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Tuesday, July 10, 2012

First light AstroProfessional APO 115mm f/7

After the new AstroProfessional 115mm f/7 telescope (Serial No #1533) has arrived, Holger and me decided to make a first light during ... the day. Yes, the Sun were up there and we couldn't wait even a minute ;-). So we mounted his new telescope on a Losmandy G-11 mount and we put my Baader Astrosolar filter on it in order to observe* the Sun. Our neighbor star was very active that week, promising an exciting gazing day :-)
 Image 1: AstroProfessional 115mm f/7 APO on a Losmandy G11 (Gemini)

The AstroProfessional 115mm (f/7) is a air-spaced triplet. It is a full-metal construction, no plastic parts anywhere. The lenses had a greenish coating, the telescope tube was white and stable built. It was securily mounted with two stable tube clamps on the mount. As I observed the Sun through this scope, I remembered the exellent views I had last year with Mike's TMB 115mm, as I observed the Sun from the backyard.
 Image 2: The famous TeleVue Evebrite diagonal on its sturdy focuser

The focuser has a reduction gear. It is well built and beefy. I didn't detect any backlash, so it was already well adjusted in the factory. Let us be honest, it is not a Starlight focuser but it works fine and it does not need to be changed or tuned even for astrophotography.

Markus, a friend of mine, owns a same telescope and he is also very convinced about its capabilities and its overall quality. After inspecting Markus's scope a couple of days later, I had the impression (better said "I was quite sure") that the factory producing this telescope (AstroProfessional) has a well organized test team with competent test engineers, and a serious quality assurance department.

  Image 3: The dew shield is long enough to prevent icing at night

That's funny. The Solar filter shown above (Image 3) has been custom made for my Takahashi FS-102 telescope but it fits also on the AstroProfessional APO :-) The dewing cap of the AP has a smaller(!) diameter than Tak's one.

Image 4: The first photons hitting the telescope lenses are coming from the Sun

Visually, this scope offers sharp views across the field. Is it a TMB? No! I think, it is an AstroProfessional :-) Anyhow, I loved the views through this scope. We were using my japanese Takahashi 7.5mm and 12.5mm LE eyepieces for our observations.

 Image 5: A Baader Astrosolar foil is mandatory for Sun observations.

There is a dedicated 3 inches flattener for this beautiful scope. To be honest, I am not a fan of focal reducers, since most of them introduce chromatic aberrations, and spot sizes having unequal thickness across the field. Also vignetting could be an issue with most reducers if you are working with large camera chips. So I think the best way to work with a scope is by using its dedicated flattener at its native focal length! Hence, if you want to work with two focal lengths, I honestly recommend you to buy two scopes ;-) A short one and a long one :-)

Anyway, I've heard there is a good reducer called Ricardi reducer (click here) able to work with this scope but I don't have any experience with it. For sure the dedicated flattener (click here) gives you the tightest spot size across the field by also keeping most of the optical capabilities of the scope.

Image 6: The Sun
AstroProfessional 115mm (f/7) telescope, Canon 7D, Astrosolar foil
Property of Holger Weber, Germany

The photo above confirms my visual experience I reported above. The Umbra and Penumbra regions of the Sun spots were clearly and with high contrast visible at all magnifications up to 105x. Holger and me were gazing the Sun for many hours before we decided to end our observation session.

Conclusion: I have never observed the Sun so brilliant at this price tag.
This scope is a fun to use and highly recommended.

Thanks for reading.

Panagiotis Xipteras

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More HiRes shots: dark.astrodigital.net
Manufacturer: AstroProfessional.de

*CAUTION: Use always a special solar filter for your Sun observations. This is mandatory!

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