Gain and Offset settings for ASI071MC Pro - Pixinsight can't find any stars for registration

pdarmody

A friend advised me to shoot with "unity gain" on the ASI071MC Pro, namely gain = 90 and offset = 65. I tried that, but there is so little signal in the FITS light files, even after 300 seconds on a bright target like the Orion Nebula, that PixInsight can't find any stars for registration.

This is my first go with CMOS for deep sky imaging (I am now using Sequence Generator Pro). I am used to DSLR. I understand that gain is essentially ISO. More gain is more signal boost. Not really sure what offset is? Also not sure what a good starting point is for gain and offset for general deep sky imaging, and whether I should be using the native ZWO drivers in SGP or something more generic?

Appreciate any thoughts.

Thanks,

Pat

chad

Hi Pat,

Thanks for your choosing our product.

First, our default value is only our recommended value, but it is not the most suitable for you. So you should use your own setting with your situation.

Second, for gain, yes, you are right, it is like ISO. Higher gain not only increases sensitivity to light, but also results in some noise. This is why the graininess of your image is more noticeable at high gain. So it is not a good idea to increase the gain/ISO continuously.

Third, For offset, it also means birghtness, it will add a value to all of the pixels. In this way, it will increase the brightness of the whole image. And if you are taking the dark field, then you will get lots of pixels which value is 0. But this does not mean these pixels are the same, So we need to add a value(brightness/offset), then this different will be uncover. This is the most important effect for us, and this is the reason why we call it offset.

Thanks

Chad

privateer

I heard the Offset was fixed in the Pro cameras? Is this true?

Also for Unity Gain what Offset would you recommend for the ASI071?

pdarmody

Chad - thanks for the details. This is my 3rd ZWO camera (I have an ASI120MM-S and an ASI290MC also). This is my first time using CMOS cameras for deep sky imaging, and my first time using a cooled camera.

Privateer - I am able to change the offset on my ASI071MC Pro , via Sequence Generator Pro - when I choose one of the "ASI Camera" selections for the camera. I believe these are the native ZWO drivers. I found a good article by Craig Stark that gives some background on this subject

http://www.stark-labs.com/help/blog/files/GainAndOffset.php

It sounds like you are more familiar with this subject, so the article may not be much new info for you, but figured I would share it.

Thanks,

Pat

https://www.astrobin.com/users/pdarmody/

chad

pdarmody wrote:

Chad - thanks for the details. This is my 3rd ZWO camera (I have an ASI120MM-S and an ASI290MC also). This is my first time using CMOS cameras for deep sky imaging, and my first time using a cooled camera.

Privateer - I am able to change the offset on my ASI071MC Pro , via Sequence Generator Pro - when I choose one of the "ASI Camera" selections for the camera. I believe these are the native ZWO drivers. I found a good article by Craig Stark that gives some background on this subject

http://www.stark-labs.com/help/blog/files/GainAndOffset.php

It sounds like you are more familiar with this subject, so the article may not be much new info for you, but figured I would share it.

Thanks,

Pat

https://www.astrobin.com/users/pdarmody/

Thanks, good job.

Thanks

Chad