Maximum exposure time

[spaceboy]

Hi All

What would be the recommended maximum exposure time from a run of the mill DSLR, avoiding noise, amp glow and messing up the sensor etc?

Thanks

[Earl]

I have used 5 mins without any problems.

[spaceboy]

I'm asking as I was thinking of having a go at star trails. I would consider 5 minutes as a largely underwhelming as far as they go. I see full star trails in magazines and the like, so I take it these are a good few 5 minute exposures layered over each other ??? What would the cool down time be for the chip in between subs ???

[Komet]

Startrails are easy ....

Take a few test exposures so you get any foreground nicely exposed and the whole thing focused. I use 20 second exposures at about f8 at ISO800 on an unmodded 1000D. An intervalometer (available quite cheaply from a well known auction site) is pretty much essential unless you can link the camera to a laptop and allow that to control it. The intervalometer way is much neater though.

Take loads of images (in jpeg - not RAW) and stack then in Startrails which is free software from Startrails application

Took this a few nights ago .... nowhere near enough subs I know but you get the idea

[spaceboy]

Thanks Mick that's great. So just for reference 5mins would be considered a max then ?

[spaceboy]

I forgot to ask.... Is a dew shield of some sort recommended as the lens facing skyward is just asking for trouble this time of the year.

[Komet]

Thanks Mick that's great. So just for reference 5mins would be considered a max then ?

Totally unnecessary for just startrails where 20 - 30 seconds is just fine.

[Komet]

I forgot to ask.... Is a dew shield of some sort recommended as the lens facing skyward is just asking for trouble this time of the year.

Some sort of dew protection is sometimes essential yes. You can just use a hair drier onto the lens from the side every few minutes.

[astromerlin]

Hi All

What would be the recommended maximum exposure time from a run of the mill DSLR, avoiding noise, amp glow and messing up the sensor etc?

Thanks

hi, I'd like an answer too, for any imaging with a DSLR.

[Tinker1947]

If you have a motorized mount, setting it the the Southern Hemisphere should make it go the wrong way and there for give you star trails in a lot shorter time..

[Komet]

If you are doing startrails you need a static camera otherwise anything in the foreground moves. You generally want a static foreground that the stars move against.

Also you don't want to overexpose anything in the foreground which is why a short exposure is necessary.