first m20

[blink138 (Pat)]

hello members the first time i have been out for a month and a half so managed a couple of sessions last night
the first:
m20 f10 iso 1600 120s (14) umodded 1000d jpeg
a bit noisy but my first crack at this one
very frustrating taking a 2min image and then waiting 2min and 10 seconds to download all the time though....... ah patience they say is a virtue
pat

[Gem (Grant)]

Wow - that is a long download! Mine is only a couple of seconds. I am sure the noise will decrease as you can get longer images and more numerous images. Good start though.

[Garbz (Chris)]

Do you have long exposure noise reduction turned on in the camera? That would account for the extra 2 minutes at the end of your exposure.

I don't believe you gain any benefit from long exposure NR when stacking images. A few dark frames at the end of your shooting session should be much better than doing long exposure NR on every image.

[blink138 (Pat)]

Originally Posted by Gem

Wow - that is a long download! Mine is only a couple of seconds. I am sure the noise will decrease as you can get longer images and more numerous images. Good start though.

thanks grant..... i thought everybodys would be that long when you only have those thin little memory cards..... i will have to look into that one
pat

[blink138 (Pat)]

Originally Posted by Garbz

Do you have long exposure noise reduction turned on in the camera? That would account for the extra 2 minutes at the end of your exposure.

I don't believe you gain any benefit from long exposure NR when stacking images. A few dark frames at the end of your shooting session should be much better than doing long exposure NR on every image.

yes garbz the internal reduction is on.... but i thought that was an "absolute"!
do you think it would make any difference to the download times... as i said previously i thought those times were just normal
pat

[vanwonky (Dave)]

Originally Posted by blink138

yes garbz the internal reduction is on.... but i thought that was an "absolute"!
do you think it would make any difference to the download times... as i said previously i thought those times were just normal
pat

Hi Pat,
Pretty sure that internal noise reduction increases the download times significantly because of the onboard processing of the image ie. - taking the dark frame as well as the image and doing the subtraction etc.
Cheers
Dave

[Gem (Grant)]

Originally Posted by blink138

thanks grant..... i thought everybodys would be that long when you only have those thin little memory cards..... i will have to look into that one
pat

I haven't imaged with a DSLR though. I use an ATIK 320E... no memory cards - only a printer style usb cable.

[blink138 (Pat)]

Originally Posted by vanwonky

Hi Pat,
Pretty sure that internal noise reduction increases the download times significantly because of the onboard processing of the image ie. - taking the dark frame as well as the image and doing the subtraction etc.
Cheers
Dave

ah thanks dave did not even consider that one and to be honest know virtually nothing of dslr
pat

[TanjaC (Tanja)]

It's definitely your in camera noise reduction, and you don't need it! As the guys said taking dark frames (and then making a master dark frame to use for future at same iso/exposure) will help with noise.
But more importantly the more subs you stack, the more the SNR (signal to noise ratio) will improve.
Have a look at this image, it's 2 pics of M20 - one with 33x60 sec subs and one with 12x60 sec. It shows more detail and less noise in the 33 stacks. will be even better if it was 50 images. (and 20 dark frames subtracted)
http://www.flickr.com/photos/astro-t...in/photostream

Also if you don't have your polar alignment perfect, your stars will show trails. I also don't have a guide scope, and that is why I keep exposures to 60sec, but then just take more of them.

It's also much easier when you can set your computer to run the whole imaging sequence. I'm on a Mac and use Nebulosity. Love it! After setup and finding the right settings, I just tell it i want - lets say 70 exposures and it does all the work for me.

Hope this helps

[blink138 (Pat)]

thanks everybody i found the NR setting in the camera and turned it off
i will try and get out again tonight....... the perth sky has been wonderful and the dew hasnt been around to curtail a promising session
pat