37 replies to this topic

[erik]

the deep views will show a lot of coma and field curvature in a fast f/4.7 scope such as yours. i'd recommend the optiluxe ($139) over the deep views, or if you can afford them, pentax makes some great 2" ep's for around $250.

[wilash]

Coma is an optical abberation. It affects the edges of the image. Stars look like little commas.

Slickmm, before we can answer if the 25mm EP is enough and the controller would be better, I have a few questions. How long have you had the scope and how many times have you used it? What star charts are you using? Are you observing in the city or the country?

[erik]

2" ep's give a wider field of view which is desirable in deep sky viewing since many objects are spread out. 2" ep's are also nice for low power scanning. they don't necessarily give a higher quality view than an equivalent sized 1 1/4" ep, just a wider fov. higher power ep's, such as the 10mm size you mentioned are normally 1 1/4", and suited more for planetary viewing since you don't need a wide fov for that. a 25mm ep is a good start, giving you a magnification of 48x in your scope. if you we're planning on getting 2 more ep's, i'd recommend a 40mm optiluxe (30x) for deep sky viewing, and a 7.5mm ultrascopic (180x) for planetary viewing. if you can't afford those ep's, good plossl's like orion's highlight series will work well in the longer sizes. a barlow is also a good thing to have since it effectively doubles your available magnifications. the shorty-plus by orion is an excellent barlow at $70. the standard shorty ($35) is decent as well if your on a budget. 2" ep's don't normally need to be barlowed so a 1 1/4" barlow will work fine. i'd recommend learning the night sky a bit before you buy the controller. even with the controller, you still need to know where the alignment stars are. start with a planisphere (a simple star map wheel) and learn the constellations. hope that helps, and good luck!!

[Craig Simmons]

The GSO 30mm works very well in an f/5 XT10 for stuff like large Open Clusters and Nebulas. Soft at the edges, but not that bad. For small DSOs like Globular Clusters and Planetary Nebulas, something in 9-12mm range. An orthoscopic would be good on these objects. Your 25mm is a good EP and unless you need a wider FOV it will work fine on most larger objects.

I use the Pentax 40mm XL, 14mm and 10.5 (discontinued series) which are expensive premium EPs and have recently added the GSO 30mm.

To answer the 10mm 2" vs. 1 1/4" question, the same.

[Norvin]

Has anyone suggested the Celestron EP Kit? The 32mm is a good DSO EP.

Norvin
Post #525

[Derek W]

I've had my XT10 for about a month, and here are some of my findings:

You shouldn't have any problem finding DSOs with your 25mm piece. That's what I've been using. No, the field of view isn't huge, but it works. I enjoy looking through it - it's all I know!

When I find the DSO, I pop in my 10mm and see how it looks.

Basically, I believe you need lower powered eyepieces for scanning the sky in search of DSOs, and, for taking in entire large object DSOs. (think m31, open clusters, some nebula)

For globs, planetary nebula, and many galaxies, you want to keep pushing up the power. So, I just always pop in the 10mm piece after finding it with the 25mm.

So, YES, without a doubt, you can find DSOs with that 25mm piece just fine. I've found a messiers up to 11 mag so far. And I find most of them from the backyard of my city home. (pop 125,000 - we get 4 something mag skies most of the time)

I'm not bothering to buy the controller.. not for a while at least. It's too much fun star-hopping to find them yourself.. the hunt is half the fun many of times! (OK, so the first time you find M13, the hunt will quickly be an afterthought - although it's easy as *bleep* to find again after that)

Anyhow, I'd just get to know the sky... get a book that lists the constillations and find out where those DSOs are. All I've used are Sky and Telescope monthly charts, and my audobon society guide to the night sky.

Once you find your first one, it gets much easier finding them after that.

You've probably heard this advice before, but I figured it couldn't hurt.

On eyepieces though, I figure I'll end up with a couple of good 20-30mm widefields to hunt down those DSOs, and a number of higher powers to get the best view I can find.

[erik]

while the 25mm ep you have is certainly usable, a 2" ep such as the 40mm optiluxe is great to have, especially with summer aproaching. if you've never scanned saggitarius with a low power 2" eyepiece on a dark night....there's nothing else like it. i mentioned the 7.5mm ultrascopic because they make great planetary eyepieces, and you probably want something that's going to give you 180-200x for high power viewing. plossl's in the short f/lengths tend to have a tiny bit of eye relief and for that reason i don't like using anything shorter than my 9.7mm super plossl. quality issues are also more apparent in the shorter sizes, so if you do want to buy a short plossl, make sure it's one of good quality. i prefer just barlowing a longer plossl to reach the desired magnification. it can also help with fast scopes such as yours.

[jfaaz]

I'm new to the group and have an XT10. I had the 2" 35mm Deep View, it performed poorly.

Then I bought the 2" BW Optic 30mm. Much better with an 80 degree field of view, but the outer third of that wide field suffers from severe coma.

After trying other low power wide fields I came to the conclusion that I prefered medium power 1.25" widefields.

The 19mm Panoptic has been a wonderful eyepiece for finding DSOs. M81 & M82 both frame well within the field of view and M3 is easy to spot. Sometimes the added magnification makes all the difference.

Buy a Panoptic (24, 22, or 19mm) and a good Barlow (1.5, 2, or 3X) and you will have optics that are sharp to the edge.

You may buy many cheap eyepieces, or just a few premium ones; however, you will end up spending about the same.

Go with TeleVue or Pentex and you won't be sorry.


Jon Faasen

[David Knisely]

I have an Orion SkyQuest XT10 with IntelliScope and am wondering what eyepiece would I most benefit from for viewing DSOs. I have been hearing good things on the Orion Deep Views, if so, which size mm? Or is that just up to me? Is there another brand thats really good that you like? As you can see, I am in the blue here. Thanks for clicking, reading, and responding.

---Slickmm---

For 1.25" eyepieces, I would go with the 24mm Panoptic which should give you about 1.27 degrees of true field at 50x. Another possiblity which I use a lot is Meade's 14mm Ultrawide, which in your scope would give you nearly a degree at 86x, ideal for teasing detail out of some of the larger galaxies. Granted, these aren't exactly inexpensive eyepieces, but they do offer very good wide-field performance. Clear skies to you.

[erik]

yeah, you're right david, those aren't exactly inexpensive ep's! if he was considering the $75 deep view, he's probably not ready to drop $300 on a 2" ep. that's why i'd recommend the optiluxe. in my f/6 scope, it's sharp to about the last 5% of the fov. i'd think in a f/4.7 scope such as the xt10 the performance would only be slightly worse. i've also heard a lot of good things about the inexpensive GSO 2" ep's, may want to check them out as well...

[dgs©]

Optiluxe is from Orion www.telescope.com

[dgs©]

Slickmm - If you are using the Search link at the top of this page, you will get lead to Cloudy Nights forums every time because that is all it searches thru. Have to drop back to altavista.com or one some other search engine to peruse the rest of the web.

[dgs©]

Oh, I see... look for a recent thread in this Eyepiece forum on the GSO's it is a hugely popular thread with lots of responses. I think at the beginning of it there were some links to sellers.
Sorry if I am wrong about that though.

[Tom L]

Slick, go read the GSO thread...there are numerous links in there to the sellers on eBay that sell them.

[Craig Simmons]

The 9mm or 10mm that comes with the 10" XT style Dobs are not that great. Orthoscopic EPs work very well in these scopes (very sharp), but have a narrow FOV and shorter eye relief (eye to EP distance) as the focal length of the EP decreases. A 6mm sized EP works great for average seeing conditions. This can be achieved with a 2x barlow and a 12mm EP or with a 6mm EP. Barlowing preserves the eye relief of an EP. It also can correct abberations in an EP. I use a 30mm GSO Super View with a GTO Proxima 1.5X barlow and it performs better (sharper towards the edge) with the barlow than by itself.

[dgs©]

For the kind of magnification you need for planets something like a 5mm Radian might be just what you need. I think your scope is 1200mm Focal Length right? If so the 5mm will give you 240× which is usually attainable for me. Sometimes the sky conditions hold me to 200×, so 240× should be OK (and great on the moon too.). The entire line of Radians has ~20mm of eye relief (way more than the 10mm plössl), which makes them quite comfortable compared to plössls in short FL's. Their field of view is a little wider than a plössl of the same FL.
Retail new for $240. Astromart often has some for ~$170 to $180.