by Ron Bhanukitsiri
Have you ever look at the beautiful pictures or CCD image taken of the moon and marvel at such details? One example is the superb images by Legault
http://perso.club-internet.fr/legault/lunar.html
taken by a 12-inch SCT.
So tonight, my 4" TV-102 Light Cup beckons me to print out a photo quality image of the Crater Gassendi. Out we went to watch the 11-day old gibbous moon. Let me say that I'm a real tyro when it comes to watching the moon; heck, I'm still waiting for the latest version of the Rukl to come out and don't even have a detail moon map yet :-(!
I'll be frank with you. Knowing the extremely detail, high resolution image by Legault, I didn't have much expectation from my TV-102 tonight. Surprise! I could see every features in the crater, all of the rilles, all of the craterlets on the floors, all of the mountain ridges in and around the crater, various tiny hills, etc. All of the these features could be seen with the 6mm TV Radian (146x), 5mm Radian (176x), 4mm Radian (220x) 3mm Radian (293x) and 5mm Tak LE + 2X Ultima Barlow (352x). The best view was at 176x and 220x, crisp and sharp during moment of steadiness, sharper and brighter than the CCD image and much more 3-D.. Seeing was only OK with wavering, but with many moments of steadiness. At 293x, the image scale is nearly identical to the CCD image printed at 65% reduction and is still sharp enough. 352x softened noticeably.
Alas, there was one craterlet on top of a "hill" to the right just below the large crater that occupies the rim of Gassendi. It was nowhere to be seen! I tried all of the above magnification for about 30 minutes to no avail. Note that this craterlet is smaller than all of the craterlets on the floor. Then, I noticed that the angle of the shadow is different from those in the picture. I realized then that the picture was taken after the new moon. Ah, I must make sure to reschedule the Light Cup for a rematch after the new moon ;-).
There is a wealth of beautiful lunar pictures and CCD images on the web. Try it with your telescope and see how close you can come to see the same detail as the CCD saw ;-).
Now, please don't get the wrong message. The 4" cannot hope to resolve small features like the 12" could. But the 4" TV-102 Light Cup continues to catch me by surprise and continues to excel up to the extreme limit of its aperture!