Unable to select a narrow ROI

[Prasad]

I have been trying out Sol'Ex, the SHG for the first time and my camera is ZWO ASI178MM to capture. To begin with, I want to capture a narrow ROI of the maximum possible width which is 3096 pixels wide, and a very narrow height of approximately 208 pixels. I tried so many times with varying height settings and I always got a dark screen for live view. I would see every frame got dropped. After struggling for two days I discovered that I must reduce the width by at least one click to 3080 width and then suddenly everything began to work. Keeping the width at its full setting simply does not work. Just one step down solved the problem.

Just sharing this strange discovery. I think it is a bug with the ZWO camera. I tried my other camera ASI224MC and it worked fine.

Thanks everyone,
Happy SharpCapping
Prasad

[admin]

Hi Prasad,

thanks for sharing your discovery. The normal rule for choosing the width of the image on a ZWO camera is that it must be a multiple of 8, so 3096 should be fine (8*387), but obviously not in this case...

In theory I could change the rule programmed into SharpCap to 'must be a multiple of 16', but I suspect that the problem you have encountered is a rare issue specific to the IMX178 sensor and if I made that change it would affect lots of other sensors that do work correctly at widths of a multiple of 8.

cheers,

Robin

[Prasad]

Hi Robin

I am not sure but the 8 multiple rule may still work. What I did was use the mouse to click the down button after I had reached the upper limit of 3096 pixels and it brought me to 3080. I may have clicked it twice, but I can't say for sure. Whatever, I know for sure that if you want to select a really narrow ROI then you must not choose a slightly lower width like one or two clicks down. Then only it works.

I am confident it is a bug within the ZWO system. I know how to live with it. LOL

Prasad

[Prasad]

Hi Robin

I have made progress with my Sol'Ex instrument and I have discovered that I would never need to set the ROI at such wide levels like 3080 pixels. I am now setting the ROI to around 1040 wide x 128 tall, etc.

Prasad