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New Contributor
Posts: 2
Registered: ‎11-30-2018

Is this amount of focusing noise for EF 50mm f/1.8 STM normal?

I just purchased my first DSLR (EOS Rebel T7i with 18-55mm kit lens) and after reading so many good things about the 50mm f/1.8 STM prime lens purchased that as well. I got both yesterday and did a few tests. When recording video with the 50mm lens there was very obvious noise in the audio when the camera was auto focusing. By contrast, the kit lens was silent. I posted a comparison video here: https://youtu.be/SiLl0yxJNWw

Is this amount of focusing noise normal or should I be looking to replace this lens with a better unit?

Thanks!

Reputable Contributor
Posts: 563
Registered: ‎12-24-2013

Re: Is this amount of focusing noise for EF 50mm f/1.8 STM normal?

[ Edited ]

There are 2 types of STM AF motors. One type is slightly noisy and the other type is virtually silent. 

The EF 50mm f/1.8 STM has the noisier motor and what you are hearing is normal. 

 

If if you were to use an external Microphone you can reduce or even elimate the AF noise.

 

 

Lead-Screw STM

  • +PRO = FAST and Completely Silent
  • - NEG = BIG SIZE motor = Bigger lens size, weight, and COST
  • used in canon 18-55 STM, 18-135 STM and 55-250mm STM

Lead Screw Type STM 

 

 

 

 

Gear Type STM

  • +PRO = tiny compact, lightweight, cost effective
  • - NEG = small motor = slower performance.  Not completely silent due to gears
  • used in canon 24 STM 40 STM 50 STM  

Gear Type STM

 

 

 

Mike Sowsun
S110, SL1, 80D, 5D Mk III
New Contributor
Posts: 2
Registered: ‎11-30-2018

Re: Is this amount of focusing noise for EF 50mm f/1.8 STM normal?

Thanks for the response Mike. I find it troubling that the noise depicted in the video can be normal for that lens, especially when Canon describes the stepping motor as "near silent."
The version I purchased also appears to be grey market (the documentation in the box is all for the Malaysian market), which was never disclosed by the seller, so I want to make sure the lens is operating properly because it will not have a standard Canon warranty.
If others can verify this sounds normal I will just live with it since I bought the lens mainly for stills and I will see if an external mic improves the issue for video.
Reputable Contributor
Posts: 563
Registered: ‎12-24-2013

Re: Is this amount of focusing noise for EF 50mm f/1.8 STM normal?

There are many videos on Youtube showing the same noise as yours:

 

Mike Sowsun
S110, SL1, 80D, 5D Mk III
Honored Contributor
Posts: 7,177
Registered: ‎08-13-2015

Re: Is this amount of focusing noise for EF 50mm f/1.8 STM normal?


@MikeSowsun wrote:

There are 2 types of STM AF motors. One type is slightly noisy and the other type is virtually silent. 

The EF 50mm f/1.8 STM has the noisier motor and what you are hearing is normal. 

 

If if you were to use an external Microphone you can reduce or even elimate the AF noise.

 

 

Lead-Screw STM

  • +PRO = FAST and Completely Silent
  • - NEG = BIG SIZE motor = Bigger lens size, weight, and COST
  • used in canon 18-55 STM, 18-135 STM and 55-250mm STM

Lead Screw Type STM 

 

 

 

 

Gear Type STM

  • +PRO = tiny compact, lightweight, cost effective
  • - NEG = small motor = slower performance.  Not completely silent due to gears
  • used in canon 24 STM 40 STM 50 STM  

Gear Type STM

 

 

 


STM lenses are generally recommended for use with Dual Pixel AF when shooting video.  But, not all STM lenses are listed as being compatible with DPAF.  The two types of STM motors seems to explain it perfectly.  All of the prime lenses you mentioned, with gear type STM motors, are not listed as being compatible with DPAF.

 

Some lenses are just too noisy for shooting video because the onboard microphone will pick up the focusing noises within the lens body too easily.  

 

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"I don't rent software. I use Photoshop CS6, ACR 9.8 and Lightroom 6.8 ."
Reputable Contributor
Posts: 563
Registered: ‎12-24-2013

Re: Is this amount of focusing noise for EF 50mm f/1.8 STM normal?

[ Edited ]

@Waddizzle wrote:

 STM lenses are generally recommended for use with Dual Pixel AF when shooting video.  But, not all STM lenses are listed as being compatible with DPAF.  The two types of STM motors seems to explain it perfectly.  All of the prime lenses you mentioned, with gear type STM motors, are not listed as being compatible with DPAF.

 

Some lenses are just too noisy for shooting video because the onboard microphone will pick up the focusing noises within the lens body too easily.  

 


This Dual Pixel AF Compatibility Chart says the gear type 40mm f/2.8 is compatible with Dual Pixel AF. The EF 40mm f/2.8 STM is the first gear type STM lens and I am guessing the chart is not up to date. 

 

This is the first time I have heard that gear type STM lenses are not compatible, and a quick Google search didn't show any for me either. 

 

Where did you hear that gear type STM lenses are not compatible?

 

DPAF chart.jpg

 

 

Mike Sowsun
S110, SL1, 80D, 5D Mk III
Honored Contributor
Posts: 7,177
Registered: ‎08-13-2015

Re: Is this amount of focusing noise for EF 50mm f/1.8 STM normal?




@MikeSowsun wrote:

@Waddizzle wrote:

 STM lenses are generally recommended for use with Dual Pixel AF when shooting video.  But, not all STM lenses are listed as being compatible with DPAF.  The two types of STM motors seems to explain it perfectly.  All of the prime lenses you mentioned, with gear type STM motors, are not listed as being compatible with DPAF.

 

Some lenses are just too noisy for shooting video because the onboard microphone will pick up the focusing noises within the lens body too easily.  

 


This Dual Pixel AF Compatibility Chart says the gear type 40mm f/2.8 is compatible with Dual Pixel AF. The EF 40mm f/2.8 STM is the first gear type STM lens and I am guessing the chart is not up to date. 

 

This is the first time I have heard that gear type STM lenses are not compatible, and a quick Google search didn't show any for me either. 

 

Where did you hear that gear type STM lenses are not compatible?

 

DPAF chart.jpg

 

 


Mike, I think you may have missed part of my point.  But, first, I did not say I heard that gear type STM lenses are not compatible with DPAF, per se.  Your chart lists a number of lenses that are compatible with DPAF, but that does not mean that they work well in Movie Servo AF mode.

 

I was allluding to my experiences with video mode and Movie Servo AF.  You definitely want to use only select STM lenses.  Your chart is identifying those lenses that will work with DPAF in LIve View mode shooting stills, which does not necessarily translate to working well in Movie Servo AF mode.

 

At the end of this article, Rudy Winston alludes to the fact that STM lenses perform better when shooting video.

https://www.usa.canon.com/internet/portal/us/home/learn/education/topics/article/2018/July/Intro-to-...

But, he does not go into any detail.  “Oh, by the way, you want to use STM or nano-USM lenses when shooting video.”  One major difference is how much noise some lenses make.  Many lenses have surprising noisy apertures, which is easily picked up by the in-camera microphone.  When shooting stills, the shutter typically drowns it out.  So, while the lens might seem quiet when it focuses, many of them are quite audible when the aperture moves.

 

There are only a few STM lenses that can do it all.  DPAF began in the Cinema EOS line.

 

https://community.usa.canon.com/t5/Cinema-EOS-Discussions/C100-MKII-Auto-Iris/m-p/166028#M501

Look at Tim’s comment in this article.  He lists the 4 STM lenses that are compatible with all of the video focusing and tracking features, including auto aperture control and facial tracking.  Remember, this is for shooting video, not tracking to shoot stills.  When you are shooting video, you must maintain focus.

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