Stars, beginner and focus

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Oblit3ration

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Hi all,

Quick question, I'm trying to figure out how to photograph stars? (the ones that twinkle, not the ones that reside mostly in LA!)

I'm firstly looking to simply get a half decent photo of the night sky. Nothing fancy, just an exposure of some of the stars.

However the first and main thing I'm struggling with is simply focus - How do you get focus on something that I can hardly see through the lens!? The after that how do I start working on getting a nice crystal clear image? Is it down to exposure time? what ISO do you use? I really am at the beginning of the beginner’s stage here!

My equipment is:

Nikon D60
Standard 18-55 VR lens
Sigma 70-300 APO DG
(also have a wide angle, but not sure this is needed for what I'm attempting?)
Tripod and remote control for shutter release

Just would appreciate some really basic (baby step), beginners advice please on things like how to focus, setting up manual mode, how long do people tend to leave the shutter open (or is that like asking how long a piece of string is?)

Many thanks in advance to anyone with the time to help, and hope to share some work with you all in the future.
 
Shouldn't be hard. You obviously need a clear night and away from any light polution.

Tripod, noise reduction on, everything manual, set focus to infinity, point at sky, and make an exposure (using the self-timer and mirror lock-up if you have it) at say 10secs at f/5.6 ISO400. That's purely a guess but probably as good a starting point as any. Using a mid-range f/number will cover any slight focusing inaccuracy and put the lens at its optical best.

That should at least give you something to begin your trial and error process with. Chimp the result on the LCD (the image will take an extra 10secs to appear while the noise reduction to works its magic) and adjust as necessary.
 
Great, thanks.

I can understand guidance fully for once - except for one word - "chimp"?
 
pretty vacant said:
Great, thanks.

I can understand guidance fully for once - except for one word - "chimp"?
Click to expand...

Haha! Chimping :D

Not sure how the term came about, but it means to check the LCD image, the histogram and blinkies (highlight over-exposure alert). Like an inquisitive monkey perhaps :shrug:
 
The problem is, and I have this on all my lenses... infinity is not at the end of focus movement. It's back a bit. Does the camera have liveview ? if so, pick a bright star, centre it, zoom in all the way, and adjust focus till the dot is as small as possible. Then shoot a 30 second exposure and again zoom in all the way on the review. The Histogram isn't going to be of much use, as there is so much dark.

Have a look at http://www.talkphotography.co.uk/forums/showthread.php?p=1184389#post1184389 for some more info.

What is it you're trying to achieve (apart from focus that is ;))
 
HoppyUK said:
Haha! Chimping :D

Not sure how the term came about, but it means to check the LCD image, the histogram and blinkies (highlight over-exposure alert). Like an inquisitive monkey perhaps :shrug:
Click to expand...

chimps are apes...ape-ing...new photographic term based on darwinian principles and proving cameras evolved from the jurassic

The chimpanzee-human last common ancestor (CHLCA, CLCA, or C/H LCA) is the last individual, an african ape, that both humans and chimpanzees share as a common ancestor. The CHLCA is generally used as an anchor point for calculating SNP rates in human genetic studies where chimpanzees are used as outgroup. The CHLCA is frequently cited as an anchor for molecular TMRCA determination because Chimpanzees are the species most genetically similar to humans. There are no known fossils that represent the CHLCA, as such, the age of the CHLCA is an estimate. The fossil find of Ardipithecus kadabba, Sahelanthropus tchadensis, and Orrorin tugenensis are closest in age and expected morphology of the CHLCA and suggest the LCA is older than 7 million years.

Earliest studies of apes suggest the CHLCA may have been as old as 25 million years, however protein studies in the 1970s suggested the CHLCA was less than 8 million years in age. Genetic methods based on Orangutan/Human and Gibbon/Human LCA times have then been used to estimate Chimpanzee/Human LCA of 6 million years and LCA times between 5 and 7 million years are currently used in the literature.[note 1] White et al. (2009) suggested that errors and poor assumptions in previous studies predicted a recent LCA and that the CHLCA should be considerably older.[1]

:D
 
Oblit3ration said:
Hi all,

Quick question, I'm trying to figure out how to photograph stars? (the ones that twinkle, not the ones that reside mostly in LA!)

I'm firstly looking to simply get a half decent photo of the night sky. Nothing fancy, just an exposure of some of the stars.

However the first and main thing I'm struggling with is simply focus - How do you get focus on something that I can hardly see through the lens!? The after that how do I start working on getting a nice crystal clear image? Is it down to exposure time? what ISO do you use? I really am at the beginning of the beginner’s stage here!

My equipment is:

Nikon D60
Standard 18-55 VR lens
Sigma 70-300 APO DG
(also have a wide angle, but not sure this is needed for what I'm attempting?)
Tripod and remote control for shutter release

Just would appreciate some really basic (baby step), beginners advice please on things like how to focus, setting up manual mode, how long do people tend to leave the shutter open (or is that like asking how long a piece of string is?)

Many thanks in advance to anyone with the time to help, and hope to share some work with you all in the future.
Click to expand...

if you focus on a far object which you can see on earth....it will be as near infinity as damn it...
so your f no will broaden the dof in the usual manner...
will autofocus the problem is that there is no real contrast to jig the sensor
so i use the above technique..

stars move...or rather we do...terrestrials...et aliens not included here
 
As others have said, setting your lens to infinity will probably not work, as most lenses focus beyond infinity. I have used the lights on a tower several miles away to focus my lens, before pointing it towards the night sky, making sure that it was set to manual focus first, so that it didn't change.

You probably want to use a fairly high ISO, as a lot of the objects in the night sky are quite faint. If you use a wide angle lens, you should be able to expose up to about 30 secs before star trailing becomes apparent. Anyhting less than wide angle will give star trailing after a much shorter period.

If star trailing is what you are after, you will be better off making several exposures of 30secs each, and then combining them with a program like Startrails. The reason I would advise this is twofold. One is to keep the level of noise down. The other is that for really long exposures of the night sky, light pollution starts to make its presence felt, and can result in a very light and unnatural looking sky.
 
It might be a good idea to invest in a 50mm f/1.8 or 28mm f/2.8.

The wider max aperture will enable a shorter exposure to minimise star trails.

They both have a hard infinity stop.

I find it completely impossible to manual focus accurately on a cropped viewfinder. I can't imagine how cross I would be to go to the bother of waiting for a cloudless night and making some nice star photos only to find that they're out of focus.
 
Firstly, thank you to all that have contributed to this thread so far, I've not had a chance to check back until now, but a lot of information for me to digest there.

Clearly some key things I've been doing wrong from the off, firstly, I was using my Sigma 70-300 as the lens to focus! I've since swapped back to the standard VR 18-55 that came with the camera (I guess the VR bit will help with the long exposures!) - Add to that, I was attempting shots (in manual mode) using ISO 100 instead of 400!

I will wait for the next clear night (God knows when that will be!) and try again using the changes mentioned in this thread.

...also, in answer to:

"It might be a good idea to invest in a 50mm f/1.8 or 28mm f/2.8.

The wider max aperture will enable a shorter exposure to minimise star trails.

They both have a hard infinity stop."

I do own one of these:

http://www.zen87038.zen.co.uk/image/DSC_0236.JPG
http://www.zen87038.zen.co.uk/image/DSC_0237.JPG

A wide angle lens, bought in America whilst on holiday in Vegas from these people: Millennium Foto - Where I was lucky enough to find a helpful sole who helped me pick a decent wide angle lens that wasn't going to cost the earth. Not sure if this is the sort of thing you mean?

Two more questions if you don't mind...

1: Regarding this "infinity stop" - would someone mind explaining exactly what that means, and how to find it on my lenses? The numbers on my lenses move from 18-55 and 70-300, is it a case of focusing all the way to one side and then backing off slightly?

2: General question about the F stop on a lens (sorry, slightly off topic, I could create another thread on this, but if it goes further than one or two paragraphs I will do so) - If I have a lens fitted to a camera and enter manual mode (for example, using my 18-55 VR Nikon lens) the lowest F I can get to is F5.3, if I fit the wide angle lens and zoom all the way out (so the fish eye mode is engaged) the F drops to F3.5 - is this normal? Does the camera move the F stop based on the lens fitted, and if you have a better quality lens the F can go lower and higher?

Sorry for the lengthy post, but as they say, if you don't ask you don't get! However, I really appreciate the help and advice offered so far - Thank you!
 
The maximum aperture should be marked on the lens somewhere, but your understanding is correct - different lenses have different maximums.

The maximum on some (most) zoom lenses will also vary, depending on the level of zoom, with widest aperture being available at the zoomed out end of the range.

With regard to infinity focus, most lenses will focus beyond infinity. All this means in reality is that in manual focus mode, if you turn the focus ring to the end of it's travel, everything will be out of focus. To actually focus on faraway objects, the focussing point will be a short way back from the end of travel.
 
I still think you should follow the advice in post #2. The lenses you have are fine. Don't use any optical adpators, they are naff. Use a mid-range f/number for the reasons given, at least as a starting point.

Infinity focus is indicated by the horizontal number 8 symbol on the focusing ring. The L-shaped symbol indicates a range beyond infinity which the AF system needs in order to work properly - it needs to 'see' beyond infinity so that it knows when to stop. When focusing manually, set the focus mark to align with the vertical end of the L symbol. That will be extremely close. If you prefer, AF on the moon using centre-point AF, then switch the lens to manual.

Switch off VR for long exposures on a tripod.
 
Using the 18-55mm lens i think you're gonna have to use it wide open (lowest number for aperature). I think you're gonna have to use a very high ISO as well. Use it at 18mm (no zooming). Use a tripod and make sure it is on something solid so that when you walk by it or just standing near it, it won't shake. To get focus i take a 30 second shot then look at the pic, zoom in on the pic to a star and check the focus. If it's not focused move the focusing ring and do another 30 second shot and test it again. Keep doing this untill you have good focus. Using software afterwards like curves in photoshop will bring out the stars very nicely. If you get star trailing at 30 secs up the iso and try 20 secs. Here is a few of the night sky i took. http://www.talkphotography.co.uk/forums/showthread.php?t=181026
 
Thanks again guys, will get out there and give it a go as soon as nature allows!!

Edit: The mirror-lock on my D60 appears to only be able to be lowered by turning the camera off - I guess (as the power button is on the top) this is a bad idea as it will judder the photo. Shall I just set it to "bulb" instead for any exposure longer than 30sec? (I can use the remote to take / finish the photo)
 
Oblit3ration said:
Thanks again guys, will get out there and give it a go as soon as nature allows!!

Edit: The mirror-lock on my D60 appears to only be able to be lowered by turning the camera off - I guess (as the power button is on the top) this is a bad idea as it will judder the photo. Shall I just set it to "bulb" instead for any exposure longer than 30sec? (I can use the remote to take / finish the photo)
Click to expand...

TBH mirror lock-up doesn't make any difference when exposures go over about half a second so don't worry about that.

Use a remote cable on Bulb for longer than 30 secs. Be aware that the earth rotates! I'm not sure at what kind of exposure duration you need to consider this, but it will be pretty insignificant with short lenses and will kick in much sooner with longer lenses.
 
The mirror lock up needs to be enabled in the menu. It's probably set to disable. If you do use mirror lock up make sure you press the shutter button once to lock the mirror up then a sec or so after press it again to start the exposure. First when i started using mirror lock up i would only press shutter button once and wait for it to take the pic but no pic lol...
 
With an 18-55 lens set the aperture back by one click (although you will get good results at the widest aperture) then autofocus or manual focus on something such as a sreetlight, moon or whatever that is a few hundred feet away, switch to manual focus to lock focus :) Don't use long exposure compensation. Try about 10 to 30 secs exposure with an ISO of about 400 and see what happens?

If you are pointing towards Polaris then you can get longer exposures, if you are shooting towards the horizon then the exposure will have to be much shorter and of course the wider you shoot will allow for longer exposures :cool:
 
I took some shots of the Nortern Lights recently (will post pics on here once sorted out) and I was getting star trails with 100 second exposures at maximum aperture and ISO 1600. it was dark out there!
 
Goody13 said:
I took some shots of the Nortern Lights recently (will post pics on here once sorted out) and I was getting star trails with 100 second exposures at maximum aperture and ISO 1600. it was dark out there!
Click to expand...

That's interesting.

Simple maths says that the earth turns 0.25 degrees every minute, and given that a 'standard' lens (say 30mm roughly on crop format) has an angle of view around 45 dgrees that's something to consider. With longer lenses you're could well be under 10 degrees angle of view, to that 0.25 degrees suddenly becomes very important!
 
I was quite surprised, but, then again, it's the first time I've tried my hand at anything like that and didn't have much choice given the darkness and maximum f3.5 aperture.

I would like to go back and hopefully encounter a brighter lights display with a shorter exposure.
 
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