How to Focus Objects in the Dark when Taking Star Trail Photos?


#1


Hi everyone, i took this star trail (my first try) with MF (i had to coz too dark, cant AF) and while it looked sharp on the cam screen, it turned out blur on computer screen..i regret not enlarging it to see the pic after taking it. :(

But point crying over spilled milk...i will like to find out how did you guys focus in the dark? Had to use MF right? then if use MF how to check if it's focused? Isit by taking a 20 or 30 sec shot to see if it's focused then proceed with bulb mode?
 

Numnumball

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Mar 6, 2009
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#5
Manual focus to inifinity.. live view should help if ur viewfinder is too dark.. else open up ur aperture to compose and lock focus before stopping down to tk the shot :)
 

aspenx

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Aug 10, 2008
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#7
Focusing to infinity rarely works if you don't have a hard stop for infinity for your lens.

With a conventional SLR, you'll have to guesstimate. Just bring the focus just a tad closer from infinity and stop down. Works well for me so far.
 

sabee

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Mar 12, 2009
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#8
Hi everyone, i took this star trail (my first try) with MF (i had to coz too dark, cant AF) and while it looked sharp on the cam screen, it turned out blur on computer screen..i regret not enlarging it to see the pic after taking it. :(

But point crying over spilled milk...i will like to find out how did you guys focus in the dark? Had to use MF right? then if use MF how to check if it's focused? Isit by taking a 20 or 30 sec shot to see if it's focused then proceed with bulb mode?
If you want to focus in the dark... Shine a torch to assist AF then switch to MF. Else use a hyperfocal chart / calculator to find your best focus distance for a particular focal length / aperture that will allow you to keep the most of the shot in focus.
 

giantcanopy

Senior Member
Feb 11, 2007
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#10
icic..i tot got a foolproof 100% way to do this. :(
my prev attempts at star trails and star shots, i put it at infinity.
but if u have live view and a relatively large aperture lens, u can try to zoom in the stars and "fine tune" the infinity focus first.

ryan
 

ortega

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Nov 2, 2004
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#12
use WA lens
use small aperture

AF then switch to MF, snap a picture and check on LCD
if everything is OK
then proceed with your shot

btw there is already a bright light in your frame, how come still cannot focus?
 

#13
By the way, the flashlight technique DOES NOT work if you are trying to focus on the stars.

I'm not sure if even a laser would help for that.
He is trying to focus on the foreground, the stars are just points of light millions to billions of light years away and focusing to infinity will suffice. :)
 

sabee

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#14
Might also be worthy of note that infinity focus depends on temperature. That's why infinity focus is not a hard stop on your lenses but is represented by a line - so usually trying to dial in to infinity focus on your own is a bad idea and you will likely focus beyond infinity. Instead try to AF on something far away or at least check your MF using live view 5x or 10x.
 

aspenx

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#15
He is trying to focus on the foreground, the stars are just points of light millions to billions of light years away and focusing to infinity will suffice. :)
Eh.......

It does not work in practice unless you set the lens at hyperfocal distance and the appropriate aperture.

sabee is right. Focusing to infinity does not solve the problem.

Anyways, TS could have checked his images before starting on capturing the trail (which looks like it took at least 1.5hours). That's what we have digital cameras for right? :sweat:
 

#16
By the way, the flashlight technique DOES NOT work if you are trying to focus on the stars.

I'm not sure if even a laser would help for that.
Haha...this i know!

use WA lens
use small aperture

AF then switch to MF, snap a picture and check on LCD
if everything is OK
then proceed with your shot

btw there is already a bright light in your frame, how come still cannot focus?
When i took the shot, the light wasn't switched on. The hotel staff then suddenly appeared from nowhere and on it. It didnt occurred to me that i shd have the light on to AF..my 1st attempt mah and i tot it was focused enuff.

Eh.......

It does not work in practice unless you set the lens at hyperfocal distance and the appropriate aperture.

sabee is right. Focusing to infinity does not solve the problem.

Anyways, TS could have checked his images before starting on capturing the trail (which looks like it took at least 1.5hours). That's what we have digital cameras for right? :sweat:
Actually this shot was only ard 14mins exposure. I took 3 shots of 14 mins each. This is my 1st shot. My other 2 shots are without the bright light as i switched the light off.
 

aspenx

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Aug 10, 2008
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#17
Actually this shot was only ard 14mins exposure. I took 3 shots of 14 mins each. This is my 1st shot. My other 2 shots are without the bright light as i switched the light off.
Hmm, this was a single shot and not stacked? Where were you?

For the star trails I've tried (still trying out...), each shot doesn't last more than 30s.

I worry about the body heating and also the noise generated because of this heat. 14mins... wow. I don't know if I should try it too, but isn't Singapore's sky too polluted for such a long exposure?
 

night86mare

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Aug 25, 2006
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#18
Hmm, this was a single shot and not stacked? Where were you?

For the star trails I've tried (still trying out...), each shot doesn't last more than 30s.

I worry about the body heating and also the noise generated because of this heat. 14mins... wow. I don't know if I should try it too, but isn't Singapore's sky too polluted for such a long exposure?
don't think that's singapore.

and yes, the hot pixels will be a problem.
 

#19
Hmm, this was a single shot and not stacked? Where were you?

For the star trails I've tried (still trying out...), each shot doesn't last more than 30s.

I worry about the body heating and also the noise generated because of this heat. 14mins... wow. I don't know if I should try it too, but isn't Singapore's sky too polluted for such a long exposure?
It was taken in a beach in mui ne, vietnam. It was not pitch dark, but was just dark enuff not to be able to AF.
 

Sivakis

New Member
Sep 26, 2008
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#20
Either use VF-MF or LV-MF. That's the best way. If it's the hut you want in focus but it's too dark, try setting small light source, MF or AF then switch to MF. If it's the stars, then use VF or LV and MF on it.

That's the easiest way, imo.
 

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