Dewshield:
I found a coiled tube of pre-curved, black, plastic sheet in a supermarket. Designed as a bin bag support for gardeners. It looked ideal for making an extension dewshield for the 6". Which has always suffered from objective dewing due to its ridiculously short dewshield length. The objective also projects well forward of the shoulder on which the dewshield is fitted. (by friction) Further increasing its exposure to dewing.
The plastic cut easily with scissors provided I held it flat with weights. It had a strong curling tendency. In fact it wanted to coil into a neat 4" diameter cylinder. Ideal for my purpose!
I slid the Celestron dewshield back into the middle of my new, smaller cylinder and taped the lengthways cut edges neatly on he outside with black gaffer tape. Then I removed the metal dewshield and taped the inside. I made the plastic cylinder 18" long overall. It now slides easily over the original dewshield but stays firmly in place.
I put the 6" onto the MkIV mounting and after several hours the lens was still dry. Though everything else was dripping wet with dew. So the dewshield extension is working as intended.
The inside of the plastic is a bit shiny but the dew matted it down. I intend to line the new dewshield with thin, matt black foam from a toy/model shop. I'll post some pictures of the dewshield when it is light enough for photography.
Jupiter:
Having fitted the dewshield I spent the evening trying to take better images of Jupiter. I'd take a dozen images. Then go back indoors to see if I was making progress by viewing them in Picasa3. After each photo session I would take a snap of the monitor to separate the images into groups. Otherwise they all looked so similar it was hard to see where each sequence started and finished.
The TZ7 failed to capture a single image worth keeping. My old Sony DSCP71 produced something useful with almost every exposure!
As usual, I simply held the camera up to the eyepiece and centred it by touch. I took an exposure when there was a bright blob visible on the camera screen.
The images which had potential were put through PhotoFiltre. I played endlessly with Gamma, Contrast, Dust Removal and Colour to bring out as much detail as possible. The four visible moons were captured but lost in the processing.
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None of these is particularly good but satisfying enough considering the crude methods I used. The Great Red Spot is just visible on the lower belt, left limb on my screen. I doubt it shows on the blog images. The third image shows it best. The Sony camera has captured all that I could see visually.
I tried a number of eyepieces and even the 2x Barlow and moved the Baader "Fringe Killer" filter across to each new option.
I tried all sorts of settings on the TZ7. Including spot metering and zoom but nothing helped show any belts. Though the moons were well captured as were a few background stars. The trend was always overexposure.
The evening session ended when the inside surface of the objective dewed up. The front surface was still dry. I had swung over to the rising Moon to see if the seeing was any good that low. It was then that I discovered the misted lens surface. The telescopes are parked nose down so the 6" may have collected some fluff on the back surface. I'll have to take the objective cell off and clean the glass.
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