Noob - Which Barlow to get? 12" Dob

[MiniMaster]

Hello, I got a great deal on a 12" Dobsonian telescope by Apertura from craigslist which came with 9mm and 35mm lenses. I am looking to pick up a Barlow lens maybe around the 3x range but don't know which one to get (so many brands and different price points). 

More specifically looking for a 1.25" Barlow with great clarity of course. Hoping you all can steer me in the right direction. 

Also which other lenses would you say are "Must Haves" for this size dob?

Thanks,

[Ricochet]

A 3X barlow is unlikely to be of much use in such a long focal length scope. A 2x option, such as the Explore Scientific 2x Focal Extender is a good choice, but it depends what your budget is.  However, given that you only just got the telescope I would start by just using the eyepieces that came with it for a while before looking at other eyepiece options rather than a barlow. More magnification is not always better and many new users try to push beyond the limits that either their scope or atmospheric conditions allow. You're probably not going to need anything shorter than about 5mm  with that scope and for DSO viewing an eyepiece around 10-12mm is probably going to be the most useful, as well as longer focal lengths for objects that require a wider field of view and/or filtered nebulae. To give suggestions we really need to have an idea of budget and whether you need to observe wearing glasses.

You haven't mentioned collimation tools, but I would suggest investing in a good quality Cheshire/sight tube and learning how to use it. 

[RT65CB-SWL]

Hi @MiniMaster and welcome to SGL. 

Good advice given by @Ricochet.

FWIW - I have an obsession, (not the 'scope), with TeleVue 13mm's...

left: 13mm Plossl - centre: 13mm Nagler / Type 1 - right:  13mm Nagler / Type 6.

 

[Stu]

Very much agree with Ricochet here. Many people think they need a Barlow straight away, when actually another eyepiece or accessory would be much more useful. Whilst a x2 can be useful on shorter focal length scopes, they are not really necessary on longer focal lengths and the higher multiples such as x3 or x5 are very much for planetary imaging.

I think a x2 CAN be useful with a carefully chosen eyepiece set to avoid duplication. Eg

A 20mm and 10mm eyepiece plus x2 Barlow only gives you 20mm, 10mm and 5mm equivalent eyepieces so you may as well buy a good 5mm.

A 20mm and, say, 14 mm plus a x2 Barlow gives you 20mm, 14mm, 10mm and 7mm so does actually add to your range. You just have to consider whether a 7mm is useful in your scope ie doesn't give too high a power.

What sort of budget do you have? If you do choose a Barlow, the Baader x2.25 1.25" is very good and a reasonable cost.

[Carbon Brush]

I have gathered barlows over the years. Often part of a scope or eyepiece package.

To be honest, they rarely come out of the boxes as a magnification device.
Only sometimes to help bring a DSLR to focus.
I have preferred to spend on eyepieces.

I would be tempted to look for an eyepiece with wide AFOV to get the stunning views available from your light bucket.

Hope this helps, David.

[rockinrome]

Also agree with Richocet here. I would also add that (in my opinion) Barlow's are over-rated, especially for beginners.
I fell into the trap as I started off of thinking I could see hubble-like images when my magnification increased by 2/3 fold.
All I got was a fainter, blurrier image that dampened my spirits.

I would much rather go for a range of good quality eyepieces when budget allows that can be used over a range of scopes over the life-time (or near future!) of this hobby.
When I say "range" though I only mean (say) 3 ....

All the best.
MJ

[MiniMaster]

11 hours ago, Ricochet said:

A 3X barlow is unlikely to be of much use in such a long focal length scope. A 2x option, such as the Explore Scientific 2x Focal Extender is a good choice, but it depends what your budget is.  However, given that you only just got the telescope I would start by just using the eyepieces that came with it for a while before looking at other eyepiece options rather than a barlow. More magnification is not always better and many new users try to push beyond the limits that either their scope or atmospheric conditions allow. You're probably not going to need anything shorter than about 5mm  with that scope and for DSO viewing an eyepiece around 10-12mm is probably going to be the most useful, as well as longer focal lengths for objects that require a wider field of view and/or filtered nebulae. To give suggestions we really need to have an idea of budget and whether you need to observe wearing glasses.

You haven't mentioned collimation tools, but I would suggest investing in a good quality Cheshire/sight tube and learning how to use it. 

Thank you all for your responses. Great info here.

This is the kit I bought from someone on craigslist: https://www.highpointscientific.com/apertura-ad12-12inch-dobsonian-telescope-ad12. I have all of these tools here including the laser collimator. Also I do not wear glasses. I didn't really have an initial budget in mind, just wanted to get the feel for what the recommended ones cost. I'm the type of person that likes to try to only buy things once if I can afford to, so I don't mind shelling out some cash on something that I will keep for a while even if I have to save up (It's ultimately cheaper this way). I see what you all are saying about using eyepieces over Barlows. Another reason I was looking at getting a Barlow though is to attach my dslr to the Dob. I understand it isn't great for long exposure photographs but as a photographer i'm naturally curious with what I can achieve haha and maybe eventually I will upgrade to a refractor with a tracking system. But that is far future, I plan to use this scope for quite a long time. 

Edited September 3, 2019 by MiniMaster

[Rob Sellent]

I'm quite a fan of Barlows. I bought a simple x2 TeleVue some ten years ago and it's still in use. I wouldn't mind getting myself a x2 Powermate but just as I save the readies, along comes another expense and it gets pushed to the back of the queue again

The main use the Barlow gets is with a 24mm to 8mm zoom. Rather than picking out individual eyepieces, I insert the Barlow and simply run through the focal lengths until I find what's perfect for the night's seeing conditions. If I feel the given object warrents a better view, I'll then use that focal length from an individual eyepiece.

Again, I find a Barlow useful when out and about or traveling light. Rather than carrying a seperate case of eyepieces. I'll either just take out the zoom and Barlow or the Barlow and 2 eyepieces, a low power eyepiece and a second eyepiece about 1.5/1.4 the focal length of the low power. So if I head out with a 24mm for example, the other eyepiece will be around 15mm. That way I'll have a simple run of 24mm, 16mm/15mm , 12mm, 8mm/7.5mm.

Suffice to say, this argument is not perfect and not ideal if viewing planets, for example, but for a light and cost effective approach it's a good way to head out.

[Ruud]

Hi Minimaster,

A 2x Barlow makes a lot of sense, unless of course your eyepieces are 4, 8, 16 and 32 mm, then a 2x makes little sense.

I have 1.8, 2, 2.5 and 3x Barlows. Together they enormously expand the magnifications I can choose from. But I must say, the ones that get used the most are the 1.8 and 2x.

For your Dob: You don't want your Barlow to stick into the light path. The longest models may not be the best choice for that reason. But although they can be just as good, short Barlows need to be made to more exacting tolerances, which makes them either slightly more expensive or just a little less good. They seldom are more expensive.

A in-between-length Barlow, like the Televue 2x might be your best choice, even if it costs a little more than some others. It's a very good Barlow and it  will lasts a long, long time.

For power factors above 2x a tele-extender/powermate might be a better choice than a Barlow. Stronger Barlows, especially short ones, produce more strongly diverging light cones, which not all eyepieces can handle. Especially longer focal length eyepieces with views of 60° and wider may vignette with strong Barlows. High power tele-extenders/powermates produce near-parallel light cones and won't cause vignetting. Short Barlows, by the way,  always have more strongly diverging light cones than long ones.

The divergence of of light cones isn't always a disadvantage. While it may cause vignetting in some eyepieces, it also extends the eye relief of all eyepieces. This can be a great benefit for short eye relief eyepieces.

[Louis D]

I would get a GSO/Revelation coma corrector before I'd get a barlow.  The CC will help flatten the field as well as correct coma.  I added a 25mm M48 spacer ring to mine to achieve very good correction for eyepieces focusing within 5mm of their shoulder.  It is also useful for achieving focus with only a 10% increase in magnification.  I used it to take the following Mercury transit image with my 8" Dob:

[Louis D]

As far as getting another eyepiece, I'd get a mid-power, work-horse in the 16mm to 20mm range to achieve a good, general magnification of 75x to 100x.  There are so many choices in this space.  Because you don't need to wear eyeglasses, you can save money, weight, and bulk by buying eyepieces with shorter eye relief.

[Science562h]

I use an Apertura 12", with a 2 inch Orion Q70 26mm 70' SWA & SVBONY 34mm 72' SWA eyepiece. They are 5-Element and I use them before any barlow. 3x is too much. Personally, I would get 2 in EPs & use the focuser's full potential first. 

[joe aguiar]

there arte a lot good barlows out there

I have a Televue 2.5 barlow

meade 5000 2x barlow

meade had a 4000 triplet 140 barlow u can sometimes find them used

ES has some goos barlows

just don't get the cheap ones you norm can tell by the price point if you are looking on line

joejaguar