New eyepiece or Barlow 2.5X

[meddyliol]

My Revelation Dob is 1200mm and I have 9mm and 26mm lenses. They will give me magnification of 133 and 46. If I want to increase the magnification to around 200 is it better to get a Revelation Barlow 2.5X for £31.99 or get another eyepiece of say 6mm? I cannot afford too much money and is a magnification of 200 about the most I should go for anyway?

Cheers

Brian

[ronin]

My preference is always for an eyepiece as opposed to an eyepiece and barlow.

There is a Vixen NPL (plossl) ate £35 which are reported as good by many here. Others like the BST  and the X-Cel are more.

There are planetaries at 6mm but they get varied reports, I have 2 and I much prefer the BST's. £^%Astro do planetary's at £36.60, GSO plossls are £27.60 there as well.

Harrison have Revelation plossls ar £22. One of these two used to do Lacetera eyepieces (I think) but cannot locate now).

Also check the used side here at ABSUK, eyepiece tend to appear on a regular basis asn someone clears out a few or gets rid of one they don't use or have replaces with a better.

[meddyliol]

Thank you for that. I believe that GSO are the same as Revelation. Will have a look at the other brands you suggest and the classifieds. I think you are correct about Barlows, it's the same as having a converter for cameras, never as good as a prime lens or zoom.

[LeeB]

a 6mm plossl is tight on eye relief I would go with the barlow I use the rev one and it spot on, if you want to go with a 6mm eyepiece get one with longer relief , but be aware that most short focal eyepieces with more relief do it by having a barlow lens or similar included in optic chain anyway.

The bst's are good , without breaking the bank though.

[Qualia]

Sometimes a Barlow is a very useful tool, other times I prefer not to use it.

If I had an 8" Newt, I'd start by scouring the secondhand market for three tasty, premium eyepieces, one with a magnification of around 50x, one around 90x, and the other around 120x. I'd be looking for eyepieces with a decent amount of field as view (60º+) and in terms of exit pupil one around 4.8mm, and the others around 2.8mm and 2mm respectively.

If it took me a few seasons to get this sorted, so be it. While I'm on my mission, I'd not only get to learn more about the night sky and to appreciate and evaluate my kit but I'd also know that these three premium eyepieces will become an essential part of my gear and should last me years. In that way, in the long term, I'm not only saving myself money by not having to 'upgrade' in the future but I'm also adding to my comfort of mind, acknowledging that this end of my optical kit is going to be about as good as it is going to get.

To this three eyepiece set up, I'd also be looking at purchasing a premium x2 Barlow. In that way, I'd have magnifications of 50x, 90x, 100x, 120x, 180x, and 240x which would cover me for most of my DSO viewing. Of course, the 3 eyepiece set up isn't perfect but it will be a decent workhorse kit

[RT65CB-SWL]

As per 'ronin', quote: "...preference is always for an eyepiece as opposed to an eyepiece and barlow."

Adding a Barlow is adding more glass in the light path. I do not have anything against Barlow's as I use mine from time to time, and a MagniMax http://www.astroboot.co.uk/AstroBoot/telescope-and-astronomy-stuff.html?highlight=AB3949#AB3949, which simply screws into the nosepiece.

I would suggest a wide-angle eyepice, ie a TeleVue Radian* http://www.telescopehouse.com/acatalog/TeleVue_Radians.html  I have a 6mm and it is very comfortable to use. Or maybe these... http://www.skysthelimit.org.uk/telescope%20eyepieces.html or http://www.365astronomy.com/eyepieces-317mm-125-magellan-wide-angle-eyepieces-c-4_25_60.html?

* link to Radian eyepiece instructions... http://www.televue.com/pdf/literature/Radian%20Eyepiece%20Instructions.pdf

[meddyliol]

Thanks everyone. Lots of info there. Will inwardly read and digest. I will probably go for Revelation as they seem to be decent for the price but will have a look at the others as well particularly the http://www.365astron...c-4_25_60.html? ones. The Radian ones are a little outside my scope (no pun intended) price wise.

[bingevader]

I don't think that a reasonable barlow would make much difference these days in adding more glass.

However, a 2.5x barlow would only be any use on the 26mm, so although cheaper, it wouldn't add much to your set.

I have the WO SPL 6mm and it's very good indeed, just to add another option.

[Charic]

I have both options, and use both options. A Barlow virtually doubles the focal length of your telescope by the factor printed on the barrel. Dividing your focal length by any eyepiece focal length gives you your magnification. F-1200mm or. F-2400mm with a 2x Barlow fitted. The theoretical power of your standard 8" is about 400x power, but limited from the Earths surface due to asmospherics. Barlowing my 8mm EP and / or the 6mm, 5mm is pushing the limits for general use, but good for me to impress anyone who wants to see the rocks inside the craters ( big rocks-mountain sized ?) A Barlow adds a bit more glass into the optical train, but doesnt affect my use when Lunar observing.

[swamp thing]

Personally I built my eyepiece collection around a Powermate (barlow)

Good barrows add nothing but power and certainly don't detract from the view at all.

Using a barlow allows one to build a considerably better eyepiece collection at a budget than eyepieces alone.

I use Naglers, These and many wide field eyepieces have in built barrow elements in them.......... and are amongst the best eyepieces available.

[Liquid360]

Whenever there's an "or" turn it into an "and"! You can never have too much beautiful kit!

[meddyliol]

What exactly is 'eye relief' I keep hearing about?

[RT65CB-SWL]

What exactly is 'eye relief' I keep hearing about?

Not read them myself, but these look interesting...

http://en.wikipedia.org/wiki/Eye_relief

http://en.wikipedia.org/wiki/Exit_pupil

[meddyliol]

Cheers, will have a good read of both.