Many stars to bright for my set-up?

I run the V-curve first light on my Esprit100 with a ASI071C camera without a problem.
Recently I rigged-up my 10" f4 Lacerta newton with a ATIK16200 camera.
When I now want to do a 1st light V-curve I need to set my 7nm Ha filter and even then the exposures are 0.4 sec. The minimum exposure of this CCD camera is 0.2 sec.
I use the default settings.
When I set the Lum filter, the star image is over exposed (flat top) and Robofire can’t make any sense out of it and keeps endlessly on running in one direction until I get a message about the algorithm being unable . . .
How do you guys handle this?


Hey Arie,

I’m not sure I can help much, but, did you set up your focusing star magnitudes in the filter window? You’ll probably need to raise the magnitudes to 6 - 7 (I think this is as high as you can go, not sure) for your broadband filters. Maybe try to do Ha at 3 - 5 or so. Sorry I can’t be more of a help but I’m sure someone will chime in with some useful advice!


Not use the HA for vcurve, you must use luminance like always. Change the mag to 6-7 like suggested from Mark for the luminance filter but first of all change the flux. Between a CCD and CMOS there is a lot signal on plus on CCD in terms of flux and also the resolution higher the flux more and more. So change the Max flux from 500 to 5000 or 10000 this depend on flux generated by your system under the star flux parameters and activate the smartflux flag to help Voyager detect the right way:

you can read flux value on the dashbaord of autofocus just over the framing drawing and under the peak value, this number is complete , the Max Flux in setting like written is divided by 1000 so the correct evaluation:

There is nothing wrong in RoboFire , just try to get the right HFD and flux value for some tries before exit for error, the reason for exit is written in red. Voyager not calculate the focus parameter at focus so if star is satured doesn’t change anything in term of result.

Like always if you want direct support i will happy to help you.

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Thank you Leo.
I know I could have asked you directly.
We can approach you 24/7 and always receive a answer.
That is why Voyager users are so loyal.
But by putting it in the forum, there might be some learning value for other users too.

I have no understanding of these flux values and how much they should or can be.
It would never cross my mind to increase a maximum value from 500 to 5000. Or even 100.000
10x 20x as much. But I will try again at the next opportunity.
I understand that the software is ok, because it worked ok at default values with my Esprit100 telescope at the first attempt.

So the idea is to set the LUM filter and run a initial V-curve again with the current settings.
This will then fail.
Then read the flux value from the displayed window and set the max flux to higher value than this?
Then run the V-curve again with the new higher value for max-flux.
Can I pick any star, or should I aim for a Robofire selected star?

Clear skies are not often at the moment.


Support is incuded in price … so this is really difficult to explain.

Anyway flux quickly and dirty is the sum of ADU values of each pixels where a star spam. More is higher resolution more pixels a star will use bigger will be the flux, more is the ADU value of the pixel more is bigger the flux, more you are oversamplex more bigger is flux. The good thing is that the flux at focus or out of focus condition is the same … this is the reason HFD is not really too much affected from satured star out of focus (Vega or similar star apart) and focus work fine. HFR is not good because use half star and dont mind about star shape with a big final error. Voyager use AI to reconstruct you usual stars and clustering for evaluate it and learn the neural network.

So your stars in new telescope span more an more pixels than before and with higher signal (CCD is more clean and efficient than a CMOS).

Fix the mag interval, and leave voyager to find star with green button and run wizard.
If you dont solve not continue in circle … ask support. AP is not easy … and if a program promise you to be easy and with few parameters to setting mean that someone (developer) have choosed them for you … be sure this one is a good AP !

There was a moment of clear sky tonight.
After increasing the max flux to 5000 and setting the star magnitude for LUM at 6-7 and letting Voyager select a star, I was able to create a 1st V-curve. Still saturated, but the curve developed ok this time.
Thereafter did a few focus runs on a star and a field. Both were successful.

This what I have:
Lacerta 10"f4 newton.
Lacerta MFOC focuser controlled by UPBV2
Atik16200 camera