Hi Doug/Colin. Having used an FW8G with an AOX for a long time, I can distinctly remember being able to set exposures at the 1/1000th of a second and be able to guide on the very brightest of guide stars. For example, with a mag 5.5 star, I could operate the guider at 0.005 seconds and the AO would guide at 7hz. I dont know when things changed, perhaps with a driver update, but I can have a mag 5 star on the guider with an ADU value of 50,000 counts with an exposure of 0.015 seconds, but if I reduce that exposure by just 1/1000th of a second to 0.014, the star completely disappears. Put it back to 0.015 and it returns again with an ADU value of 50,000 counts or so. Is there an explanation for this? If something was implemented in a driver update, I request it be reinstated as I get better results (as you would expect) the faster the AO can work. thanks Martin
Hi Colin. Sorry for slow reply….just back from overseas. Current version of sbigudrv.dll is 4.99 Build 7 dated 2-11-19. The remainder are all dated 1-27-15. Of course, I dont remember the last time it was updated, but clearly its been a few years. I guess you guys have a history of what has changed in each update? Regardless, I would like to get that level of exposure back if possible. thanks martin
OK, no worries. What version of what software is driving this? e.g. MaxIm DL Pro 6.40 e.g. TheSky X 10.5.0 13572 64-bit ?
Hi Colin it appears that my drivers were out of date but it has made no difference. I tried it on Maxim DL v6.30 and SkyX 32bit. I have an identical camera on another scope in Chile which is running SkyX 64bit and Maxim DL v6.30 and will try that. I suspect upgrading to v6.4 will not make a difference? To recap, I can have a star on the guider in the FW8G at say, 40,000 with an exposure of 0.015 seconds. Drop that to 0.014 and it disappears altogether, just 1/1000th of a second less. Is it possible to trace back to where this happened or better still is it possible to update the driver to reinstate this? thanks.
Hi Martin, MaxIm 6.40 has some AO related changes. Details in the release notes: https://cdn.diffractionlimited.com/help/maximdl/Release_Notes.htm It is going to be nearly impossible to trace this issue - we'd have to be able to reproduce it consistently. Those exposure times differences are very short.
Hi Colin nothing to do with the AO, this is the guider in the FW8G. the KAI-340 is capable of exposures as short as 0.001 secs - it says that in your documentation and I have used those exposures in the past but it appears min exp is now 0.015 secs so clearly some driver update has done this. isnt it at matter of updating the driver?
So you've disabled the SBIG+AO and are just using regular guiding with SBIG Universal? I'm confused. AO update rates and exposure times are controlled by a different piece of MaxIm code than regular guider handling. The KAI-0340 CCD sensor is capable of fast operation as it does not require a shutter - it is an interline device, not a full frame device. As far as SBIG drivers go, 4.99 build 7 and 5.1.1.0 are the best of the bunch. MaxIm versions around 6.16-6.20 had a bug that showed up with filter wheel handling if you moved from 4.99 to 5.x. The solution was to update MaxIm. TSX 64-bit may be using a driver installed with TSX. I can ask @Adam Robichaud about that.
There's no reason I can think of that a 0.015 second exposure would work, and a 0.014 second exposure would not. That's pretty weird. Unfortunately firmware/driver maintenance has been discontinued on the older, obsolete hardware. At least there's a simple workaround for the issue...
you are missing the point Doug. I can get faster AO guide rates if the selected guide star is bright enough so I can reduce the exposure time down to 1/1000th of a second. but I can see this is not going anywhere, so mark it resolved.
