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Subject: "Manually focusing to infinity" Previous topic | Next topic
jbl_inAZ Registered since 18th Aug 2013Mon 02-Sep-13 11:27 PM
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"Manually focusing to infinity"


Elfrida, US
          

I love taking night shots on my D70, as well as astronomical (though naked eye) subjects. With the remote shutter release and a decently steady tripod I have solved all the major problems but one: I can't properly focus the camera. I'm currently using a kit standard zoom (from a D80 kit, for irrelevant reasons).

I can't use autofocus on a distant horizon or the moon (for instance); and unlike the old large zoom lenses I used to use with my old film Nikon and Nikkormat, I can't zoom in, focus, and zoom back. I must focus at the focal length at which I intend to take the picture, and with the manual focus and the viewfinder this is almost impossible, even if I choose something really bright to focus on. What I wish my camera had is a button or mode (part of the autofocus mechanism, probably) that automatically focuses the lens at infinity at the currently set focal length. Does anyone know of some trick that accomplishes the equivalent on my camera?

(I also have access to a D3000 and a telephoto zoom from the same family of lenses as its kit lens; I haven't tried this yet, but my experience in playing with that camera does not make me feel that I am likely to fare any better.)

The advantage over film of being able to experiment with exposure interval and ISO setting and see the best result immediately is tremendous. I just wish I could make the pictures less fuzzy.

  

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Replies to this topic
Subject Author Message Date ID
Reply message RE: Manually focusing to infinity
f5titan Gold Member
07th Sep 2013
1
Reply message RE: Manually focusing to infinity
f5titan Gold Member
07th Sep 2013
2
Reply message RE: Manually focusing to infinity
jbl_inAZ
07th Sep 2013
3
Reply message RE: Manually focusing to infinity
MEMcD Moderator
07th Sep 2013
4
Reply message RE: Manually focusing to infinity
jbl_inAZ
07th Sep 2013
5
Reply message RE: Manually focusing to infinity
meadowlark2 Silver Member
07th Sep 2013
6
Reply message RE: Manually focusing to infinity
MarkM10431 Silver Member
23rd Sep 2013
7

f5titan Gold Member Nikonian since 12th Jul 2006Sat 07-Sep-13 10:52 AM
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#1. "RE: Manually focusing to infinity"
In response to Reply # 0


HILO, US
          

An autofocus lens uses "fuzzy logic" to find infinity focus by going beyond infinity and back making it difficult to manually set infinity on an autofocus lens.
I've used MF28mm f3.5, MF50mm f1.8, MF135mm f3.5 and MF55mm f2.8 lenses at their "hard" infinity stops using manual exposure at 20 to 30 seconds and 400 to 1250 ISO settings. I got my lenses from KEH and have been pleased with the results from my D70 cameras. (I use these same lenses with my D700 and D800 for astrophotography)
I hope this helps.

"Great things are not done by impulse but by a series of small things brought together." Vincent Van Gogh

  

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f5titan Gold Member Nikonian since 12th Jul 2006Sat 07-Sep-13 10:55 AM
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#2. "RE: Manually focusing to infinity"
In response to Reply # 1


HILO, US
          

Also, I know of no way to make the autofocus system set infinity and lock it under very low light conditions.

"Great things are not done by impulse but by a series of small things brought together." Vincent Van Gogh

  

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jbl_inAZ Registered since 18th Aug 2013Sat 07-Sep-13 03:29 PM
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#3. "RE: Manually focusing to infinity"
In response to Reply # 1


Elfrida, US
          

> ... I've used MF28mm f3.5, MF50mm f1.8, MF135mm f3.5 and
>MF55mm f2.8 lenses at their "hard" infinity stops using
>manual exposure at 20 to 30 seconds and 400 to 1250 ISO
>settings. ...

I hadn't thought of obtaining older style manual-focus lenses with a hard stop at true infinity. What a great idea!

>I hope this helps.

Indeed it does. Many thanks!

  

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MEMcD Moderator In depth knowledge in various areas Nikonian since 24th Dec 2007Sat 07-Sep-13 06:15 PM
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#4. "RE: Manually focusing to infinity"
In response to Reply # 0
Sat 07-Sep-13 06:36 PM by MEMcD

US
          

Hi JB,

Since most of the kit lenses don't have a distance scale and will focus past infinity the problem is common.
Try manually focusing to infinity in daylight until you know the position on the focus ring.
With some practice you should be able to nail the focus using muscle memory.
Depending on the lens you are using, you could also place a small strip of gaffers tape or frog tape on the focus ring and make an alignment mark for infinity focus.

There could be other factors besides focus contributing to the "fuzzy" images you are getting. For example:

1. Motion blur:

When shooting long exposures of stars or the moon you must keep in mind that the earth is rotating and the longer the exposure the less sharp the image.

Another factor is wind: Wind blows the tree branches causing them to move so in a long exposure there will be motion blur. It can also move your camera.

2. Vibration

Generally vibration caused blur happens at shutter speeds between 1/15th and 4 sec. but can be a problem at faster or slower shutter speeds as well.

This can be caused by mirror slap or a tripod that is not rock solid.

Best Regards,
Marty

  

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jbl_inAZ Registered since 18th Aug 2013Sat 07-Sep-13 08:27 PM
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#5. "RE: Manually focusing to infinity"
In response to Reply # 4


Elfrida, US
          

>Hi JB,
>
>Since most of the kit lenses don't have a distance scale and
>will focus past infinity the problem is common.
>Try manually focusing to infinity in daylight until you know
>the position on the focus ring.
>With some practice you should be able to nail the focus using
>muscle memory.

I don't think this is necessarily true for kit zooms, though, as I understand it: since they went to autofocus, they eliminated the need to have a lens remain focused when you change the focal length (thus making the glass and gearing simpler and cheaper) - hence the infinity point on the focus ring is varies as you zoom.

>Depending on the lens you are using, you could also place a
>small strip of gaffers tape or frog tape on the focus ring and
>make an alignment mark for infinity focus.

Or several for various focal lengths.

>There could be other factors besides focus contributing to the
>"fuzzy" images you are getting. For example:
>
>1. Motion blur:
. . .
>2. Vibration
. . .

Thanks, these have always been understood problems regardless of focus. I am just trying to overcome the added difficulty I have alleviating that factor. You've given me some good ideas and things to think about.

Regards / JBL

  

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meadowlark2 Silver Member Nikonian since 03rd Sep 2012Sat 07-Sep-13 08:54 PM
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#6. "RE: Manually focusing to infinity"
In response to Reply # 0


Lethbridge, CA
          

A low tech solution might appeal to you. I focus my lens in the daytime and use tape like green frog painters tape to hold the focus in place for my shots at night.
Marsha

Visit my Nikonians gallery.

  

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MarkM10431 Silver Member Nikonian since 15th Apr 2013Mon 23-Sep-13 05:34 PM
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#7. "RE: Manually focusing to infinity"
In response to Reply # 6


jacksonville, US
          

>A low tech solution might appeal to you. I focus my lens in
>the daytime and use tape like green frog painters tape to hold
>the focus in place for my shots at night.
>Marsha
>
>

Visit
>my
>Nikonians gallery>.



that's what I'm going to do next trip to astrophotography-land.

Visit my Nikonians gallery.

  

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