Jump to content

SkySurveyBanner.jpg.21855908fce40597655603b6c9af720d.jpg

6 or 7mm Planetary EP choice?


russ.will

Recommended Posts

I was out a while back and as my session was drawing to a close, I decided to finish with viewing Jupiter as it was riding high. The seeing was excellent and I was rewarded with quite breathtaking views. The view was so stable, I felt I could have pushed the magnification a bit further than my 8.8mm ES82 would allow at 170x. Not much, but I figured somewhere on the far side of 200x would have been do-able.

The thing is, planetary is occasional for me and it's not my main concern. The ES82 6.7mm is the obvious choice given the current crop, but it will cost £71 if I'm lucky with customs and £96 if I'm not - Either is too much for the use it will get.

I'm not commited enough to planetary viewing to go ortho, as I don't seem to get on too well with tight eye relief based on Plossl experience. I had an 8mm 'TMB designed' thingy off Sky's the Limit (which are now called 'BST 58deg Wide Angle Planetary) which was comfortable enough, but the quality of view was completely stuffed by my current ES82 8.8mm, so I don't expect the shorter ones to fare any better. But they're about the right money.

I had a brief look at Jupiter (in daylight!) through a Williams Optics SPL 12.5mm a while back and whilst it was extremely comfortable to use, it was hardly a situation in which to make quantative judgements about the range as a whole. The WO SPL 6mm seems to get some very complimentary CN reviews (can't have been used in one of their focusers! ;p), but I'm interested to hear any first hand accounts of anybody using similar EPs in an F4.9 Newt.

So, £50-70 for an occasional planetary EP. I'm not to fussed about a wide FOV, but reasonably sharp at the edges would be handy for lunar work*.

Thanks in advance,

Russell

*Has anybody else noticed the rare number of clear nights that seem to coincide with near full moons? No. Damn! It's just me then. :(

Link to comment
Share on other sites

  • Replies 31
  • Created
  • Last Reply

The answer is yes and I've tried it.

I have a 2" ED barlow, that I use as the 50mm extension tube to the focuser because it has a compression ring for securing 2" EPs. To use it as a barlow in the stock Skywatcher focuser, you have to take the stock 2" extension tube out, which means swapping between the 2" extension tube, 1.25" extension tube and no extension tube, but inserting the barlow set 50mm out from the focuser, depending on the EP and/or combination in use. This routine, got old very quickly.

I bought a small pile of 1.25 to 2" low profile adaptors to fit to the 1.25" EPs and took the nose piece off the barlow-now-extension-tube. This makes swapping between EPs an absolute breeze as they are all effectively 2".

Before anybody says it, screwing the 2" ED nosepiece back onto the tube does not seem to give the same results. Barlowing the 18mm is noticably inferior to the 8.8mm, in part because of the huge eye relief and the same goes for when I tried doing the same to the 14mm which was the obvious solution. ED it may be, but the contrast wasn't the same either, which seems more important on planets. Funnily enough, screwing the nosepiece directly onto the 30mm ES82 works surprisingly well, possibly because this only results in 1.6x magnification which is a bit easier to deal with in terms of eye relief, so it's saved clamouring for the 24mm ES82. For now...

The thing is, given my current modus operandi, buying a 6-7mm EP isn't that much more expensive than a decent 1.25" barlow and it is a lot more convenient.

Russell

Link to comment
Share on other sites

One problem you have is what I call the ratchet effect. If one EP in your collection is clearly better than the rest, you will start to feel uncomfortable with the others, hence. You could certainly try the Celestron X-cel LX, which get a very good press, or the SPL 6mm. Alternatives are secondhand Radians (Not that common, are they), but also have a look at the Vixen LV (or NLV secondhand). These do not sport the wide FOV of the others, but are very comfortable, and the LV 6mm can be had for EUR 87,50 over here. I had the 7 and 9mm, and the Radians were better, but not by a large margin.

I do think you will start to use them more, as 200x and above is doable in my 8" scope on many nights, so your 12" should be fine. These are not just planetary EPs, they also work very well on small planetary nebulae (I used an XW10 on the Eskimo nebula at 203x a week or so ago, really nice).

Link to comment
Share on other sites

How about the celestron exel-lx 5mm or 7mm, they get very good reviews, if it were me i would be looking at the circle T orthoscopic, but you stated you dont like these

It's not so much don't like, as don't get on with. They're great to start with, but then I find my eyelashes mess them up and it's game over.

Maybe I should just persevere and start observing with a face wash?

Russell

Link to comment
Share on other sites

Mmm. Maybe I should re-examine my Barlow predujice. I calculate that if I get clouted for import duty and VAT, one of those could land in my lap for £80. £58 if it slips through...

Assuming the worst case, £80 to end up with an EP range of 4.4, 5.5, 7, 8.8, 11 & 14mm seems too cheap to ignore the inconvenience factor. I'll ping Sherry Hands an email.

Am I right in thinking these are a Powermate clone? They seem to be a 4 element telecentric design, so they don't mess with eye relief.

Link to comment
Share on other sites

Rumour has it.... that or the Meade Telextender, which was itself purported to be a PM clone.
Almost certainly and as that seemed to have a good rep, it's no bad thing.

Russell

Sent from my iPad using Tapatalk HD using chubby fingers. Sorry.

Link to comment
Share on other sites

Cheers Russell.

I'm a big fan of barlows whilst building up a decent EP set as my barlow, like many others, splits so you can have the full 2x or attach just the lens directly to the eyepiece (or 2" adaptor) and get about 1.5x So with my 14mm Meade UWA I can have 14, 9.3(ish) and 7 all from the same eyepiece and with a little bit of faffing. It's nothing major tho.

If I add the 11mm ES I'd have 14, 11, 9.3, 7.3, 7 and 5.5mm all from 2 decent quality eyepieces. You can't deny that's great value :)

Link to comment
Share on other sites

Hands On Optics have confirmed a price of $79, plus $15 shipping. That's £12 less than an ES82 6.7mm, so common sense says I should overcome my predjudice and buy one.

Keith & Moonshane have extra 'Like This' for being right all along. :)

Russell

Link to comment
Share on other sites

The ES82 1.25" EPs have 14-15mm of eye relief across the range, so had it been a barlow, then the same issue would have cropped up with all of them, unlike with a Plossl where it can actually help.

The Tele Extender side steps the problem completely and at worst, is only a bit more than I wanted to spend. Anyway, it wouldn't be an asto purchase if there weren;t a bit of budget creep. :grin:

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.