camera settings advice

[LouisJB]

Hi,

after trying guiding for the first time last night and getting results for longer exposures I'm now wondering how to get the best from the captures.

What ISO and exposure lengths would be a good starting point? My equip is as per my sig, imaging is K5 prime focus (through x2 barlow) on a 130P

Should I say aim for 5minute at ISO1600 or is that too much leading to overexposure.

Also, I should be capturing multiples and taking a dark frame? How many would be good for a beginner like me, say 5 shots, each of 5 mins at ISO1600 would be a start?

Should I turn off Noise reduction? Should I turn off dark frame subtraction and take my own (if possible)

I guess a lot of these questions are camera generic, but I'm using a Pentax K5 at the moment. Also white balance, what would be a good starting point?

I'm trying to shoot galaxies, say M31, M33, M82, M81 and maybe some nebula to start with.

Any advice would be much appreciated.

[Zuben Elgenubi]

I am new to imaging myself but I'll try to advise as best I can. Hopefully someone will correct me if I give you any incorrect advice!

I would think that ISO800 or 1600 should be ok but you'll probably find the best settings for your kit by trial and error. Generally the more light frames you take, the better you final image should be as it improves the signal to noise ratio (I believe). Also, as long as your tracking and guiding are good, then generally the longer you expose for you should get better results.

Not sure about the noise reduction, but I would imagine you would want it turned off. When shooting in RAW mode (or equivalent) you want to capture as much data as possible. Take your own darks and let DSS or whatever your stacking software is do the calibration of master darks and subtraction. 

Hope this helps. I'm sure someone with far more knowledge than me will be along shortly 

Gareth

[iksose7]

The above poster is correct, ISO 800-160, any higher and the noise gets bad. Turn noise reduction off and take calibration frames - flats, bias, darks.

Basically just try to gather as many images as possible. The more data you have the better the result!

[LouisJB]

That's great, thanks.

So sounds like exposure isn't necessarily that accurate, some number of minutes, maybe 5 at 800-1600 ISO should get some results. I tried a 1600ISO 4 min of M82 and it came out, so I guess it's about right. I've not tried flats, bias and darks yet.

So if I take many images I don't need to reduce the exposure to allow for stacking, they are all normal images that the software puts together and optimises?

What about white balance, leave on auto. I've not worked out how to turn of dark frame subtraction yet, apparently it's good on the K5 but it can take an age so maybe grabbing a number of shots (these are called subs?) and then 1 manual dark would definitely save time.

[PorkyB]

I am a relative newbie and like to keep things simple.

Exposure time is limited by how good your polar alignment is and how much light pollution you have to contend with.  My PA usually limits me to 120 seconds before I get trailing, but last night the light pollution limited me to 90 seconds at ISO800.

Definitely switch off automatic dark subraction and make sure you are taking raw format images (not JPEG).  Raw images can be converted to uncompressed TIFF files.

Take plenty of light frames and also plenty of darks.  I do 25 of each.  You need a set of darks for each combination of exposure time and ISO (and, in theory, temperature) but you can save time by making all your images on any particular night the same time & ISO.  If I am at a dark site then I take the darks in the car on the way home, although that means driving home without the heater on.  If I am at home then I take the darks while I am packing up my kit.  I don't do flats or bias frames.

You can see the settings I have used and the sort of results I get in my Flickr gallery (link in signature). 

[Spikey]

Any particular reason for the Barlow lens in the imaging train? Can you only achieve focus with it for example?

Introducing a barlow will greatly increase your exposure times and the results are generally rather dire.

Stick to prime focus if at all possible.