Dark frames

[robindurant]

I have been using the "long exposure noise reduction" facility on my Canon 350d but it takes double the time to take subs. So I want to try using Dark frames instead and would welcome advice regarding how many I should take etc. If I need to take the same amount as the subs I may as well stick with the previous method.

[daz]

IDEALLY yes, you want the same number at same length at the same ISO for your darks

BUT you can be doing the darks while packing away, it doesn't need to be mounted to do them

[moondog]

Robin

As Daz says, but most imaging books I've read state that the darks should have a longer exposure than the lights.

I've tried both darks with same number and length as lights and also fewer, but longer darks. If both methods have same total exposure time, the longer darks method seems to provide the best results for me.

I also take the darks as I'm packing up - and the single bias frame (cap on set to fastest shutter speed).

MD

[cygnusx1]

I have been using the "long exposure noise reduction" facility on my Canon 350d but it takes double the time to take subs.

How do you access this function, i havent seen it on my 350D

[robindurant]

Thanks all for the info.

Kevin - Page 145 in the manual - go to Menu - go to last setting ( a Spanner Arrow and a 2) - scroll down to Custom Function Settings - select Fn-2 which is Long Exposure Reduction Noise. You can toggle this on & off. What it does is: After any long exposure ( over 30 secs on at ISO 100-800 & over 60 at ISO 1600 secs) it will go into a "BUSY" mode for the same length of time during which time it reduces the noise. It does work but as I say it doubles the time of taking subs.

[Vega]

Oh dear, i've been doing 1 equivelent dark exposure for every 5 light :shock: Oh well, you live and learn. I like the idea of doing them afterwards while packing away.

Vega

[jcm]

Oh dear, i've been doing 1 equivelent dark exposure for every 5 light :shock: Oh well, you live and learn. I like the idea of doing them afterwards while packing away.

Vega

I usually do about 6 to 10 darks. Most software will average these out to produce a master dark. Seems to work for me.

John