Posts Made By: Walter Hamler

Any movement in RA, E or W, is due to inaccuracies in the RA drive, either motor or gears and not due to alignment. It sounds like your polar alignment is fine. Does your drive have provision for varying the drive speed? Does it have PEC?

Walt

I have one that I bought about a month or so ago. There are several problem areas.
The focuser has the "chinese glue" that must be removed and relubed. Even then there is a little backlash left but it is usable.
The rear baffle that is located in the end of the drawtube leaks light around the outer edge that SEVERLY degrades the image contrast. Once that is repaired it makes a huge improvement.
The 45* diagonal is a POS bigtime! Mine had a casting defect right down the middle of the PLASTIC prism. Throw it away and go to a quality 2" of 1.25" diagonal.
The 18mm K ep is actually quite nice, sharp and contrasty.

I have used it with a 3.8mm ep to resolve the double double, but had to add a light yellow filter to remove the slight blue haze.
However, with a 2" 30mm 82* fov ep, 2" diagonal it gives really good wide field views.
For the price it is a good deal but it will require the tweaking above to make it usable.
FWIW

Walt

My opinion only, but if the focal ratio is over f/6 you would probably not get maximum benefit from a 2" focuser and 2" ep's.
The 14 would most likely be a shorter focal ratio, ie, 5 or 4.5, and would definitely have a larger and steeper light cone, needing a 2" to prevent vignetting.
If you are planning on keeping both scopes then make them each to fit your needs. If you will get rid of the 8" and keep some parts, then investing in a 2" now to save for later may make sense.

Walt

Have you checked out meridiantelescopes.com

Walt

The only thing I would add is that removing the corrector and cleaning the inside is not a major undertaking. Just observe the orientation, carefully remove the screws, watching for any shim placement, and clean as per the Celestron instructions. No need to remove the secondary at all.
Just use common sense,a safe technique and a large clean working area.

Walt

Alex, the f/ratio's remain the same. The actual focal lengths and f/ratios don't change, just the area covered. The brightness per unit area also remains the same, it's just that in the dslr the light isn't being used beyond the sensor area. Therefore, the image brightness at the focus screen "should" be the same. However, as manufacturers moved from the older 35mm slr's to the digital slr's a lot of other design changes took place as well. Some started using penta mirrors rather than penta prisms, and the focusing screens themselves changed somewhat. All this simply means that there is probably no way to make a DIRECT comparison between a dslr and a 35mm slr as far as image brightness is concerned.
I will say that most of the dslr's I have looked through have had good to excellent screen brightness, and at least seemed comparable to the film versions of just a few years ago. I did recently compare my film slr viewfinder (Pentax ZX5n) to a Digital Rebel and a Nikon D70, each with the normal lens. My Pentax was MUCH brighter, but, it has a 50mm f/1.4 normal lens. The other two were f/3.5 at the WA setting, and closer to 4 or 4.5 at the equivalent normal fl setting. BIG difference in the quantity of light hitting the focus screen, and it was apparant. BUT, my Pentax lens is manual focus, the other two cameras were autofocus, and very fast and accurate at that! Personally, I will trade the somewhat dimmer view for the faster and more accurate focus capability any day, especially factoring in my 62 year old eyes

Walt

How are the images. Are these available in the US?

Walt

As you approach the dewpoint, another critical part is how much your equipment is radiating heat to the atmosphere, thereby reducing its actual temp below the dewpoint. That is typically what happens here in the south on low humidity nights. As long as there is a slight breeze it helps prevent the dew, but as the humidity levels rise, there is nothing that will stop it, unless you agressivly attack with dew heaters from the very beginning
Another reason to live out west in the more arrid environs.

Walt

probably somewhere between 20 and 30 arc sec.

Walt

About 4 minutes at the most. I had gone out mostly to shoot the comet and really wasn't expecting to get any of the nebulosity. Next time I will double or triple the time to see what happens
I'm almost to the point that I'm thinking hard about some type of autoguider but don't want to spend a lot

Walt