skimmel Posted May 22, 2015 Share #1 Posted May 22, 2015 Advertisement (gone after registration) Hi, I'm posting this in the M forum although it is based on the Monochrom 246 that I am renting. I assume it's the same between the 2 but maybe not. Anyway, I set AutoISO to max ISO 12,500 and max shutter of 1/125 in A priority. However, the camera will pretty regularly, but inconsistently, ramp up the ISO before it lowers the shutter. For example, it will should a 1/250 or even faster and push the ISO to the max, rather than shooting at 1/125 and keeping ISO lower. Is this normal? If so, doesn't make much sense. (I can also post this in the MM section but that section has a lot more M9-style body info) Thanks. Link to post Share on other sites More sharing options...
Advertisement Posted May 22, 2015 Posted May 22, 2015 Hi skimmel, Take a look here I don't get the Auto-ISO. I'm sure you'll find what you were looking for!
thighslapper Posted May 22, 2015 Share #2 Posted May 22, 2015 The possible explanation of what you are seeing is although the algorithm is forced to work in fixed ISO steps, the shutter speed isn't ...... if you look in the EXIF data the the shutter speed is recorded as the exact speed ....... 1/139 sec etc. This is then rounded up or down to the nearest value that you would normally expect for display. That accounts for why you would sometimes see 1/250 due to whatever leeway is built into the algorithm...... but it may not explain anything higher..... Link to post Share on other sites More sharing options...
FlashGordonPhotography Posted May 22, 2015 Share #3 Posted May 22, 2015 have you set the multiplier option by mistake? You can set 1x, 2x a4x the focal length. Gordon Link to post Share on other sites More sharing options...
skimmel Posted May 22, 2015 Author Share #4 Posted May 22, 2015 Thanks. I have shutter set to a fixed value (not a focal length multiplier) so that doesn't explain it. I am getting some shutter speeds that don't look like rounding: for example, set to 1/60 in Auto-ISO, I'm getting shutter speeds of 1/250. Wonder if this is something about the M246 that needs to be fixed. Has anyone seen this in the M240? Link to post Share on other sites More sharing options...
Luke_Miller Posted May 23, 2015 Share #5 Posted May 23, 2015 Since you are in aperture priority perhaps the higher shutter speed is necessary for correct exposure. Don't have either the 240 or 246, but use Auto ISO frequently with my M9 & Monochrom. I tend to avoid having the camera adjust both shutter speed and ISO when calculating exposure. So normally I will be in manual mode with Auto ISO active. That way I am assured of getting the shutter speed I want. Link to post Share on other sites More sharing options...
thighslapper Posted May 23, 2015 Share #6 Posted May 23, 2015 Ditto ...... Thats how I use auto-iso when I want a particular shutter speed that is higher or lower thal 1/f ......... Then it's all entirely predictable. I have looked at all my low-light shots and can't see any behaviour that replicates the OP's issues ...... Just the rounding up/down factors as mentioned above. Link to post Share on other sites More sharing options...
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