My latest

[Peter.M]

Hi all,

I had a chance to get some photos taken tonight here is my Lagoon.

I wanted to use a program to take the exposures for me, and being that I have a Nikon I was forced to use DIY photobits. Unfortunately this means that I was limited to 30 second exposures. So this is 20 minutes of 30 second exposures at 1600 iso.

[Mark_Heli (Mark)]

Hi Peter,

Is your camera 'modded'?

I took a photo of the lagoon nebula from Sydney a few nights ago using a Canon 550d (10 x 20 seconds exposures at 3200 ISO) and the picture looks quite different - see http://www.iceinspace.com.au/forum/s...ad.php?t=81026 .

I am wondering why the 2 pictures would look so different given the exposure length is similar. I am guessing that some reasons could be:

* Different camera;
* Different camera settings;
* Different location;
* Different post-processing??
* Modded camera (my is not modded)

Thanks,
Mark

[Peter.M]

Hi Mark, my camera is not modded. I bought it primarily for taking photos around the place so I havnt really looked into it yet.

The first thing is probally the speed of our scopes. Mine is F4, and yours is F8. Dont quote me on this but I think that my scope gathers light 4 times the speed of yours.

The second is that your image is only 3:20 of exposure. My image is made from 20 minutes (40 X 30). With more exposures I think that you could pull out more when post processing.

Maby someone who knows what they are talking about can confirm this.

[alistairsam]

Hi,

focal length, number of sub-exposures (higher number of subs, higher s/n ratio), location would all make huge differences.

the F4 would gather more light than the F8, 30 sec sub on the F4 against 20sec on the F8, a lot depends on post processing as well.

I think you can use a focal reducer on the meade, not sure if that will reduce exposure time for similar results.

[keni (Ken)]

Hi Peter,
That looks very good.Stars don't look "eggy" either.
Did you stack darks and flats too ???
Sorry for all the questions just another AP newby hungry for knowledge but what do you use for post processing ???

Cheers,
Ken.

[Peter.M]

Im pretty sure this one was cropped to stop most of the eggy stars are discarded. For this one I did flats but no darks.

My camera has a built in noise reduction that takes a dark frame after each light frame, so with this on no dark frames are needed.