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Many years ago after I scanned and digitised all the BAA Journals from 1890 I scanned all the Circulars, The Moon, the Handbooks, Memoirs and several of Waterfield, Lenham, Peek and Elger material.
It is strange that apart from the Journals this material is not accessible to members in the same way as the Journals.
Sheridan Williams
I took over from Gordon as Director of the Computing Section. His main role was the BAA Handbook and he passed me all his software written in the oldest version of BASIC I’d seen, but it worked. I visited his place many times and he was incredibly friendly and helpful. He was still running into his early 90s and was full of beans. I’ll certainly miss him.
Sheridan Williams
I may be wrong but the latest Sky Notes by Brian Mills (Vol.125 No.3 P.184) reproduces data from the Handbook without any credit or mention whatsoever.
Surely the Handbook should be mentioned out of courtesy.
Sheridan Williams
With such vast financial resources this is something that the BAA could take on and save affiliated societies money. Rather telling that it is down to the RAS to provide this service to amateur societies!
Sheridan Williams
Please let’s end this discussion. There have been some very good postings, but I still think that the absolute beginner should experiment with simple images, and only then graduate to using calibration frames. Graham’s book is aimed at absolute beginners and should have been reviewed as such.
Sheridan Williams
Alex, I’m afraid that Graham has gone for good as a result of David’s unfair review. What of the future for the computing section? I wonder why David has not defended his review in public?
Sheridan Williams
The trouble is that as a result of David’s (over-critical in many people’s opinion) review we have lost an extremely valuable member of the Association and section webmaster. The Computing section’s future is in jeopardy as the workload has increased to a level that I’m not happy to bear without such a skilled and knowledgeable webmaster.
Sheridan Williams
If you subtract a dark frame you are ADDING more random (thermal) noise, just as much as if you add a real data frame to the stack. If you add enough frames the random noise eventually smoothes out, and this happens whether they are dark frames or data frames. But with dark frames you are adding only noise, not signal. Therefore it is better to stack as many real data frames as you can. There is no problem using 100 data frames! Mechanical shutters in DSLRs are rated at well over 100,000 operations (MTBF) and in compact cameras the “shutter” is electronic and so should have no practical limit (something else will fail first).
So the key is to use MANY exposures and appropriate stacking software. (Fixed-pattern noise and bad pixels are smoothed out by the fact that images taken on fixed tripods or unguided EQ mounts are all shifted in relation to each other, which the stacking process addresses.)
As to the idea that you cannot use bottom-of-the-range cameras, that is also wrong.
Sheridan Williams
I think we ought to go back to the subtitle, which explains what the book is about. David says “But I disliked the didactic style and felt the author had not thought-through at what audience it was aimed” both Graham and I were definite about the target audience as the subtitle says. Personally I prefer a didactic style, and obviously Graham does too, saying you dislike the didactic style is like saying you didn’t like the font or size of the book. Many people I have spoken to say they thought the review a bit nit-picking. The review will inevitably result in a loss of sales so Graham feels he will be out of pocket on his first self-publishing venture and we have lost his goodwill and membership.
Sheridan Williams
Surely the quickest way to put an absolute beginner is to say that calibration frames are essential. Once the beginner has mastered the basics, then they should be encouraged to look into ways of improving their images.
Sheridan Williams
