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Just starting out, any basic tips!


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Hi all finally getting my head around astrophotography.

I've had a good go at Planetary pics & now want to move on to other challenges

I know this has probably been asked a million times so I apologise in advance but I just wanted to pick everyone's vast experience, so with regards to DSO are there basic guides as to--

1/ What ISO settings to use for 1/Galaxy, 2/Nebula, & 3/Clusters

2/ Is there a set amount of calibration frames per amount of lights taken or is it just down to personal preference?

3/ I've read that the shorter the focal point the better which is why I'm trying to have a go with the f5 newt but would the f11 Mak not be any good for say a go at a Galaxy?

My setup is a Skywatcher 150p on an unguided NEQ6 mount with a Canon 1100d

sorry if the question's seem to obvious, but the advice I've been given on this site has been priceless

thanks

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With my Canon 5Dmkiii ISO 800 works perfect for faint stuff. 1600 is usable but you'll have a bit more noise to deal with and i find the color to be off in some cases. I normally take at least 50 lights for faint objects and at least 20 darks. I have had a lot of success with using a lot of bias frames. I usually use 100 for every final image. Fastest shutter speed available and same temp and ISO as the others.

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First tip would be start saving for a guiding solution! That will be where you want to be going next.

I use an 1100d, and stick to iso 1600 most of the time. 

Biggest problem with DSO photography is that it costs so damn much! You always want that next bit of gear.....and chances are it will be cloudy....FOREVER (at least that's how it seems to me)

Get used to getting pics. Depending on your polar align, I think you can get upto 5 mins unguided, although most people cap out at ~2 mins. Galaxies are pretty faint, so you might be able to get a few of the brigher ones (andromeda, M81 etc) but after that you will need to be guided. Nebulas are the same. If your camera is unmodded, you are going to need pretty long subs to see all the feint detail. 

Practice really does help though, so if I were you, I would spend lots of time doing the brigher DSO's and getting used to the setup and processing etc.

Good luck!

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You can easily get 30-60s unguided exposures with the NEQ6 mount - even more with skill and good alignment - this is a really good mount, but an auto-guider is where you ultimately want to be :)

Also, I would recommend getting the book "Making Every Photon Count" from FLO. It will answer most of your questions, and even those you don't know you have yet :)

As for the questions:

1. ISO should generally be kept low to avoid noise as much as possible. Try 800-1600 depending on the object.

2. Personal preference with limits on both ends - DeepSkyStacker help section will help you with calculating these.

3. F10 will simply require you to take longer exposures to get the same result as F5 - but - for Galaxies, Planetary Nebulas, Planets and Clusters - a longer focal length is actually your friend as it gives you narrower FOV and more details. So, if you want to image galaxies - the F10 scope will actually be a better choice.

Hope this helps even a little.

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You could use a Mak but at f/11 your going to need very long exposures and guiding for sure.

Anyway you really want to guide so you can push for longer exposures.

I went the shorter faster route, not very good for small galaxies and PNs but excellent for nebs and widerfield.

For ISO, 800 or 1600 normally works ok, my 60Da does best at these two ISOs.

As well as buying MEPC go and buy Jerry Lodriguss's DVD, it explanes everything about DSLR AP.

At todays exchange rate it's around £25 and does'nt attract any taxes.

http://www.astropix.com/GADC/GADC.HTM

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With my Canon 5Dmkiii ISO 800 works perfect for faint stuff. 1600 is usable but you'll have a bit more noise to deal with and i find the color to be off in some cases. I normally take at least 50 lights for faint objects and at least 20 darks. I have had a lot of success with using a lot of bias frames. I usually use 100 for every final image. Fastest shutter speed available and same temp and ISO as the others.

Thanks

So you should have at least 20 darks & 100 Bias for every try. Do you also have Flats if so how many?

You can easily get 30-60s unguided exposures with the NEQ6 mount - even more with skill and good alignment - this is a really good mount, but an auto-guider is where you ultimately want to be :)

Also, I would recommend getting the book "Making Every Photon Count" from FLO. It will answer most of your questions, and even those you don't know you have yet :)

As for the questions:

1. ISO should generally be kept low to avoid noise as much as possible. Try 800-1600 depending on the object.

2. Personal preference with limits on both ends - DeepSkyStacker help section will help you with calculating these.

3. F10 will simply require you to take longer exposures to get the same result as F5 - but - for Galaxies, Planetary Nebulas, Planets and Clusters - a longer focal length is actually your friend as it gives you narrower FOV and more details. So, if you want to image galaxies - the F10 scope will actually be a better choice.

Hope this helps even a little.

Thanks, didn't think to look at help on DSS

+1 for guiding.There's no limit to the length of exposure if you are guiding on an neq6pro.

Without the guider, you need to be within 2 or three seconds of the pole

thanks for the info, what's the longest exposure you have practically achieved?

You could use a Mak but at f/11 your going to need very long exposures and guiding for sure.

Anyway you really want to guide so you can push for longer exposures.

I went the shorter faster route, not very good for small galaxies and PNs but excellent for nebs and widerfield.

For ISO, 800 or 1600 normally works ok, my 60Da does best at these two ISOs.

As well as buying MEPC go and buy Jerry Lodriguss's DVD, it explanes everything about DSLR AP.

At todays exchange rate it's around £25 and does'nt attract any taxes.

http://www.astropix.com/GADC/GADC.HTM

Thanks, again this might be a silly Q but do you have to have the same ISO setting on all pics you want to stack or can you have some at 800 & some at 1600?

Also forgive my ignorance but what are PNs?

First tip would be start saving for a guiding solution! That will be where you want to be going next.

I use an 1100d, and stick to iso 1600 most of the time. 

Biggest problem with DSO photography is that it costs so damn much! You always want that next bit of gear.....and chances are it will be cloudy....FOREVER (at least that's how it seems to me)

Get used to getting pics. Depending on your polar align, I think you can get upto 5 mins unguided, although most people cap out at ~2 mins. Galaxies are pretty faint, so you might be able to get a few of the brigher ones (andromeda, M81 etc) but after that you will need to be guided. Nebulas are the same. If your camera is unmodded, you are going to need pretty long subs to see all the feint detail. 

Practice really does help though, so if I were you, I would spend lots of time doing the brigher DSO's and getting used to the setup and processing etc.

Good luck!

Many thanks, you're right its an expensive hobby but good fun, I seem to be able to get 3 mins unguided at the moment. When the clouds actually pass GGrrr! I'll get practicing.

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PNs are planetary nebulae.

You can use different ISOs when stacking but I believe you may need to put them in a seperate group in something like Deep Sky Stacker.

Someone else may confirm that hopefully.

Personally I just stick to 1600 and get as many subs as I can get.

Three minutes unguided is pretty good, most of my subs are in the region of 5minutes, sometimes a little more.

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my longest that I actually did was 10 minutes - the image had round stars, but was flooded with amp glow and hot pixels from the hot camera.

It wold have been ok in a cool climate, but the sensor temp was up in the 35-40C area and that doesn't bode well for noise.

when the sensor gets down to aout 25c it works much better

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Hi all finally getting my head around astrophotography.

I've had a good go at Planetary pics & now want to move on to other challenges

I know this has probably been asked a million times so I apologise in advance but I just wanted to pick everyone's vast experience, so with regards to DSO are there basic guides as to--

1/ What ISO settings to use for 1/Galaxy, 2/Nebula, & 3/Clusters

2/ Is there a set amount of calibration frames per amount of lights taken or is it just down to personal preference?

3/ I've read that the shorter the focal point the better which is why I'm trying to have a go with the f5 newt but would the f11 Mak not be any good for say a go at a Galaxy?

My setup is a Skywatcher 150p on an unguided NEQ6 mount with a Canon 1100d

sorry if the question's seem to obvious, but the advice I've been given on this site has been priceless

thanks

Without guiding there is not a lot that you can do above 30s subs, so if you are serious about DSO imaging this is one area that needs addressing.  There is no rule for the number of calibration frames but below a certain number they fail to do a good job but the more the better. What you have to learn about these is if they are not done properly then they do more damage than good. The Bias is the easiest to  take, take the camera off the scope, put the cover on the front to make sure there is no chance of a light leak, set the shutter to the fastest speed the camera is capable of and take about a 100 Bias as a minimum. You do need the a large number so that a clean ( noise free ) master Bias could be created and this is the foundation of calibrating. For a DSLR if Darks need to be taken then 30 is a good number but you have to maintain the temp to within a couple of degrees C of the lights as these are very temp dependant and if not taken correctly will do more damage than good ( 5 correctly taken Darks are much better than 30 mismatched ones ) about the same number of Flats will do as a minimum but do read about taking good Darks and Flats in particular with a DSLR as they are not as easily done as the Bias. Whatever you do you have to understand and accept that DSO imaging is very different to daytime or for that matter Planetary photography and there are no short cuts. Hopes this gives you a bit of useful info.

For 1100d either 800 or 1600 is close to unity gain for " iso" setting.

A.G

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PNs are planetary nebulae.

You can use different ISOs when stacking but I believe you may need to put them in a seperate group in something like Deep Sky Stacker.

Someone else may confirm that hopefully.

Personally I just stick to 1600 and get as many subs as I can get.

Three minutes unguided is pretty good, most of my subs are in the region of 5minutes, sometimes a little more.

Hi Yelsac.

Just getting started my self, so no expert.

I have stacked frames of different ISO and expotiure length in deep sky stacker, and the software groups and stacks all of them by it self.

Just remember that if you have frames of 800 and 1600 ISO you need dark, bias and flats for both iso's

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Basic tip:

Forget visual, and forget thinking in terms of a visual scope and equipment.

It is not difficult you need in it's simplest form a good equitorial mount, with motors but goto is a lot better and a small, fast short scope.

If these are not what you have in all forms then you have the wrong equipment either somewhere or everywhere.

So:

1) Have you a good solid EQ mount?

2) Is the EQ mount fitted with motors or goto?

3) Is the scope relatively small?

4) Has the scope a short focal length?

5) Is the scope classed as fast?

Any No's and something is wrong.

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Hi Yelsac.

Just getting started my self, so no expert.

I have stacked frames of different ISO and expotiure length in deep sky stacker, and the software groups and stacks all of them by it self.

Just remember that if you have frames of 800 and 1600 ISO you need dark, bias and flats for both iso's

Thank's that really makes sense.

Can't wait to have a go!

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Without guiding there is not a lot that you can do above 30s subs, so if you are serious about DSO imaging this is one area that needs addressing.  There is no rule for the number of calibration frames but below a certain number they fail to do a good job but the more the better. What you have to learn about these is if they are not done properly then they do more damage than good. The Bias is the easiest to  take, take the camera off the scope, put the cover on the front to make sure there is no chance of a light leak, set the shutter to the fastest speed the camera is capable of and take about a 100 Bias as a minimum. You do need the a large number so that a clean ( noise free ) master Bias could be created and this is the foundation of calibrating. For a DSLR if Darks need to be taken then 30 is a good number but you have to maintain the temp to within a couple of degrees C of the lights as these are very temp dependant and if not taken correctly will do more damage than good ( 5 correctly taken Darks are much better than 30 mismatched ones ) about the same number of Flats will do as a minimum but do read about taking good Darks and Flats in particular with a DSLR as they are not as easily done as the Bias. Whatever you do you have to understand and accept that DSO imaging is very different to daytime or for that matter Planetary photography and there are no short cuts. Hopes this gives you a bit of useful info.

For 1100d either 800 or 1600 is close to unity gain for " iso" setting.

A.G

Thank's for the advice

When taking the bias can you just leave everything as it is & put the telescope cap back on?

When you talk about a master bias does that mean you can use it over & over again so you don't have to take 100 for every session of lights?

Lastly (I promise) obviously taking 100 bias frames is going to take a while is there a way to set up your camera to just do it?

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I use a 450d and stuck with ISO 400. Never saw the point in going higher. I use guiding, and hit 10 minute exposures for most targets on my HEQ5. Bias and Flats are the most important. Bias for the generic readout noise and Flats to get rid of dust artefacts and scratches and wear and tear on the sensor/internal fiters etc. Darks are hit and miss and as mentioned above need to be taken at the same temperature etc etc and its all too much hassle and they usually mean more noise in the resulting image. I just accept I will need to process out some noise. I leave 60 seconds between subs when doing an imaging run to give the sensor a chance to cool.

For bias, just put the scope cover on and blast away. When you create a master, just use that for every subsequent image you process with that camera. I haven't regenerated a master bias frame in months. Flats on the other hand I have to redo more regularly as more dust and nonsense accumulates and the flats slowly lose their worth.

I use the Canon EOS utility and use that to control the camera. This can automate the capturing of the images as well as gaps between exposures if you want. It also means you can download the images direct to the laptop.

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Thank's for the advice

When taking the bias can you just leave everything as it is & put the telescope cap back on?

When you talk about a master bias does that mean you can use it over & over again so you don't have to take 100 for every session of lights?

Lastly (I promise) obviously taking 100 bias frames is going to take a while is there a way to set up your camera to just do it?

I try  to take neither Bias nor Darks on the mount, there is a lot of chance of light leaks in particular with Newtonians. Yes you can use a master Bias but I would say that  try and redo them every other month as the temp goes up also the sensor itself changes its Bias noise with time so do 4 or 5 times a year unless you know that you are imaging with a large temp difference from when the Bias were taken. If you are serious about DSO imaging then the use of a laptop with dedicated AP capture software is mandatory, I use APT for Canon which also works with a lot CCDs through the Ascom platform. You can download it and the license is only about £10.00 or so. Hell of a software at a give away price.

A.G

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I use a 450d and stuck with ISO 400. Never saw the point in going higher. I use guiding, and hit 10 minute exposures for most targets on my HEQ5. Bias and Flats are the most important. Bias for the generic readout noise and Flats to get rid of dust artefacts and scratches and wear and tear on the sensor/internal fiters etc. Darks are hit and miss and as mentioned above need to be taken at the same temperature etc etc and its all too much hassle and they usually mean more noise in the resulting image. I just accept I will need to process out some noise. I leave 60 seconds between subs when doing an imaging run to give the sensor a chance to cool.

For bias, just put the scope cover on and blast away. When you create a master, just use that for every subsequent image you process with that camera. I haven't regenerated a master bias frame in months. Flats on the other hand I have to redo more regularly as more dust and nonsense accumulates and the flats slowly lose their worth.

I use the Canon EOS utility and use that to control the camera. This can automate the capturing of the images as well as gaps between exposures if you want. It also means you can download the images direct to the laptop.

The advantage of using a higher ISO is that you can do shorter subs to get to the same saturation. This then gives you more subs to play with and reduces the chances that you lose a sub due to tracking errors etc. 

I'm no expert in this, just re iterating information that I have read on here and I have found it works for me.

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You are correct in using higher ISO if there are other factors in limiting your sub lengths, in which case necessity can take over.

However, as I understand the technical details, a higher ISO on the camera at a basic level simply increases the gain settings, so it applies an increased multiplier internally to the pixel value as well as introducing additional noise due to the implementation of the higher gain. This leads to faster saturation of star cores and is the reason noise is proportionally greater, as fluctuations are magnified more as well as higher ISO having more inherent noise due to the way it is handled in the camera. The same signal from the sky is received in the same exposure duration, no matter what ISO level chosen, it is how that is represented in the RAW data in the image file that is different. I have found that ISO 400 gives me the most detail for the longer durations I can manage/dare with my setup to give the best dynamic range without having too much star core saturation (or any other bright detail, such as galaxy cores or bright nebula) and it is the level which keeps the noise to a minimum. A higher setting will indeed allow you to make shorter subs, but this is not really a gain in the standard sense, as you have not gained more signal, you have actually captured less photons as the exposure time is less, it is just represented differently and will have more noise.

A nice answer to the question of what ISO level to choose and a more coherent answer than my ramblings is given on the astrobin QA site : http://questions.astrobin.com/question/1309/longer-exposure-time-or-higher-iso-which-is-the-best-for-a-dslr/

Cheers

Matt

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I use a 450d and stuck with ISO 400. Never saw the point in going higher. I use guiding, and hit 10 minute exposures for most targets on my HEQ5. Bias and Flats are the most important. Bias for the generic readout noise and Flats to get rid of dust artefacts and scratches and wear and tear on the sensor/internal fiters etc. Darks are hit and miss and as mentioned above need to be taken at the same temperature etc etc and its all too much hassle and they usually mean more noise in the resulting image. I just accept I will need to process out some noise. I leave 60 seconds between subs when doing an imaging run to give the sensor a chance to cool.

For bias, just put the scope cover on and blast away. When you create a master, just use that for every subsequent image you process with that camera. I haven't regenerated a master bias frame in months. Flats on the other hand I have to redo more regularly as more dust and nonsense accumulates and the flats slowly lose their worth.

I use the Canon EOS utility and use that to control the camera. This can automate the capturing of the images as well as gaps between exposures if you want. It also means you can download the images direct to the laptop.

Thanks Matt

Lots to think about.

So am I right in thinking that the Canon EOS utility is part of the software that came with the camera? Does that mean you can program the capturing of images & the gaps between exposures?

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I used to use Canon EOS utility and I switched recently to Backyard EOS (demo is free to use fully functional for 30days and the software is $35-$50 USD to buy). What I liked about it was how it assisted in the imaging process with the naming of the target, date taken, and type of frame (light,dark,bias,flat,etc). It also has some great tools built in for focusing and framing the target. I also found its language on setting up the batches much easier to decipher than the EOS utility.

http://www.otelescope.com/index.php?/store/product/4-backyardnikon-10-premium-edition/#compareedition_bookmark

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The EOS utility comes with the camera, although my camera was second hand, but the app is downloadable. It allows you to choose exposure times and gaps, set ISO, use liveview, all the features of the camera using the laptop basically. I use a Mac so the other cool tools like APT and BackyardEOS are not available to me. If I could use those, I would.

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Do you also have to buy a Windows license for that? I thought you did. Am a bit of a stickler for trying to keep my Mac Windows free. I did have parallels a few years ago, but never really enjoyed the experience. I have to work a bit harder to get things to work, but it is worth it in the end, assuming it does eventually work that is...

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Yeah you need a license. You could try out nebulosity I believe they make a Mac version that is compatible with eos cameras. I had a demo but never really fully tested it after I discovered backyard eos.

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