepiece so much. Ultimately, I'll probably be better off getting a beloved 22mm T4 Nagler again.

Edited by Procyon, 25 April 2025 - 10:33 AM.

[Procyon]

Easy….100mm f5 achro with ES 40 68 or ST 120 with a 20mm 100.  Done both and prefer the 120 f5 20/100 combo.

How do you like your 40mm ES 68? Do you observe with the eyecup upwards or folded? How's the comfort, notice any annoying blackouts or stray light seeping into the eyecup when observing? I had a 40mm ES 62 once and that stray light part really annoyed me. As if the eyecup was too large to fit an eye socket and cover it properly. Maybe I should stop messing around and try this eyepiece.

Edited by Procyon, 25 April 2025 - 10:16 AM.

[davidgmd]

I’ll second Jon Isaac’s recommendation: TV NP101 plus the 31 mm Nagler. No field flattener needed.

Almost 4.5 degrees at 17.5X. Exit pupil of 5.7 mm unlikely to exceed your scotopic pupil size by much.

Not the smallest or lightest option, but fits within your stated budget of 3-5k.

[vrodriguez2324]

 

ST120 + TSFLAT2 + 31NT5 = 4 full degrees of amazing (4.01 degrees TFOV)

 

8 inch f/5 Reflector + Paracorr + 31NT5 = 2 full degrees of awesome. (2.09 degrees TFOV)

 

I can't decide which is better. 

Edited by vrodriguez2324, 25 April 2025 - 11:37 AM.

[Houdini]

I did not purchase it for observing, only for testing, but the views have been surprisingly good (despite the poor focuser on this model).

8 inch F/4 reflector with 20 mm eyepiece, producing 40X and a 2.15° field of view, on an altazimuthal mount.

The Moon passing in front of the Pleiades three weeks ago was very nice.

 

[russell23]

One eyepiece, one scope and a gadget like a field flattener or focal reducer, for a dark site trip for rich field views, which are you taking and why?

 

What is a better wide field view for you? 3º, 4º, 5º, 6º, 7º?

 

No cameras..

My answer to this question is dependent upon exit pupil.   I prefer my largest exit pupil being in the 2-3mm range.  When the exit pupil is larger than 4mm my astigmatism becomes a problem - even with my dedicated astronomy glasses correcting for it.

 

In addition, I also generally prefer observing at 30-50x over less than 30x.  

 

A lot of nights I almost exclusively use an eyepiece that gives 30-50x with the scope I am using.  Since I have dark skies from my backyard my answer comes with specific experience on many nights.

 

So with my main scopes I use it would be the following:

 

94mm f/7 Brandon APO:  16.5mm Pentax --> 39x, 2.2 deg, 2.3mm exit pupil

 

102mm f/11 Altair ED:  30mm Pentax -->  37x, 1.8 deg, 2.7mm exit pupil

 

115mm f/7 Astrotech APO:  16.5mm Pentax -->  49x, 1.7 deg, 2.3mm exit pupil

 

Most people would choose larger exit pupils and wider TFOV, but if I am selecting just one magnification with the goal of an enjoyable wide FOV for a night of observing, I'll take the above over magnifications less than 30x an exit pupils greater than 4mm.

 

Dave
 

[Sketcher]

The following would be my preferences among what I have available to use:

 

152mm achromat 988mm focal-length + 32mm 2" eyepiece = 31x, 2.3°  FOV, 4.9mm exit-pupil

 

130mm apochromat 830mm fl + 27mm 2" eyepiece = 31x, 2.1° FOV, 4.2mm ep

 

25x100 binoculars = 2.3° FOV, 4mm ep

 

80mm achro 400mm fl + 20mm 1.25" eyepiece = 22x, 3.3° FOV, 3.6mm ep

 

Why?  This I've answered in substantial detail in the past.  So, here I'll just say: "I've been living and observing under "seriously dark" skies for the past 40+ years.  I know what works for me and what i prefer."

 

With all except the binoculars, I have the capability to achieve lower magnifications and wider true fields of view, but my preferences are for the somewhat narrower true fields and somewhat higher magnifications -- I know what I prefer . . .

 

The below sketch/observation was made while observing with the 80mm 400mm fl achromat along with the 20mm eyepiece that was specified above -- a strictly visual observation from right outside my front door, but with that telescope's 80mm aperture stopped down to a 1-inch clear aperture -- just to show the deep-sky capabilities of such a tiny aperture under a "seriously dark" sky:

 

 

Naturally, the 6-inch telescope (as well as all of the other instruments) that I mentioned in the above listing is far more capable 

[sevenofnine]

My average guy set-up would be an AT80ED with a ES 28/68 on S/W AZ-GTi for 3.4* TFOV. My gadget would be an Oberwerk 20x70EDU on a 4000 tripod while I'm seated on a TeleVue Air Chair.

Good enough for me 

 

.

Edited by sevenofnine, 25 April 2025 - 03:13 PM.

[davidgmd]

My answer to this question is dependent upon exit pupil.   I prefer my largest exit pupil being in the 2-3mm range.  When the exit pupil is larger than 4mm my astigmatism becomes a problem - even with my dedicated astronomy glasses correcting for it.

 

In addition, I also generally prefer observing at 30-50x over less than 30x.  

  
A dedicated pair of astronomy glasses should correct any regular astigmatism. Makes me wonder if you could have some subtle or minor irregularity or opacity in the paracentral cornea or lens, perhaps between 2-4 mm from the optical axis of the eye. Probably irrelevant given your preference for >30x.

[Procyon]

I thought I'd see some 60-72mm f/5-7 Apo Refractors as favorites. It seems the consensus is 80-125mm f/5-6.

 

With big AFOV eyepieces in the 82-100º range. Mostly 20mm 100 XWA's, 22mm T4's, 28mm UWA and 31mm T5 Naglers instead of the 35-40mm range.

 

Interesting 

 

PS> Having said all that, do you guys like something like a 72mm f/6 APO for rich fields? As a secondary or very light grab n go refractor.

Edited by Procyon, 25 April 2025 - 04:26 PM.