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NearStar 70mm Evaluation

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#1 Larry Alvarez

Larry Alvarez

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Posted 07 September 2008 - 07:36 AM

I recently aquired a NearStar 70mm scope.  As far as I know the NearStar I have was sold around the 2001-2002 time frame. You can see them in the Coronado ads for that time if you have any old Sky or Astronomy magazines.

Since I got my Calcium 70mm scope I have been actively looking for a scope with similar specs to view H-alpha through.  I've tried several Synta models but only came close with the Orion 90ST model. Still it just didn't have that view that the Calcium scope gave. I was looking through some classifieds and found someone that was looking for an offer or trade for this scope and I offered up a Televue scope for it. I traded sight unseen in hopes of getting a good scope. Based on all my other H-alpha scopes I fully expected the diagonal's ITF to be hazed over.

The scope arrived in a black aluminum case and had a design I was unaware of. The newer NearStar models resemble the 60mm MaxScope but this scope has a different diagonal and different back end to it. It also has the clamshell build into the mid section. The front lens housing is also different from the advertised models and is black instead of gold like the ones in the ads. The rear diagonal has a small thumb screw that changes the angle on the mirror and thus detunes the filter like a t-max would.

The coatings are much different on this scope. The front ERF is much darker and I believe it has more blocking coatings than the current Solar Max filters and MaxScopes. The front erf reminds me of a Baader Cool ERF. The rear diagonal does not have the same filters as the newer SolarMax or MaxScope BF. It only has one silver filter on the front of the diagonal and the mirror which appears to have special coatings on it like a dielectric mirror. I suspect that it is a hot mirror of some sort. The internal etalon is a 40mm size with central obstruction.

I must say that the view is comparable to the PST scope. With little detail on the Sun its hard to tell. All the H-alpha features are visable and I do believe the scope is around <.8 in its view. The field is incredibly even though and this was really surprising because I am used to seeing a sweet band or sweet spot but this was even across the whole field. Very pleasing to the eye. The detuner is pretty weak and probably why they went to the T-max in the later models but its pretty much dead on already with little tuning needed. One down side is its in focus travel. My homemade cameras have difficulty focusing at prime. The scope also will not work with a standard barlow and eyepiece combination. The only way to get it to work is to use the barlow head on what ever you are using to view with, camera, eyepiece, or second barlow. All that aside it delivers some pretty good <.8 images.

Clear Skyz, LA

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