Author Topic: Advice on planetary viewing with Nexstar 8SE  (Read 542 times)

Jody Mukherjee

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #15 on: January 21, 2018, 01:10:07 AM »
Seeing is a big factor. Also the planets height in the sky, the higher it is the less atmosphere to look through.
Your scope should be fine for planets. I have the ES8.8mm and it works well with the scope. It will give you 230X which is
a lot. You just have to wait for that perfect night to see a lot of detail.
Just saying.
Congrats on the new scope neighbor.

Devon Dank

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #16 on: January 21, 2018, 06:16:28 AM »
I have a similar scope 8" SCT and because of seeing conditions I rarely go beyond my ES 11mm for 184x and sometimes have to drop down to my 13mm for 150x on Jupiter. It just doesn't handle too much power like Saturn can. I do have the ES 8.8mm for exceptional seeing nights for planets and the moon at 225x, but I'm talking about 4/5 and 5/5 for seeing. I bought that EP to use in my other smaller scopes. You can go to the website cloudynights.com to get a form of weather and seeing report for your area. I use it every time I'm going out observing. If the seeing is not good but the transparency is good, I'll plan on observing deep sky objects (DSO's). You also have to take your scope out a couple of hours for it to cool down to get rid of internal currents. I leave the back port of the scope open.

I have the same zoom as you and it's pretty decent. What you can do is zoom in and out to see what size image Jupiter is that gives the best detail and then switch out to another EP that matches the same power as the zoom and see if that single EP is sharper.

I do use a 2" diagonal to get wider lower power from my 34MM SWA. I can fit both M81 and 82 in the same FOV and also the double star cluster and some big nebula's like the Veil with a filter and some large galaxy like M31.

Did you get a dew shield yet? Besides cutting down on dew, it acts as a lens hood for the front lens.

Jeff Weiss

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #17 on: January 25, 2018, 07:37:34 PM »
I have two eyepieces I use the most with my 8i; both are Televue Nagler T6's, 13mm and 9mm. I find that the views with the 13mm seem to be what I enjoy best. I often use the 9mm when seeing is good, and I've used a 5mm on occasion when seeing is exceptional and there is no wind to vibrate the single fork arm.

As for the question on 2 inch SCT diagonal, I would like to get one since I have a few nice eyepieces in 2 inch that I can't currently use with that scope. They are great with the dob and APO, so I'd like to use them on the 8i as well for wider field views.

ecapwaiwa

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #18 on: January 25, 2018, 07:43:52 PM »
I am using ES 82 EP for Jupiter not because of 82 degrees fov, but because of sharp focus and great lightscatter control. In my tests it clearly outperformed so called planetary EPs like Zhumell Z series and Celestron LX X-Cell. I use 4.7mm because I keep .63 reducer on my scope. Without reducer 8.8mm would be appropriate.

belohalcu

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #19 on: January 29, 2018, 10:37:50 PM »
I agree with others on 2" diagonal. You don't need it for planets. But I do use it for DSOs with 2" EPs

coepupinsynch

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #20 on: January 30, 2018, 12:10:13 AM »
I agree with others on 2" diagonal. You don't need it for planets. But I do use it for DSOs with 2" EPs

vieproltesro

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #21 on: January 30, 2018, 07:15:25 AM »
The thing to remember is that the more you magnify, the less detail there is in the image. You might be able to see some more, but in fact every bit of additional magnification makes the image dimmer and less contrast. You want to go out from Jupiter a bit, I suggest no more than 10mm, in an 8" SCT with no focal reducer.

If you magnify past that you are frankly just going to make it look fuzzy and poor, IMHO. You need a bigger scope to go higher than that.

percufareg

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #22 on: January 31, 2018, 12:41:19 AM »
Hi.

This Winter in North America (at least the north east) the 'seeing' has been quite bad. It's been my experience and that of others that maximum magnifications was around 25X per inch of aperture with scopes around 8" in aperture. With smaller aperture scopes, it can get higher a bit, about 40X per inch with a 102 mm aperture, say. The only time I saw the 5th and 6th stars of the Trapezium was with a 4" scope, not with the bigger ones.

The formula is quite simple: an eyepiece with focal length in mm equal to the f-ratio of the telescope gives 25X per inch of aperture and an exit pupil 1 mm in diameter (this is because of the magical fact that there are exactly 25.4 mm in an inch). With a f/10 instrument, no point going much below an 8 mm eyepiece. With one exception: when doing a star test, where 50X per inch or more is required. I would not use a barlow for that unless I knew that the barlow was essentially perfect...

As for maximum field of view, the 8" SCT is designed to work well with 1.25" eyepieces and the prism diagonal it comes with. A 32 mm 'Plossl' like the one linked to above, or a 24 mm 68 degree AFOV will maximize the field of view. The 2" eyepiece format only has benefits for focal lengths above 30 mm. But for an SCT, adding a 2" diagonal doesn't give the expected increase in field of view because the added light path requires moving the mirror for focusing, and this is accompanied by an increase in telescope focal length. Have fun!

--Christian

faubloginac

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #23 on: January 31, 2018, 06:27:34 AM »
Hi Everyone,I did some more testing on jupiter last night. I first just used my 32MM Omni, which does not magnify Jupiter qutie as much as I like, so I put my 2x barlow in , and that gave a pretty decent view.

I think took the advice of Billytk, and whipped out my 8mm-24mm zoom eyepiece, and discovered that at 8mm it was a lot closer to the magnification that I want. I then tried it with the barlow, and at 8mm on that eyepiece, it looked really bad, very distorted and blurry.

So I then tried my 10mm Celestron luminos with and without the barlow. That eyepiece combo with the barlow provided me with my best viewing option. The conditions were pretty bad last night, clouds kept flying by so I had to keep waiting for them to pass.

So the 10mm w/ 2x barlow, does that basically equal a 5mm eyepiece? If so, maybe it would be best if I go ahead and get a good 8mm eyepiece such as the ES , and use that with and without my barlow.
Any thoughts on that?

Thanks!

rennlispuring

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #24 on: January 31, 2018, 10:28:07 AM »
A 10mm eyepiece with a 2x barlow is equivalent magnification to a 5mm eyepiece.  And that 400x is about as much useful magnification as you will ever get out of an 8" SCT.  Yes, more magnification can make things bigger, but it will also make them dimmer, and will almost always make them fuzzier.

Now the 8mm WITHOUT a barlow may give you a better view than either the 10mm or the 10mm + barlow-- it is a better quality eyepiece and gives you 250x magnification compared to the 200x you get from the 10mm. If seeing conditions are good enough to support using the 8mm (and its not so much clouds-- although they are obviously a problem-- it is the amount of turbulence in the atmosphere), then it will be better.

I use (discontinued) Vixen Lanthanum LER (Long eye relief) eyepieces for most of my planetary viewing.  For me, they are crisp, and the eye relief is wonderful (20mm for all focal lengths), and they don't have ghosting or black out issues.  I also have a couple of "research grade" orthos that are even crisper. I only pull these out when the conditions are wonderful, because they require me to take off my glasses which is a major issue for me. I don't have anything shorter than than 7mm, and I almost never use my barlow (at least with my 8" SCT).

My recommendation is to find friends and/or a club so you try some different options to see what works for you.
If you live somewhere that makes that difficult, try buying used so you can resell at a minimal loss.  Also, observing skills definitely improve with practice, and its not like you are looking though junk eyepieces at present.

Nassim Zaragoza

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #25 on: February 02, 2018, 07:10:12 PM »
Thanks Jallberry and everyone.

So is it safe to say that my best choice would be to get the ES 8.8mm 82 deg FOV eyepiece?

Daniel Horton

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #26 on: February 02, 2018, 10:26:15 PM »
Hi.

Eyepieces for a f/10 instrument don't have to cost much. Yes, right now the ES82 8.8 mm is my high magnification eyepiece with my 8" SCT and Mak 180. But I would have liked an ES68 of similar focal length if they made one... When it's cold or I'm lazy, it's the 8-24 Baader zoom that comes out, complemented by an ES68 24 mm. The Baader zoom is very good, but some of the best (as in high contrast) views were through a Delos 10 mm I bought used, so if you can get one of those... And for the $$$, AT Paradigm/Agena Astro Dual ED are hard to beat. My small 'travel' kit of these: 25 mm, 15 mm and 8 mm. You can have all 7 of those for the price of one Magic Green Paint eyepiece! Cheers!

--Christian

Derek Vail

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #27 on: February 03, 2018, 07:42:07 AM »
I've popped about 40 different eyepieces into my C8 for a look about.

My personal favorite is a 15mm Nagler. It does make a big difference to have a good EP.

I thought about upgrading the visual back to a 2" but it you're going to get a "cropped" view anyways so probably not worth the fuss. For planetary viewing, most of the best sizes are compatible with 1.25" anyways.

trimarnado

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #28 on: February 09, 2018, 02:54:30 AM »
Quote
So is it safe to say that my best choice would be to get the ES 8.8mm 82 deg FOV eyepiece?


No doubt it is a fine eyepiece. If you really want a quality eyepiece for high-power viewing, it is certainly a good choice.

However, you already own a 10mm Luminos, which is hardly a piece of junk. On days of average or below seeing, I question if the 8.8 is really going to provide you with a view that is really all that much superior. And even when the seeing is excellent, is 14% extra magnification really the next best place for you to invest in?

Some questions for you to consider...

Do you have a set of filters? These are also useful for coaxing out additional planetary detail. How about a dew shield? No eyepiece works well when your corrector plate is fogged in dew...  How about a light pollution filter?

Do you have the F6.3 focal reducer?  Combine this with your 32mm Omni, and you get an even wider, lower power field that is great for large open clusters and the like.

What about a quality eyepiece in the 15-18mm range that could serve double purpose: a quality mid-to-high view and a high power view when paired with your barlow?

Andre Ransom

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Re: Advice on planetary viewing with Nexstar 8SE
« Reply #29 on: February 09, 2018, 05:53:44 AM »
And 8.8 eyepiece is about as much magnification as you'll be able to use most nights. On nights of good seeing you can try something like a 6.7. But will help make the details pop is trying some different filters like a polarizer, Moon & Sky Filter or Contrast Filter.