Need help with stacking this image apologies for the size

[daverave83]

[Freddie]

Not sure what help you want as I just see a single image.

[Steve Ward]

Gonna need a touch more than this provide an answer sir ...????

[daverave83]

Sorry guys

im trying to get a better image of M42 but there seems to be alot of noise, im using my lumix lz20 , iso 1600 with exposure of about 15 secs. 

its about a zoom 15x on prime focus.

is there any way to tweak it?

[Russe]

Put the pic into Gimp or Photoshop and play with the levels and curves tool to bring out faint detail.

[daverave83]

Thanks for this,

What does it mean when people talk about dark's in an image? is that a image taken with the lens cap on so that i can be used as the background i.e. 0 noise?

first of all how do you guys normally do it?

understandibly there are limitations as most DSLR's can do upto 2 min exposures where i can only get 15-30 secs.

So my current setup is

F4.5 < this varies on the zoom

ISO1600

15 Secs

Auto Lamp on < this im not sure about???

Stablisation off < this causes issues with the camera taking the pick as the stars are so faint it tries to focus on it.

quality > 16mp 4.3 ratio.

[Russe]

Get yourself the book "every photon counts" - invaluable advice and by far better at explaining how to take calibration frames (darks, flats, bias).

Darks = same exposure length & same temperature as lights but in complete darkness

Bias = shortest possible exposure in complete darkness

Flats = point camera with telescope with unchanged focus at an evenly lit surface and expose in a way that the bulk of the histogram of the exposure is about 2/3 up from the black zero point

Makes sense?

[daverave83]

Get yourself the book "every photon counts" - invaluable advice and by far better at explaining how to take calibration frames (darks, flats, bias).

Darks = same exposure length & same temperature as lights but in complete darkness

Bias = shortest possible exposure in complete darkness

Flats = point camera with telescope with unchanged focus at an evenly lit surface and expose in a way that the bulk of the histogram of the exposure is about 2/3 up from the black zero point

Makes sense?

lol no,

but im sure google can help.

my understanding if im reading it right.

Darks = Same exposure length in complete darkness and temprature as lights??? where is the complete darkness taken same temprature??

[daverave83]

Ok, I think I get it know.

Google is my friend.

Bias Frames = shortest exposure on the lowest ISO possible (the quickest shutter speed 1/8000’s) normally with the cap on. (50 bias frames)

Darks = same exposure, ISO and temperature < outside temp of when your taking images normally taken after you finished your session (is this also taken with the lens cap on ?) (20 frames)

Flats = Normally taken during the after the setting sun before stars are visable or a light box, ISO isn’t crutial but you can use the same ISO short exposures (20-30)

So people normally do the flats before the darks during the session.

[Russe]

Yes, you'd usually set up your gear, focus, frame target, guide. Now you could do Flats with a light panel sometime around this (after focus). Then you'd do your lights. At the end of the lights without changing your setup you'd do flats. Then you could disconnect everything and cover your camera to shoot bias and darks.

Most people will have a temperature based bias and darks "library" (I have for 300s and 600s exposures at ISO800 and ISO1600 at various temperatures). I btw take darks in my freezer during the day... If you'd have money you'd have a temperature controlled CCD camera...

[daverave83]

Yes, you'd usually set up your gear, focus, frame target, guide. Now you could do Flats with a light panel sometime around this (after focus). Then you'd do your lights. At the end of the lights without changing your setup you'd do flats. Then you could disconnect everything and cover your camera to shoot bias and darks.

Most people will have a temperature based bias and darks "library" (I have for 300s and 600s exposures at ISO800 and ISO1600 at various temperatures). I btw take darks in my freezer during the day... If you'd have money you'd have a temperature controlled CCD camera...

I'm going to use this as an example so highlight the area's which i have done wrong.

Target M42.

1. Setup during the day what target, 6pm take flats ISO400 about 4 secs exposure. 20 Images

2. Take Dark Flats ISO800 - 15 secs subs  - 20 Images < Lens Cap On

3. Test Target M42 with camera facing West-East due to it's wide field view. - Align goto scope ensuring that it's polar aligned to avoid field tracking to much.

4. Capture image - 50 images

5. Take Bias Frames - ISO400 1/8000 - 20 images

6. Take Darks - ISO800 - 15 sec subs - same temp - < lens cap on 20 images

7. Take Flats - ISO400 4 Sec Subs - 20 images < "Light Box"

Finish Session.

[Russe]

Target M42.

1. Setup during dusk. Balance scope and connect electronics. You could take flats at this stage with a white T-shirt draped over the scope pointed at the still relatively bright sky. flats ISOany about 1-3s exposure. 20 Images (histogram should be around 2/3 up from the black point)

2. Don't take Dark Flats

3. Polar align now with Polaris visible as it's darker. If not guiding, improve polar alignment with I.e. "Alignmaster". Slew to target, sync planetarium software on three stars (focus on the brightest one of them with your camera) which form a triangle around the target. Slew to target. Frame target. Then slew only West with your EQ mount and note when it is about to hit the mount. Set your meridian limit here if you are using EQMOD/ASCOM. Slew back to target.

3.1. start PHD and calibrate your guiding setup & start guiding (wait for it to settle)

4. Capture lights - as many as possible

4.1. Take Flats - ISOany 1-3 Sec Subs (depends on your histogram - 2/3 up from black) - 20 images < "Light Box" (iPad)

(Maybe next day)

5. Take Bias Frames - ISOany 1/8000 - 20 images

6. Take Darks - ISOsameaslights - same sec length as subs - same temp - < lens cap on 20 images

Finish Session.

[dph1nm]

Hmm - the LZ20 is a compact camera, not a DSLR. I would be very surprised if it did not automatically subtract a dark (my lumix does), in which case darks and biases are irrelevant. I think this will also be jpeg output.

Personally I think that shot is about as good as it gets with this kind of camera in that exposure time, although it may be slightly out of focus. To do better you have to stack several 15s images.

NigelM

[davew]

Dave. I was trying to imagine myself in your position and I really do think this is all way too complicated for a first try.

I've read what Nigel has said and agree that just doing a load of lights to start with may be the best bet. Set up and get as many lights as you can before your boredom threshold is breached !

Then stack and look at what you've got. Once you have some signal, then you can work on the rest,

Dave.

[daverave83]

But wouldn't

Hmm - the LZ20 is a compact camera, not a DSLR. I would be very surprised if it did not automatically subtract a dark (my lumix does), in which case darks and biases are irrelevant. I think this will also be jpeg output.

Personally I think that shot is about as good as it gets with this kind of camera in that exposure time, although it may be slightly out of focus. To do better you have to stack several 15s images.

NigelM

Wouldn't the Flats and Darks get rid of the noise? im guessing when it's stacked the darks are used as the base image which is why most images bring out the stars.

[Russe]

Flats get rid of vignetting. Darks get rid of (not quite exact) thermal noise.

Only many lights get rid of noise!

[daverave83]

Ok it's clear outside again, so i'm going for another prime focus shots. 

it seems my images are not in focus.

Polar Align, take over 30-40 shots of the M42 then darks, then flats.

Already have my bias frames. 

[daverave83]

My camera cannot get used to the exposure, the camera tries to autofocus and cant take a picture

[Russe]

Yeah well mhm ... Might be that your camera is really not up to the task...

Webcam photography for planets and the moon might be the way forward for you...

[daverave83]

Yeah,

At the beginning of the night i would be ok, then midway through a session it would throw a wobbly and wont take any exposure images even at iso100.

May be a temprature issue or dew within the focus? when i try Autofocus on jupiter it couldn't focus properly i ended up raging and finishing the session.

I'm looking at the Nikon D3100 which is DSLR

[Russe]

ISO 100 is quite dark though. I usually image at ISO800, have done at ISO400&1600...

[Russe]

If you are thinking about buying a DSLR - think: 2nd hand, body only and Canon (maybe with liveview if you can afford it). Canon has better software support for AP.