Posts Made By: Mike Hosea

Well, *I* use a 14mm with a 2x or 3x Tele Vue Barlow on my 7" f/6.7 sometimes, but only because I like to leave the rest of my eyepieces inside sometimes and just go out with a couple.

I highly recommend this kind of activity as a "get over the equipment obsession and observe" kind of thing, but for somebody who is constructing their set and looking to expand into the next quality tier from regular Plossls and Barlows, I'm reluctant. As for Radians and Pentax XLs, you *can* use them with Barlows, but for best planetary use I think you should buy them for the focal length you need for PLANETARY use to keep the number of air-to-glass surfaces down.

If it isn't the wide field you want but better image quality, consider high-quality orthos and Plossls, with a high-quality Barlow or Powermate for below 7mm focal lengths if you don't like getting poked in the eye. The contrast in a 15mm Tele Vue Plossl in a 2.5x Powermate should rival a 6mm Radian any day of the week. Tak LEs are good in the 5mm and 7.5mm focal lengths. Hey, if you can wait and you're willing to spend $200 on an eyepiece, consider a new TMB Super Monocentric. I can't personally vouch for them yet, but they're billed to be the best thing to come along since the famouse Carl Zeiss Abbe Orthos. Eye relief is also about 0.8 times focal length, but the field of view is only 30 degrees on these, so you need a driven mount for the most part.
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Mike

Cooldown is a big factor. If storing your scope indoors you may have to wait an hour or more to get good planetary views with a big Newt. Of course, 15" of aperture admits an off-axis aperture mask of something like 6", so after cooldown you should be able to beat your AP 130 that way even if seeing is a factor.

A lot depends on the quality of the mirror, and I'd sure feel more comfortable about Zambuto or Pegasus than Nova, Galaxy, or Torus, but that's because Carl and John have built a reputation for excellence, and I just don't know where Nova, Galaxy, and Torus are right now. You can't have great planetary performance without a smooth, well-corrected mirror. For planetary observation I'm not sure a 15" mirror is that much better than a 12.5" on anything but the best of nights, and 12.5" is a more manageble size. If you can afford a 12.5" or so Dob with great optics I think you'll find having BOTH refractor and reflector is really nice. Of course 15" is going to be a noticeable step up from 12.5" for deep sky.
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Mike

Well, all this stuff works okay. I'd keep the Plossls and UO Abbes for planetary use and upgrade to whatever you'd like for deep sky, but if there is a focal length where you want dual use for deep sky and planetary, you might want to consider a type 6 Nagler. I use type 6 Naglers for planetary use in my 10" f/5 Newt, but I don't recommend them OVER Plossls and Abbes with Barlows in that scope (or over Plossls and Abbes even without Barlows in somewhat slower scopes).

When switching like this, especially for planetary use, it's best to take it slow and do selected comparisons yourself before going whole hog.
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Mike

Dave, if you like the 26mm Nagler, I wouldn't change anything, except perhaps if you want higher magnification sometimes. The 3.5mm and 2.5mm Nagler Type 6's are just like the 5mm.

I say "if you like the 26mm Nagler" because I myself couldn't justify keeping it since my skies aren't really dark enough for low magnification observing. I just use a 40mm Pentax XL as a "finder" eyepiece and jump straight down to a 14mm Radian. I'd buy a 13mm Nagler Type 6 instead, but I generally move so quickly down to the 7mm Nagler Type 6 on objects of all types that I can't justify it, or a Paracorr either, for that matter.
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Mike

Chuck, it should be as easy as removing some screws, but depending on how the corrector was centered it may require some patience. Two things to bear in mind:

You want to return the corrector to the same orientation, not a rotated one, so mark it somehow--that blue painter's tape is great stuff--peals off without leaving a residue, or use some kind of felt pen and clean up afterwards with a q-tip and some rubbing alcohol. Just mark it somehow in a non-damaging way so that you can put it back exactly the same way.

Second, the corrector may be centered in the holder using shims. If so, be methodical, mark and record what you need to in order to return everything the way it was when you put the corrector back. Otherwise you might lift off the corrector and the shims just go flying--not good.

And there is a third thing. Don't drop it. :-)

I'd clean with cotton balls soaked with isopropyl alcohol diluted with distilled water. If the secondary is also dirty, you'll probably want to clean it as well, but its coatings are more easily damaged, so seek advice on how to go about it. I'd be inclined to clean it first, treating it like a Newtonian primary, but I've never had occasion to clean the secondary of an SCT, and I'm only ASSUMING it has an SiO2 overcoat (otherwise it should be touched only by air or liquid). I'm sure Uncle Rod (Mollise) knows all about this stuff, so if he's lurking he might pipe up here, or you can find his web page with a Google search I'm sure.
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Mike

The Type 6 Naglers are excellent eyepieces. I would expect even the type 1 Naglers to beat the Orion Epics, but I really don't know for sure.
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Mike

"Final Reduction" doesn't have to imply desperation. I never sold an excellent 7mm Tak Ortho and 3x TV Barlow because for some reason other people just didn't see the value the same as I did, or maybe the timing just wasn't right. So, I hit my bottom price, didn't sell, and have happily kept them. Maybe people think because you're offering something for sale that you don't want the items. All it usually means for me is that I want to minimize my out-of-pocket on something I want MORE.
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Mike

Well I don't think I believe either the so-called conventional wisdom or the so-called truth of (4). While two eyes helps, no doubt, dropping the intensity of the light to the retinal rods by a half or more is bound to drop ALL the available detail at the threshold of visibility when viewing without the beamsplitter, and if the rods don't detect it, the brain won't have any of that signal to work with. The CW is more like binocular viewers are good for all objects, but it sure helps to have a little extra aperture to make up for the light loss. Is this not so?
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Mike

My sympathies as well, empathy actually, as I find it very easy to imagine what you are feeling.

Can you capture the scarring in a photo? Just be curious to see it.
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Mike

The TV model has a captive thumbscrew, maybe even a compression ring these days (not sure). However, they probably both come from Vixen, or at least they both used to. Here is where Tele Vue's extra QC helps. I once bought one from Orion and much later noticed it had several sleeks on the coatings. They also sometimes need a minor collimation adjustment, and they aren't really adjustable. So if you can imagine Tele Vue tossing out more of the bad ones first, you can see how your probability of getting a good one goes up. Orion's return policy is excellent, though. If you go that way, just make sure you _thoroughly_ check it out when you get it.

I hate to say this because they are more expensive, but I much prefer the ones that have casing machined out of aluminum rather than casted since they probably come collimated. I'm not sure if the reborn Lumicon is still producing it, but the Lumicon 1.25" used to be a good one, as is the Tele Vue everbrite model.
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Mike