Sometime in the late 1970's John Dobson invented a type of telescope. This
was driven by necessity, in that cheap materials were relied on the build a
telescope that resembled a cannon and used large bearings of Teflon and
Formica.



I owned such a telescope, a 13.1 inch dobsonian sold by Coulter Optical back
in the 1980's. It was a beast, and was almost impossible to move. Coulter
also sold 17.5 inch and 29 inch Dobsonian models in blue livery. Their bulk
is the reason that I don't see any Dobsonian telescopes around today. There
was a brief period when there were many such telescopes being made, as
recorded in the pages of the now defunct TM magazine. They were made of
plywood or chipboard, with a tube of cardboard. This design allowed a
considerable number of amateurs to afford a larger aperture telescope.



What changed this was the publication in TM issue 17 in 1981 of Ivar Hamberg
's truss tube alt-az telescope. Despite them being called Dobsonians, they
bear as much relationship to Dobson's design as the VCR does to DVD. Almost
all modern alt-az mounted telescopes these days copy this design, which has
been considerably refined by David Kreige. These Kreigescopes are called
"Obsessions".



Ivar's article in TM#17 introduced the collapsible truss tube, allowing
disassembly and transport to dark skied from urban areas. This opened up a
whole new field of large aperture deep sky observers, a whole new trend.



Ivar's design has been further evolved to some ultra light designs to
reinforce this trend.



Yet Ivar is almost forgotten. They are not called "Hambergians". His
contribution is almost forgotten. Why? Is it that Dobson is a citizen of the
USA whilst Ivar is from Stockholm, Sweden? Is there a jingoistic bias here?
Does everyone really think that Ivar's design is really just another
Dobsonian, just because it uses an Alt-Az mounting, just like Herschel used?
I don't think so. I think Ivar needs a bit more recognition than what he is
currently given.