How do you focus the XF80/2.8 in the dark?

meystel · Jan 14, 2021

Hello,

I thought I might be able to take some photos of the sky at night with my Fuji X-H1 and new Fuji XF 80mm F2.8 R LM OIS WR, but discovered that I have no idea how to focus the lens to infinity. How does one do that?

A thousand apologies for the newbie question and thank you in advance for any assistance or advice. I did try to Google this, unsuccessfully, before asking. And I obviously tried to play with the lens in the freezing cold night. Got a bunch of blurry dot smears after a minute or so of exposure at 200 ISO.

Thank you,

Michael

Nick on the Baltic · Jan 15, 2021

That's a question that has been asked a few times here. If you search the forum you'll turn up some answers amongst the not-so-useful posts.

ccarrier · Jan 15, 2021

Hi,

you have to focus manually. On most camera, when focusing manually, you can magnify the image on the LCD screen. You can then see the stars and focus so that they are sharp.

Also, for a 1 minute exposition time, even with good focus, the stars won't appear as dots, but rather as small circle arc, because they would have moved a little.

Have a good day!

Mark S Abeln · Jan 15, 2021

meystel said:
I have no idea how to focus the lens to infinity. How does one do that?

I usually use a terrestrial light source, such as a distant streetlight that's 'close enough' to being infinitely far away. Alternatively, you can focus on a distant object during the day, and then fix the lens with a piece of tape.

Back in the old days, lenses often had a hard infinity stop: you turn the lens all of the way until it stops, and that's infinity focus. However, that isn't always precisely accurate, and modern lenses often focus 'beyond' infinity in order to allow for autofocus.

Leonard Migliore · Jan 15, 2021

Mark Scott Abeln said:
meystel said:

I have no idea how to focus the lens to infinity. How does one do that?

Click to expand...

I usually use a terrestrial light source, such as a distant streetlight that's 'close enough' to being infinitely far away. Alternatively, you can focus on a distant object during the day, and then fix the lens with a piece of tape.

The tape's really important. It's very easy to turn the focusing ring when you're blundering around in the dark and then you're doomed.

I believe that some cameras with "focus by wire" make your life very difficult in this area. They don't hold focus when they power down or go to sleep. But I don't own any such camera.

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How do you focus the XF80/2.8 in the dark?

meystel

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