Star Trails?

[Andy M]

I've managed to borrow a pretty sturdy tripod, and would like to attempt to catch a few star trails.

I'll be honest, it won't be my first attempt - I've just tried it but the result was appallingly bad and has been instantly deleted

With my 17-40 set at 17mm I tried:

15mins (in bulb mode) @ f8 ISO 100.

Can anybody recommend better settings, or any other recommendations?

I'm thinking a larger aperture may be better, possibly a lens with a larger focal length and obviously more time (45mins+?!).

[robdickinson]

The earth turns 15 degrees every hour, and stars will rotate about a fixed point (polar) in the sky depending on where your viewing from.

I havnt tried but IMO your going to need hours, 2-3 at least, and a setting which will damp down background light in favour of brighter stars. so very small apature/ISO 100 and/or ND filter.

[speedychrissie]

i quite like the idea of trying this. i mihgt have a go this weekend

[megy]

I have had a little play with this in the past, and some stuff i found usefull.

If the tripod has a hook on the centre strutt, hang something heavy off it, will provide more sturdyness.

When you open and shut the shutter, put something over the glass at the front, this will illiminate any shake that might occur as the mirror moves, probably not noticeable, but cant be too carefull.

Avoid as much light pollution as possible, any ambient light will be magnified during the exposure due to the time.

When i did it, i was using a much smaller apperture, F20 or higher.

A handy website for help. star trails

[Andy M]

Thanks guys

Am considering using my 135mm f2. Firstly, because it has a huge hood which should eliminate most light, and secondly because I can try shooting at f2 (a few of the guides recommend f2.8).

I guess the question now is; how long will a 5D's battery last? And, am I going to do it any harm if the power shuts off while the mirror is open? (I have another battery which I could pop in to power up the camera, and manually turn it off).

[megy]

Not sure if the 5D has it, but i thought my 30D was broken when i tried it a few weeks ago, i did a 5 minute exposure, and then the camera locked up for 5 minutes, i later found it was the noise reduction that was enabled, basically it takes another exposure, same ammount of time but with no open shutter, so whatever the exposure time you want, it will double it(i think that makes sense, it did in my head).

[JonRB]

I remember doing this as a lad with a standard 50mm lens on an Olympus OM-2n film camera running ISO 100 B&W film and a fairly bog-standard tripod. Went up on the flat roof at my parents semi-rural house and just opened the shutter on bulb (with a cable release) and hoped for the best. Got some brilliant shots.

The OM-2n's off-the-film metering feature probably accounted for the exposure being correct, but I don't recall having to do anything too extreme to stop shake. Maybe the flat roof was significant?

[therossatron]

Neat idea, never heard of this before. This possible on a 400D? Didn't think these cameras has shutter speeds of that length.

[Andy M]

therossatron said:

Neat idea, never heard of this before. This possible on a 400D? Didn't think these cameras has shutter speeds of that length.

Yes, but you'll most likely need a remote release cable (same as any Canon dSLR)

[megy]

therossatron said:

Neat idea, never heard of this before. This possible on a 400D? Didn't think these cameras has shutter speeds of that length.

And use the bulb feature.