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ISO setting help



I have a Canon 40D, and I'm able to go into the menu and increase the ISO setting in the camera to "HI" (3200), however, once I've done this BYEOS does not allow me to increase the ISO past 1600.  Is there a way to get the program to recognize this adjustment so I can shoot at 3200?




Mike (Doc Blues)

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BYE only knows about those ISO settings that are reported by the Canon SDK.


That said, I also believe that BYE also caches those values for performance reasons.  You could try enabling the high ISO value(s), then go into BYE's Advanced Settings screen, Delete the Cached data and then reconnect to the camera.  If the Canon SDK gets the list of ISO values from the camera you may then see the high value, if not then you won'.


It may be worth a try.

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I'm wondering if " enabling the high ISO value(s)" in the menus is the key, and maybe different from "increase the ISO setting in the camera to "HI" (3200)".


I know with my T3i(s) that enabling high ISO values in the function menus allowed BYE to see it (12800). I think there might have been a few different settings that were relevant?




ISO expansion should be on

Highlight Tone Priority must be zero 

High ISO Noise reduction, should be off


Make sure your camera is set to manual. if in ISO AUTO it will limit the ISO range.


Again, that's for T3i. Lookup "ISO Expansion" in your Camera manual index.

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Unless you are Imaging under Unusual Circumstances, you probably won't want to utilize the HI ISO setting - it really does NOTHING for the "Sensitivity" of the Camera but instead Amplifies the existing Noise PLUS adds more...


The best approach to AP Imaging isn't to try for "Visibly Bright" Images straight out of the Camera, but rather to Collect Good Data and then use Astro Image Stacking software to combine those RAW Images and then use Stretching Techniques to "Lift" the Brightness and Color to appealing levels...

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The high iso settings are very useful for:


Rapid plate solving with AstroTortilla (1 to 10 seconds depending on how dark it is)

Previewing for rough focus prior getting on a bright star (a prep step for AstroTortilla)

Focusing when a bright star isn't available

Quickly determining the proper exposure for the iso you will actually use for your sub exposures


E.G. I use iso 1600 for my sub exposures. So that is 4 iso stops from 12800. I try different preview exposures @12800 until the histogram looks good. Typically 60 seconds for my setup. That tells me I need to expose for 480 seconds @ iso 1600. 8*60=480. Multiply the exposure by two for each iso stop between your H iso and your sub exposure iso.

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