Capture image with a digital camera...

[EWHB]

Dear all,

I was just wondering what settings I should set my digital camera to (e.g. ISO, exposure etc.) that would enable me to take a picture of the night sky without the use of a telescope?

Thanks.

[Davey-T]

Trial and error is the only way, using manual mode, needs to be on a tripod, if it's the point and shoot / compact type use the time delay so it stops wobbling after you press the shutter before it takes the picture.

Dave

[johnfosteruk]

What he said ^

I'd add one thing, if your camera has ISO adjustment you want it as low as possible. My order of operations if I'm needing more is lengthen exposure (up to the limit where the motion is apparent) open aperture (up to the point I start to see weirdness in my stars, coma/CA) then increase ISO.

If you're capturing multiple subframes to stack then you can afford a little noise and increase ISO some more.

It all depends on your target obviously.

[rotatux]

^ What others said +

Depending on your camera (e.g. P&S vs Hybrid vs Reflex) your sensor may not have much color depth available. Thus you need to raise exposure more to counteract that limit and get some signal to stack: add time (limited by star motion on a tripod) or ISO (but stay below the "extension" zone, which is digitally amplified so not good for astro).

For a starter, a "hand-motorized barn-door tracker" is quite simple to make and will buy you more exposure time (allowing to release the pressure on ISO).

[alacant]

1 hour ago, EWHB said:

what settings I should set

I don't think anyone has answered because we don't have enough information but how about 10s, f5.6, ISO800 and get back to us? HTH.

[EWHB]

2 hours ago, alacant said:

I don't think anyone has answered because we don't have enough information but how about 10s, f5.6, ISO800 and get back to us? HTH.

Thanks I will give it a go when it's clear - no idea when that'll be!

[rigradio]

15 hours ago, EWHB said:

Dear all,

I was just wondering what settings I should set my digital camera to (e.g. ISO, exposure etc.) that would enable me to take a picture of the night sky without the use of a telescope?

Thanks.

You can start from -> here

[ronin]

Set the ISO to either 400 or 800, I think someone looked at the ISO and found that above these the DSLR magnified the noise as much as the signal, however I think one make of DSLR topped at 400 and another at 800. Try both.

Assuming a standard DSLR kit lens set lens to something like the maximum aperture and then back it off 1 full stop, done via the "A" on the dial, Likely to be around f/5 or f/6 therefore.

Set the Exposure via the "S" to 20 seconds.

Set the DSLR to M, Manual mode on the dial. You are about set to take a 20 second exposure at f/5 or 6, at ISO 400/800. On mine and I guess yours you have the set the A and the S individually. These are used when the DSLR is in M mode.

Head out to a dark place. Set Focus to Manual (usually on the side by the lens bayonet, and then manually focus on something distant - not always easy. Once happy do not adjust. Put DSLR on tripod (Fixed camera type I assume), aim at bit of sky - cassiopeia maybe, or Hercules for M13.

Take a series of 10 exposures, allow a bit of time between exposures for the sensor to cool a bit. I used an Intervalometer set for a 20 second exposure and a 10 second wait and a cycle of 10. Only takes about 5 minutes but try to leave the DSLR alone.

You should now have 10 exposures to load into DSS and stack.

You have the option to increase the ISOm alsoto open up the aperture, and extend the exposure to say 25 seconds more the 25 expect trailing. Not sure how much movement DSS can compensate for. Found 10 was OK so maybe 12 could be handled. But more time and more exposures means the sky has moved more so eventually cannot be aligned.

[happy-kat]

As to how long assuming crop sensor dslr.

400/lens focal length gives a starting point of how long to expose in seconds before star trails. Point camera high in south or north and this will be less time before star trails. Point camera low in east or west and get time or longer before star trails as earth rotation is less apparent in those directions.

Take many and after stacking DSS can handle rotation you'll find you need to crop the edges more heavily off final image if rotation has been high as edges will have elongated stars.

[iapa]

23 hours ago, EWHB said:

Dear all,

I was just wondering what settings I should set my digital camera to (e.g. ISO, exposure etc.) that would enable me to take a picture of the night sky without the use of a telescope?

Thanks.

I always started at ISO 800.

For the exposure I used the 'rule of 600'; maximum exposure to prevent star trails is 600/focal length

I should point put that others say '500 rule' for higher resolution very large prints.

and yet again, others say 400.

LOL

Remember to take account of the crop ratio if you are not using full frame sensors, e.g. my Canons have crop factor of 1.6

Using the 600 rule for a 50mm lens

600/50/1.6 = 6.25 seconds. So, I'd start at 6s, and then may be 10. If it trailed, split the difference and repeat until I had the longest usable exposure.

 

 

[happy-kat]

If you have a fairly new camera then you'll need DSS 3.3.4

[rotatux]

Also look at "Pinpoint stars" Android app (if you're on that kind of smartphone/tablet): tell it your camera and (focal) lens and it gives you a starting exposure time. It's for 60° declination, but times are easily divided by 2 to have the (minimum) value for celestial equator (Dec 0). It has shown to be pretty correct, though a bit optimistic at times, so take it as a start value and adjust.

[Stub Mandrel]

Having spent ages looking at ISO recommendations, these are very specific to individual sensors and cameras. Even if you can find a graph or rcomerndsation for your vamera, tehre will be another one somewhere advising an ISO that is one or two stops different.

You have plenty of time to experiment with short exposures. Take, say, ten minutes worth of exposures of the same bit of sky with several different ISOs, stack each one and see which gives you the least noisy image. Don't worry about the noise in a single image it's only the end result after stacking and stretching to give comparable levels of detail in each final image that matters.

Extreme example, 160 10 second exposures at ISO1600 will be individually noisier than 10 160 second exposures at ISO 100, buit you have more subs to stack out the noise in the first case. It is unlikely that the final stacked images will be the same.

 

[dph1nm]

This is one of the best summaries of the choice of ISO I have seen

http://www.lonelyspeck.com/how-to-find-the-best-iso-for-astrophotgraphy-dynamic-range-and-noise/

NigelM

[Stub Mandrel]

1 hour ago, dph1nm said:

This is one of the best summaries of the choice of ISO I have seen

http://www.lonelyspeck.com/how-to-find-the-best-iso-for-astrophotgraphy-dynamic-range-and-noise/

NigelM

There's a missing 'o' in your URL it should be:

http://www.lonelyspeck.com/how-to-find-the-best-iso-for-astrophotography-dynamic-range-and-noise/

That said, that's the best explanation I have seen, if only because it says to EXPERIMENT rather than use some arcane formula.

This does remind me of the many arguments for choosing speeds, feeds, cuts and tools for best lathe performance, whereas the real test is to actually turn something!