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Two-inch Focus Extension tubes 50mm
Quality CNC machined black-anodised focus extension tubes.
Brass compression ring fittings, safety under-cut in barrel and threaded for filters.
These 2" focus extension tubes are everything you want in a simple piece of metal that extends your back-focus in a 2" focuser. They are really well built, very sturdy and have an excellent, large compression ring for tension. The price on them is fantastic as well. I bought two 50mm ones for flexibility of back-focus. They are used stacked one into the other and attached to my 2" FeatherTouch focuser on my Altair Astro 8" RC. Since eyepieces require significantly more back-focus than my imaging optical train, I bought these to avoid having to remove the focuser and attach more focuser extension rings. Both of my 50mm tubes add much-needed 100mm of back-focus to reach focus on my eyepieces without touching the focuser.
This is a superb choice for extension tube - it's solidly built, yet very lightweight. It has a good quality compression ring, is well blackened, has a smart black finish and the safety-undercut is of a compatible design. One minor niggle is the locking screw, which is quite slim and difficult to get really tight.Best of all, it's very reasonably priced.
If you use a camera with a telescope and you add a barlow lens to increase magnification then you quickly discover that it has the effect of moving the plane of focus even further back behind the telescope. I discovered how much further back by holding my camera behind the barlow and moving it backwards with live view on until I saw a focused image. Then I measured with a ruler and worked out how much extra tube I needed, taking the travel of my telescope focuser into account.Once I knew that I bought one of these extension tubes and now I use it every time I use a barlow with my camera. It's well made, sturdy and never comes undone. Can't do without it.
First Light Optics LtdUnit 7 Budlake UnitsBudlake RoadMarsh Barton Trading EstateExeter, DevonEX2 8PY
Company No. 5892293VAT No. 907 2895 01
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