3 replies to this topic

[gokidd]

Hello, folks.

I get wildly different estimates of sensor tilt when examining a FIT sub-exposure in Siril versus ASTAP. This is a sub-exposure, not a stacked FIT.

Both Siril and ASTAP are the most current versions.

Siril indicates only a mild tilt. ASTAP shows a horrifying convoluted graphic not even recognizable as a square.

In case it makes a difference, my setup: Celestron EdgeHD 800; Celestron OAG with ASI174MM for guiding; ASI2600MC-P for imaging; AM5 mount; coordinated by ASIair Plus.

As far as the final images being produced, I am pretty pleased with the setup. It's still early times with this rig.

Does anyone have specific experience with the sensor tilt estimates being so radically different in these two programs?

 

 

[Robert7980]

None of them are accurate, I just use them to get get an idea about what I actually see in the images, if what you see and what the software says tend to agree then it’ll help. It will be unpredictable once you get below a threshold… So my experience is the same, just take the number with a grain of salt… 

[fmendes]

ASTAP has two methods: triangle and octagon. The second also measures back focus. A correct back focus should appear as a square; what you're seeing is (probably) both tilt and wrong back focus. Sometimes the triangle gives great results but the octagon shows bad resutls. I never saw the triangle with bad results and the octagon with good. But note that results also depend on the tracking. With less precise tracking, tilt may be all over.

[gokidd]

Thank you, gentlemen.

I looked again. ASTAP says my tilt is in the range of 50 percent! Siril says 4 percent. That is really a huge inconsistency in results between the two programs.

 

Felipe, thanks, I looked in ASTAP at both the hexagon and the triangle. They pretty much agreed with one another.