It's my first night out with my new toy, so I don't know what I'm doing. Random settings and the AVI bunged through registax using defaults. A little added contrast, but that's it
Great work . A very suitable target for your FL (2540mm). You've resolved some nice detail in the outer shell. This scope would be dynamite mounted on a large GEM or equatorial tracking platform - produce some exquisite narrowfield images with an AO unit. Looking forward to seeing more of your work.
That's about as good as it got for the night - there was a rather large shiny moon after all! It promises to be a fun toy. I'll have to get more scientific tonight.
Just out of interest, Jonathan, how does that object look to your eyes as a visual object through SDM 6?
It is one of the most impressive objects I have seen through my scope. To my eyes, the inner shell looks a turquiose colour, and the outer shell a lilac/light purple colour
The camera is much more light sensitive than the eye, so it can get more detail, but on a good night there is still plenty of detail to be seen visually, and in colour for a change.
I have become much more interested in planetaries since getting some serious light gathering ability - I'm planning to see how many I can track down.
Reflecting on this scope further (no pun intended)... it would be a prime candidate for CCD TDI methods as you don't need to guide or at least not very accurately. I suspect a dedicated astro CCD would provide you with more image depth than the g-star, but I haven't had any experience with the latter. Can help out with CCD TDI techniques if desired.
Do you know what the image circle is on the scope?
I've heard of TDI - sounds an interesting technique, and i'll look into it when I have a clue what I'm doing! I was going to have a go at autoguiding tonight to see if any degree of accuracy is possible with ServoCat.
Magnificent images. 5080mm is stoking it! Your seeing is undoubtedly good or at least your arcsec/pixel combo suits the conditions very well.
Quote:
Originally Posted by AstroJunk
How do I calculate/measure the image circle?
Image circle at the focal plane is defined by two factors. Firstly, the i.d of your focuser. If you’re using a typical 2” (50mm) focuser then obviously you’ll never get an image circle larger than this. Most astrographs have a 3” (76mm) or 4” (101mm) focuser to cater for larger format chips. Secondly, how much of the light is usable or put another way - the flatness of your light path. Commonly, coma in parabolic mirrors distort the edge of the FOV, thus the full light path can’t be utilised without some form of flattener in place. I did have a formula for calculating field flatness in an optical design, but it was based on a refractor’s objectives. As you’d expect, this also depends on chip size. It is typical, that even if you have a large 4" focuser, the image circle will not be 101mm. An example of this is the Takahashi FSQ, it uses a 4" focuser, but the image circle is 88mm.
