Televue eyepieces.

[jamieren]

Okay I'm done waffling. I'm going to invest (I say invest because resale is a cinch with these from what I've seen) a good $1000 into Televue eyepieces. According to Terrence Dickinson, it's the only way to go to get consistent across the view high quality performance. Now I've been pouring over the naglers and the panoptics and am narrowing down the field. With the scope listed below I intend to first get a paracorr. That will increase f/ratio to 5.7 and reduce my budget by around $400. Next I think the 7mm & 17mm naglers are the choices to round out my eyepiece selection at $300 & $395 (see below) -there goes the rest of my budget already! I'm tempted to go with the less costly panoptic on the med. power, but for $150 less on the 19mm panoptic I'll lose .1 degree fov and the mag will be lower, so it's kind of a lose - lose scenario in my mind. I also tossed around the idea of getting a 35mm panoptic -it seems like a deal at $390 but which of the 7 or 17 to leave out I'd be hard pressed to decide. Also I do have the 32mm plossl which I do rather like and the view couldn't be that much wider ..certainly not worth the $$$ price tag as opposed to filling the gaps in my collection of EPs.

Suggestions anyone?

[Ben Ritchie]

The 17T4 sounds a very good idea to me, i've always been a great fan (i've had two!). It'll give 100x magnifciation with your 12" dob, and should deliver some great views. However, I think the 7mm is probably too high powered, i'd be tempted to go for the 9mm. The 7mm will give 240x, the 9mm 190x and I think the second option is probably more generally usable. I'd usually recommend a barlow in there, but with the Paracorr and a dob it becomes a bit ungainly.

Like you say, I don't think there's much point in picking the 35Pan over the 32mm Plossl if it means passing on a higher-powered eyepiece.

[Andrew*]

Jamie,

I don't think Terrence is being entirely fair. TeleVue and Pentax are not the only eyepieces that will give good views in your scope. I don't have any of the top-dollar TeleVues in my collection and I don't even have a Paracorr. And that's for use in an even faster scope than yours. Seriously, the coma doesn't bother me a lot, and my eyepieces cope with the fast focal ratio just fine. You just need to take a little bit of care choosing and you'll be fine.

As has been said to you more than once, look into the second hand market. Canada has an excellent second hand sales site here: http://www.astrobuysell.com/ Scammers are few and far between and if you're careful, you won't get stung. What you will get is superb value top-quality excellent condition astro gear at a fraction of new prices. If you don't like what you get,your seller might be okay with a refund. If not, you simply put it up for sale and the most you could lose is the cost of postage.

A coma corrector is a good idea, but as I can testify, IT IS NOT ESSENTIAL! Baader hyperions offer excellent value for money, especially on fast scopes. Meade UWAs are excellent if you really want ultra wides. As are William optics UWANs. In fact, to go with your 10mm S-W, the 7mm, 16mm and 28mm UWANs would complete your collection admirably. Go do the maths and see what you can save with that lot over TeleVue's equivalent.

Honestly, if you don't want to spend a fortune for perfection, then don't. Spend half a fortune, get 95% of perfection and put the savings to a nice filter or finder or whatever.

Andrew

[jamieren]

Thanks Astro! Here's a site that's worthwhile! There are actually eyepieces available here and even a few worth considering!

BTW, here's the original message from Terrence:

Dear Jamie,

I'll save you the agony of making a long and drawn out decision--possibly the wrong one. But you are not going to like the answer.

With an f/4.9 Newtonian you are giving the eyepiece--any eyepiece--its toughest challenge. The only way you are going to get sharp performance edge-to-edge across the field is by spending big bucks for top-of-the line glass.

You start by getting a coma corrector to correct edge-of-field aberrations inherent in Newtonians. Use it for everything except high power planetary. I use the TeleVue Paracorr. As for eyepieces, TeleVue Panoptics are superb, as are TeleVue Naglers and Ethos. The only eyepieces that match these in performance are the Pentax XW series. Anything else is second rate, especially on a fast Newtonian like yours.

Expensive? Yes. But if you want to smile every time you look in the eyepiece, that's the answer. For more, see my book Backyard Astronomers Guide, 3rd Edition (2008), which has an entire chapter on eyepieces with comments about many brands.

Clear skies,

Terence Dickinson

[Andrew*]

Hi Jamie,

I read that message over on CN already.

As I said, he's not being fair. You only need to look for yourself at the reviews of Meade UWAs and WO UWANs and even Speers-WALERs to see that they are almost up to TeleVue standards. A lot of people's argument is "if you can go up to the price of e.g. a Meade, it's worth paying the extra for a TeleVue". I think the price increase is quite significant.

I think where Terence confuses matters is "sharp performance edge-to-edge". The definition for "sharp" and even "edge to edge" can vary from person to person and unless you are very fussy about this, TeleVue's alternatives are more than good enough.

Some, including you, may disagree with me. These matters are very subjective and I have learnt to live with slight imperfection. YMMV

Good luck

Andrew

[John]

I guess I'm a little biased as a confirmed Tele Vue fan and having eyepieces that are all that brand.

I do think that TV produce the best eyepieces available if what you are looking for is sharpness across an ultra-wide field of view, even in fast scopes.

One thing that has suprised me is how little the shorter focal length Naglers (I use the Type 6's) give up to simpler designs in lunar, planetary and double star performance so to some extent I feel you can "have your cake and eat it" with these.

If however you do not require a fully sharp, ultra-wide field of view and / or you don't use a fast scope then there are many other fine eyepiece choices, many of which will save a lot of £'s.

I've read what Terence Dickinson has said above and the only line I would disagee with is where he says "Anything else is second rate ..." which is a bit strong I feel. There are many other perfectly valid alternative choices of eyepiece for a fast Newtonian scope which will give a lot of enjoyment - as Andrew says, many people are not bothered by what the outer parts of the field looks like or are happy with more moderate fields of view.

You pays you money and you takes your choice as the saying goes. At least there is lots of information freely available now so that it's a better informed choice

John

[jamieren]

Once again thanks for the link Astro. I'm in the process of acquiring a pentax 14mm for $100 less than new -from someone in Canada no less! All of a sudden it's looking like a steal in comparison to the $1200 or so it would have cost me for the TVs and paracorr I was intent on buying!

I think on the contrary I would tend to agree with you on the 'edge to edge' sharpness issue. I wrote up a short review on the 10mm speers-waler I have and really had to think about just that. After going back out the next time and looking intentionally I noticed there was some distortion on the outer (less than 20%) fringe . I realized I'd never noticed this before, so maybe it's less of an issue than has been communicated to me in some cases.

Thanks to you too, John. The message did paint somewhat of a black-and-white picture. Since it was coming from someone respected I forgot to think about what was said and remember it really is just one opinion (back to the subjectivity). I am also waiting for a response on a 7mm nagler, so if things pan out I can see what nagler has to offer as well.

*edit* I wonder if Terrence holds any shares in Televue? Just a thought...