P_E_T_E_R
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Im gerade erschienenen S&T November-Heft gibt es einen Test Report zum Lunt 80-mm H-alpha Solar Scope (US-Preis $2,999.95).
Facit:
What we like:
- Exceptional views of the sun
- Pressure-tuning system
What we don't like:
- Standard Crayford focuser required frequent adjustment
- Pressure tuner difficult to "reset"
Bei dem "reset" handelt es sich um einen Druckausgleich durch Abschrauben und anschließendes Wiederanschrauben einer großen Druckkontrollschraube:
The manufacturer suggests unscrewing the black cylinder completely to equalize pressure in the system before tuning the scope for the first time. You need to be careful when threading the cylinder back on since it has a four-start thread that can be difficult to engage. You have to push the piston back in while turning the cylinder at the same time to get it back on. I had difficulty doing this at times, especially since I was concerned about cross threading. After using the scope for a few weeks, I found that it was occasionally necessary to equalize the system. For example, taking it to observing locations with elevations that differed by only a few hundred feet usually required equalizing the pressure-tuning system.
Na, das schreit ja geradezu nach einem trivialen Upgrade mit einem simplen Hahnverschluss ...
Interessant ist auch der folgende Abschnitt:
Sweet Spot: All H-alpha systems that I've used have a "sweet spot" in the field of view where you see the maximum amount of contrast in detailed solar features. In some scopes the sweet spot appears as a curved region, which sweeps across the field as the filter is tuned. The Lunt scope has a large sweet spot that radiates outward from the center of the field and doesn't appear to move as the filter is tuned. The only thing that makes you ware of the sweet spot is that some solar features become more pronounced when moved to the middle of the field and fade slightly when placed near the edge.
Wobei "sweet spot" wohl ein Euphemismus für Inhomogenität vom Etalon ist ...
Der standardmäßig Crawford OAZ hat anscheinend gewisse Macken und sollte besser gegen einen Feathertouch getauscht werden. Der Tester (Sean Walker) fragt sich auch über den Sinn oder Unsinn einer langen Taukappe an so einem Instrument. Immerhin kann sie eingefahren werden.
Summa summarum: The views through the LS80T H-alpha were stunning, but images taken through the scope were even better. Lunt offers a version of this scope with a larger B1800 blocking filter intended for imaging applications, but I had great success with the basic B1200 filter ... the T-thread on the outer edge of the eyepiece holder allows direct coupling of a DSLR or CCD camera. Although this is handy, the LS80T H-alpha used at prime focus with a DSLR records the Sun as a very small image only 4.9 mm across. The setup really calls for a Barlow lens or other optical amplification. The basic LS80 H-alpha is, however, ideal for imaging with the high-speed video cameras popular with today's planetary imagers. I spent many days shooting close-ups of active regions and large prominences with an Imaging Source DMK 21AU618 video camera and a variety of Barlow lenses. With a 2x Barlow, for example, I could create a superbly detailed image of the entire solar disk by overlapping nine frames captured with the camera's small chip. Overall I found the Lunt Solar Systems LS80T H-alpha a joy to use, especially given the fine adjustment that's possible with the scope's pressure tuning system. Marketed as an intermediate-level instrument, the scope performed like a top-of-the-line system.
Na, wenn das nichts ist ...
Mit freundlichen Grüßen,
Peter
Facit:
What we like:
- Exceptional views of the sun
- Pressure-tuning system
What we don't like:
- Standard Crayford focuser required frequent adjustment
- Pressure tuner difficult to "reset"
Bei dem "reset" handelt es sich um einen Druckausgleich durch Abschrauben und anschließendes Wiederanschrauben einer großen Druckkontrollschraube:
The manufacturer suggests unscrewing the black cylinder completely to equalize pressure in the system before tuning the scope for the first time. You need to be careful when threading the cylinder back on since it has a four-start thread that can be difficult to engage. You have to push the piston back in while turning the cylinder at the same time to get it back on. I had difficulty doing this at times, especially since I was concerned about cross threading. After using the scope for a few weeks, I found that it was occasionally necessary to equalize the system. For example, taking it to observing locations with elevations that differed by only a few hundred feet usually required equalizing the pressure-tuning system.
Na, das schreit ja geradezu nach einem trivialen Upgrade mit einem simplen Hahnverschluss ...
Interessant ist auch der folgende Abschnitt:
Sweet Spot: All H-alpha systems that I've used have a "sweet spot" in the field of view where you see the maximum amount of contrast in detailed solar features. In some scopes the sweet spot appears as a curved region, which sweeps across the field as the filter is tuned. The Lunt scope has a large sweet spot that radiates outward from the center of the field and doesn't appear to move as the filter is tuned. The only thing that makes you ware of the sweet spot is that some solar features become more pronounced when moved to the middle of the field and fade slightly when placed near the edge.
Wobei "sweet spot" wohl ein Euphemismus für Inhomogenität vom Etalon ist ...
Der standardmäßig Crawford OAZ hat anscheinend gewisse Macken und sollte besser gegen einen Feathertouch getauscht werden. Der Tester (Sean Walker) fragt sich auch über den Sinn oder Unsinn einer langen Taukappe an so einem Instrument. Immerhin kann sie eingefahren werden.
Summa summarum: The views through the LS80T H-alpha were stunning, but images taken through the scope were even better. Lunt offers a version of this scope with a larger B1800 blocking filter intended for imaging applications, but I had great success with the basic B1200 filter ... the T-thread on the outer edge of the eyepiece holder allows direct coupling of a DSLR or CCD camera. Although this is handy, the LS80T H-alpha used at prime focus with a DSLR records the Sun as a very small image only 4.9 mm across. The setup really calls for a Barlow lens or other optical amplification. The basic LS80 H-alpha is, however, ideal for imaging with the high-speed video cameras popular with today's planetary imagers. I spent many days shooting close-ups of active regions and large prominences with an Imaging Source DMK 21AU618 video camera and a variety of Barlow lenses. With a 2x Barlow, for example, I could create a superbly detailed image of the entire solar disk by overlapping nine frames captured with the camera's small chip. Overall I found the Lunt Solar Systems LS80T H-alpha a joy to use, especially given the fine adjustment that's possible with the scope's pressure tuning system. Marketed as an intermediate-level instrument, the scope performed like a top-of-the-line system.
Na, wenn das nichts ist ...
Mit freundlichen Grüßen,
Peter