37 replies to this topic

[erik]

i always recommend the orion ultrascopic ep's for high power viewing. they have great eye relief and sharp images. they're a bit pricier than standard plossls, but well worth it. the coatings are excellent and they have no glare. the 7.5mm would be a nice choice for your xt10, as it would give you 160x. i use that in my 8" quite a bit. i also have the 5mm which comes out to 240x, which only works well when conditions permit. some people don't like the 5mm and 3.8mm versions because they use an internal barlow (i've never had a problem with my 5mm), but i've never heard anyone say anything bad about the rest of the ultrascopic/ultima series. they're the best planetary ep's out there, and they're less than $100.

[matt]

Matt: Norvin is right has a good point in suggesting the Celestron EP kit. It's an extensive batch of decent (for an experienced AND rich observer) to good (for a beginner) eyepieces, so it's a great way to get started. After using them for a while and getting better experienced in observing, you will be in a better position to decide what to buy if you want to expand your collection with premium eyepieces.

Adrenochrome: you have to buy another finderscope. Most finders are built "in one piece" so it's difficult at best to add a diagonal to a finder. As for the Radian, I own 5 of them, they're the eyepieces I use 90% of the time.

As for coma: usually wide field eyepieces used with fast scopes do not suffer from coma but from off-axis astigmatism (which, to be fair, looks about the same); it's the mirror which can have coma. Coma does not come from "comma" but the latin "coma", which means "hair", because stars at the edge looked like little comets. So budget wide field eyepieces suffer from astigmatism; expensive ones (at least those that stay on the market!) don't. You might see off axis astigmatism in a 25-35mm plossl, it's up to you to decide if you can live with it or not.

[erik]

I'll look into the ultrascopics. Thanks Erik.

In a totally unrelated question, is there any way to add a diagonal to the finderscope, or do I have to go buy a whole new finderscope? Shooting towards the zenith with the stock finder was painful.

most finderscopes are not really modifyable (not a word!), but maybe there's a way to use an old cheap 1 1/4" diagonal with a straight finder. i would think it'd be easier just to buy the right angle finder. but don't dismiss the straight finder so quickly, they can be easier to use when starhopping because, unlike the right angle finders, you're able to "sight along the tube" to see precisely where the scope is pointed at. for that reason, sometimes i wish i'd just kept my straight finder. i added a red dot finder and i actually use that 90% of the time. a red dot finder will also be easier on the back because you can view the illuminated dot from further away, so you don't have to contort your body to get in close like with the straight finder. the only time i use the right angle finder is when the stars i'm hopping are below naked eye visibility and therefore aren't seen in the red dot finder...

[Relativist]

Here is the ideal:

http://www.televue.c...page.asp?ID=221

The reality, I have a 30mm GSO (also have the 42mm and the barlow - I like the barlow and the 30mm, but the 42mm has to much eye relief), a 23mm and 19mm Axiom, a 10mm X-Cel, and a 7.5mm Ultima. I used to have a 5mm vixen lantanum but I returned it because I found that I could hardly ever use the 5mm and it seemed like a waste that that was the most expensive EP in my collection at the time. I also had an 18mm ultima, which I liked but retured with the 5mm because I wanted a wider FOV, so I got the 19mm. The 23mm was aquired through astromart. What would I suggest you get?

* 30mm GSO
* 24mm Panoptic (substitude a 23mm Axiom if have to)
* 12mm Nagler
* 7mm Nagler (substitude a 7.5mm ultima if needed)
* 1.5x or 2x or 2.5x Barlow (ideally a powermate or similar)


Good Luck deciding!


.........Curtis

[Craig Simmons]

I use 2 10" Dobs (in different locations) One has a Telrad, the other a straight thru finder (for the time being). I prefer the Telrad and don't even bother putting a ST finder on that scope. I use a 40mm Pentax as a widefield and finder EP. The trade off with an EP that size is getting a larger than usable exit pupil (8mm) vs. a large FOV (2.1 degrees).

[Dave Mitsky]

Thanks DGS. Yes, it’s 1200mm. I’ll look into the Radian. I’m hoping to have just two or three really good EPs, rather than a slew of lesser ones, so I’m willing to spend perhaps as much as $250 on each. I have two (very) young daughters and a wife whom I’m hoping to introduce to astronomy, so things like the “wow” factor of a large FOV and generous eye relief are more important to me than perfect color or pincushioning. The first EP I’d like to get is something to push the magnification of the scope so that the planets really stand out, and a large FOV is important since in the time it takes to switch viewers, things have already drifted halfway across the FOV.

You may want to consider Type 6 Naglers, which are superb for all types of observing, if long eye relief is not an issue. They're a bit more than your price limit but you may be able to find used ones on Astromart. I have the 7, 9, and 13mm models and prefer them to the Radians.

Dave Mitsky

[Relativist]

I would highly reccomend the 30mm GSO, but in all actuality, you should probably buy and try both, enough people like those EP's that you should have no problem selling the one you don't like. The problem with to much eye relief is that my eye is so far from the EP that i'm not up against the eye guard, and I find that to be uncofortable personally. These EP's are cheap enough though, that I'm keeping both for now. The second problem I had with the 42mm that I recieved was that I could not thread the bottom of the barlow into it like I could the 30mm. This is probably a defect but I do not know for sure. On direct comparison I found that the 30mm was very close in terms of AFOV to the 42mm. Have fun with the 7mm Nagler!


.........Curtis

[Tom L]

I keep hearing David K. rave about his 5-8 S-W zoom. At $235 or so, it might be a good high-power eyepiece. I personally have UO Orthos in 5, 7 and 9mm lengths and find that I use the highest mag that the sky will support and leave the other EPs in the case for that particular night. This EP may allow you to have a wide FOV and to also "dial-in" the highest mag that the sky can support for that particluar evening. These are the thoughts that I banter around, atleast. I hope to get to try one of these before I buy one since I do like my orthos...but not the narrow FOV when used in a dob.