Best high power eyepiece for C102GT?
Posted 13 October 2013 - 11:16 PM
Any recommendations? I'm guessing a 1.25 inch will be better than a 2 inch for high power viewing. Is 10mm enough, or should I go even higher power? Or a 10mm with a barlow?
Posted 13 October 2013 - 11:50 PM
Posted 13 October 2013 - 11:58 PM
The ES 82* 1.25" series are very nice EPs at modest prices. Tighter eye relief though; about 15mm possibly a little tighter.
That Agena 38 is pretty sweet in the 102GT!
Posted 14 October 2013 - 12:29 AM
I recommend Eyepieces, Etc. or Agena for the Baader products. And you can buy them over a couple of months, picking up the 12.5mm one month, and the Baader ep & Barlow the next, to make the financial bite more manageable.
Posted 14 October 2013 - 05:49 AM
This pretty much nails it. I have a TV3-6 zoom for the best nights, but on average nights most of the time, 7mm to 8mm provides a sharper with more contrast view. In good seeing the scope will run with 3mm on Saturn at least, its just that the seeing has to cooperate and it won't be used as much as a 8-7mm.
A 10mm with a Barlow is one option or you might consider something in the 6-8 mm range as well. I have the 102mm f/9.8 Omni XLT that I have used a 5mm Hyperion with mine a few times but will generally drop back to 6 or an 8mm for sharper views on viewing the planets. A 5mm can come in handy for helping to split close doubles from time to time as well.
Posted 14 October 2013 - 09:53 AM
Posted 14 October 2013 - 10:44 AM
I like the ES 82 degree 6.7mm. The 4.7mm works too but not as sharp.
+1 on the 6.7ES82
Posted 14 October 2013 - 11:05 AM
Edit: Just so you know, I wrote that *before* I saw the other recommendations for the same EP above mine.
Posted 14 October 2013 - 11:19 AM
Posted 14 October 2013 - 11:32 AM
The 6.7 I would think would get more use - more nights when seeing would not limit the useful magnification,cas well as higher power than the 8.x EP.
However, if you are thinking you want a Barlow for the future, to use with other 1.25" eyepieces you might buy in the future, that's different. Personally, I would save that expenditure for later, when you would need the Barlow. The ES 6.7mm gets awfully good reviews.
Posted 14 October 2013 - 02:26 PM
Posted 14 October 2013 - 03:37 PM
I don't think they're worthless, or anything, only saying my old Meade 5000 6.7mm (read -- same OEM as the ES 6.7mm) couldn't hold a candle to the Nagler 7mm T6, and especially the Barlowed 12mm Brandon. If you want the best view and can't afford the higher end vista Nagler, Pentax, Delos options, get a good Plossl or Ortho. The 6mm BCO would be a great choice, but the eye relief may be too tight for you. A Barlowed AstroTech/Sterling Plossl or BCO will produce a better planetary image. The ES' for planetary are okay, but when you want the best, either suck it up and pay for the widefield view, or settle for a little less real estate, and get a low glass count gem, and the options I'm proposing happen to be low cost, too. The Baader 2.25x Q Barlow & 17mm AstroTech High Grade/Sterling Plossl combo will provide a 56* AFOV (not 82*, but not bad, either) and an effective 7.56x power eyepiece (besides the nice medium powered 17mm eyepiece view in its own right).
This is the better path, if the Nagler T6 or Pentax XW 7mm options are too much for you.
Posted 14 October 2013 - 06:08 PM
Posted 14 October 2013 - 07:18 PM
Despite our differences between the Long Perng Plossls, Rob, we clearly do agree that the Baader Classic Orthos are very good choices -- something Bill Paolini agrees with as well. But I will concede that, en el mundo de eyepieces, folks, YMMV.
Posted 15 October 2013 - 07:04 AM
I've found that the Sterling Plossls have excellent light transmission, better than XW, Brandon, BGO and UO Ortho. I'm not sure how they compare with the TV Plossls in that regard. I keep Sterling 12.5, 17, 20 and 25mm in my deep sky case, but no TV Plossls.
I've removed all the TV Plossls from that case because I do not like warm eyepieces for DSO. But I do like them for Jupiter and lunar maria. (I prefer neutral-to-cool tone eyepieces for observing the lunar terminator.) I keep binoviewer pairs of TV Plossls from 7.4 to 26mm.
Posted 15 October 2013 - 08:34 AM
IIRC, Bill prefers the Sterling Plossl 12.5-25mm over the TV Plossls because of their wider field. He says the Sterlings below 12.5mm are not as sharp - even on-axis - as the TV Plossls.
I find the 6mm and 4mm Sterlings no where near as sharp as the rest of the line. I also see more scatter in them. All the TV Plossls are very sharp. We all have different eyes and different equipment...FWIW I find it easy to tease out on-axis differences between eyepieces, especially with the APO...you just have to know where to look on a target and for what features that are most susceptible to minor performance differences on-axis.
What I find as disadvantages with the TVs over the Sterlings in 11mm and shorter is their smaller AFOV, their warmer tone, and their need for an amplifier instead of a Barlow to not vignette. Yes, the star points will not be perfect at the larger off-axis and the 25mm has a good amount of distortion right near the field stop when planets are there, but I don't view planets at the field stop so never a problem. And since I like to Barlow that extra wide AFOV gets nice and sharp which is super nice.
It's all a balance of things and one attribute for me never trumps others. So for the overall gestalt I feel the Sterlings do a better job overall than the TVs. They also have killer good transmission and wonderfully uniform backgrounds with no lightening near the field stop. I usually keep the 25mm, 17mm, and 12.5mm in the Baader Turret on my TSA-102. Those three and a 7mm Pentax SMC Ortho or a 6mm ZAO-II in the 4th slot makes a great workhorse turret, and nice in that the wider AFOV of the Sterlings make them feel like mini-wide fields Just love their convenience. Also, they are killer sharp with that Baader 2.2x Barlow that is part of the BCO set. Was out this morning with that arrangement on my TSA observing Orion and the Perseus Double and Jupiter, and the Moon last evening - Nirvana
Posted 15 October 2013 - 08:56 AM
Posted 15 October 2013 - 10:21 AM
However, one thing the OP mentioned, and since we have Bill's ear, perhaps he can chime in. I've not done a lot of testing of the ES 8.8 82*. I recall Bill liking this particular model in the series best. Perhaps this one would be in the BCO/Sterling/TV Plossl class? I feel confident from my own experiences referenced above the 6.7mm is not, but since I haven't had a lot of experiences with the 8.8, and Bill has rated it best of the series, perhaps it bears consideration?
If I could coax a response on this, Bill, it looks relevant to the OP's inquiry.
Posted 15 October 2013 - 10:36 AM
FWIW I find it easy to tease out on-axis differences between eyepieces, especially with the APO...you just have to know where to look on a target and for what features that are most susceptible to minor performance differences on-axis.
It does help to know the target and to have a very good idea what to look for. When I read a comparo between eyepieces with a planet or the Moon as subject, I want to hear specifics about surface features. Ideally, the observer should have years of experience in teasing out fine details. No astronomical tourists need apply.
I don't want to hear anything like, "The image was essentially the same," "No appreciable differences, "Any differences were too subtle to be concerned about." Everytime I read comments like those, I can't help but think, "Does this observer even know what to look for?" Please, give details about how fine surface features appear differently in the two eyepieces, even if those differences are only "subtle." IME & IMO, subtle differences are what it's all about for planet/lunar observation. That's what separates the XO's from the BGO's.
Posted 15 October 2013 - 10:46 AM
It's all a balance of things and one attribute for me never trumps others. So for the overall gestalt I feel the Sterlings do a better job overall than the TVs. They also have killer good transmission and wonderfully uniform backgrounds with no lightening near the field stop.
Have you ever done a direct comparion between Sterling Plossls and TV Plossls for light transmission? I suspect the Sterlings might have a little better throughput because of the neutral tone vs the warm tone of the TV's. I regret having sold both my TV Plossl 25's before I could compare them to my Sterling 25 on the Horsehead.
I usually keep the 25mm, 17mm, and 12.5mm in the Baader Turret on my TSA-102. Those three and a 7mm Pentax SMC Ortho or a 6mm ZAO-II in the 4th slot makes a great workhorse turret, and nice in that the wider AFOV of the Sterlings make them feel like mini-wide fields
You don't bother with the Sterling 20mm on the Turret? I suppose it made most sense to jettison that one to allow room for a shorter focal length eyepiece.
Just love their convenience. Also, they are killer sharp with that Baader 2.2x Barlow that is part of the BCO set. Was out this morning with that arrangement on my TSA observing Orion and the Perseus Double and Jupiter, and the Moon last evening - Nirvana
I've never tried the Sterlings for Jupiter or the Moon. I'm used to Orthos, XO's or TV Plossls for those objects.
Posted 15 October 2013 - 10:06 PM
Posted 16 October 2013 - 08:03 AM
Since the OP though wants a planetary eyepiece, then with his scope something along the lines of a 7mm focal length (143x and .7mm exit pupil) would probably be best. So the 6.7mm would probably be the best option if he wants to keep it an 82 degree. I would go the traditional route myself though since teasing out the best the eyepiece can get is important for me and get a 7mm Ortho (Hutech, Fujiyama, UO HD). Might be handy to have an 8mm around also for when the seeing not as good. Basically IMO 6mm, 7mm, 8mm would be the perfect planetary trio for this scope that would get the most mileage. So in current marketplace of new stuff, probably the Fujiyama 6mm and 7mm Orthos, then the 8mm Brandon (or alternatively the TV 8mm Plossl if couldn't afford the Brandon).
Posted 16 October 2013 - 08:21 AM
For someone on a budget these are excellent eyepieces and coupled with a TV Powermate barlow you will get excellent results on your 102mm refractor.
Remember your scope is limited to about 300x on very good nights and you will find most nights your max will be around 150x to maybe 200x (depending on your site) so choose your eyepiece and barlow set with this in mind.
Enjoy your scope !!