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5x barlow on sw250 flextube and phillips webcam

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Marky1973

Marky1973

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Or you could try the Revelation 5x Barlow? Only 3 element, but seems to be quite popular and half the price - Harrison Telescopes have them (and I am tempted) - I personally wouldn't risk anything like that from ebay.

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meryck

meryck

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I have had my best results (although I'm still very new to astronomy) with stacking a 2x and 3x barlow (both together cost me only about £40). So I wouldn't think x5 is fundamentally too high. But as I see it (FWIW), the advantage of getting the x2 and x3 barlows is you can mix and match them with your existing one to see what works best with your setup. You're effecively getting a 2x, 4x , 5x and 6x at once. You might not be able to combine 2.5x and 5x... x11 would be pushing it a bit! :) 

Can you share some images you've been getting with your 2.5x? I was thinking about buying one myself...

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JamesF

JamesF

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5x certainly isn't too much for the 250P when used with an SPC900 or similar.  It might be tricky to keep the target on the sensor at that kind of focal length though.

James

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JamesF

JamesF

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I have had my best results (although I'm still very new to astronomy) with stacking a 2x and 3x barlow (both together cost me only about £40). So I wouldn't think x5 is fundamentally too high. But as I see it (FWIW), the advantage of getting the x2 and x3 barlows is you can mix and match them with your existing one to see what works best with your setup. You're effecively getting a 2x, 4x , 5x and 6x at once.

This isn't necessarily quite true.  The multiplier effect you get with a barlow is only true at one specific spacing.  Closer than that and the multiplier is smaller, greater and it's more.  Stacking barlows is likely to mean the distances between optical components are smaller than the design length,  so the multiplier may well be lower.  That is, you might stack (say) a 2x and a 3x barlow and get 4.5x overall (that's just an example -- I have no idea what it would be and will vary depending on the design).

James

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JamesF

JamesF

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Thanks James. Meant to say that my 250p is on and goto. Sent from my iPhone using Tapatalk

That should make it easier then.  I know there are people using similar size GOTO dobs with 5x barlows or powermates for planetary imaging.

James

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