8 replies to this topic

[Charlym]

Hello, 

 

I've noticed my stars turning from red to blue using due heater strap on my Zwo refractor using a 2600 MC AIR camera. I thought first it was a colour calibration change in the ASIAIR monitoring but it's in the raw fits files...

 

Do you have any idea why it is happening ?

 

I share some pictures showing the effect.

 

Thanks to all.

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[pyrasanth]

My thoughts would be your dew band is on too high a setting causes the optical elements of the lens to change. Try a test with the dew band turned off then gradually increase the temperature. It might be worth you looking at a dedicated controller to keep the optics temperature just above the dew point. Other issues noticed in this scenario can be spikes around brighter stars.

[BucketDave]

Is it me, or does the image with the redder stars have slightly less detail in the galaxies? I'm thinking it's not a problem with the scope, just that the sky transparency changed while you were imaging. If there was more scattering of blue light that would enhance the reds.

Dave

[mayhem13]

Not enough info to put it on the dew heater but some possibility.

 

Acclimation maybe 

[Charlym]

Thanks for your answers,

 

I've just heard from a ZWO technician, indeed it is linked to over heat, that shifts the optics and colour.

Will look for a dedicated controller or put the strap more on the edge of the dew shield, and farther from the optics.

 

Thanks again guys!

[KGoodwin]

Thanks for your answers,

 

I've just heard from a ZWO technician, indeed it is linked to over heat, that shifts the optics and colour.

Will look for a dedicated controller or put the strap more on the edge of the dew shield, and farther from the optics.

 

Thanks again guys!

You will probably cause poor seeing in front of the dew shield if you move it up to the end.  It also won't do much good for heating the lenses there.  You definitely want a controller.

[Marshalll]

Reminder that you really only need to heat it up to just above ambient.  If its warm to the touch its too warm. 

 

Interesting to know though that dew heater can do that.  Dew heaters seem to affect different optical system differently lol.

[michael8554]

The heater is speeding up the incoming photons, causing Blue Shift.

[Charlym]

Thanks, all your comments make perfect sense