first astrophoto with the 400D

[vesitata]

Finally the clouds have dispersed for a short while..so I tested the 400D on the night sky for the first time...

They have opened a window on Orion for a few minutes..so I headed for the balcony, put the settings on 30s, f/3.5, ISO 800, manual focus....oh I don't fully understand
why the focus isn't actually right if I turn it to the infinity end...could someone explain?
Had to focus on the bright town hall first..

I can barely see Sirius, the brightest star through the viewfinder...it'll be hard to focus when I won't have bright distant objects. Is there a better way to do it than taking shots until the focus is right?
Can you replace the viewfinder of a 400D with a brighter one? (if there are any 'brighter' viewfinders).

Of course it's terrible...the clouds glow pink from the city lights, done a lot of editing to eliminate most of it...the stars have drawn a trail through the long exposure... anyway...I like the frame provided by the clouds..best viewed at large size..

I know, this is not an astrophotography forum but maybe someone can answer my questions...Thanks!
Tibi

[Apophis]

i think it's a very nice picture,actually never seen an astro photo made with a 400d,u're making me courage, i barely wait for that trypod to come ,i think its a very nice exAmple of picture

[Nicole]

First, I like how the clouds frame the stars, it adds quite a bit of interest to the picture.

Originally Posted by vesitata

why the focus isn't actually right if I turn it to the infinity end...could someone explain?
Had to focus on the bright town hall first..

Lenses are actually able to focus beyond infinity. Reading says that it's because of the barrel expanding / contracting with temperatures. So your best option is to focus on something sufficiently far away, and then switch to manual focus so that the focus doesn't change when you try to take the picture.

Oh, and an extra link for some astrophotography reading for you

[vesitata]

Oh...now it's clear...couldn't have imagined why they would make a lens to focus past infinity
Can't wait to get the 1,25" adapter, put it in the place of the eyepiece of a telescope (which has equatorial mount and motor drives) at our astronomy club....yep...I'm going to start with the Orion nebula
And thanks for the link...it's great
Tibi

[jsl]

Originally Posted by Nicole

Lenses are actually able to focus beyond infinity.

Hi Nicole,

Can you elaborate a bit on WHY manufacturers make lenses that focus beyond infinity? It doesn't make sense to me because surely if you want things in the far distance to be in focus, you just set the lens to infinity?

Thanks for clarifying!
Jonathan

[ressalg]

Originally Posted by vesitata

They have opened a window on Orion for a few minutes..so I headed for the balcony, put the settings on 30s, f/3.5, ISO 800, manual focus....oh I don't fully understand
why the focus isn't actually right if I turn it to the infinity end...could someone explain?
Had to focus on the bright town hall first..

I can barely see Sirius, the brightest star through the viewfinder...it'll be hard to focus when I won't have bright distant objects. Is there a better way to do it than taking shots until the focus is right?
Can you replace the viewfinder of a 400D with a brighter one? (if there are any 'brighter' viewfinders).

Of course it's terrible...the clouds glow pink from the city lights, done a lot of editing to eliminate most of it...the stars have drawn a trail through the long exposure... anyway...I like the frame provided by the clouds..best viewed at large size..

I know, this is not an astrophotography forum but maybe someone can answer my questions...Thanks!
Tibi

I don't know that there are any brighter view finders out there. Part of the problem may have to do with your lens, too. Although they are very expensive, usually prime focus lenses are best for astrophotos like this. I've actually used my Canon 50mm f/1.8 lens with a decent amount of success. With the larger available aperture you can do shorter exposures (which would eliminate the star trails) and I've never had a problem seeing the brighter stars through the view finder.

Generally, when doing a shot like this, I just take pictures, zoom in on LCD screen to check focus then take another picture. I keep repeating this process until I've acheived focus. There are other methods but as far as I know, they all involve using a telescope as a lens. However, they might be adaptable to camera lenses, too. Try looking up Bahtinov Mask and see whether you can find one that might suit a camera lens.

[sfisher]

Originally Posted by jsl

Hi Nicole,

Can you elaborate a bit on WHY manufacturers make lenses that focus beyond infinity? It doesn't make sense to me because surely if you want things in the far distance to be in focus, you just set the lens to infinity?

Thanks for clarifying!
Jonathan

The trouble is that the lens will expand or contract as it heats up or cools down. If the lens manufacturers limited the focusing mechanism to give you infinity focus at a specific temperature, using this lens at a different temperature (not sure whether hotter or colder would cause this problem) would prevent the lens from focusing to infinity. By allowing a little bit of extra room 'beyond' infinity at 'normal' temperatures, the lens designers allow the user to focus the lens to infinity at a wider range of temperatures.