focusing infinity !!

[dervisali]

How can i focus to infinitiy with the lenses (such as 18-55 kit lens) that does not have inifinity mark?

Thank you.

 

[pixelationX]

What I do is just put it to manual focus and point it to something far away, use the camera screen and zoom to make sure the focus is perfect and you are done.

 

[AlbertoGarcia]

Hello,

If you focus to the infinite, the tears will not let you see the stars... eeeep no, I mean, if you focus to the infinite, you miss more than half your deph-of-field...

Try to reduce your f value (to f11 or f16, for example), then just point some area "far away" - you got it.

Check the link



for example, at f22, you may get "everything" in focus - from 0.43m to infinity... small black lines show where to point at when focus (at f22, it is about 1 metre)

have fun!
--
Alberto García-Briz
http://albertog.over-blog.es

 

[dervisali]

Hello and thank you very much for the replies.

I am going to visit a countryside and i will get the opportunity to take shots of stars. One of the rules to take star shots is to focus infinity.

My lenses are 18-55 IS II and 50mm f1.8 . I am planning to use 18-55 lens. Because i will use long exposures i don't want to do anything wrong to save my equipment.

That's why i asked focusing infinity.

Thanks again for the replies.

 

[Narcosynthesis]

The simplest way is to pick something appropriately far away (anything over 50m really) and focus on that - at night the moon or streetlights can be good (and high contras) targets.

If you know in advance you could also mark the lens during the daytime to show you where the infinite mark is - again just pick something suitable far away - a distant landscape, building or cloud, and use some tape to mark the focus ring to show infinite.

With most lenses infinite is the far end of the focussing scale, and back a touch (to allow some leeway for the focus mechanisms), though I will admit that in the field I can never remember which way is infinite and which is minimum (however long I have been doing this)...

As mentioned above though, with wider focal lengths and narrow apertures you can have quite a large depth of field, so you won't always need to focus all the way to infinite - perhaps not so useful if all you are shooting is billion light year distant stars, but something well worth reading into if you want to add in some foreground interest to 'ground' your sky shots.
--
http://www.flickr.com/photos/narcosynthesis
http://www.illaname.deviantart.com

 

[AlbertoGarcia]

Me again,...

for sky pictures, you definitely need as much light as you can get... then, select the fastest aperture (but avoid extreme f3.5) - in your case, set the mode to Av and then pick f4, for example.

According to the graph above, you will need to point at something that is a minimum 8 - 10 meters away from you - a tree, street light, a friend with a torch...

This way you will avoid exposures over 30s, that would show blurred stars (if this is not what you look for!)

again, have fun! (and get you a coat for the night shots)
--
Alberto García-Briz
http://albertog.over-blog.es

 

[PhilPreston3072]

How can i focus to infinitiy with the lenses (such as 18-55 kit lens) that does not have inifinity mark?

Thank you.

Have you tried manual focusing with liveview? Use the zoom button to view the lcd at x10. A tripod can help keep the camera stable when using long focal lengths to make manual focusing easier.

 

[Le Kilt]

Infinity focus is acheived manually by turning the focus ring anti-clockwise all the way then back a little. A little margin is left to compensate for hot/cold environments and infra-red focussing.

I usually switch the lens to manual focus and focus manually using the viewfinder, or use Liveview for auto-focus on a bright star or planet or moon.

You mention long exposures, so If you use a tripod (highly recommended for stars) you can use liveview if your camera has it, quite a good method. With Liveview on, you can focus automatically or manually, both can be good.

If you're going for long exposures to get star trails (several seconds to several hours, then you need to try a few settings to get it right.

If you're not going for star trails, then you need to go as 'fast' as possible, ie open up to max aperture, push iso up as high as possible until the noise gets too much, and keep the shutter-speed to about 1/10' if hand-held with steady hands, or up to about 1 second on tripod. In this case the 50mm f/1.8 will be better (at 1.8).

This one took three hours to take.
(assembly of 36 shots of 5 minutes at iso 100, f/9.0, 16mm)

 

[AlbertoGarcia]

Le Kilt,

nice pic... Did you try any start tracker system (to get still images - not trails)?

A colleague is working on some home-made system...

(but maybe this is for a new thread)
--
Alberto García-Briz
http://albertog.over-blog.es

 

[Le Kilt]

Le Kilt,

nice pic... Did you try any start tracker system (to get still images - not trails)?

A colleague is working on some home-made system...

(but maybe this is for a new thread)
--

No, although I did start looking at some. There is a system call a "barn door" tracker that can be made reasonably simply to start off with.
http://en.wikipedia.org/wiki/Barn_door_tracker

 

[dervisali]

Hello Le Kit,
Thank all of you very much for the explanations.

Your shot is great. This is what i want to do indeed. I want to take startrail shots.

After making some research (abouıt AstroPhotography) i have taken some notes to determine my settings :

1. Auto focus OFF (i will focus manually as you described by using LiveView- by the way i have T3i),
2. ISO 400 (maybe 200 or 100)
3. f-stop 4 or 8
4. Shutter : bulb mode , Exposure time : 15 or 20 minutes
5. Noise reduction OFF
6. Lens ( I have 18-55 kit lens and 50mm f1.8) : 50 mm f1.8

I hope these settings will be enough for me to catch a photo as you have attached.

 

[Le Kilt]

Hello Le Kit,
Thank all of you very much for the explanations.

Your shot is great. This is what i want to do indeed. I want to take startrail shots.

After making some research (abouıt AstroPhotography) i have taken some notes to determine my settings :

1. Auto focus OFF (i will focus manually as you described by using LiveView- by the way i have T3i),
2. ISO 400 (maybe 200 or 100)
3. f-stop 4 or 8
4. Shutter : bulb mode , Exposure time : 15 or 20 minutes
5. Noise reduction OFF
6. Lens ( I have 18-55 kit lens and 50mm f1.8) : 50 mm f1.8

I hope these settings will be enough for me to catch a photo as you have attached.

Try out a few different settings, I did a few test shots before I let it shoot for 3 hours!

3 hours gives you about 1/8th of a full circle (24h/8 = 3h). 20 minutes will give you trails about 1/10th of the ones on my pic, so they'll be a bit short, but will will get the sense of movement.

My shots came out well exposed at 5 minutes at iso 100, f/9.0, 16mm, but obviously I had to take 36 of them and assemble them on the PC.
It was a very bright full moon.

A 20 minutes shot would have been a bit overexposed in my case, I would have had to reduce the aperture a bit more.

If you take several shots in order to assemble them later in software, keep the time between shots to the minimum possible, even one second between shots becomes visible and gives a doted-line effect, so for several shots you have to disable the long exp. noise reduction which takes a second 'black' shot after a shot.

It's great to get the stars, but what is visible on the ground makes a huge difference in these shots if you can get something interesting in view.

Time can seem long, so it's good to be warm, and to have something else to do (a second camera?) or someone to talk to!
Enjoy yourself and I Hope you have a great clear sky !

 

[UTphotographer]

SO my question is if i make the settings on my camera and get it to focus. then i should set my intervalometer to take 5 min pics with just 1 sec in between?