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JamesL
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Reged: 10/19/12

Loc: Pacific,MO
to view peleades?
      #5595422 - 12/30/12 12:48 AM

Hi folks, I am trying to view Peleades in my c8 f/10 and cant seem to get the whole cluster in view. I purchased a meade 4000 series 56mm super plossl for this purpose but it still doesnt all fit in the field of view.Do I need to get a focal reducer? Would one be handy to have for wider views or would it be something that wouldnt be used much? I just look visually, no photograghy, thanks..James

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Jon Isaacs
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Reged: 06/16/04

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Re: to view peleades? new [Re: JamesL]
      #5595442 - 12/30/12 01:14 AM

James:

No matter what you do with a C-8, fitting in the entirety of Pleiades is beyond it's capabilities. A focal reducer is a help but the focal reducer cannot change the fundamental limitations of the telescope.

The C-8 has a focal length of 2032 mm with a rear port of 38mm. This means that anything greater than a 1.07 degtree field will vignette. You can push this but the Pleiades are close to 2 degrees.

The 55 mm Plossl provides a 1.3 degree TFoV you might get some more with a focal reducer but the exit pupil will be quite large and you may begin to see the shadow of the secondary. There are 40mm eyepieces that provide the same TFoV as the 55 mm Plossl, they would be a better bet.

In general, smaller, shorter focal length scopes and binoculars are the best choices for viewing the Pleiades, the strengths of your C-8 lie elsewhere.

Jon


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JamesL
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Reged: 10/19/12

Loc: Pacific,MO
Re: to view peleades? new [Re: Jon Isaacs]
      #5595478 - 12/30/12 02:10 AM

ok, thanks Jon for that explaination. I have an old dob 8"f/4 maybe ill clean it up and take a look through that one but it doesnt track, but thats ok.

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Tony Flanders
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Re: to view peleades? new [Re: JamesL]
      #5595621 - 12/30/12 06:50 AM

Binoculars do a great job on the Pleiades. Life without binoculars is barely worth living, and astronomy without binoculars is barren indeed. If you don't already own a pair, they're the best astro investment you will ever make.

A high-quality finderscope also does a fine job.


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Jon Isaacs
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Re: to view peleades? new [Re: JamesL]
      #5595631 - 12/30/12 07:14 AM

Quote:

ok, thanks Jon for that explaination. I have an old dob 8"f/4 maybe ill clean it up and take a look through that one but it doesnt track, but thats ok.




With the right eyepiece, your 8 inch f/4 would take in the entire Pleiades. Normally I would not suggest a 55 mm Plossl for an f/4 telescope because of the whopping 14 mm exit pupil. With your eye only open to 7mm or less, most of the light does not enter the eye.

But the Pleiades are plenty bright and the large exit pupil transforms your 8 inch f/4 into a 4 inch f/8 which should provide cleaner views away from the center of the field. The CO would be doubled.. that could be a problem.

A 3 inch off-axis aperture mask would do the trick. It's just a piece of cardboard with a hole.

Jon

Edited by Jon Isaacs (12/30/12 07:46 AM)


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edwincjones
Close Enough
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Re: to view peleades? new [Re: Tony Flanders]
      #5595642 - 12/30/12 07:35 AM

Quote:

Binoculars do a great job on the Pleiades. Life without binoculars is barely worth living, and astronomy without binoculars is barren indeed. If you don't already own a pair, they're the best astro investment you will ever make.

A high-quality finderscope also does a fine job.







edj


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newtoskies
Pooh-Bah


Reged: 07/15/12

Loc: SE Ma.
Re: to view peleades? new [Re: edwincjones]
      #5595661 - 12/30/12 08:05 AM

I found binos great for M45.

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Ed D
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Re: to view peleades? new [Re: newtoskies]
      #5595688 - 12/30/12 08:37 AM

Jon and Tony nailed it! The only thing I can add is that with the 8" f/4 and a good wide FOV eyepiece the lack of tracking is almost a non-issue. Make sure the Dob bearing surfaces are clean and you have smooth motions.

Ed D


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lamplight
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Re: to view peleades? new [Re: Ed D]
      #5595892 - 12/30/12 10:55 AM

See a used pair of 7x50 bushnell fog proof for $60, good deal? Need to get a pair , think wife will like it if she ever decides to observe with me again. Pleiades is gorgeous through my stellarvue finder!

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Achernar
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Re: to view peleades? new [Re: JamesL]
      #5595936 - 12/30/12 11:22 AM

Your telescope as it is right now can't take in the Pleiades into a single field of view not only due to the focal length, but also due to the diameter of the rear port where the diagonal is attached. Using a reducer with that eyepiece will result in a drastic loss of aperture and increased sky glow, and there could also be vignetting due to the size of the rear port. You may be able to use that reducer with a 30mm or so 82 degree eyepiece, or even a 24mm 82 degree eyepiece, which will accomadate an object this large. Using a 30mm eyepiece with a F/6.3 focal reducer will give you an exit pupil just under 5mm, a good range for both light pollution and aging eyes considerations. And you will get a true field of view nearly two degrees across, more than enough for the Pleiades, or Beehive clusters. A focal length no greater than about 1200mm is a must if you want to fit objects as large as the Pleiades into one view. A smaller telescope with shorter focal length and a wider field of view would be an invaluable partner for your C-8. I can fit the Pleiades into the field of view of my 6 and 10-inch Dobs with an Explore Scientific 24mm 82 degree eyepiece. Both telescopes have a focal length of 1,200 and 1,315mm respectively, similar to what a C-8 would have with a F/6.3 focal reducer in place. The reducer will also help you a lot with other deep sky objects like the Andromeda Galaxy and M-42, which benefit from the larger field of view. The reducer also improves star images at the edges of the field, SCT's do have coma but not as much coma as my F/4.5 Dobs do without a Paracorr in place. If you decide to try prime focus photography, it will dramatically reduce exposure times.

Taras


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WAVT
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Reged: 08/22/10

Loc: Bellingham, WA
Re: to view peleades? new [Re: Achernar]
      #5596186 - 12/30/12 01:36 PM

a 32mm plossl eyepiece will take in the Pleaides quite nicely in your 8" f/4 scope. The exit pupil is still a bit oversized but I suspect the view will be quite good. If your 8" f/4 scope takes 2" eyepieces you would have even more options for taking in a big wide field.

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kenrenard
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Reged: 12/13/12

Loc: Dunmore, PA
Re: to view peleades? new [Re: Tony Flanders]
      #5596428 - 12/30/12 03:56 PM

Quote:

Binoculars do a great job on the Pleiades. Life without binoculars is barely worth living, and astronomy without binoculars is barren indeed. If you don't already own a pair, they're the best astro investment you will ever make.

A high-quality finderscope also does a fine job.





Nothing works as easy as binoculars. As a beginner not that long ago I found binoculars to be the best tool you can use. I use my 10 X 50 binoculars all the time for astronomy and birds.


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JamesL
member


Reged: 10/19/12

Loc: Pacific,MO
Re: to view peleades? new [Re: kenrenard]
      #5597184 - 12/30/12 11:54 PM

ok, I ordered a focal reducer and I have a 32mm 2"Rini eyepiece and 11mm es 82 eyepiece. Its cloudy tonight(snow coming again)so I cant use either scope tonight. The 8" dob is one that I built a few years ago and its ra movement is kind of stiff but the views were nice.Also it is too heavy and bulky to set up. Think ill concentrate on the c8.Last night I had great views of jupiter with 17mm tv plossl and 10mm orion explorer ii eyepieces. Then looked at orion nebula with es 11mm 82 and it was awesome!Having lots of fun with the c8.Also have the 20 and 15mm superviews, 25mm silver top. A new eyepiece is always coming in the mail, I gotta stop spending for a while. Anyway thanks for all of your input...James

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Mark Costello
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Re: to view peleades? new [Re: WAVT]
      #5601374 - 01/02/13 02:45 PM

Quote:

a 32mm plossl eyepiece will take in the Pleaides quite nicely in your 8" f/4 scope. The exit pupil is still a bit oversized but I suspect the view will be quite good. If your 8" f/4 scope takes 2" eyepieces you would have even more options for taking in a big wide field.




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 cluster. 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.

Edited by Mark Costello (01/04/13 09:59 AM)


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Widespread
professor emeritus


Reged: 05/11/11

Loc: Bowling Green, Kentucky
Re: to view peleades? new [Re: Mark Costello]
      #5602762 - 01/03/13 11:17 AM

I have an 8SE (C8), and had the same problem with insufficient TFOV for large objects.

I got an Orion ST80 for $179 and sold off the Expanse EPs on Astromart for a net cost of about $115.

Since you have a fast Dob, this may be superfluous information, but I think a short FL refractor is a great complement for powerful but FOV-challenged SCTs.

If I'd known how much I would love this little refractor, I would have gotten small ED scope. (I still might ;p)

Best,
David


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kenrenard
Carpal Tunnel


Reged: 12/13/12

Loc: Dunmore, PA
Re: to view peleades? new [Re: Widespread]
      #5602830 - 01/03/13 11:52 AM

Quote:

If I'd known how much I would love this little refractor, I would have gotten small ED scope. (I still might ;p)






I know what you mean. I have an astro Tech 72ED and its a great wide field scope.


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soliari
journeyman


Reged: 11/12/12

Loc: New Mexico, USA
Re: to view peleades? new [Re: Mark Costello]
      #5602850 - 01/03/13 12:00 PM

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?


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ensign
scholastic sledgehammer


Reged: 12/16/08

Loc: Southwestern Ontario
Re: to view peleades? new [Re: soliari]
      #5603002 - 01/03/13 01:26 PM

To the OP, I solved the problem of narrow fields in an SCT by dual mounting a small (80mm) refractor with the SCT. The little scope does double duty as a finder and a wide-field viewer.

With a 40mm eyepiece in the 80mm refractor, I get a whopping 5.2 degrees of true field - way more than enough for the Pleiades and other extended objects. The same EP in the SCT gives a mere 1.1 degree true field, but the views are magnificent.


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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]
      #5603033 - 01/03/13 01:42 PM

Quote:

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?




I'm not sure about "success." The Pleiades are still pretty nice viewed piecewise. But to my taste, you need a 2-degree field of view to frame them to best aesthetic effect. Maybe even a little more than 2 degrees, if anything.

Quote:

If so, it seems my 1000mm refractor will have a hard time viewing it.




That's correct, unless your refractor has a 2-inch focuser. The maximum FOV achievable with a 1000-mm focal length and a 1.25-inch eyepiece is about 1.6 degrees. Personally, I would use a 32-mm Plossl rather than a longer eyepiece with a narrower apparent field of view to achieve that.


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soliari
journeyman


Reged: 11/12/12

Loc: New Mexico, USA
Re: to view peleades? new [Re: Tony Flanders]
      #5603167 - 01/03/13 02:55 PM

Tony,

What I meant by success was to frame them in all together.

Hmm ... i didn't think about the 2" eye piece route. Right now i'm setup for 1.25, but i think it can easily host a 2".


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Tony Flanders
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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
Pooh-Bah


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
Carpal Tunnel
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Reged: 01/01/13

Loc: Sugar Land, TX
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
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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

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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
Carpal Tunnel


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
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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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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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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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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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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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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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Jeff2011
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Re: to view peleades? new [Re: Jon Isaacs]
      #5605739 - 01/04/13 11:06 PM

Jon,

Your explanation on true fov calculation using the f stop of the eyepiece is very interesting. How would this work for the baader Hyperion eyepieces. They have a built in Barlow type element that is 1.25 but the rest of the eye piece is like a 2 inch. I happened to pick up a used 13 mm Hyperion for 60 bucks. It gives me about a 3/4 deg TFov. The afov is 68.

Thanks,

Jeff


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Widespread
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Re: to view peleades? new [Re: Jeff2011]
      #5606015 - 01/05/13 04:39 AM

Last night I tried my new 36 mm Baader Planetarium (72 degree field of view) in my St80.

Jupiter was a tiny dot, with lots of false color (due to the scope, not the eyepiece), but the Pleiades and Hyades were outstanding. This is my lowest magnification telescope view ever.

The Seven sisters blew me away. The view was lower magnification than my 15x binoculars, but rock solid. I have my binoculars on a mono pod, but not a tripod, so it's always a little bit shaky.

This is a modular eyepiece, and can be used with either 1.25 or 2 inch diagonals. It gives the widest TFOV possible in 1.25" format.

In a 2" diagonal, the view is even wider, of course. Used with a 6.3 focal reducer, it should give the maximum (vignetted) TFOV for an 8SE.

It's still won't quite fit the Pleiades, though.

Cheers, David


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Jon Isaacs
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Re: to view peleades? new [Re: Jeff2011]
      #5606224 - 01/05/13 09:59 AM

Quote:

Jon,

Your explanation on true fov calculation using the f stop of the eyepiece is very interesting. How would this work for the baader Hyperion eyepieces. They have a built in Barlow type element that is 1.25 but the rest of the eye piece is like a 2 inch. I happened to pick up a used 13 mm Hyperion for 60 bucks. It gives me about a 3/4 deg TFov. The afov is 68.

Thanks,

Jeff




Jeff

With eyepieces like your Hyperion one uses an effective field stop diameter. Televue provides this for information all their eyes as do some other vendors. One can also measure the Tfov by measuring the time a particular star takes to drift across the field and then back calculating the field stop.

One can search the web and find values that may or may not be correct.

I always use the field stop to calculate the Tfov because it is more accurate but for most practical purposes tfov = AFoV/mag is plenty good, generally within 5% though sometimes it might be as much as 10%. In my experience, it always overestimates the Tfov.

Jon


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Jeff2011
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Re: to view peleades? new [Re: Jon Isaacs]
      #5606465 - 01/05/13 12:07 PM

Jon,

As I was reading your reply I had a slap my head moment. Baader does publish the F stop information in a nice little PDF at http://www.baader-planetarium.com/pdf/hyperion_brief_description_e.pdf

Thanks for taking the time to respond to us newbies. I have learned a lot in a year and a half by reading posts such as yours and am trying to pay it back by helping others.

Thanks,

Jeff


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Dennis_S253
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Re: to view peleades? new [Re: Jeff2011]
      #5607269 - 01/05/13 08:40 PM

"The Seven sisters blew me away."
"It's still won't quite fit the Pleiades, though."

You mean you can see the seven sisters only in the EP, and not the two parents?
The Pleiades are the seven sisters and two parents.


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Pat at home
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Re: to view peleades? new [Re: brianc99]
      #5607337 - 01/05/13 09:33 PM

Quote:


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."

Brian




I once made the mistake of "looking up" with a pair of binoculars and the first thing I saw were the Sisters.

The next day my wallet was empty but I had an 8 inch newtonian on an EQ6-Pro in my yard. I've not regretted that one bit. The Sisters are still a favourite winter target for me. I always make a point of aiming my ST-80 that way whenever someone new comes over to the house and are curious about astronomy.


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Dennis_S253
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Re: to view peleades? new [Re: Pat at home]
      #5607382 - 01/05/13 10:08 PM

I can fit the Pleiades in my Meade 4000 series "26mm" EP. They only have a 52 degree aFOV. It's a little stuffed, but it can be done. Some site's say Pleiades is 110' but I look at it as the seven sisters and two parents. And that don't take 110' to do that. Stellarium says it's only 30' but I don't think that includes the 2 parents.

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Jon Isaacs
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Re: to view peleades? new [Re: Dennis_S253]
      #5607523 - 01/05/13 11:27 PM

Quote:

I can fit the Pleiades in my Meade 4000 series "26mm" EP. They only have a 52 degree aFOV. It's a little stuffed, but it can be done. Some site's say Pleiades is 110' but I look at it as the seven sisters and two parents. And that don't take 110' to do that. Stellarium says it's only 30' but I don't think that includes the 2 parents.




The 7 sisters are about a degree but the entire cluster is about 2 degrees.
Personally I like to see the whole thing plus a little to frame them.

Jon


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Dennis_S253
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Re: to view peleades? new [Re: Jon Isaacs]
      #5607573 - 01/05/13 11:53 PM Attachment (15 downloads)

Well, here's your 2 degree framed.

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Dennis_S253
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Re: to view peleades? new [Re: Dennis_S253]
      #5607577 - 01/05/13 11:55 PM Attachment (12 downloads)

And here's my stuffed view

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Dennis_S253
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Re: to view peleades? new [Re: Dennis_S253]
      #5607578 - 01/05/13 11:56 PM

I like mine better

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Dennis_S253
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Re: to view peleades? new [Re: Dennis_S253]
      #5607586 - 01/06/13 12:02 AM Attachment (10 downloads)

Maybe I shouldn't have inverted the colors. Lets try again..
2 degree...


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Dennis_S253
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Re: to view peleades? new [Re: Dennis_S253]
      #5607589 - 01/06/13 12:03 AM Attachment (10 downloads)

Stuffed...

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Dennis_S253
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Re: to view peleades? new [Re: Dennis_S253]
      #5607599 - 01/06/13 12:11 AM

I had to fudge the numbers on the 40mm to get the 2 degree FOV but theres your framed view. I still like mine better. So is this a personal preference? I just wanted to know what they were looking at. Show me some pics... Maybe there looking at the Hyades???

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Jon Isaacs
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Re: to view peleades? new [Re: Dennis_S253]
      #5607839 - 01/06/13 07:36 AM

Dennis:

I am looking at your scope list and I believe the widest field of view is possible is with your 6 inch with the 1000mm focal length which has a 1.25 inch focuser. My calculation based on the field stop indicates the maximum possible field of view is no more than 1.6 degrees, enough to take in most of the cluster.

At some level it is a matter of personal choice but it is worth remembering that a scope capable of framing the Pleiades in a 2.5 degree TFoV is also capable of a 1.6 degree view or whatever else might be of interest. So, if one is looking for a scope well suited for viewing the Pleiades, one that can show all the different aspects is nice to have.

Jon Isaacs


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Tony Flanders
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Re: to view peleades? new [Re: Dennis_S253]
      #5607957 - 01/06/13 09:33 AM

That's missing my very favorite feature, chopping off the chain reaching down to HIP 17776.

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Perigny270
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Re: to view peleades? new [Re: Tony Flanders]
      #5608141 - 01/06/13 11:33 AM

I look for them every time I go out. Any time, for any reason. If I want a real lift, I reach for the binos. Top of the list for first time viewers. But my favourite is 31mm Baader aspheric in my 102 APO. It was the first thing I looked at with that EP - I couldn't tear myself away from it. These days it's a double treat as it's a short jaunt to Jupiter and Aldebaran...

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Dennis_S253
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Re: to view peleades? new [Re: Tony Flanders]
      #5608143 - 01/06/13 11:33 AM Attachment (5 downloads)

Yes Jon, I know the limitations of my scope very well. That's why I said I had to "fudge" the numbers to get the 2 degree FOV. If you want to "frame" the Pleiades in a 2 degree FOV then that's a personal preference. But it is not required to see the seven sisters and 2 parents. I was wondering if someone was confusing Pleiades and Hyades. That was why I questioned it.
LOL Tony, that's one of my favorites also. That's why I use my 32mmm.


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newtoskies
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Re: to view peleades? new [Re: Dennis_S253]
      #5608156 - 01/06/13 11:41 AM

Yep, my favorite as well and view it every time when the scope is out, or the binos. I use my 32mm and get good views.

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Jon Isaacs
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Re: to view peleades? new [Re: Dennis_S253]
      #5608467 - 01/06/13 02:05 PM

Quote:


Yes Jon, I know the limitations of my scope very well. That's why I said I had to "fudge" the numbers to get the 2 degree FOV. If you want to "frame" the Pleiades in a 2 degree FOV then that's a personal preference. But it is not required to see the seven sisters and 2 parents. I was wondering if someone was confusing Pleiades and Hyades. That was why I questioned it. LOL Tony, that's one of my favorites also. That's why I use my 32mmm.




Dennis:

M-45 consists of more than just the 7 sisters and two other bright stars. Most sources seem to identify M45 as being 2 degrees. It's worth nothing that M45 is different than many clusters because one sees about all there is to see with a relatively small scope. In contrast, M-7 is quite different in this regard. It is very nice in a smaller scope but if one points a 16 inch scope at M7, one suddenly sees a great deal more.

So, to play the devil's advocate, your 32mm eyepiece provides something close to a 1.6 degree field of view, if you scope were capable of a 2.0 or 2.5 degree field of view, would the 1.6 degree TFoV still be your preference?

Jon


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Dennis_S253
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Re: to view peleades? new [Re: Jon Isaacs]
      #5609226 - 01/06/13 09:04 PM

Hey Jon, I've really been thinking hard about your question. For some reason, I really like the stuffed look. So I guess it is a personal preference. Maybe that's why I don't use my Bino's very often. I do like my 6X30 7* FOV finder scope though.

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