Widefield with camera on a Tripod questions?

[carastro]

Hi,

Going on holiday soon to Majorca. Can't take my Imaging kit with me so thought it might be a good opportunity to take some widefield stuff just with the DSLR on a tripod which I have not done before.

Star trails is one aim - no tracking needed.

But

How long a sub can I get away with without tracking for doing say the Milky Way? (Or indeed can I get away with this at all?)

How does one focus a DSLR on it's own, does a Bahtinov still work?

Thanks for your help.

Carole

[Jannis]

if the moon is up, i recommend to focuse on that, it's bright enough fro AF to work. Simply focuse on it, then turn off AF, and go ahead with long exposure. usually this gives you a pretty much spot on focuse.

unfortunally i can't say how long exposure you'll need. what lens are you going to use, btw?

[Psychobilly]

I find zoomed liveview works OK check focus on a star in the corner as well as the center...

A simple Y mask will work over a whole range of FL's take short high ISO exposures and review at max mag...

If your using zoom lenses resist the temptation to zoom to max FL focus and then zoom out... focus at the FL your going to be shooting at... Wasted a a couple of nights with my L's because the focus changes as you zoom even though they claim they are parafocal across the zoom range...

Peter...

[Digz]

The amount of exposure will depend on your focal length. With a wide angle lens, say 10mm you might get away with 30s but at 200mm you may only get away with 5s. Please note that these figures are hypothetical.

The best thing I can suggest is to do a trial run with varying focal lengths before you go and note the results.

[iwatkins]

Hi Carole,

18mm on my 7D (same sensor size as your camera) I settled on 30secs max exposure before serious trailing occurs.

Have a great holiday

Cheers

Ian

[Stephen]

This was posted a while back, I find it to be pretty accurate.

ScenePlanner - Tools for camera users - Astrophotography Exposure Calculator

I'm afraid I can't remember who authored it, sorry!

[carastro]

Thanks for the tips every-one.

It's an EFS 18 - 55 on a Canon 450D.

Kh3ldar - great website, saved to favourites thanks.

Will try those focussing ideas and try it out before I go. Trouble is normally image on a laptop, so will have to get used to doing it on Live view.

Carole

[iwatkins]

In that case Carole, remember mirror lock-up. And if you don't have a cable release you can usually use the 2 second self-timer trick.

Cheers

Ian

[carastro]

remember mirror lock-up

Thanks for that, have looked it up. Have no real experience of using the camera normally except to use it on auto.

I'll give it a try before I go and if I find it too difficult to work out I'll have to take my laptop with me.

Carole

[Glen]

Grab you camera and practice with what your not comfortable with. Hands on before you go will be well worth it. 800 iso 15 sec is worth a shot at 18mm. all the best

hope you have a great time

[carastro]

Thanks Glen

Carole

[Psychobilly]

If your using the 18-55 I wouldn't bother with mirror lockup... unless you have a rubber tripod...

[carastro]

Thanks Psychobilly

Carole