How to achieve proper focus of stars at night?

haring · Sep 5, 2014

I would like to take some photos of stars at night. I have found the location. No problem. I have to keep an eye on the alligators while I am doing this because the location is in the Everglades. No problem. The only problem I am facing is that I have hard time focusing at the stars because the viewfinder is black. (It is 1:00am at night after all.... )

I manually focus at infinity and the stars are out of focus.

I have tried to use the screen in video mode after increasing ISO. No luck. Even the screen on the back of the camera is dark so I am not be able to see the stars for proper focusing.

My question: How do you focus in total darkness? Did I miss something?

RowanBloemhof · Sep 6, 2014

Hi.

Interesting problem. It would seem to me that infinity should be close enough to get some decent sharpness. I must say however that certain lenses from sigma have this issue where you can actually focus beyond infinity. I'm not sure wether this is to compensate for backlash on the mount etc or if it might simply be a production flaw.

I must say im not a pro on astrophotography, but i gave a shot at it once. And i think in my case i was having issues with blur due to longer shutter times. Although it may not be visible to the naked eye. The stars, or rather the earth constantly moves. I think that if you wanna have perfectly sharp photo's you need an equatorial platform which moves to compensate for the turning earth.

I however must say that i cannot very easily judge your situation. Over here stars are generally very dim, or obscured by light polution. It might just be that in a darker area it is easier to take sharp photo's of stellar objects.

haring · Sep 6, 2014

Yes, the problem is that most lenses are out of focus if you set them to infinity all the way down. The photos are totally out of focus.

RalphLambrecht · Oct 3, 2014

haring said:
I would like to take some photos of stars at night. I have found the location. No problem. I have to keep an eye on the alligators while I am doing this because the location is in the Everglades. No problem. The only problem I am facing is that I have hard time focusing at the stars because the viewfinder is black. (It is 1:00am at night after all.... )

I manually focus at infinity and the stars are out of focus.

I have tried to use the screen in video mode after increasing ISO. No luck. Even the screen on the back of the camera is dark so I am not be able to see the stars for proper focusing.

My question: How do you focus in total darkness? Did I miss something?

all stars are at a distance that qualifies for infinity. If they are out of focus if focused manuallythen, there is a focusing problem with your camera or lensEven f/8 should pull them into DOF.sounds like time for CLA

Hatchetman · Oct 3, 2014

Time for a classic manual focus lens from the 70s - Nikon, Pentax, etc.

L Gebhardt · Oct 3, 2014

Focus the lens on a distant object. Illuminate it with a strong laser pointer or flashlight to focus. Then point the camera at the stars and frame. You can also put a flashlight far away and focus on that, but a laser pointer is so much easier.

L Gebhardt · Oct 3, 2014

ralphlambrecht said:
all stars are at a distance that qualifies for infinity. If they are out of focus if focused manuallythen, there is a focusing problem with your camera or lensEven f/8 should pull them into DOF.sounds like time for CLA

It all depends on the lens. The newer Nikon AF lenses will focus past infinity when turned all the way to where you think infinity should be. The manual focus Nikon lenses all have an infinity stop. So it will really depend on the OP's equipment as to whether he needs a CLA.

RalphLambrecht · Oct 4, 2014

L Gebhardt said:
It all depends on the lens. The newer Nikon AF lenses will focus past infinity when turned all the way to where you think infinity should be. The manual focus Nikon lenses all have an infinity stop. So it will really depend on the OP's equipment as to whether he needs a CLA.

of course it does!

ray*j*gun · Oct 8, 2014

ralphlambrecht said:
all stars are at a distance that qualifies for infinity. If they are out of focus if focused manuallythen, there is a focusing problem with your camera or lensEven f/8 should pull them into DOF.sounds like time for CLA

Correct its the camera ..... a test for proper adjustment is to focus on the moon. If thats OOF then the camera need a service.

Clay2 · Nov 7, 2014

Check out this site:

Focusing for Astrophotography

/Clay

haring · Apr 13, 2015

ray*j*gun said:
Correct its the camera ..... a test for proper adjustment is to focus on the moon. If thats OOF then the camera need a service.

What happens if there is no moon....

haring · Apr 13, 2015

L Gebhardt said:
Focus the lens on a distant object. Illuminate it with a strong laser pointer or flashlight to focus. Then point the camera at the stars and frame. You can also put a flashlight far away and focus on that, but a laser pointer is so much easier.

Great idea!!!! I will try this! I can focus on my car's taillight and turn it off later.

RalphLambrecht · Apr 13, 2015

haring said:
I would like to take some photos of stars at night. I have found the location. No problem. I have to keep an eye on the alligators while I am doing this because the location is in the Everglades. No problem. The only problem I am facing is that I have hard time focusing at the stars because the viewfinder is black. (It is 1:00am at night after all.... )

I manually focus at infinity and the stars are out of focus.

I have tried to use the screen in video mode after increasing ISO. No luck. Even the screen on the back of the camera is dark so I am not be able to see the stars for proper focusing.

My question: How do you focus in total darkness? Did I miss something?

I also just manually focus on infinity and trust that lens setting;so far so good

Arctic amateur · Apr 18, 2015

If possible, I let the AF focus on Venus or another bright celestial object, and then switch to manual focus, taking care to not touch the focus ring.

RalphLambrecht · Apr 18, 2015

Arctic amateur said:
If possible, I let the AF focus on Venus or another bright celestial object, and then switch to manual focus, taking care to not touch the focus ring.

Sure, DOF should cover any differences in distance.

MartinCrabtree · Apr 18, 2015

Manual focus lens with infinity stop.

How to achieve proper focus of stars at night?

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