"RS" wrote in message
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How do I reduce the focal length on an ST80 refractor? I have seen
references to modified /reduced focal lengths for refractors on the
captions of some astrophotos. I use a reducer on my SCT. Is there a
refractor equivalent?

This _might_ work:
http://www.scopestuff.com/ss_tafp.htm

But, you will need enough inward focuser travel.