Tips for first proper imaging session ?

[SAW]

Just got myself a Polemaster ?
I have lots of little questions now I've had some practice setting up and using my mount/Scope,

If I use backyard eos with a bahtinov to get my focus correct what sort of settings do I need exposure etc ? 

Or can I just use live view on my camera ?

How much do I need to adjust the focus while adjusting ?

Can I choose any star Vega for example ?

How many images should I try and get for my first DSO and roughly what sort of settings, exposure etc using a 600d modded. 

How many lights and darks should I get ?

Between each shot do I need to do anything, adjust anything or just give the camera time to cool down, how long ?

Thinks that's it ?

[PeterCPC]

Wow, a lot of questions.

For focus, choose a bright star, so Vega should work ok.

I use BYE and I suggest starting with ISO800. On a DSO try 300 secs to start and see what your histogram display looks like. You should aim to get it at least 1/3 of the way across but not more than 1/2 way I would suggest. You want as many lights as you can get. If you dither you probably don't need darks but rather use bias frames. You want 20 or so at least and the same for flats.

Really it's all about experimentation and will be affected by light pollution in your location. You will need to ensure that you are getting good guiding - you don't mention guiding but you will be restricted on exposure if you don't guide. You can also take lots (hundreds) of short exposures if you don't guide.

Try it and see how it goes.

Peter

 

[spillage]

Sorry I do not use backyard eos but apt.

iso 800 and depending on your target will determine the exposure time.

I always use the canon software at 200% live view with my bahtinov but I know this is not perfect.

I just make small adjustments and you can easily see which way to go and I normally use a bright star near my target.

I would make sure that you dither and get as many lights as possible.

Use flats and bias. This may help bias flats

If your dslr is not cooled then in hotter weather you may need to allow longer between shoots. Maybe 30-40 seconds but this is just trial and error. 

cheers

Spill.

[MarsG76]

For focussing I use live view on my 40D, focus as close as I can while looking at the screen and take 5 second exposures on a bright star through the bahnitov mask, slightly adjusting the focus only a little bit at a time, seeing if its getting better/worse or overshot with each exposure until the diffraction spikes are symmetrical. I do this for all filters I plan to image through. On my SCT, I do adjustments turning the knob anticlockwise, where the mirror moves up against gravity, minimizing the potential mirror shift, possibility becoming slightly out of focus during the night. 

Any bright star is fine... Vega is a good choice.

The sub exposures is a bit of trial and error, a combination of your sky darkness quality and the length of time you're able to image with out drift. I recommend starting at ISO800 for 300s. 

300s is a good time to get the faint nebulosity on a lot of DSOs. If your frame is overexposed or milky than first drop the ISO to 400 and so on...

If you're going to, or did, mod your DSLR for narrowband, than you'll find that your subs will need to be anything from 15 minutes and up.. there are time where I exposed my subs for 1800s at ISO400 because I found that those were the best setting for me to capture some good detail in Halpha or SII data.

If you find drift on you images than shorten your exposure time.

Try capturing 20 or 30 Subs and stack them, that way you will have a good SnR.

I don't capture flats or dark frames, I image only in CR2 RAW and photoshop is very good at determining what is noise and what isn't on the fly as I open and convert the RAW files to 16bit TIFF for stacking. I used to take darks and flats but compared to what can be done in PS, I found that there was no improvement in the final image and just a waste of time.

Cooling a DSLR, or allowing time for it to cool, is not necessary as it will be a certain temperature as you're exposing your subs depending on the length of your subs and the ambient temperature.. of course that's the case for DSLRs that were not modded with a cooling system like a cold finger. Some people let the camera sit idle 30 seconds between exposure to allow the sensor to cool down, again , I didn't find it to be necessary comparing the end results, I typically give it 10 seconds between subs, but that is only time to allow any possible shutter shake to dampen down.

Hope that this was helpful, and good luck, clear skies.

[ronin]

4 hours ago, SAW said:

Just got myself a Polemaster ?
I have lots of little questions now I've had some practice setting up and using my mount/Scope,

If I use backyard eos with a bahtinov to get my focus correct what sort of settings do I need exposure etc ? 

Or can I just use live view on my camera ?

How much do I need to adjust the focus while adjusting ?

Can I choose any star Vega for example ?

How many images should I try and get for my first DSO and roughly what sort of settings, exposure etc using a 600d modded. 

How many lights and darks should I get ?

Between each shot do I need to do anything, adjust anything or just give the camera time to cool down, how long ?

Thinks that's it ?

Once set leave the focus alone, you have to trust that it was correct and cannot be improved on during the effectively continuous process of getting exposures.

Never found Live View to be much of a "View", certainly could not determine if the displayed image is in focus or not.

Vega if high should be OK, otherwise find another, Deneb or Capella maybe.

Settings, ISO 800 seems about best on a Canon, above that it boosts the noise equally so no advantage. Exposure length, try 60 seconds - nice round number and polar alignment should be reasonable.  Are you using the DSLR+Lens or the DSLR+ED80. Going to presume ED80, means no aperture setting = easy.

Use a new memory card, set DSLR to manual and exposure length to B, set the image type to RAW, disable the Noise Reduction.

Set the Intervalometer to say 10 second Delay, Exposure to 60 and wait to either 40 or 60. I allow some cooling time and also it allows the DSLR to write the file to the memory card. Number of exposures, try 20. Seems a nice number. The Wait time means that the DSLR is not in the middle of one action when it starts on the next cycle of action. They have a habit of just freezing when that occurs, so supply some kust to make it all as trouble free as possible if nothing else.

Set it all up, get target in view, cover the rear view finder bit to reduce ingress of light. Press the Go button on the intervalometer. Hopefully the first exposure goes off after 10 seconds and you relax and take a look around with a set of binoculars. Do not walk round in front of the scope - yes people do that.

For Darks I tend to leave everything as it is, reduce the exposures to half, so 10 in this case, put lens cap on and put DSLR in the fridge press Go and close door. Make coffee and you have 10 darks . So far I have not entered into the Lights area.

[geordie85]

For focusing I'd advise using ISO 6400 (the highest ISO setting) and setting exposure to 30s so your focus star will be as bright as possible, making it easier to focus.

Just remember to set ISO back to 800 before starting your imaging sequence. 

You can use either BYEOS or live view. I always found live view easier as there is a slight delay in BYEOS making it easy to go past the focus point.

[SAW]

4 hours ago, ronin said:

Once set leave the focus alone, you have to trust that it was correct and cannot be improved on during the effectively continuous process of getting exposures.

Never found Live View to be much of a "View", certainly could not determine if the displayed image is in focus or not.

Vega if high should be OK, otherwise find another, Deneb or Capella maybe.

Settings, ISO 800 seems about best on a Canon, above that it boosts the noise equally so no advantage. Exposure length, try 60 seconds - nice round number and polar alignment should be reasonable.  Are you using the DSLR+Lens or the DSLR+ED80. Going to presume ED80, means no aperture setting = easy.

Use a new memory card, set DSLR to manual and exposure length to B, set the image type to RAW, disable the Noise Reduction.

Set the Intervalometer to say 10 second Delay, Exposure to 60 and wait to either 40 or 60. I allow some cooling time and also it allows the DSLR to write the file to the memory card. Number of exposures, try 20. Seems a nice number. The Wait time means that the DSLR is not in the middle of one action when it starts on the next cycle of action. They have a habit of just freezing when that occurs, so supply some kust to make it all as trouble free as possible if nothing else.

Set it all up, get target in view, cover the rear view finder bit to reduce ingress of light. Press the Go button on the intervalometer. Hopefully the first exposure goes off after 10 seconds and you relax and take a look around with a set of binoculars. Do not walk round in front of the scope - yes people do that.

For Darks I tend to leave everything as it is, reduce the exposures to half, so 10 in this case, put lens cap on and put DSLR in the fridge press Go and close door. Make coffee and you have 10 darks . So far I have not entered into the Lights area.

Exposure length to B ?

Disable the noise reduction ?

Yes I am using the camera in the ED80 with a reducer/flattener. 

[geordie85]

1 hour ago, SAW said:

Exposure length to B ?

Disable the noise reduction ?

Yes I am using the camera in the ED80 with a reducer/flattener. 

Exposure length to bulb mode which is 1 further than 30s

For noise reduction to be turned off you'll need to press the menu button on the top left hand side, just above the flip screen and go through the options till you find it. I can't tell you exactly where it is as I don't have my DSLR with me at the moment 

[PeterCPC]

If you use BYE make sure the camera is set to M - the exposure is set in BYE. You may also want to consider using a light pollution reduction filter such as an Astronomik clip filter.

Peter

[SAW]

Ok so think I understand now, hopefully Saturday night will be clear. I will try something like this,

Focusing I'll just try live view for now (what ISO ?) until I get BEOS.

I am using an intervalotmeter and I will set it to 5-10sec delay, 20 shots at 60s with a 30s break between, ISO 800. (Should I try longer than 60s ?)

Camera set to Bulb and I have disabled noise reduction also images saved as RAW.

Then I'll do 10 dark shots with the same settings (end cap on)

Does that sound correct, have I missed anything ?

[spillage]

The amount of exposure time is limited by the accuracy of you polar alignment. I would try experimenting with exposure times. Try a 60 and then increase by 60 and see if you get any star trails. But just go for and as you make mistake learn from them. That is sometimes the fun part. If you really think you are going to struggle make a check list, it may help.

 

spill.