C90 test

Well since I have been posting picture from this spotting scope, I figure I should say something about it.

First off it is a Celestron C90.  Which I picked up from Optics Planet.  I happen to get it on sale.

http://www.opticsplanet.net/celestron-90mm-maksutov-spotting-scope-package-52268-op-90mm-spotting-scope-with-trip.html

Also from this link you will see all the pieces that come with it.  I also purchased a T-ring 2x Barlow tube and a T-ring to Nikon adaptor for my Nikon D7000.  What I learned later is that the C90 actually has a built-in T-ring and I did not have to purchase the Barlow tube.

T-ring Barlow  Nikon T-ring adaptor

So some general comments about these pictures.  I really just wanted to see what the C90 was capable of.  I was in the Berkeley marina shooting across the SF bay to the Golden Gate Bridge.  This is about 8 to 9 miles away.  It also was a hazy day which did not really clear up.  And lastly, there is a lot of vignette in the images, it became more pronounced when I enhanced the images.  (The enhancements made the picture a bit more visible, thus at this time it is a tradeoff that I can live with.)  Also all pictures except the 300mm one was taken with a tripod.  (The tripod provide with the C90 is not very sturdy, thus I used my old Bogen.)

This first picture the D7000 is attached directly to the C90.  This is a very secure connection since this makes the spotting scope seem almost like a camera lens.  This is nice because of the built-in T-ring adaptor that the C90 has.

Camera directly attached the the C90

This picture was taken with the camera attached to the Barlow tube and the Barlow tube was placed directly in-line in the C90.  The tube in this case is held into the C90 by 2 friction thumb screws.  These screws normally hold the eye-pieces in place.  In general if you are careful, this should be enough to hold things together.  You would not want to carry this around in this configuration.  This is very much a setup that you would leave on your tripod.

Camera attached to the T-ring Barlow tube

 Here I have placed the 2X lens in-line with the Barlow tube.  This was a little screw in lens at the end of the tube.  First thing that was real noticeable is the bright center.  I am pretty sure this is the center mirror of the lens.

Same as above except the 2X lens is attached to the Barlow tube

Here I just enhanced the photo with Aperture.  Now the center is very noticeable and you can also see chroma rainbows in the shot.  Simply too much magnification.  This would also explain why I could see the circular mirror patterns through the viewfinder.

This is the same shot except with my 300mm Nikon lens.  Yes a very hazy day.

This image actually came out nice.  It has that old time postcard look to it.  The vignette is desirable.

Overall the C90 is turning out to be a nice find.  Sure it is a manual focus lens.  It has no VR functions. I have to play with exposures and work on focusing.  Actually this lens may force me to because more technical in my picture taking.

Other interesting facts is that viewing through the 144X eyepiece looked about the same as the direct attached camera (if my memory serves me right), except that the eyepiece had a much wider field of view and was much brighter.  Because of this, I looked up eyepiece photograph.  This is basically mounting the camera on the back of a telescope/scope and projecting the image through the eyepiece into the camera.  This setup has the advantage that one can change magnification just by changing the eyepiece.  The major downside is the mount the camera sits on.  This looks like it could be the source of a lot of issues; but from the net, a lot of people are using it very successfully.  The type of camera is also an issue.  Most do not use a DSLR.

So enjoy and try something new.