topic Re: Best Way To Set Focus on Infinity? in EF & RF Lenses

EF-S 18-135mm f/3.5-5.6 IS STM - Best Way To Set Focus on Infinity?

wchettel — Sat, 12 Oct 2024 13:39:27 GMT

I am using a Canon EOS Rebel SL2 with a Canon EF-S18-135mm f3.5-5.6 IS STM lens. Is there an easy way to set the focus on infinity when I'm using MF mode on the lens? I just want to set it and forget it.

Re: Best Way To Set Focus on Infinity?

Ray-uk — Fri, 06 Dec 2019 21:00:40 GMT

I assume you are using it for astro-photography, if so then set your focus using the moon.

In normal photo conditions just focus on something as far distant as you can find, although I don't understand why you would want your focus fixed on infinity for everyday photo situations.

Re: Best Way To Set Focus on Infinity?

Waddizzle — Fri, 06 Dec 2019 21:11:14 GMT

Look into what lens bands do. They are big rubber bands that go on a lens to prevent zoom ring creeping. I guess they could lock a focus ring down, too.

Be aware that focus may drift as temperature changes. I think it is best to focus on a bright star, instead of the Moon.

Re: Best Way To Set Focus on Infinity?

RobertTheFat — Fri, 06 Dec 2019 22:06:07 GMT

@Waddizzle wrote:
Look into what lens bands do. They are big rubber bands that go on a lens to prevent zoom ring creeping. I guess they could lock a focus ring down, too.

Be aware that focus may drift as temperature changes. I think it is best to focus on a bright star, instead of the Moon.

I would think that a point source with a tendency to flicker ("Twinkle, twinkle, little star ...") would be harder to focus on than the Moon.

Re: Best Way To Set Focus on Infinity?

wchettel — Fri, 06 Dec 2019 22:08:29 GMT

@Ray-uk wrote:
I assume you are using it for astro-photography, if so then set your focus using the moon.
In normal photo conditions just focus on something as far distant as you can find, although I don't understand why you would want your focus fixed on infinity for everyday photo situations.

Ray-uk, It's not for everyday photo situations. I live just off the flight path of Fort Lauderdale-Hollywood International Airport. A few times each day there's a flood of planes either landing or taking off. I'd just like to take some pics of the planes without worrying about the focus.

And, I occasionally like to take pics of the moon and stars but I usually do that using a tripod and remote control using the app on my phone.

Re: Best Way To Set Focus on Infinity?

RobertTheFat — Sat, 07 Dec 2019 04:01:25 GMT

@wchettel wrote:
@Ray-uk wrote:
I assume you are using it for astro-photography, if so then set your focus using the moon.
In normal photo conditions just focus on something as far distant as you can find, although I don't understand why you would want your focus fixed on infinity for everyday photo situations.
Ray-uk, It's not for everyday photo situations. I live just off the flight path of Fort Lauderdale-Hollywood International Airport. A few times each day there's a flood of planes either landing or taking off. I'd just like to take some pics of the planes without worrying about the focus. ...

Well, that's what autofocus is tor, isn't it? I would think that your camera, like other recent Canon DSLRs, must have at least one motion-sensitive AF mode that would suit your purpose.

Re: Best Way To Set Focus on Infinity?

Waddizzle — Sat, 07 Dec 2019 04:26:18 GMT

@RobertTheFat wrote:
@Waddizzle wrote:
Look into what lens bands do. They are big rubber bands that go on a lens to prevent zoom ring creeping. I guess they could lock a focus ring down, too.

Be aware that focus may drift as temperature changes. I think it is best to focus on a bright star, instead of the Moon.
I would think that a point source with a tendency to flicker ("Twinkle, twinkle, little star ...") would be harder to focus on than the Moon.

I agree. It would probably be easier to focus on the Moon than a bright star. But, that's the whole point. Besides, if I were photographing images of the night sky, I don't think I would be doing so on a night with the Moon in the sky.

Re: Best Way To Set Focus on Infinity?

Waddizzle — Sat, 07 Dec 2019 05:41:23 GMT

@wchettel wrote:
.

And, I occasionally like to take pics of the moon and stars but I usually do that using a tripod and remote control using the app on my phone.

Different types of light sources can focus in different ways.

Notice the red dot on the focus ring next to the vertical white line on the focus ring? Both are infinity focus marks.

Re: Best Way To Set Focus on Infinity?

kvbarkley — Sat, 07 Dec 2019 15:12:42 GMT

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

Re: Best Way To Set Focus on Infinity?

ebiggs1 — Sat, 07 Dec 2019 15:39:27 GMT

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

It may take more than 10K for some folks.

Re: Best Way To Set Focus on Infinity?

ebiggs1 — Sat, 07 Dec 2019 15:41:23 GMT

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

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

Re: Best Way To Set Focus on Infinity?

ebiggs1 — Sat, 07 Dec 2019 15:50:51 GMT

" 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.

Re: Best Way To Set Focus on Infinity?

Waddizzle — Sat, 07 Dec 2019 16:04:57 GMT

@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.

Re: Best Way To Set Focus on Infinity?

ebiggs1 — Sat, 07 Dec 2019 16:05:53 GMT

"...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.

Re: Best Way To Set Focus on Infinity?

ebiggs1 — Sat, 07 Dec 2019 16:11:28 GMT

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.

Re: Best Way To Set Focus on Infinity?

kvbarkley — Sat, 07 Dec 2019 17:03:08 GMT

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.

Re: Best Way To Set Focus on Infinity?

ebiggs1 — Sat, 07 Dec 2019 17:35:31 GMT

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?

Re: Best Way To Set Focus on Infinity?

kvbarkley — Sat, 07 Dec 2019 17:42:53 GMT

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

Re: Best Way To Set Focus on Infinity?

kvbarkley — Sat, 07 Dec 2019 17:46:39 GMT

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

Re: Best Way To Set Focus on Infinity?

wchettel — Sat, 07 Dec 2019 23:50:45 GMT

@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.