Quote:
Originally Posted by Aster
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But I go back 40 years in AMATEUR Astronomy of mirror making, instrument making and deep space photography. CCD imaging is totally new to me. Taking photos of DSO's is old hat.
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Hi Alexander
Nice to hear about your experiences and see a photo of your rig – both are quite impressive. Not too happy to hear about your blood pressure though – take it easy,
we’re a friendly bunch here all doing the same thing and trying to help each other by sharing our experiences; whether long or short; correct and sometimes not so correct; often wise but occasionally naïve!
Anyhow, I have dabbled both in 35mm film and CCD astrophotography; not as an accomplished practitioner, more as a recreational amateur, for enjoyment and at times, relaxation. The demands on my mount, skills and technique were noticeably increased when I migrated from 35mm film DSO photography to CCD DSO imaging.
I used to attach my Pentax 35mm film camera to my 200mm F9 cassegrainian. Using an off axis guider (with built in x3 Barlow), I was able to keep a guide star centred in the (small) inner square of a 9mm illuminated cross hair guiding eyepiece and achieve round stars (mostly) through making manual guiding corrections on a Vixen GPDX mount. This was done by eyeballing the guide star in the reticule and pressing the Up/Down Left/Right motor movement buttons at a guide rate of x2 sidereal to keep the star confined in the square. Generally, a 30 minute session wasn’t too demanding, but once I headed into 45 and 60 min territory, boy it was tough work!
When I replaced the 35mm film camera with a CCD camera this technique proved impossible – I just could not get un-trailed stars using this set up. I would estimate that the CCD camera was some 3 to 4 times more sensitive to guiding corrections than 35mm film. I know that a few here, such as Scott (Adler) and Paul (Mayo) have manually guided DSLR’s, but very few have the will power and stamina to do that these days, so they resort to auto guiding.
Cheers
Dennis
PS – I know you are intimately familiar with much of the above re film photography, but I have included my experiences for those readers who will never experience film astro photography, as the digital age is well and truly here.