Problem with Bulb Setting on M10 with highest ISO?

[AlexCarey]

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I was trying to get some photos of the Milky Way Galaxy with my M10 (homework assignment), with (B)ulb shutter speed, and my first test shots came out fine after a few ISO and aperture adjustments.  On a whim, I wanted to see how the camera would react at the highest ISO I could select, and try after try, the shutter closed after 8 seconds.  Nothing seemed to fix this, but I had just taken a photo of the "Lucy launch" from Cape Canaveral minutes before, so I knew the "B" setting was working.  I dropped the ISO setting one click, and now the shutter stayed open for a bit longer.

My question is why the camera's shutter speed would care what ISO I selected?  Is this normal behavior, or a flaw in my M10, or a flaw in all M10's, or ?

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[Ba Erv]

It’s normal.  Maximum shutter duration is tied to ISO. 

[Stevejack]

Unfortunately they are terrible for astro.  I was also massively disappointed when I used my M10-M for the milky way,  mainly due to it forcing an equal length exposure for noise reduction.. in RAW... Completely ruins the experience for any long exposure work.

[Anakronox]

9 hours ago, AlexCarey said:

I was trying to get some photos of the Milky Way Galaxy with my M10 (homework assignment), with (B)ulb shutter speed, and my first test shots came out fine after a few ISO and aperture adjustments.  On a whim, I wanted to see how the camera would react at the highest ISO I could select, and try after try, the shutter closed after 8 seconds.  Nothing seemed to fix this, but I had just taken a photo of the "Lucy launch" from Cape Canaveral minutes before, so I knew the "B" setting was working.  I dropped the ISO setting one click, and now the shutter stayed open for a bit longer.

My question is why the camera's shutter speed would care what ISO I selected?  Is this normal behavior, or a flaw in my M10, or a flaw in all M10's, or ?

It’s on page 174 of the user manual.  Though not explicitly stated, the higher the ISO, the shorter the maximum exposure time can be. You can see the results outside of bulb mode by trying different long shutter speeds. 

[SrMi]

8 hours ago, Stevejack said:

Unfortunately they are terrible for astro.  I was also massively disappointed when I used my M10-M for the milky way,  mainly due to it forcing an equal length exposure for noise reduction.. in RAW... Completely ruins the experience for any long exposure work.

Almost all cameras have long exposure noise reduction for raw files. Only a few do not have an option to turn it off.

[Jeff S]

The M10-R and M10 Monochrom provide extended long exposure times to 16 minutes, varying based on ISO settings.  Combined with better low light noise performance compared to the M10 body, these cameras are more capable for Astro photography. I don’t shoot Astro, but there are others who have written about it.

 

Jeff

[Ba Erv]

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This video will help explain the constraints of the ISO/Shutter speed algorithm.  Although the video is directed to the Q2 a similar issue is also seen in the M10.

 

[Stevejack]

I took this as a test shot on the M10M, which was 6sec, f/4, ISO12,500.

I haven't done this in a while and I can't remember the exact shutter vs ISO restrictions now, but I remember being frustrated by the limitations. Your shutter speed is also limited by your lens though (unless you're using a motorised tracker).  At 35mm you really only get 10-12 seconds before you notice the stars move. At 50mm you're looking at under 10 seconds.  If I was using the 24mm summilux I could feasibly be at ~ 20 seconds and lower my ISO accordingly for a longer shutter speed - but it's give and take there. For astro you need to be able to choose any ISO, any shutter speed, and do away with any built-in noise reduction.

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[AlexCarey]

On 12/18/2021 at 10:27 AM, AlexCarey said:

I was trying to get some photos of the Milky Way Galaxy with my M10 (homework assignment), with (B)ulb shutter speed, and my first test shots came out fine after a few ISO and aperture adjustments.  On a whim, I wanted to see how the camera would react at the highest ISO I could select, and try after try, the shutter closed after 8 seconds.  Nothing seemed to fix this, but I had just taken a photo of the "Lucy launch" from Cape Canaveral minutes before, so I knew the "B" setting was working.  I dropped the ISO setting one click, and now the shutter stayed open for a bit longer. omegle  xender

My question is why the camera's shutter speed would care what ISO I selected?  Is this normal behavior, or a flaw in my M10, or a flaw in all M10's, or ?

thankyou