Difference between long and short barlows?

[that_guy (Tony)]

what are the differences between a short barlow and long barlow?? Do they have any significant differences in quality??

Thanks,
Tony

[that_guy (Tony)]

while im at it can i ask if the cheap ($30 under) eyepieces are any good like the Andrews Series 500 1.25" Plossl eyepieces at andrews com?

[mental4astro (Alexander)]

From what I've been able to gather, short style barlow lenses use newer technology glass elements to allow them to be shorter. This new glass also tends to provide better quality images.

The $30 GSO barlow is of decent quality, for occasional use. I doubt good enough for photo quality.

The Andrews' plossls you mention are cheap eyepieces. As cheap as eyepieces get. I wouldn't really think they would be too good in the quality that I would be looking for. By that I mean:

*not "fully multi-coated" to minimise internal refections and optimse light transmission.
*The glass elements would not have thier edges blackened
*utilise the cheapest glass, hence reduce light transmission and struggle to provide good focus of the entire spectrum of light
*narrow field of view- objects drift through the viewing area too quickly
*poor eyerelief- you will need to park you cornea on the eye lens to view through the short focal length EPs.

These eyepieces fill a niche. That is why they are there. The GSO super plossls are a little better.

If you want to upgrade, spend some money on something a little higher than these, not necessarily big bucks. You will get more enjoyment from the scope. Unfortunately, many eyepieces can cost more than the scopes we use.

The GSO Superview range is very good for thier price. Short focal length eyepieces are notoriously difficult to use- short eyerelief. If you can't afford $100+ on a decent one of 5mm, get a barlow to use on a 10mm plossl. Otherwise you will struggle to use them, especially novices.

Mental.

[that_guy (Tony)]

Great Advice Alex! So don't get the cheap eyepieces but okay for barlows... Got it...

[orestis]

Hi Tony,

I own a 2x barlow which i bought from bintel (most likely the same as the gso)for $40 and it works great with my 10mm super plosoll from andrews but i have a 6.5 mm ep from andrews aswell and works allright but i'd go with better quality eps if you have the cash.
i want good quality eps but i'm only 14 yrs old and can not afford them so the gso ones are cheap.I'd say get the 2x barlow its good.i'm thinking of getting one of andrews wide fields as i use low power most of the time when not viewing planets.

orestis
ps-what telescope are you going to use it with?

[that_guy (Tony)]

Originally Posted by orestis

Hi Tony,

I own a 2x barlow which i bought from bintel (most likely the same as the gso)for $40 and it works great with my 10mm super plosoll from andrews but i have a 6.5 mm ep from andrews aswell and works allright but i'd go with better quality eps if you have the cash.
i want good quality eps but i'm only 14 yrs old and can not afford them so the gso ones are cheap.I'd say get the 2x barlow its good.i'm thinking of getting one of andrews wide fields as i use low power most of the time when not viewing planets.

orestis
ps-what telescope are you going to use it with?

i'm the same age as you are so, yeah same situation here... Can't afford expensive eyepieces. And I have a 8" dobsonian.

Cheers,
Tony

[mental4astro (Alexander)]

Gentlemen, if you can get your parents to take you to a local 'star party' or astro club, I'm sure the astro-nuts there would be quite helpful, share some of thier experience and maybe you may get to use an eyepiece or two in your scopes to see what to expect (you will need to ask realllllly nicely).

Your scopes are each very capable. A couple of decent EPs will help your experience, but be patient. It is worth the wait. In the mean time the EPs you have will serve you nicely to cut your teeth. What you will learn in moveing your scopes to suit the EPs you won't otherwise gain. Learn to 'see' with them and you will get even more out of what ever new EPs you get. Push them and your eyes. The detail they can reveal is still very good.

By the way, I tend to see barlows as a second best solution. For me, barlows loose light with thier extra elements and make for another thing to drop in the middle of the night. They have a place in the kit, but for special occassions and situations.

[that_guy (Tony)]

My mum already said yes to SAS and i'll never stop bugging the astro nuts (as alex puts them), with tedious but hopefully useful questions.

Best of luck,
Tony

[PeterM]

Originally Posted by that_guy

My mum already said yes to SAS and i'll never stop bugging the astro nuts (as alex puts them), with tedious but hopefully useful questions.

Best of luck,
Tony

Hi Tony,
You would be most welcome at the SAS meetings and you will gets lots of assistance from us astronuts no problems, we are very much about fostering young peoples interests.
If your mum can bring you along that would be great.
I won't be at this months meeting on the 23rd but will be there in
February so if you come along then I will catch up with you. If you go to the meeting this month then please introduce yourself to Noeleen, Kevin or Ray. Have a look at the SAS site www.sas.org.au and look at the current Event Horizon listed there (club newsletter) as it will give you lots of info as well as the new meeting place.

PeterM.

[that_guy (Tony)]

Thanks Peter, I'll see you in February. Just one more question... How will I know who's who??

[PeterM]

Many wear name tags, or just ask, it's a pretty informal friendly bunch and you won't be bugging anyone at all. Will see if we can get someone on the night to demo some barlows for you.

PeterM.

[orestis]

Originally Posted by mental4astro

Gentlemen, if you can get your parents to take you to a local 'star party' or astro club, I'm sure the astro-nuts there would be quite helpful, share some of thier experience and maybe you may get to use an eyepiece or two in your scopes to see what to expect (you will need to ask realllllly nicely).

In the mean time the EPs you have will serve you nicely to cut your teeth. What you will learn in moveing your scopes to suit the EPs you won't otherwise gain. Learn to 'see' with them and you will get even more out of what ever new EPs you get. Push them and your eyes. The detail they can reviel is still very good.

Yes, i'm going to the meeting at MAS this monday.Can't wait ,although i might feel sorry for the members as i might over-load them with too many questions.

Yes ,i have been observing with these eps for about a year now and they have shown me quite a lot.Very good advice for any beginner.

orestis

[StevenA (Steven)]

If you need to save money and buy cheaper EP's like I do may I suggest you try BINTEL's EP's. They make therir own EP's and so far I find them to be really good. They Have a few Plossl's. I bought the 6mm, 10'mm 15mm and 25mm. They also have larger focal lengths for wide feild veiwing. They come in both 2" and 1.25" versions.
While I am at it they make a few other things too. I bought their UHC and their Oii filters. Of course they have a range of colour filters too. However I do not recomend their Barlows as I have had problems with my 2" since I bought it. If you do buy their 2" Barlow it comes with an adapter so you can use your 1..25" EP's. That way you don't have to buy another when you upgrade to 2" ep's. I will slowly buy 2" ep's to replace my 1.25's as time goes by. Before you ask: No I don't work for them, but I highly recommend this place to anyone. They are friendly and know what they are talking about.. They will spend time with you when you ask a question and don't fob you off with the "I am busy, sorry" routine. Check them out on the website for a better idea of what they have and it includes the prices too. Good luck and clear skies. StevenA

[dannat (Daniel)]

just to clarify bintel don't make their own ep's but source them - probably from GS or synta..they should be similar to the andrews ones, although diff companies can order diff levels of coatings

[V-Man]

Originally Posted by StevenA

If you need to save money and buy cheaper EP's like I do may I suggest you try BINTEL's EP's. They make therir own EP's and so far I find them to be really good. prices too. Good luck and clear skies. StevenA

Cool if you are happy with "Bintel" brand EPs but lets not get carried away here. Bintel do not make EPs, or any optics for that matter. Actually all a dealer needs to do is place a sufficiently large order with a manufacturer (usually Chinese not that that is a biggie either, a lot of Chinese optics these days are pretty bloody good) to have their own brand/logo placed on that production run. Some "house branded" optics are excellent value, some very ordinary.

[V-Man]

Originally Posted by dannat

just to clarify bintel don't make their own ep's but source them - probably from GS or synta..they should be similar to the andrews ones, although diff companies can order diff levels of coatings

Yes that is correct. Things that look the same may not necessarily be the same. Its also possible to mix'n'match if a dealer has the budget for a sufficient order volume. Maybe not so much with EPs (apart from coatings) but definitely with complete scopes. Take a Lens cell from here, a focuser from there, and assembly in a third plant and hey presto, a refractor that looks the same as everyone else's but may offer better (or worse) performance than price v expectation.

Also don't fall into the idea that everything comes from either GSO or Synta. It doesn't. There are about 20 players that I am aware of (so there could be a lot more) between China and Taiwan that manufacture either complete items, or components, or assemble to order.

The winners are us, the consumers, as long as we know what to look for and give honest evaluations of any given product that we have used/tested/tried.

Any Australian dealer that claims that they are a manufacturer of "Glass" is AFAIK not trustworthy, as that would not be the truth. However I will concede the benefit of the doubt if a consumer assumes that because a product is "house branded" that that brand is the manufacturer's.

Very naive, because I am certain that when anyone buys a "home brand" product from Woolworth's they don't think that its manufactured by Woolworth's, but I guess in a small specialist market like Astronomy Supplies it is an understandable conclusion drawn by a trusting minority

[V-Man]

And back to the OP's question. Long or Short Barlow. The short or often called "Shorty" barlow is a direct result of the advent of very fast ie short focal length scopes. In a reflector of, say f/5 using a standard Plossl EP the odds are that inward focus will not be achievable with a traditional or "long" barlow. Hence the "Shorty" . Head to head, given the same glass and coatings in a mid to slow scope the long barlow will always outperform the short version. However a "Shorty" is the only guarantee of success with a fast scope, despite the fact that a cheap "Shorty" will introduce some aberrations it will permit focus to be achieved, whilst maintaining that all important factor of eye relief.

Barlows are our friends, but don't expect that any and every barlow will work with any and every EP combination especially in fast scopes. Again, best to compare notes on what does and doesn't work in given combinations