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VIP
Posts: 11,902
Registered: ‎12-07-2012

Re: Best Way To Set Focus on Infinity?

"...that's what autofocus is tor, isn't it?"

 

I would say let the camera do its thing with AF for distant airplanes, too.

EOS 1DX and 1D Mk IV and several lenses!
VIP
Posts: 11,902
Registered: ‎12-07-2012

Re: Best Way To Set Focus on Infinity?

" I just want to set it and forget it."  " I occasionally like to take pics of the moon and stars ..."

 

That is one way to shoot nighttime stars. Set the lens to MF.  Use the widest aperture.  Focus in the day time on something you can see that is very far away and put a small piece of tape on the focus ring.  In the dark use your Liveview option to focus.

EOS 1DX and 1D Mk IV and several lenses!
VIP
Posts: 8,870
Registered: ‎08-13-2015

Re: Best Way To Set Focus on Infinity?

[ Edited ]

@kvbarkley wrote:

Uh, no. The red dot is the infrared focus mark. RTFM.


Uh, there is a lot of infrared in the night sky.  If you focus on visible light, then the infrared will be OOF.  One mark is infinity focus for visible light.  The other mark is infinity mark for infrared light.  Practice what you preach.

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VIP
Posts: 11,902
Registered: ‎12-07-2012

Re: Best Way To Set Focus on Infinity?

"...Canon EF-S18-135mm f3.5-5.6 IS STM lens."

 

Some lenses do not do a very good job at night sky photography and you have one that doesn't. If you really want to get good shots of the sky look for a more suitable lens for that purpose.

 

 

121.jpg

EOS 1DX and 1D Mk IV and several lenses!
VIP
Posts: 11,902
Registered: ‎12-07-2012

Re: Best Way To Set Focus on Infinity?

[ Edited ]

Oh, BTW, the particulars were...................

 

EOS 1DX, Canon EF 16-35mm f/2.8L II USM Lens.
30sec, ISO 3200, f4.

 

And, yes, I know, I know this isn't the best choice lens for night sky work either but it is a typical sample and settings if you don't have dedicated astro gear.

EOS 1DX and 1D Mk IV and several lenses!
Esteemed Contributor
Posts: 3,612
Registered: ‎02-17-2016

Re: Best Way To Set Focus on Infinity?

[ Edited ]

The "infinity mark" is the L mark in the distance scale. The line and red dot are the indicators of where focus is set. It has nothing to do with infinity.

 

If you want infinity focus you put the line or mark (as appropriate) on the L mark. If you want to focus at, say 5 feet, you put the dot or indicator at the 5 foot mark.

 

And while there is a lot of infrared in the night sky, I don't know if it is at the same wavelength of IR film.

VIP
Posts: 11,902
Registered: ‎12-07-2012

Re: Best Way To Set Focus on Infinity?

The red dot is used to adjust the focus if you're shooting using an infrared filter.  Nowadays it doesn't have anything to do with IR film.

10,001 anybody? Smiley Happy

EOS 1DX and 1D Mk IV and several lenses!
Esteemed Contributor
Posts: 3,612
Registered: ‎02-17-2016

Re: Best Way To Set Focus on Infinity?

But its location is based on the optical properties of the lens at the wavelength of IR film.

Esteemed Contributor
Posts: 3,612
Registered: ‎02-17-2016

Re: Best Way To Set Focus on Infinity?

I take some of it back. The wavelength of IR film is in the near infrared, just like the silicon sensor.

Occasional Contributor
Posts: 18
Registered: ‎09-24-2019

Re: Best Way To Set Focus on Infinity?


@ebiggs1 wrote:

"...Canon EF-S18-135mm f3.5-5.6 IS STM lens."

 

Some lenses do not do a very good job at night sky photography and you have one that doesn't. If you really want to get good shots of the sky look for a more suitable lens for that purpose.


Got any suggestions for a more suitable lens? I also have a Canon EF 75-300mm F4-5.6 III lens that came with my kit.

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