Shutter speed seems slower using auto ISO

[Stevejack]

Advertisement (gone after registration)

I was experimenting tonight with my M10-R and when I set the camera to auto ISO, shutter speeds between 1/15 and 1/125 or so sound audibly normal - i.e. the shutter sounds as if it’s opening / closing for the chosen duration. 
 

However, above 1/250 sec the shutter sounds like it’s staying open longer. For example, if I choose 1/2000sec, f/2 and auto ISO (range set to up to 25000 ISO) the shutter sounds like is opening for around 1/4 sec.... but the exif readout on the LCD and the image itself looks correct. 
 

when I manually select the ISO (say 12500 ISO), and then fire the shutter, all speeds over 1/250sec sound audibly correct again. 
 

Does anyone know what’s going on here??

Edited January 6, 2021 by Stevejack

[chasdfg]

I experience the same with my M10M at high ISO (not just Auto ISO at high ISO values), e.g. iso 50k, 100k. I found it quirky at first as the shutter speed, even at 1/4000, sounds too slow for what it should be. But the image would be captured as per normal i.e. reflective of the faster shutter speed, no motion blur and the exif would record it accurately as well. Only the sound is odd. It's not as if the camera is overriding the shutter speed dial and actually capturing the shot at a slower shutter speed.

I got used to it and never bothered to find the answer. I suppose one could unmount the lens and see what might be going on. Curious to see what's up if anyone has figured it out though.

[farnz]

Are you certain that you're not actually hearing the shutter re-cock?  

The shutter itself doesn't open and close as such, but the shutter 'speed' is varied by the width of the slit that's left between the first and second curtain and the shutter always moves at the same speed irrsepective of the camera's 'shutter speed'.

Pete.

[astrostl]

It's the same on the base M10. If anyone wants to try it, simply set your M ISO to the camera's limit. Take a shot at 1/250s at ISO 6400 then again at M, and you will notice a profound difference in how it sounds. I imagine it's something to do with exposure reading or potential noise reduction.

[adan]

I get an extra lag sometimes between the shutter closing and the wind-on - 0.5 second or so.

At shutter speeds that are already slow (longer than 1/24th sec. or so) - and with Auto ISO (and Auto shutter). Like a clickclick...click. It is clear the total "interrupt" is at least double the nominal shutter speed.

It has not caused any picture problems, with either of my M10s.

So generally I just ignore it - and have not wasted time trying to analyze it more deeply. It may or may not happen with faster speeds, or with manual speeds.

I've just kinda assumed maybe Leica added in an audible delay so that photographers don't move the camera too soon after longer hand-held exposures.

Or - ha-ha - maybe it is there to simulate the clickclickwrrrr of the clockwork M shutters' timing reset at 1/8th and 1/15th.

[Toastybunzz]

Odd, I don't notice any difference in shutter sound in manual or auto exposure on my M10. 

[Dennis]

Advertisement (gone after registration)

On 1/6/2021 at 5:22 AM, Stevejack said:

For example, if I choose 1/2000sec, f/2 and auto ISO (range set to up to 25000 ISO) the shutter sounds like is opening for around 1/4 sec....

Are you shooting using Live View? Because it sounds exactly how you say.

w/o LV, you shouldn't at all

[astrostl]

On 1/6/2021 at 10:08 AM, astrostl said:

It's the same on the base M10. If anyone wants to try it, simply set your M ISO to the camera's limit. Take a shot at 1/250s at ISO 6400 then again at M, and you will notice a profound difference in how it sounds. I imagine it's something to do with exposure reading or potential noise reduction.

^^ has anyone done the above, specifically? I can reproduce it easily. Not Live View.

[Dennis]

48 minutes ago, astrostl said:

^^ has anyone done the above, specifically? I can reproduce it easily. Not Live View.

You're absolutely right. Until 20,000 iSO is fine. But from 25,000 is looks like the SS is 1/15s

I didn't know about it cause my limit is 10,000. My M ISO is set at 10,000

[astrostl]

1 hour ago, Dennis said:

You're absolutely right. Until 20,000 iSO is fine. But from 25,000 is looks like the SS is 1/15s

I didn't know about it cause my limit is 10,000. My M ISO is set at 10,000

I find it interesting that it sounds very slow, but if you set it to 1/1000 and chop your hand in front of it you'll see that it does "freeze" as expected.

[Dennis]

To be honest, not shooting more than 10,000 iso I'm fine like this. But it's  good question to ask to understand the WHY

[Stevejack]

6 hours ago, Dennis said:

Are you shooting using Live View? Because it sounds exactly how you say.

w/o LV, you shouldn't at all

No that's the thing - this is just using the rangefinder. You're right, it sounds just like how it sounds in live view though. 

So after some more testing, the issue is limited to ISO25,000 and was only occuring because I had my auto ISO set to max out at 25,000 and was using large shutter speeds. 

Any shot that's ISO12,500 and below sounds as expected. It's just odd because the only reason to use ISO 25,000 (for me) is to try to get a higher shutter speed in low light, so when the sound of the shutter sounds like 1/15 sec it throws you off.