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Tony Flanders
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Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: to view peleades? new [Re: soliari]
      #5603743 - 01/03/13 09:46 PM

Quote:

Right now i'm setup for 1.25, but i think it can easily host a 2".




On a scope with a slow focal ratio, using 2-inch eyepieces will open up whole new worlds. Expensive but well worth it.


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Dennis_S253
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Reged: 11/22/11

Loc: West Central Florida
Re: to view peleades? new [Re: Tony Flanders]
      #5603895 - 01/03/13 11:36 PM Attachment (18 downloads)

I guess I don't understand what you are all looking at. Sure there maybe a couple other stars that you could include but...

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soliari
journeyman


Reged: 11/12/12

Loc: New Mexico, USA
Re: to view peleades? new [Re: Dennis_S253]
      #5603918 - 01/03/13 11:59 PM

Dennis, I am not well versed at what you're displaying here. Can you tell the novice blatantly?

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Jeff2011
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Re: to view peleades? new [Re: JamesL]
      #5603944 - 01/04/13 12:28 AM

With my 8in Dob and my 38mm ep I can view the whole Pleiades. Tracking is not that big of an issue with a low power wide angle ep.

Happy viewing!

Jeff


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Allan...
sage


Reged: 10/24/12

Loc: Penticton B.C. Canada
Re: to view peleades? new [Re: Jeff2011]
      #5603952 - 01/04/13 12:34 AM

Hey Jeff.....I was curious about the Q70 38mm for an XT8. I am almost 60 (so eyes not the greatest exit pupil) and I was told by some, that a 38mm is too low; it would have an exit pupil of 6.44 and Im sure that my eyes are about a 5 or less now. Any comments? thanks, Clare The lowest that I have now is a 30mm Owl 2" and its OK but not as bright as a 24 or 25mm (for MY eyes, anyways).

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Jon Isaacs
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Reged: 06/16/04

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Re: to view peleades? new [Re: soliari]
      #5604140 - 01/04/13 06:31 AM

Quote:

Quote:

I agree. I have a 5" refractor with a focal length of 825 mm and view the Pleiades often with a 31mm Celestron Ultima eyepiece (gives about 27X and a 2.6 deg RFOV). It does the job of framing the entire nebula. A couple of weeks ago, I observed and "mapped" M45 with a 17mm Celestron (49X and about 1.4-1.5 deg RFOV). The cluster was a bit big for the field of view but I'm glad I did this anyway because it probably helped to catch and map a few extra of the dimmer stars.




I hope you don't mind me jumping in on this thread, but what I'm gathering from what everyone is saying that you need right around 2 degrees for TFOV to view the Pleiades with any success? If so, it seems my 1000mm refractor will have a hard time viewing it ... I was looking at purchasing a 44mm eye piece with 40 degrees FOV. If I calculate correctly that should yeild 1.7 degrees of TFOV ... too narrow for gathering the entirety of the Pleiades?




Hi:

My own personal tastes is for at least 2.5 degrees TFoV but as Tony says it is still interesting piece-wise and 1.6 degrees will show you nearly all of it.

In terms of maximizing your TFoV, if you have a 2 inch focuser, then purchasing a 2 inch diagonal and a 2 inch widefield eyepiece in the 30-40mm range should provide nice views. With a 2 inch eyepiece that has a 46mm field stop, the maximum possible, your 1000mm FL refractor would provide a TFoV of about 2.6 degrees, just about perfect for the Pleiades.

Regarding the 40mm eyepiece with the 44 degree AFoV. The True Field of View is limited by the field stop of the eyepiece. The field stop is the ring you see at the edge of the field. With a Plossl eyepiece, you can look down the barrel of the eyepiece and actually see the ring. As you can imagine, the maximum diameter for the field stop is the inner diameter of the barrel, for a 1.25 inch barrel that would be about 28mm, for a 2 inch barrel it's about 46mm.

Using the field stop to calculate the TFoV is more accurate than using the 44 degree AFoV. In general, a 32mm Plossl and a 40mm Plossl have the same TFoV because both are limited by the inner diameter of the barrel. The 32mm is typically the more desirable because it provides a larger AFoV and greater magnification.

The formula to calcuate the TFoV from the field stop and focal length of the telescope is:

TFoV = 57.3 degrees/radian x (field stop/focal length telescope)

TFoV max = 57.3 x 28/1000 = 1.60 degrees.

A 2 inch diagonal and a 2 inch eyepiece are not so cheap but if shop carefully and buy something used on Astromart or CN Shop and Swap, you should be able to find something acceptable for under $100 though it is possible to spend $1000 a pair purchased new.

The ST-80, that is an 80mm F/5 achromatic refractor is a good choice for widefield viewing. With a 32mm Plossl or 24mm Superwide field, it will provide a 4 degree TFoV. An ST-80 is about 15 inches long, very portable, and does a nice job for terrestrial viewing too. I have an ST-80 with a 2 inch focuser and it is capable of TFoVs greater than 6 degrees. A bare-bones ST-80 is just a bit over $100. The downside of the ST-80 is that at higher magnifications, the false color limits the view.

A pair of 8x or 10x binoculars also is a great way to view the Pleiades.

The Pleiades are just wonderful to look at. I spend a few minutes just enjoying them any time they are visible.

Jon


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kenrenard
Carpal Tunnel


Reged: 12/13/12

Loc: Dunmore, PA
Re: to view peleades? new [Re: Allan...]
      #5604152 - 01/04/13 06:53 AM

Quote:

Hey Jeff.....I was curious about the Q70 38mm for an XT8. I am almost 60 (so eyes not the greatest exit pupil) and I was told by some, that a 38mm is too low; it would have an exit pupil of 6.44 and Im sure that my eyes are about a 5 or less now. Any comments? thanks, Clare The lowest that I have now is a 30mm Owl 2" and its OK but not as bright as a 24 or 25mm (for MY eyes, anyways).




Clare,
I have a Q70 38mm in my xt8. I like it. It does get a bit soft on the edges but it has that lost in space feeling. I'm 41 and wear glasses. I saw Orion is running a sale on these for $79.99 which was the price I picked mine up for last year. It's my only two inch so I have nothing to compare it against. I did find a TV panoptic 24mm that is 1.25 which was very cheap and I love the eyepiece, It's my only premium eyepiece and it really is great. At 3 times the price I guess it should be. I mainly use the pan in my 72mm refractor which it does work very well.

As far as the 38 Q70 being to dim. I just don't have the expertise to explain or know the difference. I like it for wide field views and find I use it quite a bit.

Maybe someone with more experience could explain the exit pupil differences. I don't want to mislead you since I only have about a year experience. It works well for me and I have showed things to other club members through the eyepiece and they like the views. Some were quite a bit older than I.


I hope I have been of some help.

Ken


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Jon Isaacs
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: to view peleades? new [Re: Allan...]
      #5604221 - 01/04/13 08:20 AM

Quote:

The lowest that I have now is a 30mm Owl 2" and its OK but not as bright as a 24 or 25mm (for MY eyes, anyways).




My guess is that you are thinking of the brightness of the stars rather than the brightness of a nebula and galaxy. Star brightness does not really change at lower magnifications as you increase magnification but the back ground sky becomes darker so the contrast increases.

The Owl 2 inch 30mm 80 degree should provide you with almost the maximum possible true field of view, just about 2 degrees. The 38mm Q70 would provide you with maybe 2.2 degrees... The downside to the Owl is that it shows quite a bit of off-axis astigmatism, the stars are not clean and sharp as you move away from the center.

At some point you may want to upgrade to something that is sharper across the field, I would be looking further up the scale than the Q-70s...

Jon


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kenrenard
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Reged: 12/13/12

Loc: Dunmore, PA
Re: to view peleades? new [Re: Jon Isaacs]
      #5604249 - 01/04/13 08:41 AM

Thank you John,
I could not articulate it the way you did. From my novice use of the eyepieces I have I notice my Q70 is kind of dull and blurry on the edges. However, on the 24mm panoptic it seems to be perfect all the way to the edge especially in my refractor. The 24 Pan was my first purchase of a premium eyepiece and I can see why folks say how good they are. The Q70 is very heavy it is too much in weight for my AT72 without counter weight on my mount.


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Jon Isaacs
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: to view peleades? new [Re: kenrenard]
      #5604318 - 01/04/13 09:08 AM

Quote:

Thank you John,
I could not articulate it the way you did. From my novice use of the eyepieces I have I notice my Q70 is kind of dull and blurry on the edges. However, on the 24mm panoptic it seems to be perfect all the way to the edge especially in my refractor. The 24 Pan was my first purchase of a premium eyepiece and I can see why folks say how good they are. The Q70 is very heavy it is too much in weight for my AT72 without counter weight on my mount.




Ken:

Dull and Blurry pretty much sums it up. Still, such eyepieces can provide very enjoyable views but the perfection of an eyepiece like the 24mm Panoptic can be addicting.

These days I am fortunate enough to own some of the best longer focal length 2 inch eyepieces, the 31mm Nagler, the 35mm Panoptic and the 28mm UWAN.. But I have a 35mm ES Scientific that cost $50 new and while the views are not as perfect as the others, it provides an ever so slightly wider field of view than the others and I am certainly able to enjoy the views it provides.

Jon


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soliari
journeyman


Reged: 11/12/12

Loc: New Mexico, USA
Re: to view peleades? new [Re: Jon Isaacs]
      #5604352 - 01/04/13 09:18 AM

Jon,

Great explanation! Thank you very much for taking the time to write it up in such a clear way for this novice.


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kenrenard
Carpal Tunnel


Reged: 12/13/12

Loc: Dunmore, PA
Re: to view peleades? new [Re: Jon Isaacs]
      #5604362 - 01/04/13 09:21 AM

I plan on picking up a Explore Scientific eyepiece. I looked at some of them through club members scopes and I was impressed. If I can get one good eyepiece a year I should have a nice collection. I still do like to Q70 for what I paid for it. I works well enough for me and I find it a good eyepiece for finding things since I have manual means to find things. Although I have been tricked thinking I found something on the edge and moving to center and realizing it was just the eyepiece playing tricks on me.

Thanks again for your help explaining things. I have learned a lot from reading your posts.


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rflinn68
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Reged: 03/09/12

Loc: Arkansas
Re: to view peleades? new [Re: Jon Isaacs]
      #5604462 - 01/04/13 10:22 AM

Quote:

I have a 35mm ES Scientific that cost $50 new
Quote:



Where do I get this eyepiece at!!!? I'll get a couple right now!

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Jon Isaacs
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Re: to view peleades? new [Re: rflinn68]
      #5604488 - 01/04/13 10:33 AM

Quote:

Quote:

I have a 35mm ES Scientific that cost $50 new
Quote:



Where do I get this eyepiece at!!!? I'll get a couple right now!




They were a close out at OPT. The field stop is 44.7mm which means they provide about the largest field of view of any 35mm eyepiece but while they are quite sharp in the very center of the field of view, things go down hill fast.

Still...

Jon


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rflinn68
Carpal Tunnel


Reged: 03/09/12

Loc: Arkansas
Re: to view peleades? new [Re: Jon Isaacs]
      #5604496 - 01/04/13 10:37 AM

Quote:

I have a 35mm ES Scientific that cost $50 new
Quote:



Where do I get this eyepiece at!!!? I'll get a couple right now!




They were a close out at OPT. The field stop is 44.7mm which means they provide about the largest field of view of any 35mm eyepiece but while they are quite sharp in the very center of the field of view, things go down hill fast.

Still...

Jon




That figures. I always miss those great deals I have a few ES82's. I love them all and plan on getting the whole set.


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Jon Isaacs
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: to view peleades? new [Re: rflinn68]
      #5604513 - 01/04/13 10:43 AM

Quote:

That figures. I always miss those great deals I have a few ES82's. I love them all and plan on getting the whole set.




The ES-82s seem to be great eyepieces.... For $50 the 35mm ES 70 was a good deal... but not for $100... definitely not up to the standard of the 68s and 82s...

Jon

Edited by Jon Isaacs (01/04/13 10:44 AM)


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newtoskies
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Reged: 07/15/12

Loc: SE Ma.
Re: to view peleades? new [Re: Jon Isaacs]
      #5604534 - 01/04/13 10:56 AM

wow what an interesting thread. Been following along and learning. Seems you could invest a lot of money in this hobby eh. I can see M45 with my 6" and 32mm Plossel. I have the best views of M45 with my 10x50 binos.
The ST 80 sounds like a good investment for wfov. I was out for a short time last night before the clouds ruined a planned evening of viewing. I was mainly wanting too view M35-38. These I had seen before but always liked viewing them. Even with my 32mm I can't get them all in fov. I'm thinking refractor is in order for viewing clusters such as M45, M35-38. I could be wrong of course, seeing I'm still very new at this.


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brianc99
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Reged: 11/27/12

Loc: Southern NH
Re: to view peleades? new [Re: newtoskies]
      #5605541 - 01/04/13 08:36 PM

Well there have been a few mentions of the ST80 here, and what I have for a scope is one of its predecessors, the Celestron 80mm WA. With my 20mm plossl, the Pleiades look just great.

I'm probably influenced by (literally) the lens though which I'm viewing, but the Pleiades are my absolute favorite feature of the night sky. Granted, my viewing experience is very limited. But most of what I view makes me think "that's interesting" or "that's cool," while the Pleiades make me think "that's one of the most beautiful sights anyone has ever seen." However you get there, it's worth making the effort to get a good view of them. I feel fortunate that I chose as my first scope, one that gives me such a pleasing view of the Pleiades.

Brian


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Gert K A
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Reged: 07/16/12

Loc: Copenhagen, Denmark
Re: to view peleades? new [Re: brianc99]
      #5605614 - 01/04/13 09:34 PM

Quote:


I'm probably influenced by (literally) the lens though which I'm viewing, but the Pleiades are my absolute favorite feature of the night sky. Granted, my viewing experience is very limited. But most of what I view makes me think "that's interesting" or "that's cool," while the Pleiades make me think "that's one of the most beautiful sights anyone has ever seen." However you get there, it's worth making the effort to get a good view of them. I feel fortunate that I chose as my first scope, one that gives me such a pleasing view of the Pleiades.

Brian




+1
I totally agree


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Jeff2011
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Reged: 01/01/13

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Re: to view peleades? new [Re: Jon Isaacs]
      #5605711 - 01/04/13 10:52 PM

On the Q70 I concur with Ken. The image is in focus at the center and slightly out of focus at the edges. I can focus to make the edges clear but then the center is out of focus. However it is quite useful to help locating objects with the 2.2 deg fov. I then zoom in with other eyepieces. I also liked the price although I did not buy it at the sale price. Clare, I don't know what the exit pupil size is but I can't see the whole image without moving my eye around. Hope that helps.

I have a baader mpcc on order. I was wondering if this would help to make the focusing more consistent throughout the eyepiece view in addition to the coma correction. I ordered the mpcc for ap but they advertise that it works for visual also.


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