Posts Made By: Barry Simon

From what I have read, the 90 degree prisms are an "optically" cleaner pathway. They also offer an advantage when observing high in the sky.

I have not personally compared the 20x100 Miyauchi 45 degree to the 90 degree so I cannot comment on personal experience. Kevin Busarow (Oberwerk) sells both, so I would get his opinion here.

Personally I like scanning just above the top of the tree line from a dark location so the binoculars are angled at 5 degrees to maybe 20 degrees. This puts the eyepieces at an angle which is quite nice to use with the binoculars are about neck high.

Once again, check with someone who sells both. Kevin Busarow or any other vendor who does would be your best source of information.

Barry Simon

Dan,

I do understand your point which is essentially - "Get it right at the beginning" then you won't need to consider collimation. One inherent problem with the Unitron refractors with collimatable cells (spring loaded ears that are 120 degrees apart)is that the easier they are to collimate, the easier they are to come out of collimation. (However once well collimated, the image improvement can be remarkable.)

2 years ago I bought a Vixen 102 f/9.8 achro tube assembly from Astro Stuff. It was a store demo unit in excellent condition. I bought it on condition that my Cheshire collimating tool proved that it was in good collimation as the cell is essentially not adjustable. It was "spot on" perfect so I bought it.

There is a lot of new stuff on the market now that can all add to miscollimation - cheaper diagonals with mirrors or prisms not properly seated and/or tube diameters both I.D. and O.D. which are either machined too large or too small, plastic components that you mentioned, or improperly machined or threaded objective cells, plus focusers with sag in the focusing tube. All of these individually "slight" problems can add up and contribute to a telescope which collectively may be a total collimation disaster.

Barry Simon

I got back into astronomy in 1978 with the building of a 6" f/5 Jaegers refractor. I originally ordered that objective and cell for $395.00. It was on backorder and by the time mine was ready (4 months later) the price had jumped to $450.00. Applying an inflation table to that price, that objective should be about $1200 to $1300 today. The Jaegers cyber catalog lists the 6" objectives at $1750, a bit overpriced.

Mine has been a good performer. Stars are pinpoint to the edge with good definiton. Tons of color on brighter stars, but a Deep Sky Filter seems to take care of that for photography.

Roland Christen may notice one of his older style focusers which I used to replace the original focuser on my 6" Jaegers. See photo.

Barry Simon

Here is another image....