Barlow Lens Question

[Polstar_UK]

Hi All,

I got my first telescope this week and had a good night looking at Jupiter, Venus, Saturn and of course the Moon. As part of the pack I got a 2x Barlow lens, now I understand that this will double the magnification of the eye pieces that I have (15mm & 6mm pieces). I used the Barlow and got some pretty good results but am I better to have the actual magnification rather than use a Barlow?

For example would a 20mm + 2x Barlow be the same as a 10mm eye piece in terms of quality?

Thanks for your help.

[Alfian]

A quick appropriate search on the forum should give you all you need to know about barlows. Briefly though a barlow lens, using a bit of optical trickery will in the case of a 2x effectively double the focal length of the scope, hence it doubles the magnification of the eyepiece in use. However, in terms of "results" much hinges on the quality of the eyepieces and barlow. Most eyepieces that are packaged with a scope, tend to be of a somewhat basic quality, so in terms of getting better quality views, which is ultimately what I think we all want, an upgrade to better EPs (and barlow?) will probably show noticeable improvements. It would be useful to know what equipment you have.

[Polstar_UK]

Hi,

Thanks for the reply.

I have the Orion Starblast 4.5 EQ reflector.

15mm and 6mm Expanse Widefield 66 1.25" eye pieces.

The Barlow is the Orion Shorty 2x Barlow 1.25".

Thanks

[Alfian]

The Expanses and the Orion Shorty are better bits of kit than what often is shipped with a scope (review here: http://www.cloudynights.com/page/articles/cat/user-reviews/eyepieces/orion-eyepieces/orion-expanse-eyepieces-a-consumerist-comparative-consideration-of-orions-taiwanese-expanse-wide-field-eyepieces-in-20mm-15mm-9mm-and-6mm-r255).

The 6mm barlowed to effectively give you a "3mm" on the 450mm scope yields 150x magnification. This in turn gives a 0.76mm exit pupil which is getting close to what is a useful maximum, although admittedly on a bright object like the moon you can push it a bit!  At the other end of things the 15mm/66 is giving you 30 x and 2.2 degrees which again is useful.

The Starblast at F4 is a fast scope and will give eyepieces (especially wide fov ones) something of a hard time compared to a slower F8-F10 scope. To get better views inevitably means spending more money on more better quality better designed "glass" and only you can decide at this point whether you want to do that. My view for what its worth is that it might be useful to explore the capabilities of your existing set up for a while before launching out.

As to barlow or not to barlow,people seem to have differing views and preferences. Regarding the 20mm and barlow question, it would be easy to say it depends on the quality of the EP and  barlow. There is the argument that a barlow adds more elements to the optical system which intuitively seems like maybe  not such a good thing, and I've been guilty of that assumption, but a good barlow should not noticeably create such issues. A good barlow can be useful in expanding your EPs capabilities for less money than buying the equivalent number of EPs. That said I started out thinking that my barlow was the best thing since sliced bread (well nearly) but with time I find I use it less and feel myself moving more towards the individual EP camp. Its hard to imagine being without one in the kit though.

[Polstar_UK]

Thank you for that, much appreciated.

At this time I'm sticking with my current kit, only arrived this week. Tonight I've had some good views of Jupiter (saw the cloud bands), Venus at half phase (think thats the correct term) and Saturns rings with the 6mm and x2 Barlow. :-)

I've also bought a 9mm Expanse EP which gives me 50x, this compliments the others and works well with the Barlow.

[ghostdance]

With my 4.5" Starblast, I found the TeleVue 3× Barlow really helpful in getting up close and personal. But the TV Barlows come at a price. The Orion Shorty Plus is good, and comes up from time to time in the used sites like Astro Buy and Sell.

As Alfian says, a Barlow is a good bit of kit to have in the arsenal...

[Alfian]

Sounds like you are doing just great. Enjoy your new hobby and a big welcome to the forum by the way.