APPTURE FEVER

Hi All
I was looking into eye sensitive and found that a light or star has to be 2.5 approximately brighter than the reference to notice a difference this means a scope has to be
2.5 times bigger than your previous one to notice any difference that means if you start with a 60mm scope you would need a 100mm your next step up is 160mm then 250mm
I have a 100mm and was going to get a 127mm but it looks like I should be going for a 200mm to get some real change
Am I wrong ?
:S

One can certainly tell the difference between an 80mm and a 100mm scope, a 4 inch or a 5 inch, a 10 inch or a 12.5 inch.. . that's a difference of about 0.5 magnitudes. A factor of 2.5 is one magnitude, a skilled variable star observers can see 0.1 magnitudes...

A more relevant question: What is your goal, purpose, in going to a larger scope? What do you hope to see with the 127mm that you cannot see with the 100mm? What scopes are these?

Jon

The leap from a 60mm to an 80mm is HUGE! My 60mm Jason can see two distinct fuzzy belts on Jupiter. That's it! With the 80mm Vixen refractor, you can actually see the GRS on a great night without eye strain. And from an 80mm to a 100mm refractor is an astounding difference. Now you can look directly at the GRS (seeing permitting). The capabilities of planetary study, for instance, on a 100mm is big enough to allow for a lifetime of pleasure. The bulk of my Jupiter and Saturn cruises still commence with my FC-100N.

However, when you graduate to a 125-130mm refractor, you now can begin a literal "relationship" with the bulk of the Solar System. Now Jupiter, for instance, will show you festoon changes, color variances from week to week, and the definition of shadow projection from Io is clearly and unmistakably evident even to a new observer.

I think a 150mm refractor is the gold spot for observing. When I had my 6-inch Tak refractor teamed next to an AP-178, planetary images on Saturn and Mars were so close I wouldn't be able to really judge a brightness difference. I mean, at that point, the optical qualities of these refractors, combined with special eyepieces and ultra-sturdy mounts meant we should have seen who lost at over 600x. But the odds that you have ANY scope able to display a steady image night after night above 400x is highly unlikely. The darn air we breath and rely on for life is an optical barrier at the same time.

A 200mm refractor will need a gargantuan mount. And being that it will need to be a special triplet design in order to get rid of that purple and yellow ring of doom around everything bright means Bently-leather prices. I remember seeing a D&G 8" f/15 up at TMSP a few years ago. Glad I didn't have to haul it around!

All the best.