Coronado SM90 Filter Shakedown
During the great Meade factory outlet sale on Coronado hydrogen alpha filters in Feb 2011, I decided to purchase 2 Coronado Solarmax 90 filters to double stack on the TSA102. One with a BF30, and the other with a BF10. They soon arrived at the doorstep after a short trip from San Ysidro in nice storage cases. An adaptor plate is needed to mount the filters on a scope, and these plates are not stocked by dealers. I have special ordered one from Preciseparts.com. An additional special adaptor will be needed to mate the etalons for double stacking, and these are also available from preciseparts.com. A temporary adaptor plate to set one etalon on the scope was put together with household items and some creative thinking, but first light for the double stack must wait for the manufactured 90 to 90 adaptor (please remember double stack 90mm filters mounted on the front end of a telescope will add quite a bit of weight to the objective, so quality of adaptors is very important). A problem was discovered after the telescope set up process began. The barrel of the BF30 would not fit in the2-inch tak eyepiece holder. It seems the barrel of the BF30 is a fraction of an inch too big. Others have reported the same problem with certain telescope eyepiece adaptors. First light was accomplished by using the BF10 that came with the second etalon. Focus was easy, and when the tuning wheel on the etalon was turned, chromospheric details sprang into view. After setting the tuning wheel, the etalon was rotated (by rotating the dew shield) to ensure the filter was on band, and the wheel readjusted. The view was absolutely stunning. Rich detail was visible in AR1164, and solar prominences and spicules appeared sharp and detailed. The large 90mm aperture allowed crisp high magnification views fibrils, rosettes, plage, filaments, etc. The Solarmax 90 specs at 0.7 ang., and that’s slightly narrower than the Lunt filters which spec at 0.75 ang. I could see a difference, and the increase of 15cm aperture really enhanced the image (compared to the Lunt 75mm). The view was exciting but seeing was bad. I obtained several images with a 2.5x Televue Powermate, and made a few movies. Results were very promising, but poor seeing affected the image sharpness ( I was so impressed with the performance of the filter that I didn’t bother to notice the poor seeing). Seeing had improved for the second round with the new filters a few days later. Once again, the view was stunning, and it was tuff to stop looking and start imaging. I had never before seen the chromospheres in such vivid clarity. I was infatuated with the high mag view of AR1164 with the 2.5x TV Powermate. It showed a lot of interesting details in the umbra and penumbra, and the fibrils and rosettes were awesome. On Day 3 with the new seeing was excellent. The views were incredible, with exquisite solar details visible in amazing clarity. For the movie below, I used the regular configuration of a Cemax Barlow screwed into a custom Lumicon nosepiece of the DMK21AU04. Backing off the focal length really helped the image quality. The AR had rotated closer to the center of the disc. Small bright flashes are visible, along with jumping fibrils, and the active region filament exhibits a lot of flow along its axis. Just click on the image to launch the giff animation. its best to right click and “save target as,” and save to your desktop.
The details in the above movie show the resolution and detail delivered by the SM90. Its awesome for sure. The diameter of eyepiece adaptor for the Tak will need to be increased to use the BF30. Other than that, the single etalon has really made a difference in imaging and viewing the sun in H alpha. Below are 2 movies made with the2.5x Powermate. both are close ups of AR1164, and were made under less than average conditions
The movie below was also made with the solarmax 90 filter. it was captured at 30 second intervals. i was hoping for a smooth movie, and i guess it worked.
