Quote:
Originally Posted by rcheshire
Nice one Doug. Those long plumes are wonderful. Long sessions, but necessary in the burbs with a DSLR. I like the round stars too, but find that they become too bloated with aperture wide open. At f/3.2 the 200mm goes spiky, but there is more control over bloat. And, to get proper exposures with the sodium filter 5 minutes or more is necessary, preferably 6 to 7 minutes.
Maybe an O ring behind the rear lens would reduce the spikiness of the Iris. It's a thought.
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Hi Rowland - I have used the cheap step filter rings that you can pick up on ebay as lens aperture masks to stop the down the lens and avoid the spikes. They work but increase the exposure time needed...
http://www.ebay.com.au/itm/77mm-58mm...item335c2681ce
I think they would be beneficial for a f2.8 lens to minimize the star bloat - stopping down f4 and f5.6 lenses is a recipe for sloth-llke performance!
Doug
