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hello new need help please

astronomer

By astronomer
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astronomer

astronomer

Posted
Posted

hi all new to site

i have been doing astronomy for about a year now,i have a

meade etx 105 orion 200mm skywatcher 80mm dsi imager

the software maximdl pro but dont understand darks flats bias

which is why i have joined this site to find things out

i have taken lots of picture but im stuck useing maxim dl

i have only done darks in meade software i have downloaded

help files for maxim but i get lost could someone give me some help

please .thanks john:confused:

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SteveP

SteveP

Posted
Posted

Hi John

Welcome to SGL

I'm not familiar with your camera so I'll try to explain the terms without reference to a particular camera. The concept of darks, flats and bias can be difficult to get your head around. But in simple terms, CCDs are very 'noisy' by which is meant there is a lot going on amplifying the signal and transferring that signal from the CCD to the PC. Darks are images taken, yes in the absolute darkness eg with the camera's shutter closed or simply the end cap on the scope to capture the noise which is generated by an exposure and which is therefore already incorported into the image. Bias frames are similar but they capture the 'standing' noise which occurs even if an exposure isn't being taken ie an exposure of zero secs. Flats are slightly different in that they look at the complete imaging train and are taken in very flat light eg through a white t-shirt or from a specially illuminated panel. They record both artefacts such as dust within the scope, filters etc and any uneven illumination of the CCD chip such as gives rise to vignetting.

The 'lights' , ie the 'raw' image is then adjusted mathematically for darks, flats and bias to create an image which has had much of the noise created by the CCD itself removed. This is usually referred to as 'calibration' or 'reduction'. This combination of darks, flats and bias frames take away noise and other crud in the imaging train from the captured image to leave a 'purer' image for subsequent processing.

This might all seem very complicated. At one level it is and will help your technique if you understand the concept. In practice, it is possible for bias frames to be ignored by selecting the darks better. However Maxim has great features in it which will do much of this automatically and describes the process very well. If you're just starting imaging, i wouldn't get fixated on these things. however, you can make a useful start by using darks and then moving on to flats when you're ready

HTH

Steve

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astronomer

astronomer

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ok thanks very much for the very warm welcome,

this seems a great site very friendly.like i said been

taking pictures for a year with the meade dsi and

doing darks which make the pic a lot better thats

why i was going to try maxim dl pro but dont understand

it to much for me to take in but ill carry on and in the end

ill get it.thanks again for the welcome and ill chat soon again

....john

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