astrophotography tips


Message posted by lone wolf on February 01, 2005 at 18:15:38 PST:

See link. Most of what is discussed on this website is useful information for photographing the base.

A few comments per page:
http://www.astropix.com/HTML/I_ASTROP/I08/I0802/I0802.HTM
Regarding positive projection, the magnification is also determined by the focal length of the eyepiece. I don't have the equation handy, mostly because the website with a java app to do the calculation went off line. However, from doing a few test shots, an eyepiece around 20mm will do. The shorter the focal length, the more magnification and less light. Given the conditions, I wouldn't go less than 18mm.

http://www.astropix.com/HTML/I_ASTROP/I08/I0805/I0805.HTM
Here an F3 is shown. You should try to get the winder with the camera to avoid trying to find obsolete mercury cells. The winder takes 8 AA batteries. Nikon will refurb F3 for a flat fee to factory specs. I think the service is $150, but I haven't had this done lately.

Some types of camera screens "go black" with long focal length optics. The "D" screen won't do this.

http://www.astropix.com/HTML/I_ASTROP/I08/I0814/I0814.HTM
The DW4 magnifier is shown here, though he lost the hood that comes with it to shield the eye from stray light. Only the magnifier technique will work for terrestrial photography.

I don't focus before every shot. This seems like a waste of time provided your telescope focus doesn't drift. Refractors have a clamp on the focus rack, so other than temperature effects on the metal tube, refractors stay in focus. By the time you wait for the wind to die between shots, it might take 5 minutes a photo and you could need 12 frame to get the base. Who has time to refocus? You should attempt to focus on something that is midway on the base and towards the front. I like the control tower or the water tower, which ever is sharpest. As you pan to the sides, technically the base is further away and you would think that refocusing is needed. However, by focusing on the nearby object, you are using hyperfocal focusing. Without going into detail, this technique gives you sufficient depth of field to photograph the rest of the base.

Attached link: tips

Replies:



[ Discussion Forum Index ] [ FAQ ]