Is it worth getting a barlow?

[Tennelle]

Hi there I have a Dobsonian 8 with a 25mm and 10mm. Im getting used to using it now and really enjoy it. How ever I have started thinking should I get a barlow and how much more will I see with it? Any thourghts or would I be better off getting a smaller lense ?

[Waxing_Gibbous]

Hi Tennelle,
I'm going with 'Not'.
Ten years ago, sure, but the prices on Wide Angle, short FL eyepieces (Explore Scientific, TMB, Agena Astro etc.) are now so low, and the quality so good, that unless you plan on doing astrophotography - where the barlow sits between the camera and the scope to magnify the image - it's a bit of a waste of cash (IMHO).
But if you're set on one I have a little used Celestron going...... :D

[Tennelle]

Hahahahaha I will pass on the Celstron. I tend to agree it is a lot of money to spend. I would just like to get a clearer image, Given Im in a urban area so maybe my investment should be on a light pollution filter instead. Honestly my head is spinning with all the diffrent attachments you can by and the cost of them!!!!!! lunar filter, nebular filter, zoom lense, planitary filters hahahahahaha need to win lotto cos Im hooked on a expensive hobby!!!!! beats watching T.V :lol:

[barx1963]

Tennelle
I agree, barlows are not as essential as they one were. Keep in mind, they make the image larger, which is not necessarily clearer. As an example compare the image using your 25 and 10 mm EPs. The 25 will show smaller but much sharper images while the 10 will be larger but (unless conditions are really still) blurrier. This occurs as the ep will magnify any poor seeing or atmospheric distortions also. Put a barlow in and you get the same effect.

Malcolm

[Hzadbhat]

Barlows can effectively double your ep collection. Your 25, using a 2x becomes a 12.5 and the 10 becomes a 5.
Sounds great so far.
But beware of poor quality or even top quality in bad condition. For a barlow to really kick off, you need viewing conditions to be just so. But even with standard viewing, I use mine quite a bit. So I would recommend getting one. The best and first option for (in my opinion) anyone considering new gear, is get along to a star party and ask others, politely, if they would be willing to let you look through their ep's, barlows and so forth. Most people will gladly do that.
This way, you can see the difference with and without barlows for yourself. You can also work out how many mortgages you need for new ep's.
A barlow will not give you a clearer image. The right viewing conditions and better ep's will.

[Barrykgerdes]

It depends a lot on what you want to see. I imagine your dobsonian has a primary focal length around 1500mm
Under good conditions the best magnification you can expect will be about 300x. using a 5mm eypiece or a 10mm with a x2 Barlow. Barlows and short focal length eyepieces in theory can give higher magnification but generally about 100x will be all you can use except on very bright objects such as moon craters.

A good Barlow on a 25mm Plossl will probably give a clearer view than a poor 10 mm plossl.
If the 10mm lens gives a fuzzy view bare it is doubtful if a Barlow will do more than make a fuzzy image larger.

However seeing conditions are the main criteria for the use of high magnification and top quality eyepieces will give better views than mediocre eyepieces and a Barlow.

Barry

[elfinke]

Just for a different opinion, I've got an 8" Dob with 25mm and 10mm eyepieces, probably extremely similar to your setup Tennelle.

The first extra thing I bought for it was some Baader Solar Film and an entry level 2x Barlow lens (like a $40 one).

I find that practically every night I'm out doing some visual observing and/or a-focal photography (working on Saturn currently), I use the 25mm with the Barlow. Which is a fabulous combination. Gives the majority of the magnification and detail of the 10mm, but with a far larger area to move your eye around in (due to the larger glass in the 25mm eyepiece - I'm sure I'm using the incorrect language here, someone with a better understanding can clarify).

It's fantastic.

[niko]

Not that I do a huge amount of visual but there's no doubt that the better the eyepiece the better the view, all other things being equal.

I have a 12" dob and a range of pretty low grade eyepieces - the views are okay. But recently I looked through a 17mm Nagler or Televue or something - the difference (under dark skies) was staggering. Mind you, that's an $800 piece of gear!

I reckon find a club near you, check out what eyepieces others are using and start saving towards one really good mid-range piece. It's too easy to throw little bits of money at cheap kit that doesn't do much more than clutter the cupboards.

Tax return time is always when I plan a decent purchase and it's coming up soon!

cheers

niko

[raymo]

Niko is absolutely right, but, until you decide to upgrade your
eyepieces, grab a moderate quality barlow, and effectively double
your range of magnifications. At this stage of your observing
experience I'm sure you will enjoy the extra options it will give you.
You can always sell your budget eyepieces and the barlow later
if and when you decide to upgrade.
raymo

[jamespierce]

I've got a 2.5x televue power mate. Hardly use it, and the views are always so-so ... Save your money and start building a collection of really good EPs one by one - they will last your lifetime, and really improve your views.

Also - It's tempting to think that more magnification will make things easier to see, but often the reverse is true. Seeing, optical and physical imperfections and the relatively dimmer view often means the reverse is true.

The most used EP for me with an 1800mm focal length scope is a 20mm Nagler...

[Tennelle]

Thank you everyone! as I am a beginner Iam going to ask a really silly question what is a EP? I have only had my diamon collapsible 8 dob for a month now so I am still learning the language. Finding a star group spounds fantastic!! Not sure that there are many in Perth but will have a look. Yes Iam trying to get a sharper image in a badly light polluted area.:)

[Tennelle]

wow sorry about the spelling mistakes hahahahaha:lol:

[barx1963]

Sorry, shouldn't use jargon! EP stands for eyepiece.

Malcolm

[Tennelle]

Hahahahahaha see I knew it was a silly question thanks