Posts Made By: joseph cannavo

I am building a cell for a 15" X 2" F5 mirror, currently being refigured by Steve Swayze. I had already built a 9-point flotation cell as per traditional dimensions - i.e. Kiege. My question is this: With a mirror of this size, 15x2",
is there any point to using PLOP optimization to redo my flotation system so as to accomidate what I anticipate will be an excellent mirror.
Joe

I am curious what people would list as galaxies that reveal the most spiral structure/detail in a moderate aperture dob, 12.5-16". Of course comments from users with smaller or larger scopes are welcome as well.
Joe

As a solution to the weight of my mirror box (15" Dob, 2" thick Swayze Mirror)and the problem of thermal equilibrium, I have toyed with the idea of a "latitudinal" split of my mirror box aprox 1/3 of the way up from the mirror cell. This could be accomplished with a clean cut around the preimeter, appropriate bracing of the corners, toolbox/cabinet latches - as in on a guitar case - and a pin in hole mechanism to allow fixed positioning. The advantage here would be a more secure means of transporting the primary - less weight and bulk - and the option of setting this smaller mirror box (which would contain the mirror in its cell) aside for cooling etc. I am surprised that this has not been done - or has it. Any thoughts?
Joe

I recently received a 15" from Spectrum after a re-coating. Aprox. 0.5" in from the edge is a long cicumferential line (scratch?) on the surface running aprox. 2/3 of the circumference. The line has the look of a very narrow abrasion and is aprox .03" wide. I have not star tested or field tested the mirror yet, since I am redesigning my cell. However, like a curved spider vein, I dont expect to see visible diffraction effects. Nonetheless its more scattered light, and the idea of such a surface defect really buges me...Thoughts?
Joe

As we all know Binoviewers split that most precious of comodities - extraterestial light - between both eyes. But while less light is presented to both eyes, our visual cortex does a better job of processing low contrast detail
when it comes from both eyes. In practice, however, I am curious how this plays out with very faint low contrast detail. Specifically, if someone is, say, just barely spotting the connecting bridge in M51 with direct vision in monocular mode how will they fare in biono mode? Thoughts...
Joe
15" Swayze

I aqm curious to know if an 18" Starmaster can be transported in a something the size of a Honda Accord. I do know that mirror boxes on the starmasters are bigger than say Obsessions...but I do like the idea of a removable mirror cell.
Joe

I am well aware of thr concerns about enhanced aluminum coatings - everyone from Royce to Swayze to Zambuto rails against them. However, what about Dielectric coatings on primaries? The finest diagonals utilize these as do critical low scatter laser and multiple reflection apps. Now true once applied these coatings must often be polished off. Therefore, a bothched coating job can result in a ruined mirror. But if these could be reliably applied what would be the down side. Obviously the upside is 99%+ reflectance. Thoughts?
Joe

:S
I recently came across the website for Star Instruments. I was struck by their implicit dismissal of the claims of "amateur" mirror makers. I suppose this generalization includes the likes of Carl Zambuto, Bob Royce and others. Any thoughts?
http://www.star-instruments.com/html/opticaltesting.html
Joe

I was recently trying to describe to a friend how fuzzies look under large aperture and the darkest skies. In trying to do so it occured to me that it would be interesting if there were any photographic images that approximated the visual experience with a large scope under ideal conditions. I later happened on this image of m31.
http://amateurastronomy.org/Picts/pc5.gif
Now apart from image scale (obviously impossible given the limitations imposed by exit pupil) and higher contrast, I was struck by the fact that the this photo seems to only slightly exceeds the detail I have glimpsed under the best conditions with larger scopes under truly dark skies. Thoughts, reactions? Also, is anyone aware of any other photos that provide a similar reference. Also, it would be interesting to process images that attempt to duplicate the visual expereience.
Joe

Hi all.
As a visual observer who greatly enjoys watching the incredible strides you guys are making, I ask for reactions to the following image:
http://www.buytelescopes.com/gallery/view_photo.asp?pid=7570
It seems that the theoretical resolution limit is being significantly exceeded.
As someone who knows nothing about CCD imaging, I pose what is perhaps a silly question:
Is it possible for the expectations of the imager (based on what they know about the actual details of the target) to somehow be inadvertantly "processed" into the final image.
Joe
Please note, I am in no way challenging integrity here. My question only addresses methodology.