Help with stars - DPChallenge Forums

Canon EF 24-105mm f/4.0L IS

06/13/2011 08:16:52 PM · #1

I am thinking about doing a shot with stars in it because I have never achieved this (good enough that I consider it worth saying I have done it). I don't want star trails... I just want a few dots...

Here is my question... How do I go about getting clean dots and a lot of them?

Like this..

I am not expecting to have a ton like this photo being that I live in a populated place but I do want a few...

Tips?

sjhuls

Canon EOS-7D

06/13/2011 08:21:22 PM · #2

you are not going to get stars like that if you live in a populated area, also you can't leave the shutter open long or you will get star trails. Looks like he left his shutter open only 30 sec and the ISO was really high.

06/13/2011 08:22:53 PM · #3

Hmm... Another thing I just checked was the moon... It looks like it is nearly full which probably doesn't help my case any... :/

06/13/2011 09:01:54 PM · #4

It's certainly possible, though it will represent a challenge. As a very rough guide, you can use 600/FL as your longest permissible exposure (in seconds) to minimize any trailing. You may want to stay on the short side of this. So if you are shooting at 24mm, you will have a max exposure time of 600/24 = 25 seconds. I'd keep it to under 20s.
If you go to 10mm, you can get away with almost 60s! There will be some slight trailing, but in a resized image it's not terribly noticeable. This shot:

Was done on a static tripod with a Canon 10D & 15mm fisheye, with an exposure of 30s, ISO 200, f/2.8. The bright spot at the top of the frame is the moon, about 1/2 illuminated.

Message edited by author 2011-06-13 21:02:04.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

06/13/2011 09:20:55 PM · #5

My maximum possible exposure is 15 seconds. My camera goes from 36-436mm (35mm EQ). What FL, aperture, and ISO would you suggest to get stars, either trails or pinpoints? Note that at ISO 400 or 800 it will probably be impossible to distinguish between stars and noise speckles ... :-(

06/13/2011 09:22:57 PM · #6

Thanks for the tip... I figure maybe if I go at some off hour like 3am or something most lights will be off and that may help me out getting the stars. My worry is still the moon but I guess I will just have to fiddle with the settings and see what I get.

Thanks for the 600/FL tip!

As for your ISO... I have heard I needed a high ISO to achieve a good "stared" photo... But my D40 is AWFUL at anything more than 200 ISO. 400 ISO is when it starts to get pretty grainy for me. Is there something I am doing wrong? Or maybe something in PP that I can do to get rid of the grain while keeping the star specks?

06/13/2011 09:38:52 PM · #7

Originally posted by mbrutus2009:

As for your ISO... I have heard I needed a high ISO to achieve a good "stared" photo... But my D40 is AWFUL at anything more than 200 ISO. 400 ISO is when it starts to get pretty grainy for me. Is there something I am doing wrong? Or maybe something in PP that I can do to get rid of the grain while keeping the star specks?

I doubt your D40 is any worse than the Canon 10D was... but you certainly don't need high ISO to achieve a reasonable number of stars. Try the same exposure time at various ISOs and see what works best...

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

06/13/2011 09:40:40 PM · #8

Originally posted by mbrutus2009:

Is there something I am doing wrong? Or maybe something in PP that I can do to get rid of the grain while keeping the star specks?

Look into using a program like RegiStax to "stack" many shorter, less-noisy exposures. I suspect

kirbic will eventually get around to telling you about "dark-frame subtraction" ... ;-)

06/13/2011 09:41:01 PM · #9

Originally posted by GeneralE:

You can use the same 600/FL rule, as long as you use the "35mm equivalent" focal length. You should be able to get a reasonable number of stars at ISO 200 using your maximum exposure time. Make sure your camera's long exposure noise reduction is ON if you have it (most do).

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

06/13/2011 11:54:33 PM · #10

I get 600/FL to determine exposure time, but at what aperture would that apply?

If I set the zoom to 60mm, then my exposure would be 10 seconds @ ISO 200?

06/13/2011 11:56:40 PM · #11

I was always told to open that bad boy up! Lowest # aperture is best... Of course this is what I have read in many place...

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

06/13/2011 11:58:39 PM · #12

Originally posted by mbrutus2009:

I was always told to open that bad boy up! Lowest # aperture is best... Of course this is what I have read in many place...

That makes sense, but I don't like to assume ...

06/14/2011 12:01:24 AM · #13

I took a look at a few more photos (including the ones here in this thread) and all seem to have wide open apertures... 2.8 or so looks like the trend...

Panasonic LUMIX DMC-LX100

06/14/2011 12:16:18 AM · #14

Okay so let me give myself another option... What if I could deal with star trails?

I don't think I want the looooooong almost full circle ones but I think some short trails would be ok..

Like this maybe

I have never combined images.. and wouldn't even know where to begin so I am a bit hesitant to get multiple shorter exposures rather than just do it all in one big shot. Will I have to just deal with the fact that I need to get out of my comfort zone?

spiritualspatula

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

06/14/2011 01:25:07 AM · #15

Definitely consider getting into the middle of nowhere for shots. All of the ones below were shot in super isolated places.
The details are in them, if you've got any questions that aren't, throw them my way. They should give you an idea of settings and all, at any rate.

ETA: The second one was shot at 1.8 and 1600 ISO I think... 20 or 30 second exposure. Can't find the original yet.

Message edited by author 2011-06-14 01:27:43.