A couple months ago, I got around to testing some diopter flippers I borrowed from my optometrist. I was really REALLY impressed with the clarity they gave my naked-eye observing. I had the results of my test quickly digested into a set of stargazing glasses. I ended up requesting an adjustment of -0.75 diopter to my otherwise pretty wimpy prescription. The glasses arrived in time for the Messier Marathon, and they turned out to be an excellent asset. Sighting down the tube is much simpler when you easily see all the fainter stars you need to begin your star-hop. Blurriness and flaring around stars is greatly reduced. I estimate that the flaring on bright stars drops by about 80% with the glasses on. And I'm seeing at least 1 magnitude fainter than before. The difference I see when I put the glasses on is just amazing. I have pretty good unaided vision, but it's like a piece of wax paper has been pulled off my eyes. Dark sky observing goes from pleasant to rapturous--I'm serious. And they even help under less than ideal conditions. I used them down in Phoenix and was able to see more under light polluted skies as well.
I just added a report about an Ursa Minor naked eye sketch I made on April 20th that shows how faint I was able to go in that constellation. I made it to 6.8 magnitude, and I think I could go a bit deeper. A fine mist of cirrus had dimmed things down by the time I had gotten that far, so it's hard to say. I'll be trying again before too long. I'm very curious to see if I can break 7th magnitude.
Anyway, if you think your naked eye night vision could stand some improvement, I highly recommend giving this a shot. See if you can find an optometrist that's willing to let you borrow some flippers and test them out. See what strength gives you the most improvement without overcorrecting. You can also purchase Night Myopia Diagnostic Flippers from Optego for $20 for a -.25/-.50 set and $20 for a -.75/-1.00 set. There is a nicely written article by Josh Roth, "Spectacles for Spectacular Skies" that covers this subject in great detail in the September 2005 issue of Sky and Telescope. [edit: OCT 20, 2009 - Tony Flanders has now made this article available for free at the Sky and Telescope website:
(By the way, I don't get kickbacks from Optego or Sky and Telescope for writing about this :)
Happy stargazing!
