Barlow Questions

[Mandy D]

I've just bought this barlow,  https://www.rothervalleyoptics.co.uk/rvo-x2-ed-barlow-lens-2-with-adaptor.html which can be disassembled as shown in my photo. The parts are in order for assembly as supplied and the lens part is on the right. Does this mean that it is possible to use this in other ways than as normally assembled? e.g. can I change the middle spacer for different lengths to achieve different magnification factors, specifically lower?

[Mr Spock]

Yes, you can. I swapped my 2" Barlow tube for a StellaLyra 35mm extension and got x1.85. If you screw the end piece directly into a 2" eyepiece you'll get around x1.3.

 

[Mandy D]

16 minutes ago, Mr Spock said:

Yes, you can. I swapped my 2" Barlow tube for a StellaLyra 35mm extension and got x1.85. If you screw the end piece directly into a 2" eyepiece you'll get around x1.3.

 

Thank you! I should have mentioned in my post that this was bought primarily for photography, so the end piece appears to have M48x0.5 threads so that should screw directly into my Nikon T-mount adapter, then?

This is all starting to look rather like my Baader Hyperion modular eyepiece which is currently in France.

[Louis D]

To be universally adaptable, it needs to have M48x0.75 threads.  My GSO 2x 2" Barlow optical element has this size thread.  Yours appears to be the Chinese made version, so I can't speak directly to its threading.  The upper part of the GSO spacer tube is not M48 threaded.  It's more of an SCT thread, although I've never verified this.

[Mandy D]

3 hours ago, Louis D said:

To be universally adaptable, it needs to have M48x0.75 threads.  My GSO 2x 2" Barlow optical element has this size thread.  Yours appears to be the Chinese made version, so I can't speak directly to its threading.  The upper part of the GSO spacer tube is not M48 threaded.  It's more of an SCT thread, although I've never verified this.

Thanks. You are correct, it should be M48 x 0.75mm. That was a typo on my part. I had noticed the upper part has a larger thread but not checked what it actually was. I guess it does not really matter as I can get extension tubes with M48 at both ends.