You don't combine them in Photoshop. You multiple expose the same image in the camera. Paul On Oct 31, 2006, at 8:53 PM, [EMAIL PROTECTED] wrote:
> Please excuse my ignorance, but how exactly do you stack them in > Photoshop? I'm > familiar wit combining images of different exposures, but how > exactly would this > work? > > Quoting Tom C <[EMAIL PROTECTED]>: > >> It's when you combine virtually identical multiple exposures, >> "stacking" >> them to reach a final image that has a total exposure time equal to >> the sum >> of the individual exposures. >> >> It's useful in astrophotography for a number of reaons. The main one >> is >> that a bunch of short, say 6 individual 30 second exposures, can be >> combined >> The result is the accumulated photons of a 3 minute exposure. The >> neat >> thing is that tracking error (irregularities in the motor drive or >> polar >> alignment) can be virtually eliminated, because software >> automatically >> aligns/registers the individual images so they overlay each other >> perfectly. >> >> The additional benefit we're talking about here is that the sensor >> can be >> run at both a lower ISO and for a shorter exposure duration, both of >> which >> reduce noise. >> >> Tom C. >> >> >> >> >>> From: "Shel Belinkoff" <[EMAIL PROTECTED]> >>> Reply-To: Pentax-Discuss Mail List <[email protected]> >>> To: "Pentax-Discuss Mail List" <[email protected]> >>> Subject: Re: K10D aimed as D200 killer/Translation of interview >>> Date: Tue, 31 Oct 2006 15:38:30 -0800 >>> >>> What's a "stacked image?" >>> >>> Shel >>> >>> >>> >>>> [Original Message] >>>> From: Tom C >>> >>>> It also is likely possible to reduce >>>> overall noise by shooting at shorter >>>> exposure times and stacking images. >>>> The stack will stack up noise just like >>>> it does with the signal, but if each >>>> stacked image is less than half as >>>> noisy as it's double-ISO cousin, >>>> results could be favorable. >>> >>> >>> >>> -- >>> PDML Pentax-Discuss Mail List >>> [email protected] >>> http://pdml.net/mailman/listinfo/pdml_pdml.net >> >> >> >> -- >> PDML Pentax-Discuss Mail List >> [email protected] >> http://pdml.net/mailman/listinfo/pdml_pdml.net >> >> >> > > > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
