2x Barlow or 3x Barlow.

[Geospacial]

Evening all,

I am looking at upgrading my EP's over the next few months. I haven't got a massive budget, but I do like the Celestron X-Cel LX's. I have a 12mm and I am very happy with it so I was going to look at buying a few more of these. I have seen them on First Light Optics for £59, which is the best price I have come across.

Along with upgrading the EP's I would like to buy a new Barlow. In the x-Cel range, a 2x and a 3x are offered. Would it be worth buying the 3x or would this be a bit too powerful for my scope (I have a Skywatcher Explorer 150P). The scope is therefore an f5 and I think maximum magnification is 300x (I think I've worked that out correctly!!).

The stock 2x I have allows good views of Jupiter (not managed to test it on Saturn yet) so I know that strength is ok. I am just curiouse as to what the 3x would offer.

Here is the link to FLO. http://www.firstlightoptics.com/celestron-eyepieces/celestron-x-cel-barlow.html

Many thanks for any advice offered.

Al.

[Irvine6]

Im in the same situation as you

People are saying to me 3x would be to much for the scope to handle

Let me know ho you get on

[Geospacial]

Will do, hopefully somebody will be able to help!

[John]

The max magnification figure you have quoted is a theoretical one based, I guess, on 2 x the aperture in mm or 50x per inch. In practice a bunch of other factors notably the seeing conditions we usually observe under mean that the theoretical maximum needs to be moderated a bit to get a figure which is actually going to be practical. For a 150mm scope that varies between 180x and 220x or thereabouts. So an eyepiece or eyepiece / barlow lens combination that delivers 300x is not going to be useful 99% of the time.

If you added the  9mm and 7mm Celestron X-Cel LX eyepieces plus the 2x barlow that, with your 12mm, would give you a range of magnifications of 63x, 83x, 107x, 125x, 167x and 214x which would be a pretty useful set. You would also want something at the lower magnfication end so the 25mm X-Cel LX for 30x would be useful there.

There are many different ways to play it depending on your budget but 300x in a 150mm scope is really not going to get out of the eyepiece case too often ! 

[Geospacial]

Hi John,

That's great advice and I did suspect as much from other threads I have read on the forum. Thanks for the suggestions on the EP's. That should fit my budget spread over a few months!

Thanks for taking the time to help.

Al

[Geospacial]

I've just been looking at EP's and found some Celestron Luminos selling for £85 for 1.25" up to £180 for the 2" 31mm. The Barlow for this range is a 2.5x.

Would the luminos range be wasted on my telescope and be more beneficial to the larger aperture ones?

[ronin]

300x is the theoretical max, as John says, but do not expet to get there, I have recently seen Skywatcher quoting something like 3x diameter so the "maximum" is, shall we say, "moveable".

I tend to say expect 1.5 times and then when when things are just right.

If you go around expecting to get to 200x quite often you are not going to get overly disappointed, if you expect 300x you will count the nights it happens each year on the fingers of one hand, quite possibly the thumbs of one hand.

If you want an X-Cel barlow then the 2x, the jump that a 3x causes means that the 5mm and 7mm X-Cel are not sensible to plug into one. The 9mm might just work but I suspect not. So half the eyepieces are not useable with a 3x barlow.

Really I would suggest a 1.6x barlow but not made in the X-Cel range, only know of Antares that produce one.