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Equipment Discussions >> Eyepieces

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titanio
sage


Reged: 02/15/09

Loc: Alicante, Spain
Re: your favorite EP for planetary observation (f/10)? new [Re: azure1961p]
      #5737693 - 03/16/13 11:42 PM

Do not waste your money in expesive eyepiece for planetary using a telescope f10 Televue Plossl work very well.

Toni


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Deep13
Carpal Tunnel
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Reged: 01/25/05

Loc: NE Ohio
Re: your favorite EP for planetary observation (f/10)? new [Re: azure1961p]
      #5737897 - 03/17/13 01:41 AM

3 to 6mm is too much power. Maybe something in the 15mm range.

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DJCalma
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Reged: 01/17/13

Loc: Northern California
Re: your favorite EP for planetary observation (f/10)? new [Re: Deep13]
      #5737914 - 03/17/13 02:00 AM

9mm. University Optics Volcano top Ortho!

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Rick M.
super member


Reged: 03/16/13

Re: your favorite EP for planetary observation (f/10)? new [Re: DJCalma]
      #5738261 - 03/17/13 09:34 AM

Reading through all the posts, I'm leaning toward 10 mm. Now to decide which one!

Rick


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Eddgie
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Re: your favorite EP for planetary observation (f/10)? new [Re: Rick M.]
      #5738297 - 03/17/13 09:53 AM

I don't have a 9.25, but in a general way I can tell you what I use.

For planets, I use a binoviwer. That made more difference to me than any eyepeice choice ever has.

Because the C14 is such a big aperture, I often cannot exploit the highest powers the scope can use (you may not be able to either), but what I tend to use the most are 17mm Hyperions, 15mm Vixen NPL Plossls, and when seeing permits (rare) 13mm Hyperions. I would say the 15mm NPLs get the most use though, but only because that is about as high as I can usually go due to seeing (about 266x).

But the binoveiewers easily make more difference to me than the differece between this or that eyepeice did.

Hard to go wrong with Televue Plossls, but at the same time, you can find similarly well performing Plossls for less money.

I had the Televue 15mm and the Vixen NPLs seem to offer the same performance. In side by side comparison, there was no detail in Jupiter that I could see in the Televue that could not be seen in the Vixen NPL.

But if you want to planetary view, before you spend a lot of money on eyepeices, consider buying an inexpensive pair of binoviewers and some inexpensive 12mm Plossls and give that a try. (Don't forget that your telescope will give more magnification with a binoviewer than it will without).

Edited by Eddgie (03/17/13 11:30 AM)


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azure1961p
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Reged: 01/17/09

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Re: your favorite EP for planetary observation (f/10)? new [Re: Rick M.]
      #5738311 - 03/17/13 10:01 AM

Quote:

I'm looking at purchasing a high power EP for a CGEM 925 HD. Do you have any favorites you would recommend? TIA

Rick




Rick if its highpower you want 10mm isnt going to get you there. Id go no less than 7mm, or 6mm for that matter. The 10mm is a nice working mag ocular for a variety of planetary an d lunar but it simply isnt highpower for that scope. 10mm by contrast is a nice medium power as is 13mm. A 5 or 4mm orthoscopic is the high end of highpower for your set up that could prove to be rather conditional for
planetary use. It has its place but its a narrow niche.

Pete


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Rick M.
super member


Reged: 03/16/13

Re: your favorite EP for planetary observation (f/10)? new [Re: azure1961p]
      #5738360 - 03/17/13 10:38 AM

Pete, I'm thinking I could get a 10 mm. and use a Barlow for those very rare times that atmospheric conditions permit. Does that sound reasonable?

Rick


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Sarkikos
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Reged: 12/18/07

Loc: Scotophobe Maryland, USA
Re: your favorite EP for planetary observation (f/10)? new [Re: Scanning4Comets]
      #5738396 - 03/17/13 10:58 AM

Markus,

Quote:

Quote:

XO 5.1. That puts an f/10 scope at about 0.5mm exit pupil, the highest I usually go for planet observation. IMO, the XO's are the best eyepieces for viewing planets, unless maybe you want to pay two or three times higher for a ZAO.

Mike




CGEM 925 HD = 92.5" FL = 2349.5mm FL

That would give him 460x....far too much power.




That is a broad generalization. Far too much power for what object, under what conditions, for what instrument and for what observer?

460x would be about 50x per inch and a 0.5mm exit pupil. As I said, that is the highest I'll usually go for planet observation. But I've often gone that high for Mars and Saturn, though I usually stay closer to 300x for Jupiter.

Unless the observer lives permanently under the jet stream, 50x per inch is certainly doable for bright planets if the instrument has decent optics. In fact, I recently pushed my C6 SCT to 294x - about 49x per inch - when viewing Jupiter under good seeing, with good results. Luckily, I have a C6 with excellent optics. I'm pretty sure a 925 HD could do as well as a C6.

Mike


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droidModerator
rocketman
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Reged: 08/29/04

Loc: Conneaut, Ohio
Re: your favorite EP for planetary observation (f/10)? new [Re: Sarkikos]
      #5738545 - 03/17/13 12:46 PM

Hmmmm interesting question.....and your liable to get dozens of answers, lol.
And theres a good reason for that , we see differantly....at 56 my eyes aint what they used to be....some one say in theyre 20s or even early 30s with normal vision, may see very differantly.

My two favorite eps for high power views, only in my f/10 4inch refractor , are the 10mm Rini planetary, puchased from Sarkikos, it has a narrower fov, and took a bit of use to learn to get my eye at the sweet spot and keep it there. And my new to me Nagler type 2 with a 2x ED barlow.for a 6mm view.
which gives me roughly 170x with the nagler barlow combo ,still under the 50x per inch. and 102x with the 10mm.way under the 50x per inch limit.
Forced to choose one, Id choose the nagler / barlow combo for obvious reasons.

But thats just my observing. And Ive never looked through dozens if not hundreds of very good eps....so your results ..will...vary.


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Rick Woods
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Reged: 01/27/05

Loc: Inner Solar System
Re: your favorite EP for planetary observation (f/10)? new [Re: droid]
      #5738659 - 03/17/13 01:55 PM

Re. the original question: When conditions allow its use, the Brandon 6mm is the finest planetary eyepiece I've ever used.

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Eddgie
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Reged: 02/01/06

Re: your favorite EP for planetary observation (f/10)? new [Re: Sarkikos]
      #5738763 - 03/17/13 02:40 PM

In theory, there is no limit to magnification.

For example, look at some of the best images taken with large reflectors. These scopes are often working with the equivilent of a 2mm to 4mm eyepeice.

But if you attempted to use this much power visually, it would produce a horrible image.

The telscope presents all of the detail it is capable of rendering with the magnification reaches about 1.1x per millimeter of aperture. This is when the smallest detail that the scope is capable of resolving is provided with sufficient angular magnification to be resolved at the focal plane.

Past this, you can go bigger and bigger, but no new detail is ever presented.

Ah, but what happens is that the illumination falls. The eye likes illumination. For a given contrast of a given detail, the brighter you make that part of the image, the easier it is for the eye to see it.

For the average observer, the illumination starts to fall once the exit pupil gets smaller than abou .8mm. Larger details with more contrats get bigger and easier to see maybe, but the smallest, lowest contrast detail starts to fall below the observer's contrast sensitivity threshold.

The right power for every obesrver will vary with the target and conditions of course, and I would never tell people that there is no value to pushing higher because image scale in itself can be pleasing.

But once you go past about 1.1x to 1.3x per millimeter of aperture, you make the image bigger, but often at the risk of loosing some of the more enrichig detail.

In my own scopes, I find a 1mm exit pupil to give me about the most detail I can extract from a planet. Past this, I can make it bigger, but usually no new detail is presented. And past about .7mm, and I can see that the most challanging detail is fading.

But this is me. We are all different.

The main reason I resist the message that 50X per inch is the right planetary detail is because over the years, I have heard so many people question if their telescopes were defective. They would read these reports about 50x per inch, but when they used their scopes, they were not seeing any new detail.

They thought their scopes must be defective because the message seemd to be that the more power you use, the more detail you would see.

And it doesn't work that way for most of us.

Factor in seeing, and 300x is the practical limit for most of us on most of the time anyway, but someone should not be surprised at all if they find that going to 50x per inch doesn't result in additional detail.


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johnnyha
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Reged: 11/12/06

Loc: Sherman Oaks, CA
Re: your favorite EP for planetary observation (f/10)? new [Re: Eddgie]
      #5738785 - 03/17/13 02:48 PM

Quote:

In my own scopes, I find a 1mm exit pupil to give me about the most detail I can extract from a planet. Past this, I can make it bigger, but usually no new detail is presented. And past about .7mm, and I can see that the most challanging detail is fading.




+1. I have confirmed this since getting my Leica Zoom, it is readily apparent that the planet dims below 1mm to a point where there is a loss of resolution - it starts getting "grainy" looking. On a good night I can go a little less but at .5mm it is much, much dimmer than 1mm and the difference is not 2X it is 4X+ dimmer.


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Sarkikos
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Reged: 12/18/07

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Re: your favorite EP for planetary observation (f/10)? new [Re: Eddgie]
      #5739089 - 03/17/13 04:47 PM

Eddgie,

Quote:

In theory, there is no limit to magnification.




Yes. Actually this has been my first response to observers who question why I don't push the power more for some objects. Of course, you can increase the magnification to whatever your telescope, eyepiece and Barlow will produce. But the resulting image may look like a wooly smudge and may show you less detail than you could have seen at a much lower magnification.

And as a matter of fact, I have often been the champion of less is more when it comes to magnification for observing planets.

Quote:

For example, look at some of the best images taken with large reflectors. These scopes are often working with the equivilent of a 2mm to 4mm eyepeice.

But if you attempted to use this much power visually, it would produce a horrible image.




I don't even want to compare photography with visual, except maybe to find out how much I'm able to see without all the fancy AP equipment and computer processing.

Quote:

The telscope presents all of the detail it is capable of rendering with the magnification reaches about 1.1x per millimeter of aperture. This is when the smallest detail that the scope is capable of resolving is provided with sufficient angular magnification to be resolved at the focal plane. Past this, you can go bigger and bigger, but no new detail is ever presented.




1.1x per mm of aperture would be about 28x per inch, or about 280x in my 10" Dob. I'm not sure if we should take this as a hard and fast rule. In fact, I'm sure it isn't. There are too many factors involved.

For instance, the adaptation level of the eye should be taken into account. If the eye can be kept closer to photopic, more detail can be seen in the image of a planet at a more moderate level of magnification. If the eye is looking at fainter objects and is well dark-adapted, then more magnification will be needed to begin to see structure in the object. I've seen both of these effects for myself many times.

Also, even among bright planets, I've seen a difference in "best" magnification. As a general rule, Saturn and Mars do better at higher magnifications than Jupiter. Many observers have seen this. The reasons are probably both the different types of contrast for these objects and also the different image scales of the objects themselves. Personally, I think Mars does well at higher than 28x per inch, sometimes much higher, particularly when its apparent diameter is less than about 7 arcsec.

Quote:

The main reason I resist the message that 50X per inch is the right planetary detail is because over the years, I have heard so many people question if their telescopes were defective. They would read these reports about 50x per inch, but when they used their scopes, they were not seeing any new detail.




I would never make the blanket statement that 50x per inch is the "right" magnification for planet detail. Just as I would never have said that 50x per inch is "too much magnification." Experience should tell us that the interaction among equipment, observer, object and atmosphere is much more complicated than that. Rules of thumb are not laws of nature.

Quote:

They thought their scopes must be defective because the message seemd to be that the more power you use, the more detail you would see.




This, of course, is a newbie attitude. Reality is more nuanced. Unfortunately, I've seen this attitude too often in more experienced observers who should know better.

Quote:

Factor in seeing, and 300x is the practical limit for most of us on most of the time anyway, but someone should not be surprised at all if they find that going to 50x per inch doesn't result in additional detail.




Of course. On the other hand, this doesn't mean than an experienced observer cannot appreciate what a good instrument can do under the right conditions when observing some objects.

Mike


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azure1961p
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Reged: 01/17/09

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Re: your favorite EP for planetary observation (f/10)? new [Re: Rick M.]
      #5739250 - 03/17/13 05:54 PM

Quote:

Pete, I'm thinking I could get a 10 mm. and use a Barlow for those very rare times that atmospheric conditions permit. Does that sound reasonable?

Rick




Sounds very reasonable . A 2x televue barlow would be a great thing. To that end dont rule out a 3x barlow farther down the road for superhighpower doublestar or planetary nebula study. Itd be too much on the planets but fine on the targets mentioned . Itd be specialty barlow while the 2x would be more of a working tool with the 10mm. On a small mars, saturn or neptune in 7/10 seeing the 2x would be a fine thing.

Stay in touch and post your finds. That IS a great scope you have.


Pete


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Rick M.
super member


Reged: 03/16/13

Re: your favorite EP for planetary observation (f/10)? new [Re: azure1961p]
      #5739341 - 03/17/13 06:28 PM

Thanks, Pete!

Rick


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CollinofAlabama
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Reged: 11/24/03

Loc: Lubbock, Texas, USA
Re: your favorite EP for planetary observation (f/10)? new [Re: Rick M.]
      #5739441 - 03/17/13 07:08 PM

Rick,

Don't own a very long focal ratio instrument, but I'd have to say the 12mm Brandon does a great job, particularly in combination with my old school, long tube Made in Japan 2x Orion Barlow (I'm sure a TV 2x would do at least as well). I also like the TeleVue Nagler T6 series. In my case, the 7mm works wonders if the Brandon/Barlow is too much power. For you, I'd think the 9 or 11mm models work work more consistently for you, since a 7mm would likely be too much power most nights in your scope.

Good luck


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mdowns
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Reged: 06/12/10

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Re: your favorite EP for planetary observation (f/10)? new [Re: Rick M.]
      #5739498 - 03/17/13 07:41 PM

Rick,
In my c11 my fav is a 12mm brandon,8mm brandon on steady nights and a bco 10mm coming in at third.


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Lane
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Reged: 11/19/07

Loc: Frisco, Texas
Re: your favorite EP for planetary observation (f/10)? new [Re: azure1961p]
      #5740104 - 03/18/13 05:01 AM

For DSO high power viewing in the 9.25 I generally use a 10mm Pentax XW. If seeing will not support it then I drop to the a 12mm Nagler or 13mm Ethos. If seeing is really good then I will use a 9mm Nagler.

I prefer Orthos for planetary viewing, but I don't generally use Orthos with my SCTs unless I attach my crawford focuser to the back. I find the narrow field of view causes problems due the mirror shift when focusing. For that reason the 10mm Pentax XW is normally what I will use on planets.


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Sarkikos
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Re: your favorite EP for planetary observation (f/10)? new [Re: Lane]
      #5740156 - 03/18/13 06:52 AM

The XW's are great wide-field eyepieces for planets. Well, they are wide-field compared to orthos - 70 degrees vs 44 degrees.

Mike


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Rick M.
super member


Reged: 03/16/13

Re: your favorite EP for planetary observation (f/10)? new [Re: Sarkikos]
      #5740227 - 03/18/13 08:31 AM

Hmmm...I will have to look into Pentax XW. How does the 10mm. Delos compare? I see a thread on Delos vs. Pentax XW but the 10mm. eyepieces are not compared.

Rick


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