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I noticed the red giant star Antares (the small orange spot in upper right) was right next to the crescent Moon yesterday evening so grabbed a shot of it through my 25cm telescope (1030mm, f/~4.1) with D200 attached. 1/320 @ISO 200.



Gordon

Gordon, you are observant, I just thought nice moon shot with a spec on my monitor

great shot! very nice and sharp
do you need to buy specific telescopes that cameras are able to connect to? i would love to look into getting one but know nothing about them.

NJ wrote:do you need to buy specific telescopes that cameras are able to connect to? i would love to look into getting one but know nothing about them.

All you need is a standard decent quality telescope, and a "T-Mount" ring for Nikon bodies.

NJ wrote:great shot! very nice and sharp
do you need to buy specific telescopes that cameras are able to connect to? i would love to look into getting one but know nothing about them.

thanks. My telescopes are made by me, so theres no problems fitting a camera, although its usually an astronomical CCD camera. El cheapo scopes from the supermarket/camera shops etc wont generally be much good for attaching a camera, you need to go to a telescope shop. Then you need a T-ring to attach the camera. I also put a coma corrector in betwen scope and camera to reduce the coma at f/4.

Gordon

Gordon wrote:My telescopes are made by me, so theres no problems fitting a camera

Really

That's impressive. Where did you learn that?

thanks very much guys

yes really been doing it since I was in high school! I taught myself how to do it, helped along by reading a few books about what others had done. I've built a few dozen of them over the years, including grinding and polishing many mirrors. Its been about 8 years since I finished my 45cm Newtonian, and I havent done any others since then, although I have all the parts here for my 20cm f/9 planetary scope, its just a matter of putting everything together some time.

Gordon

Fabulous! The photograph is fantastic. Well done!

Yes! Fantastic!!!

and you grind and polish mirrors! wow! Nice picture!!

Where do you get the optical glass lens elements to makeup the optical formula? Do you make them as well?

i was at my physics teachers place today, had a look at his $20,000 imported NEAME tracking telescope, aparently the same design as the huble. Its crazy! we (the class) were going to set it up but it was very overcast so wasnt much point so we will later in the year, is going to be fun! sorry to distract from your thread.

Yi-P wrote:Where do you get the optical glass lens elements to makeup the optical formula? Do you make them as well?

Mirrors dont have to be made of optical glass since the light does not pass through them, they have to be is stress-free (something we should all aim for ) and not have large bubbles that will be at the surface when the mirror is at its final shape. Mine are Pyrex type glass, which has a much lower expansion coefficient than plate glass, but plate glass also makes perfectly good mirrors, as will many other glasses and ceramics. These days relatively cheap Chinese mirrors are imported into Australia, so its easier to buy one than make it yourself. I have heard the optical quality is somewhat variable though.
There are no other optical elements in a Newtonian telescope other than the primary parabolic mirror and a flat diagonal secondary mirror - no lenses at all. The primary mirror has to be figured into a paraboloidal shape, and there are optical tests that are easy to do to determine how close you are to this shape. The aim is to make the mirrors accurate to within 1/8 of a wavelength of light so that they produce diffraction limited images.

Gordon

NJ wrote:i was at my physics teachers place today, had a look at his $20,000 imported NEAME tracking telescope, aparently the same design as the huble.

I suspect you mean 'Meade' telescope? They have started producing a line with Ritchey-Chrétien optics, an optical design similar to the Hubble Space Telescope, but hopefully they dont have the built in error of the HST
R-C optics are used for their relatively wide coma- free field of view in an f/8 system, its much better than the f/10 or 11 Schmidt-Cassegrain optics typically used in many telescopes made by Meade and Celestron. Meade are using a corrector plate on these scopes too, something the HST does not have.

Gordon

Great Picture..

Great image and interesting subject

Gordon, I've just been reading the October edition of Australian Photography and in page 17 the have an article about the David Malin Awards. I suspect you probably know about this, but just in case visit http://www.parkes.atnf.csiro.au/events/astrofest

Yes Zafra52, I do They wanted me to enter in it last year, but I didnt have enough time to put anything together. btw, any chance you can start using dslrusers.com instead of d70users. com?
The links to the forum in messages generated by your posts produce a page full of errors.

thanks, Gordon

Sorry, Gordon. I wasn't aware I was causing errors. I normally access the website either using an old link in my Favorites or clicking the answer address in the emails to answer postings. I have now corrected the link and logged out and in and hopefully there are no errors. Thanks for your advice.

no worries, the links work well now

Gordon