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Achromat Spacing

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3 replies to this topic

#1
Speedy

Speedy

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  • Location: Hemel Hempstead, Hertfordshire UK
What is the best material to use for Air spacing an achromatic doublet? Would some small squares of Electricians tape do the job, or does the "gap" have to be a certain size? :D
HELIOS EVOSTAR 90 F11 FRAC

Mount (unidentified)
Eyepieces: 25mm, 10mm, 8mm, 6.5mm, 6mm
2x Barlow
Sony DSC-S650 Camera
Various bits of tape/plastic & other home made bits & bobs


#2
Merlin66

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The spacing depends on the design of the doublet...
A good starting point is a couple of folds of the aluminium cooking foil....
"Astronomical Spectroscopy-The Final Frontier" -to boldly go where few amateurs have gone before.

C11, NEQ6pro, DMK41AF04, ATik314L+, 1000D modded, SM60DS/BF15, 102mmPST, Spectra-L200 and other Spectroscope(s).
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#3
HD-AP

HD-AP

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HI
I think it depends on the gap the lens designer sets, and the optical prescription .

But i have seen electricians tape and brown parcel tape used as well as the traditional aluminium foil .

#4
Speedy

Speedy

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  • Location: Hemel Hempstead, Hertfordshire UK
thanks for the replies fellas :D
HELIOS EVOSTAR 90 F11 FRAC

Mount (unidentified)
Eyepieces: 25mm, 10mm, 8mm, 6.5mm, 6mm
2x Barlow
Sony DSC-S650 Camera
Various bits of tape/plastic & other home made bits & bobs





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