struggling with star pics

iwols

iwols

Messages
872
Edit My Images
Yes
hi all always struggling getting a good star pic ,im using a sigma 10-20mm f4 lens on a d7100 on a tripod with intervalometer,but now matter what setings i use can never get the stars to have ping if you know what i mean heres a pic in my darkish garden,i know the shed and conifers dont look good but any thoughts gladly appreciated,even some of the stars look blue,
 
As above, you need to get somewhere that is properly dark and away from am made light, your picture is capturing lots of sodium scatter from the street lights polluting the sky where you live.
 
thanks guys this was the original,why are the stars blueish
 
Google a dark sky site near you but be prepare to drive a ways.

Also f4 is not going to be fast enough to capture enough light to show the stars off (unless you are deliberately wanting star trails)

To capture the stars as static objects use the "500 formula". e.g. if you have a 50mm lens then 10 seconds is the most time you can leave the shutter open without trails starting to form.
This is for FX sensors though so your 10mm lens equals 15mm in FX, therefore a shutter duration of around 33 seconds max to grab as much light as possible without the stars "moving".

The best lens for capturing stars and the Milky Way is the Samyang 24mm f1.4 due to the extra light it can pull in.

Hope this helps a bit.

I've got a shot of the Milky Way using my 16-36 f4 so I know the problem.

Cheers,

Terry.
 
thanks terry does f1.4 to f4 make a massive difference or slight,can i see your milky way with the f4 :)
 
Uploaded from phone and saved from Facebook so it's compressed to hell.
That was taken near Axminster in Devon this summer. It looked like a dark sky but even there you can see light pollution from Exeter.
 
If you want nice static stars you won't be able to get anything decent with that kit. You need f2.8 and high ISO (3200+)
 
I am far from an expert, but I would only chip in to agree with a lot of what has already been said. I have used the Samyang 14mm 2.8 ad the Nikon 17-35 2.8 and used them both at 2.8 with an iso of 3200 for around 30 seconds. Also as already said it is likely that there will be too much light pollution in built up areas.
 
Notice that was shot at ISO 12800 though. I'm not sure what your highest usable ISO is on that camera (had this problem with a D70 that maxes out at 1600 and is only really useable to 800).
 
The shot from your back garden is not at all bad considering the amount of light pollution - I can identify constellations. There is no trace of fainter stars or the Milky Way but in that situation it is not going to happen. Yes a faster lens would make things easily but with the gear you have you should be able to get some good shots. As mentioned above you need a dark site. I'd be tempted to set the lens at 10mm, use f4 and an exposure of 30 seconds and just keep increasing the ISO.

Dave
 
thanks guys just wondering how a 50mm f1.8 would compare to my 10-20mm f4 considering light input but reduced maximum time for the 50mm ,so not causing star trails if you know what i mean thanks again
 
10mm, 30 seconds, ƒ4 - 4.5, and 1600-6400 ISO depending on your camera.

The Milky Way rises and sets 1º later each day, so can be seen in different parts of the sky year-round. Although, you only see the best part (galactic bulge) for only half of the year, and the outer arm of the MW for the other half. Here in NZ the bulge is now setting at sunset, so cannot be seen until next year. But now we get to see Pleiades and Orion over summertime.

The 50mm ƒ1.8 lens is a brilliant little astro lens, can capture heaps of data but usually need stacking:

The Kiwi Way by Mikey Mack, on Flickr
 
thanks nchant but what i mean is will i get more detail with a 10mm lens f4 for 5o secs or 50mm lens f1.8 for 10 secs cheers
 
Not sure what you are meaning by 'detail'?

10mm will get you a far wider field of view, and 50mm is a a very close shot for the Milky Way or stars. Depends on what are you trying to achieve? 10mm is perfect for a landscape shot with stars in it, the 50mm not so much – unless you are going to stitch multiple shots to form a panorama?
 
well at 10 mm i could set the shutter speed at say max 60 secs to stop star trails yet with a 50mm i could theoretically set 12 secs max but the 10 mm would be f4 while the 50mm would be f1.8,which lets more light in ,so which one would catch more of the fainter stars,also whats the thoughts on a 35mm f1.8 lens as ive just found one in my kit bag :)
 
iwols said:
well at 10 mm i could set the shutter speed at say max 60 secs to stop star trails yet with a 50mm i could theoretically set 12 secs max but the 10 mm would be f4 while the 50mm would be f1.8,which lets more light in ,so which one would catch more of the fainter stars,also whats the thoughts on a 35mm f1.8 lens as ive just found one in my kit bag :)
Click to expand...

Assuming the same ISO -

60s is 5x longer than 12s. That is about 2.3 stops more light captured.
f1.8 is 2.3 stops wider than f4.

So, in theory, both exposures will grab the same amount of light, and the same number of stars.
 
With your lens at 10mm and an exposure of 60 seconds you will get star trails.

Sometimes it is called the 500 rule, sometimes the 600 rule but as in Terence's post above, if you use 500 then the maximum exposure in seconds to prevent trailing = 500/(focal length of lens x crop factor). I don't know the D7100 but think the crop factor is 1.5 which would give about 33s. Using 600 would get you to 40 seconds, but at 60 seconds you would see some movement.

Dave
 
looks like a low f and 14mm looks like a good starting point thanks for all the replies guys
 
Yes 60 seconds is too long for 10mm, even 30 seconds you will get trailing. at 10mm I shoot 25 seconds and stop down to ƒ4 (from ƒ3.5).
On my 6D I shoot:

50mm ƒ1.8: ƒ3.2, 8 seconds at 6400-25,600 ISO (See above shot)
24mm ƒ1.4: ƒ3.5, 20 seconds at 10,000 ISO
14mm ƒ2.8: ƒ4-4.5, 30 seconds at 10,000 ISO
10-22mm ƒ3.5-4.5 (modded for full frame): ƒ4-4.5, 25 seconds at 10,000 ISO at 15-17mm

I never follow the 500/600 rule as the results usually show trailing. Just get out there, try a few settings and keep using the one you like the look of :) don;t worry about noise too much, you can battle that hurdle in LR/PS.
 
NCHANT said:
Yes 60 seconds is too long for 10mm, even 30 seconds you will get trailing. at 10mm I shoot 25 seconds and stop down to ƒ4 (from ƒ3.5).
On my 6D I shoot:

50mm ƒ1.8: ƒ3.2, 8 seconds at 6400-25,600 ISO (See above shot)
24mm ƒ1.4: ƒ3.5, 20 seconds at 10,000 ISO
14mm ƒ2.8: ƒ4-4.5, 30 seconds at 10,000 ISO
10-22mm ƒ3.5-4.5 (modded for full frame): ƒ4-4.5, 25 seconds at 10,000 ISO at 15-17mm

I never follow the 500/600 rule as the results usually show trailing. Just get out there, try a few settings and keep using the one you like the look of :) don;t worry about noise too much, you can battle that hurdle in LR/PS.
Click to expand...
why do you step down on the lens please i thought more light going in would be better cheers
 
iwols said:
why do you step down on the lens please i thought more light going in would be better cheers
Click to expand...

I never shoot wide open, as you can see in this test shot I made below with my 24mm lens, the wider you shoot (yes you will collect more light) the smudgier the stars (and more chromatic aberration). Stopping down makes tighter stars and more detail.

Samyang 24mm ƒ1.4 Apertures by Mikey Mack, on Flickr
 
NCHANT said:
I never shoot wide open, as you can see in this test shot I made below with my 24mm lens, the wider you shoot (yes you will collect more light) the smudgier the stars (and more chromatic aberration). Stopping down makes tighter stars and more detail.

Samyang 24mm ƒ1.4 Apertures by Mikey Mack, on Flickr
Click to expand...
thanks for that see you have a 10-20mm as well how do you rate the other two lens you mention (14mm f2.8 and 24 f1.4 ) if you already had a 10-20mm and a 35mm f1.8 would the other two lens 14mm f2.8 and 24 f1.4 be much of a bonus thanks
 
I thought star trails were more the result of the earth's rotation that the amount of light coming in. 20 secs max unless you have astronomical tracking mounts (which incidental are astronomically priced - ok possibly not I just said that for the pun :) ) to track the movement.

Please correct me if I'm wrong
 
iwols said:
thanks for that see you have a 10-20mm as well how do you rate the other two lens you mention (14mm f2.8 and 24 f1.4 ) if you already had a 10-20mm and a 35mm f1.8 would the other two lens 14mm f2.8 and 24 f1.4 be much of a bonus thanks
Click to expand...

The Samyang/Rokinon/Bower 24mm ƒ1.4 to me is unbeatable for astro. It is super sharp, super fast (if you need it) and really easy to use - and 1/3 the price of the Canon version.
The Samyang/Rokinon/Bower 14mm ƒ2.8 is also an excellent lens, but suffers from distortion – although for landscape astro shots it's a very minor point. 14mm is very wide, so can collect a heap of data.
The Canon EF-S 10-22mm lens I use on my 600D is great, but I hardly use it now I have the 24/14mm combo. I used it on the 6D (full frame) because at the time it was the only wide lens I had, so made it work. It was ok, but had mass coma issues in the corners.

Nessie(TM) said:
I thought star trails were more the result of the earth's rotation that the amount of light coming in. 20 secs max unless you have astronomical tracking mounts (which incidental are astronomically priced - ok possibly not I just said that for the pun :) ) to track the movement.

Please correct me if I'm wrong
Click to expand...

Yes star trailing is from the earths rotation.
 
Last thoughts what would be any advantage on buying a 14mm f2.8 lens over my 35 mm f1.8 or 10-30 mm at f4,would it be worth it thanks again
 
You must log in or register to reply here.
Back
Top