Best magnification Barlow lense

[PaulCroft]

Hello everyone. Firstly my name is Paul with my first post, and a big thankyou to all the very helpfull information.

I have just ordered a Skyliner 200p, and from my research believe a Barlow lense may add to my viewing pleasure, although I'm aware some of you are not fans. Anyway as a lower budget stargazer, the Tal or Skywatcher Deluxe lenses seem to fit the bill. My real question is, would the image be less sharp the higher x you go? Appologies if this has already been discussed, but I have searched and can find nothing on the matter.

[damnut]

Hi Paulcroft,

Barlow is a very useful addition to any ep case, rather than me trying to explain how it works see url below. Also spend as much as you can sensibly afford, in effect you are doubling the range that your eyepieces give you. Check out for sale boards etc.

Link is :--- How a Barlow Lens works

Best Regards

[MjrTom]

What eyepieces do you currently have? That really dictates if you should get a barlow.

In some cases it is best to buy a new eyepiece instead of barlowing what you have currently.

Barlow lenses reduce image quality of the original eyepiece so unless its a reasonably good quality barlow and EP you might not be happy with the results.

[jamespels]

Hi Paul,

I guess from your post that this is the first scope you have bought and you don't have any other bits and bobs, EPs, etc. lying around. Again assuming that you have bought from FLO or someonebody else who ships it with the same EPs, you will get a 10mm (120x) EP and a 25mm (48x).

Perceived wisdom on here is to aim for magnification increments of about 50x up to the maximum useful power of your scope (x400 on a good day for yours), giving a smallest EP FL of 3mm.

The cheapest option available to you would be a x3 barlow, effectively adding approx 8mm (150x) and 3.3mm (363x). As others have said, barlows will slightly reduce the optical quality (more bits of glass for the light to go through) so I would definitely avoid cheap ones. From what I can tell and have read, the SW EPs and similar are not necessarily the best, byt TAL barlows (and all their other optics) are definitely better than their price would suggest - FLO are out of stock but Green Witch (also very good) claim to have them in at £40 inc VAT.

Something else to consider - if you wear glasses and need to keep them on for observing (e.g. significant astigmatism), you may find the eye relief a bit short on the 10mm plossl (you will need to have your eye 8mm from the lens) and you may need to consider replacing it with a planetary or similar.

Hope this helps,

J.

[damnut]

Would slightly disagree with MjrTom:-

Assuming that the Barlow is a good one, the only disadvantage is a slight loss of light . The barlow increases the effective focal length of the objective so is more forgiving of lesser ep's. This also means that you achieve the magnification without the use of a more highly curved ep and should increase your eye relief.

Cheers

[John]

.... My real question is, would the image be less sharp the higher x you go?....

It depends on the viewing conditions, the scope and the object being observed. Up to 150x-180x magnification planets and the moon should be sharp under decent viewing conditions with an 200mm scope, assuming that it's properly cooled and in good collimation.

Over 200x and things can get mushy although the moon and binary stars often do benefit from these higher powers. 250x and above will rarely be useful.

Taking the above guidance (and thats all it is ) into account, a good quality barlow lens can be a useful way of getting the higher powers but it does depend what eyepieces you currently have to use it with.

[MjrTom]

Would slightly disagree with MjrTom:-

Assuming that the Barlow is a good one, the only disadvantage is a slight loss of light . The barlow increases the effective focal length of the objective so is more forgiving of lesser ep's. This also means that you achieve the magnification without the use of a more highly curved ep and should increase your eye relief.

Cheers

Yes also with the assumption that the starting EP is of decent quality.

the best Barlow in the world wont improve your views if the EP is poor to start with.

A bit more info on what kit you currently have would stop the guesswork

[Smeg]

Powermate?

[damnut]

Spot on, and re guesswork see thread on where this UARS is going to land +-7 hrs at the mo!!! :-)

[MjrTom]

Powermate?

regarded as one of the best teleconverters that is available which is reflected in its £150 price tag.

Also they are slightly different than a typical Barlow in the sense that they have an additional lens element which corrects the light path which in turn keeps the eye relief of the original eyepiece the same

[glowjet]

Televue 2.5x Powermate

Although a bit dated have a read of this article from the CN forum.

[Smeg]

I have a revelation 2x barlow (photo kit), I do notice the reduction in visual quality, not as crisp when using the barlow.

Is a TAL barlow much better than a Revelation optical degradation wise?

Would an ED barlow give much improvement?

Revelations are fully multi coated, skywatcher I would avoid as I have had experience with their crappy stock eyepeices lol.

[damnut]

Yes Televue are great but at £156 v cost of 200p scope. Not a true barlow but a great piece of kit. Id love an aston, have a vectra :-)!.

[jamespels]

Is a TAL barlow much better than a Revelation optical degradation wise?

Cannot comment on the Revs (though the optics in my bins are pretty good) but the TAL is very good for the price. I'm still using the one that cam with my 2M and it introduces no defects that I can pick up on.

[Capricorn]

I don't use them.

However you will never know until you buy one and use it. Powermate would be nice, but costly, may as well buy 4 planetery's and use them.

The Tal has a good reputation, so give it a go.

The scope will I suspect come with a 10mm and a 25mm.

A 2x barlow would give therefore 5mm and 12.5mm additionally. Reasonable useful, at least the 12.5mm equilalent.

The 10mm eyepieces have never had a good reputation. Best to try that EP on it's own and if OK/acceptable then try with the barlow. Image may be degraded but hopefully still acceptable.

As said until you buy one, you'll never know, and the Tal is apparently decent. If Tal made a 1.5x barlow I would suggest that instead.

[pvaz]

I do use barlows and I like them but I also spent some money on them. Using a good barlow with good/excellent EPs allows you to double the set and save a lot of money (top quality EPs cost 200++).

As you'll only have the 2 EPs from the kit and the quality of the 10mm one is not very good, I would advice you to get some more EPs instead.

If it was me, I would get 9mm and a 6mm TMB planetary (around 30 each). This will probably give you the most out of your scope.

Later on a 32mm 2" EP for widefield and something in the 16-13mm range would complete the 4 EPs set which, IMHO, are more then enough for 99% of all observing challenges you might have.

I never find barlows above 2x any useful. Basically any EP you barlow with a 2.5 or 3x will become a planetary EP when used with your telescope.

[RikM]

I do use barlows and I like them but I also spent some money on them. Using a good barlow with good/excellent EPs allows you to double the set and save a lot of money (top quality EPs cost 200++).

As you'll only have the 2 EPs from the kit and the quality of the 10mm one is not very good, I would advice you to get some more EPs instead.

If it was me, I would get 9mm and a 6mm TMB planetary (around 30 each). This will probably give you the most out of your scope.

Later on a 32mm 2" EP for widefield and something in the 16-13mm range would complete the 4 EPs set which, IMHO, are more then enough for 99% of all observing challenges you might have.

I never find barlows above 2x any useful. Basically any EP you barlow with a 2.5 or 3x will become a planetary EP when used with your telescope.

Good advice

[PaulCroft]

I can't believe I've had so many replies in such a short space of time! Thanks everybody. Jamespels, you are correct in guessing it's my first scope [from FLO], ordered and delivered in 2 days I may add, 5 stars! Standard 10 and 25 mm ep's supplied with the Skyliner.

But for now I have to steer away from that, and tell you all about my exciting day [Hope you don't mind]. Well it turned up at my work, well ahead of my expectation, so I got it home and assembled just before it got too dark, I had to skip the spotter scope bit, and just go in and wait for dark. So a couple glasses of wine later, after convincing myself I probably wouldn't really see anything much, I confronted the beast set up and waiting in the back garden. First off nothing, and a confussion of is it collimated, or whatever the word is, have I got the right ep in. Anyway to cut a long story short, I made some adjustments and the stars filled up the scope!

A mild night, the stars were out, the Skyliner has exceeded my expectations in all departments, and I have good advice to move forward! Thanks again for all your very helpfull pointers, as I really am quite a novice, but eager to learn more.

[jamespels]

Glad you enjoyed your first night - hopefully many more to follow!

+ 1 to pvaz's advice.

[PaulCroft]

Morning James, I think I will go with your Tal 3x theory, it will as you say be comfortably short of maximum potential. I saw Jupiter this morning with the 10 mm lens and despite some people saying they were not great lenses, I was able to focus on it quite well. I did try to find Mars but couldn't find it although Stellarium showed me where it was.Maybe it's too small to see with my equipment?

[Charon]

I have the Antares 1.6x. it works well for me.

[John]

I have the Antares 1.6x. it works well for me.

I have one of those too, 2" fitting and a superb piece of kit

Not easy to source though

[jamespels]

Cheers Paul, it won't be the all-singing, all-dancing with added bells and whistles that some of the other suggestions will give you but it should be a good low cost solution that will mean you can add more later.

Your kit is plenty big enough to see Mars well - it doesn't get up out of the clag (20 degrees or greater for me) until about 4am at the moment and it is still a bit far away for good observing - hold on til after Christmas as it reaches opposition (closest approach to Earth) in early March.

[swamp thing]

IMO buy the very best Barlow you can.

Eyepieces and scopes come and go but a good Barlow will be in your eyepiece case for life.

I would also go for a 2" Barlow as you cannot put a 2" eyepiece in a 1.25" Barlow but a 1.25 eyepiece will obviously go in a 2" one.

I would also like to add that a good Barlow adds nothing but power and any talk of reduced quality is nonsense.

Anyone Barlowing a budget eyepiece of dubious quality then noting that the view isn't very good shouldn't be blaming the Barlow.

Regards Steve

[pvaz]

I think I will go with your Tal 3x

With the 3x your 25mm will work as a 8.3mm and the 10mm as a 3.3mm.

3.3mm is pretty much unusable except for 2 or 3 nights a year even here in Portugal. With that mag and seeing conditions below excellent, it looks like you're observing through boiling water.

8.3mm will be useful but too close to 10mm IMHO.

Still think if you consider a cost to quality ratio, you'll be better off with some dedicated EPs. The TAL is decent, but good barlows are more expensive (Celestron Ultima, Antares 1.6x and the various Televue ones range from 70 to 200). For that price you can get a couple of EPs that will be a good improvement over the stock ones.