Posts Made By: Andrew Riehl

for the record, it does NOT improve the light gathering abilitly (only added aperture can do that). The coatings cause an increase in light throughput (less light is reflected back into space). This 20% increase in throughput is also only when compared to standard Meade coatings. The UHTC and Celestron Starbright coatings (standard on all their sct's) are pretty much for the most part neck and neck. Comparing a UHTC Meade or a Starbright Celestron to a standard Meade is indeed a big difference in throughput.

Try Neatimage as well; it builds a noise profile for each specific image. cleans stuff up very nicely. VERY ram hungry though...

try this:
http://home.sprynet.com/~inbred/andys.htm

Basically in an sct with its moving mirror design, the focal length is changed slightly as the primary mirror is moved closer or farther away from the secondary. Since the focal length changes, but the aperture does not, you get a slight change in f/ratio. basically, what it means is that when the focal length is 2800mm, the f/ratio will be f/10. The other thing that changes is the spherical aberation correction--the spherical correction is setup to be best at that sweet spot right at 2800mm. Bottom line, yes, things change at different focal plane distances, but unless you are near extremes of the range, you won't notice a huge difference. Another thing that comes into play is the use of focal reducers. a 'standard' f/6.3 sct focal reducer will only give f/6.3 at a certain 'sweet spot' distance from the reducer. closer or farther to/from the reducer will give different f/ratios. We could talk about the physics involved with this telescope design forever. Basically, knowing your exact f/ratio really isn't that important; as there are a number of things that will have a greater effect on your images than a slight difference in f/ratio. If you really want a precise measure of it, best bet is to take a photo of a star field, then compare it to a star chart to determine your focal length. Personally, I think it's all really not necessary; I'd suggest instead experimenting with different exposure times to see what is the longest exposure your film, skies, and equipment will allow.

believe I've got one of those lying around somewhere...lemme check

thanks--yes, I plan on doing some really neat stuff with this camera. I have no qualms at all on working with the ISO1600 setting; it does get fairly noisy when you see it at full res, but it filters out extremely cleanly. The opportunities that open up at that speed rating are huge...I don't think any film photos can be taken at that speed with anywhere near the resolution this thing can give me (at modest formats at least). It does take about 10 minutes to run one of the full res pictures through NeatImage, but the results are well worth it...

purty...wish I could see that one where I'm at...whish I could see ANYTHING where I'm at come to think of it...

well, if you're going for function, not form, a saran quick-cover works quite well for a few cents...

I don't know their name either; we used to call them 'sweat bees' at football practice back in the day...