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Old 24-10-2009, 04:56 PM
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Loupy31 (Peter)
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Camera & Scope

Hi, I have a modded 300D, Not sure what settings to use for deepsky work.
My scope is an Orion 120 ED what type of focal reducer and field flattener should i be using.

Peter
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Old 24-10-2009, 05:16 PM
dpastern (Dave Pastern)
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Peter - you probably will be OK as is, without a field flattener or focal reducer. Just get the necessary t adaptors to attach the camera to the focuser, so you can shoot at prime focus.

As for camera settings, depends on what you're shooting. For DSOs, bulb mode. I'd recommend:

1) turning off the cameras in noise reduction

2) No higher than ISO 800

3) a remote control so you don't have to depress the shutter button and introduce vibrations

4) mirror lockup (you camera doesn't have that option from memory I'm afraid)

5) self timer (probably 10 seconds)

What sort of mount? Are you accurately polar aligning/drift aligning? If the answer to that is yes, you should be able to get 2 min subs I reckon. The longer you can get, without star drift, the better.

I'd recommend taking darks and flats too. This is my understanding (and guys, correct me if I'm wrong in what I say):

darks - put the lens cap on the camera. Take an exposure with the same ISO/shutter speed as your lights (data shots). Take them near the end of your shooting session I reckon, cos that's when the CCD/CMOS sensor will be warmest and create the most thermal noise. The basics here are to use the darks to remove the noise that's prevalent in your lights (data) shots. Take as many as possible, at least 10, if not 20 or 30.

flats - used to correct vignetting and dust spots etc. Don't remove the camera from the scope. Don't change focus (from what you were using with your light shots). Set the camera to AV mode. Keep the same ISO as your lights. Get a White T shirt and place it over the front of the scope. Make sure it's as flat and even as possible. Get a torch, shine it down the front of the scope, thus lighting up the outside of the T shirt. Take shot whilst doing this. Again, like darks, I'd recommend taking a bunch of them.

Use deepsky stacker to load the .cr canon raw files for darks, lights and flats. DSS will combine the darks into a single master dark frame. Same with the flats.

Hope this helps.

Dave
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Old 24-10-2009, 05:20 PM
dpastern (Dave Pastern)
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One other thing, though you really probably don't need to do them, is bias frames.

Set the camera to the same ISO as used with your lights. Cover the lens with the lens cap. Set the shutter speed to the fastest shutter speed available. Take 10-20. Use DSS to combine them into a single master bias frame.

Depending on what you're shooting, if you can get 2 min subs, that's awesome. Get as many subs as possible, the more the merrier. DSS will happily combine your lights subs into a single shot, which should be equivalent in terms of total exposure time by # of subs x # duration.

Hopefully I've explained myself well. I'm still very new to all of this myself.

Dave
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