Smaller-Sized Filters with Baader UFC-System :
It may only be an adaptor but this little piece of anodised metal will let you use a range of popular astroimaging cameras with Baader Universal Filter Changer (UFC) on Celestron's RASA 8 telescope thus allowing you to swap filters quickly and easily.
Unlike the Baader UFC telescope adaptors for the 11″ RASA and RASA 36 that are mated to the corrector lens group cell face-plate and secured with the knurled retaining ring, this adaptor screws onto the male outer threads of the lens group housing itself. So you would remove the RASA 8’s retaining, the T-2 or C camera adaptor and then the clear filter, and then attach the UFC Base with its RASA 8 UFC adaptor in place. The adaptor has female M84 threads on the telescope side and uses Baader’s S70 dovetail on the UFC/camera side for secure fitment to both the RASA and the UFC Base.
This S70 UFC adaptor itself only adds a minuscule 1.4mm to the optical path, but what is the overall optical length with the rest of UFC system in place? The UFC base is 13mm thick, and with the typical types of UFC camera adaptors (T-2/M48 etc) used being 2mm, the overall optical length is 16.4mm (1.4mm+13mm+2mm). The RASA 8 without any of the camera adaptors attached has a back focus distance of 29mm, this leaves 12.6mm so with a filter in place this configuration is suitable for use with a wide range of popular imaging cameras with ~13mm backfocus.
Below shows an example set up using 2″ mounted filter slider and with a camera that uses a T-2 mount, and the new Baader RASA 8″ UFC adaptor.
By the way:
The only function, that still might be left to desire, is an easier way to reach the front adjustment hex-screws of the RASA 8. Due to the very short backfocus available, it is somewhat difficult to reach these screws and to "tweak" the star sizes in each corner of the image to absolute perfectness.
So - in order to even reach this goal (exchange filters AND effortlessly adjust the camera tilt), in February latest we will launch a separate product - only produced for the RASA 8: the FCCT (Filter Changer & Camera Tilter). This unit will feature 3D-printed filter sliders and be only able to accept filters in diameters of 31 mm / 36 mm / and 2"(47.4 mm) w/o cell mount. This is a revolution for the RASA 8 since it makes perfect adjustment of all stars in the field a joy. Already now the first imagers are using this solution as prototypes and the results are outstanding, see here: https://www.baader-planetarium.com/en/blog/rasa-8-extreme-images-michael-jaeger-with-ccd-camera-f2-highspeed-filter/
About the author
Dr. Lee Sproats has been interested in astronomy since watching Star Wars in 1977 and has appeared on the UK Sky at Night TV programme. He then went on to study Astronomy where he obtained a degree and then a PhD in the subject at University College London/Mullard Space Science Laboratory. He has worked in Australia in radio astronomy and used optical/infrared telescopes on Hawaii and La Palma and Lowell and Kitt Peak observatories in the USA. After working for the University of Surrey to promote the use of computers for teaching in UK higher education and then as an IT trainer for a stock market company, he went on to work for Greenwich Observatory Ltd where he ran their northern branch and then worked for David Hinds Ltd dealing with our and Celestron products. He is often involved in flight excursions that take passengers to observe the northern lights, has led trips to see the great USA 2017 eclipse near Hopkinsville and was lead astronomer onboard a specially chartered 737 to view the 2015 total solar eclipse at 38,000ft. Lee`s astronomical interests include Lunar observing, astrophotography, photometry and pro-am collaborations.
Since David Hinds stopped operation in December 2020, Dr. Sproats works for Baader Planetarium as our UK representative/consultant and is responsible for looking after our UK/Eire dealers, dealing with Baader Planetarium/PlaneWave/10Micron product support, writing articles and also is involved in our large telescope and observatory instrumentation projects.View all posts from