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Barlows

beanyboy1982

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ronin

ronin

Posted
Posted

Joys Optics, based in Guildford I think.

The barlow itself is normally £16:90.

So if you get in a bidding war stop at £16:90 as you can simply buy it from the website at that cost.

Joys seem reasonable, above board and supply items that are OK.

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slothead

slothead

Posted
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Looks to be about same as the skywatcher barlow, you can get these for about 10-15 pounds, they are okay for the money but way behind some of the more expensive barlows

Nightfisher, When you say "way behind" are you suggesting not as good, and if so in what regard do they suffer?  In other words what are the primary acceptance criteria for a barlow, and which do the "cheapies" lack?  Thanks

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Dave In Vermont

Dave In Vermont

Posted
Posted

what does achromatic mean ?

Achromatic infers there are two lenses in it. Two lenses are supposed to compensate for the fact that the red-shift of light comes to a focus in a longer distance, while the blue-shift of light focuses in a shorter range. So the two lenses help the focal-point merge so that you don't end up with a view that is heavily colour distorted - with objects appearing to be surrounded in blue - purple light.

Regards the Barlow offered above, I'd avoid it like the Plague. If you want a Barlow, save up and get the best available. This way you will be able to never have to buy another Barlow. You will have the best. And a Barlow should  be the best Barlow, otherwise they can be more annoying than being useful. I'd hate to think what a no-name brand Barlow would do to the view. I can guess.

The best Barlow is invisible. This is to say that it gives no indication that it's present in the optical-path of the image you see at the eyepiece. Accomplishing this means using the highest-end glass and the best coating out there. This results in an image without dimming or distortion from scattering the light coming through it. A poor Barlow can cause a view resembling looking through a piece of crumpled cellophane that has suffered smoke-damage from a house fire. The best Barlow I have seen is ( I hate plugging this brand - but I must make an exception here) TeleVue. More money - but it's likely you'd never sell it to buy something better.

Such Joy!

Dave

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nightfisher

nightfisher

Posted
Posted

Nightfisher, When you say "way behind" are you suggesting not as good, and if so in what regard do they suffer?  In other words what are the primary acceptance criteria for a barlow, and which do the "cheapies" lack?  Thanks

The "cheapies" wont give such a sharp image, you will get sharper, and better contrast with say , a £35 TAL x2 barlow, the Revelation x2.5 is a sharp barlow and only £30 ish

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ghostdance

ghostdance

Posted
Posted

Joy is a great seller - I've bought a couple of items and she offers excellent service. But in regard to Barlows, I'm with Dave-In-Vt on this one.

Buy the best you can afford, there are good ones out there ( but I *love* my Tele Vue 3×) - I wouldn't go for an unbranded one - you just don't know what you're going to get.

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mikeDnight

mikeDnight

Posted
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In early 2004 a friend brought a Skywatcher 102mm star travel F5 refractor for me to take a look at, and to see how well it performed. In typical mad astronomer fashion I decided to push this rich field achromat to its limit. Its not a planetary scope, so I thought it would be a good idea to check out its performance on one of the most challenging planetary targets, Mars. Now it is often said that there's no point in observing Mars when it's less than 10 seconds of arc in diameter, at the time of this observation Mars was 4.8 seconds of arc and getting low in the west. I placed a 3X TV Barlow into his scope along with a 7mm Nagler eyepiece giving a magnification of approximately X218. The detail visible on Mars tiny disk stunned us both. Sinus sabaeus, syrtis major and Hellas along with other more subtle details were visible without too much difficulty. This crazy experiment proved two things to me. First, the little RFT was quite a good scope, and second that the. 3X TV Barlow was a seriously good piece of kit. I'd not hesitate to give that Barlow the thumbs up! The only thing to bear in mind is that it is a long Barlow and not one of the more common dumpy versions.

3X TV Barlow is probably the best Barlow I've ever used!

You could also consider TV's Powermate options.

Mike

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Charic

Charic

Posted
Posted

........and at the other end of the scale, I had the  2.5x Revelation Astro Barlow, but found it to be just a little to powerful for my eyes/telescope or maybe both. Then a recommendation for a  2x Skywatcher deluxe was made, and I have no regrets.

I don't see anything untoward's either  when in use,  and I often unscrew the lens cell  and use it without the barrel, attached directly to my EP giving about 1.6x Power. At this level, it works well for my needs.

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Dave In Vermont

Dave In Vermont

Posted
Posted

I wasn't going to venture into mentioning the PowerMate from TeleVue, but now that someone else has opened Pandora's Box.....

I have a 2.5X 1.25" TV PowerMate. I'll just say this: It IS invisible.

Clear Skies,

Dave

PS: The listed prices on FLO, you linked Ghostdance, are lower than what they are here in the US. Wow!

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