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15mm for binoviewers?


Mike73

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The Starguider series should be a good option at their price. Be aware though that a 15mm eyepiece will perform as a much shorter focal length one if you have to use a Barlow to achieve focus.  :smiley:

Thanks Peter.

The binoviewers are mainly going to be used with the 180 for lunar and planetary viewing with and without a x1.6 barlow and I think that should work out ok, I don't think I'II have enough inward travel to use them with my Sumerian but I'm not too worried about using the binoviewers with that scope.

I've used Starguiders before in an 8" f/6 and they were excellent so they are on the shortlist, does anyone know how Starguiders compare to WO Swan's? Also been reading about Vixen NLV's but they are right at the top of my budget.

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In a 180 I would be careful about going too low. I use a pair of 15 mm NLVs in my WO binos with a C9.25 and that is more than enough mag. With a Mak, your binoviewers will increase the optical path and hence focal length. 15 mm eyepieces may feel like 12 mm when used with binoviewers.

Optically the NLVs are top notch, but are quite wide at the top and I can only just get my conk in between. I use the 20 mm WO eyepieces that came with the binos mostly. They hit a reply nice spot in terms of mag and FOV and are optically pretty good with my C9.25. I do prefer soft rubber eyecups with binos though.15 mm BSTs will probably be quite nice though. I'm hoping to try some soon.

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With a Mak, your binoviewers will increase the optical path and hence focal length. 15 mm eyepieces may feel like 12 mm when used with binoviewers.

Makes sense Mark, I'd never even given it a thought! Does it really make a lot of difference to the focal length though?

I'm going for the WO, the same as yours, without adding the increase in focal length I'II get x135 and x216 from the supplied EP's + barlow and a 15mm would give x180 and x288. Thats a pretty nice looking spread for Jupiter and some high powers for the moon and Saturn.....  :undecided:

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Yes it will. The binos will shift the focus position quite a lot. Moving the primary mirror to focus essentially changes the focal length. There is no such thing as a single focal length in a Mak or SCT. Every time you re-focus, you change the focal length. My recommendation would be to get the binos first and try the eyepieces that are supplied. You will get an appreciation of what to expect from this. The supplied eyepieces are pretty good in slow OTAs. I use them a lot.

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Don't rush to buy a pair of 15 mm eyepieces. The quoted FL of the 180 MAK is 2.7 M and with binoviewers it will be more like 3 M+. As our American cousins say, do the math. Wait and try the 20 mm eyepieces first. I'm not a fan of the 1.6 x Barlow by the way.

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I've ordered a pair of these 9mm Ultra Wide eyepieces on the advice of someone who tested out a few sizes in the WO bv's:

http://www.pulsar-optical.co.uk/prod/skywatcher/eyepieces/ultrawide.html

Review thread here:

http://stargazerslounge.com/topic/201971-i-have-been-testing-some-eyepieces-in-the-wo-binoviewer/?hl=%2Bskywatcher+%2B9mm+%2Bultra+%2Bwide

At £30 a pop it's a no brainer unless you particularly want 15mm for some specific reason. :)

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Yep I was going to wait a while anyway and try the supplied 20mm's which a lot of people say are very good. Your the first person I've heard that doesn't like the x1.6 though?

Doing the math is a little tricky compared to what I'm used to though (newts)...With the FL changing as you focus how can you work out exactly what magnification you are using anyway? As you say the binoviewers also change things but the manufactures don't seem to give any info on exactly by how much!? Maybe I'm trying to be too precise with this but when you have to buy two EP's it would be good to know exactly what you are getting before you part with your cash.

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I was being a bit flippant with the math comment. A bottle and a half of red wine does that. It is Boxing day though and I'm not going anywhere. Try not too be too calculating. See what works for you. If you do want to do the "maths" (as it should be), approx 3M FL with 15 mm eyepieces would give 200x. That is about as far as I go under UK skies and often, less is better. The C9.25 has a FL of 2.35M, which may be 2.6 M for example with the binos, possibly more. My 15 mm NLVs don't get that much use. The 20 mm EPs get used a lot. I don't know the exact mag I get, but the 20 mm eyepieces work perfectly for me and the FL of my OTA is less than the 180. There is no substitute for experience. Try the 20 mm eyepieces and make your own mind up. As for the Barlow, you have bought a very nice OTA and the WO binoviewers are pretty damn good for the money. The Barlow is plasticy and looks nasty. I have never had a decent view through mine. I might be doing it a disservice. It is yet another glass element to look through. You will not need it with a 180.

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Mike,

I have just tried out my new BV's with a pair of Fujiyama 18mm Orthos - superb results. They gave sharp contrasty images with good eye relief and they don't break the bank. They should give me x150 in my Mak but I would say the magnification was closer to x170 - I have found this before with BV's.

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I'm planning to borrow a pair of 18 mm BGOs for my binoviewers. I suspect they (or their equivalents) are pretty good for this purpose. Is it possible to get rubber eye guards for these to reduce stray light entering?

Don't know Mark, the supplier does not advertise them. But it's a good idea - would like to do that too.

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Mike I have the Skywatcher 180mm Mak/Cass and use binoviewers on the Moon and Planets. I have 3 sets of EPs and never use a barlow. I use 25mm Antares plossls, Skywatcher 15mm ultra wide ( link - http://www.green-witch.com/acatalog/Ultra_Wide_Range.html ) and 12.5mm William Optics Planetary. To be honest I find that the 15mm gives the best view. The WO Planetary gives a mag of 216x

I did have some 9mm Plossls which were only good on doubles.

In theory the 15mm should give a mag of 180x but it is much more than that. As stated the WO Planetary gives 216x and again the mag is much more than that. The Skywatcher 15mm is not a large EP, your nose does not get in the way, eye relief is OK and the FOV is pretty reasonable.

I did think of buying some TeleVue 15mm plossls but to be honest at f15 I find the Skywatcher EPs pretty good.

Mike when you make your decision it would be interesting to get your review of the choosen EPs

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Mike,

I have just tried out my new BV's with a pair of Fujiyama 18mm Orthos - superb results. They gave sharp contrasty images with good eye relief and they don't break the bank. They should give me x150 in my Mak but I would say the magnification was closer to x170 - I have found this before with BV's.

Were they from Glen at Lyra Optics? I remember reading an old thread about them and people rated them highly then.

Mike I have the Skywatcher 180mm Mak/Cass and use binoviewers on the Moon and Planets. I have 3 sets of EPs and never use a barlow. I use 25mm Antares plossls, Skywatcher 15mm ultra wide ( link - http://www.green-witch.com/acatalog/Ultra_Wide_Range.html ) and 12.5mm William Optics Planetary. To be honest I find that the 15mm gives the best view. The WO Planetary gives a mag of 216x

I did have some 9mm Plossls which were only good on doubles.

In theory the 15mm should give a mag of 180x but it is much more than that. As stated the WO Planetary gives 216x and again the mag is much more than that. The Skywatcher 15mm is not a large EP, your nose does not get in the way, eye relief is OK and the FOV is pretty reasonable.

I did think of buying some TeleVue 15mm plossls but to be honest at f15 I find the Skywatcher EPs pretty good.

Mike when you make your decision it would be interesting to get your review of the choosen EPs

Thats interesting thanks Mark, good to hear from some one else using a 180 + binoviewers.

I plan on doing a little write up on the 180, WO Bino's and when I get round to buying more EP's I'II do those aswell. :)

Perhaps two 15mm TV plossls or maybe two 18mm Astro Hutech Orthos :).

Theres nothing like spending someone else's money is there!?  :grin:

I'm hoping to pick the 180 and WO binoviewrers up from FLO next Thursday....Cant wait!!!

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Theres nothing like spending someone else's money is there!?  :grin:

I'm hoping to pick the 180 and WO binoviewrers up from FLO next Thursday....Cant wait!!!

No, there isn't anything like it, other than spending your own money of course :rolleyes:.

Anyway, I thought you were happy with just the one scope :evil:.

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Right tool for the job....One for DSO's at dark sites and one for planets and lunar at home, just trying to maximise on the clear nights we get. 

Mike

The 180 with binoviewers on the Moon is 3D. The other week I was able to view the small craters Armstrong, Aldrin and Collins from the Lunar 100 list which can be a bit tricky. The view of the Moon gives the WOW factor. Hoping to view Jupiter tonight if it remains clear.

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