2nd of 3 questions - Achieving focus with an Imaging Source DMK31

[uplooker]

Achieving focus with an Imaging Source DMK31
I have tried on numerous occasions to achieve focus on my TAL 100RS PST Stage 2 Mod with an Imaging Source DMK31, all with no success. I even turned a few more millimeters off the rear etalon adaptor, again I had no luck achieving focus. I can see the limb of the sun on the screen, I just can not get focus. I have tried using the tutorial someone posted a while back that told you how to achieve focus using the histogram. No matter what Exposure, Gain or gamma settings I use I can not achieve the “classic” whale histogram, or focus!

Question:
What would be the suggested Exposure, Gain and gamma settings for a TAL 100RS PST Stage 2 Mod and an Imaging Source DMK31 to capture prominences?

Ian

[marktownley]

Gain 260 (minimum), exposure 1/60th sec, gamma 100

[Allcart]

hi Ian, can you get focus on the disc?

[uplooker]

Hi Allan,

No I am not able to get focus at all. I can see the separation between the limb of the sun and space, but no definition

Ian

[Allcart]

Well as others have said, you need to re check your measurements. Does sound like your focus arrangement is too long. I had the same trouble with my first borg helical. I had to change the lenses in the etalon to lengthen the optical train so that I could focus. In the end I changed all the components so that they would work with the proper etalon lenses. Cost me a few quid I can tell ya, but its all fine now.