New high mag advice please

[Nexus]

Hi all, first post but I've been a silent member for some time.

I am looking to buy a new high power eyepiece and would like to know what you guys would recommend please? I have a skywatcher 150p f/5 and the eyepieces I currently have, other than the stock that came with my scope are...

Maxvision 68° 24mm

Maxvision 68° 16mm

And I also have a Revelation Astro x2.5 Barlow.

All decided upon through reading this forum and preferring DSO observing. However I do love the planets and moon and I'm obviously lacking in the higher magnification area. I know my Barlow can increase the 16mm to 8mm, so I am a little reluctant to buy an 8mm plossle (my current price range) as it will be repeating a magnification and I know the seeing will not always be good enough to get a lot of use of Barlowing to 4mm.

Would you suggest I purchase something around the range of 11-12mm although I would have a the same issue with repeating the magnification I would most likely get more use out the 6mm when Barlowed,right? I've been looking at BST and Tele Vue plossles mostly, again as recommended on here. Also, having not experienced either the TVs or BSTs would you say one is better than the other? I do wear glasses so eye relief may play a part in my decision.

Any input would be hugely appreciated, thanks!

[Russko13]

Celestron xcel lx have been highly recommended to me a few times for planetary viewing with a fast scope, these are what I've decided on mine also being f/5, I reckon a 12mm and also a 5 mm or 7mm would be good for you

[Reeny]

I have the same eyepiece / Barlow combination on a 1200mm focal length 8" Dob

Your focal length is different at 750mm, so my advice may be slightly out.

Firstly - the 2.5x Revelation Barlow gives me exactly the same magnification as my 2x unbranded barlow (I think it's the skywatcher version - with camera threads on the top) 

So the 16mm MaxVision Barlowed down to 8mm will be near enough on the money.

I guesstimate that both my Barlows are 2.1 or 2.2x magnification.

Secondly - Plossls are great for 52 degree views on planets - but struggle to give panoramic views of the moon etc

Try to buy the wider angle eyepieces like the Maxvisions - 82^o is nice, but 68^o is all I need.

Now for the theory.

I have successfully used the 16mm MaxVision at 150-160x magnification, but struggle to get past 200x using a 12mm Plossl Barlowed to 6mm.

The 11mm Explore Scientific 82^o gives me 230x magnification - which is usable 50% of the time.

I need a 6mm Televue Delos to fill the 200x gap (or a 13mm Nagler)

To get yourself 200x mag on 750mm, you will need a 3.75mm eyepiece (or an 8mm barlowed by 2.1x down to 3.8mm)

The Explore Scientific eyepieces are good at £90-£100 from USA if you can find the correct size in stock on Ebay.

http://stores.ebay.co.uk/Hands-on-Optics-Telescopes-and-More/Eyepieces-Barlows-/_i.html?_fsub=5740570015&_sid=3310425&_trksid=p4634.c0.m322

There is a 4.7mm on here at the moment to give you 160x mag - a good eyepiece to fill the gap, but I would be looking to go higher than that.

ES only do 4.7 / 6.7 / 8.8 / 11mm eyepieces in the sizes you might need. http://www.explorescientific.co.uk/en/Eyepieces/

The 8.8mm barlowed would give you => 85x / 180x

Agena is another seller which has been recomended on the forum.

http://stores.ebay.co.uk/Agena-AstroProducts/Explore-Scientific-Eyepieces-/_i.html?_fsub=3657065010&_sc=1&_sid=586299390&_sop=10&_trksid=p4634.c0.m322

The 60^o BST range can provide the 200x magnification you need from their 8mm eyepiece (12mm = 130ish when Barlowed)

Two BST's would be cheaper than one 82 degree eyepiece.

It might be a better, more flexible choice to get you started.

[Reeny]

Forgot about the 5mm BST

You should consider the BST at - 8mm Barlowed (200x), and 5mm (150x)

http://stores.ebay.co.uk/Skys-the-Limit-Astro-and-Optical/BST-Starguider-ED-/_i.html?_fsub=2568750014&_sid=53377064&_trksid=p4634.c0.m322

or the slightly more expensive Celetron 60^o eyepieces at 7mm Barlowed (215x), and 5mm (150x)

http://www.firstlightoptics.com/celestron-eyepieces/celestron-x-cel-lx-eyepiece.html

[Qualia]

As a working guide rather than a rule of thumb, you don't want to be pushing further than 1.5 x the scope's aperture in mm. So, 150mm x 1.5 = 225x. That's quite reasonable and unless your optics are top stuff and/or your skies are rather forgiving, I'd stick for now to a maximum of 200x.

Taking into account the eyepieces and Barlow you've mentioned (about 2.2x), you've got: 31x, 46x, 68x, 78x and 103x.

So, your choices appear to be something like an 11mm giving 68x and about 150x and/or an 8mm which would give you 90x and about 206x. That'll be your maximum power.

Other than that, you could think about your 6" f/5 being a nice widefield, but not great for highpowers. So, you might want to look into getting a longer focal ratio (and bigger aperture scope ) rather than forking out more cash on eyepieces.

Another choice could be to keep the 24mm but sell on the 16mm and purchase an 11mm and an 8mm instead. That way you'd have just three eyepieces covering most of your average night's viewing: 30x, 70x, 90x, 150x, 200x.

[Nexus]

Thanks for the great advice guys! I'll look into the suggestions and post back before I make the plunge.

Qualia, this may seem like a stupid question but I'll go for it anyway... how do I achieve the x78 with my current eyepieces?

[Reeny]

Probably a typo error.

750mm focal length divided by the standard 10mm Plossl = 75x

[Nexus]

Ahhh I see. Sorry I didn't mean to pick fault, I just thought I could be missing a trick there.

[rwilkey]

As a high mag choice, plossls are out of the question as the eye-relief is poor, and you wear glasses, I would therefore suggest the BST Explorer./StarGuider range or the William Optics SPL range, the 6mm will give you 125x, a good mag for both planets and Moon, without going OTT.

[Astro Imp]

Celestron xcel lx have been highly recommended to me a few times for planetary viewing with a fast scope, these are what I've decided on mine also being f/5, I reckon a 12mm and also a 5 mm or 7mm would be good for you

I currently use the 7mm and 5mm in the same scope as you and find them excellent.

BTW when funds allow I will be adding to these, probably starting with the 12mm and 18mm.

[Nexus]

Thanks again for all your help.

I think I am have pretty much decided on the 5mm Celestron xcel lx and the BST Explorer 8mm. I know that they are different makes and may require a little more focusing when switching between them but I'd quite like to reach x200 with the barlowed 8mm. The xl's only have a 9mm and 7mm which by my calcs would achieve x183 and x235 when barlowed, where one may be too low and the other too high.

On the other hand am I being unrealisting in aiming to use the x200 often and should maybe go for the 9mm lx instead? Is there a big difference in magnification between x183 and x200?

[BigJock2005]

Celestron xcel lx have been highly recommended to me a few times for planetary viewing with a fast scope,

I am taking delivery of a 7mm X-Cel LX tomorrow for my f/5 Skywatcher - I'll do a review!

[lestergibson]

I've my eye on a high power ep too and after weighing all the options, I think I'm going to spring for the Meade 5000 5.5mm UWA.  It's a pity that the Maxvisions don't go that short.