Author Topic: Is it safe to assume there's only so much larger aperture will achieve in not so  (Read 9 times)


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Hey everyone,

So a couple days ago, I found my first ever DSO: M13. I haven't had my equipment for too long and haven't put much effort in DSOs so far, mainly due to the lack of a good finderscope/telrad (which I'm anxiously awaiting by the end of this week!), but now I'm hooked and will be looking for more!

90% of my viewing is from the backyard in a red zone, so not the best for DSOs, but I'll be extremely motivated to do the 45min drive to the nearest yellow/green zone more often.

Anyways, it was a pretty nice and rewarding feeling finding the faint M13 for the first time, and practicing averted vision, which brought up a bunch of little stars around the faint smudge of the cluster!

So that was using my Vixen 70mm refreactor and a 25mm Plossl.

I immediately thought, wow, if I can see this object with the 70mm, it will be much brighter with the 130mm reflector, so I quickly switched OTAs on the mount and finally spot M13 with the reflector....... hmm, pretty much the same faint smudge as with the 70mm...

So my question is, is it safe to assume that in a sky polluted area, larger apperture doesn't mean brighter objects that are pretty faint in the first place?
I guess the aperture difference will make a big difference in dark skies, but in a bad sky, will not help much if at all?

For what its worth, the refractor is a 70mm f/13 and the reflector a 130mm f/7, same eyepiece used on both.I'm leaving this Saturday morning for a 6 days/nights fishing trip in a "dark grey area" and the weather forecasts so far are looking very good.... I can't wait for doing some DSO observation in a real pitch black sky!!!!