2600MM light leak

robert-j-strain

I keep getting this ring of stray light that I cannot eliminate through any method. I have tried different scopes, filters, filter wheels, filter masks, OAG and no OAG, and I've thoroughly eliminated any light leaks. That only leaves the 2600MM as a potential source.

Has anyone seen anything like this?

wvreeven

robert-j-strain Do you use the screws to connect the filter wheel to the camera or a ring to screw the camera onto it? Using the screws is a know source of light leak.

Username

I see the same circular gradient when using ZWO's tilt adjuster on my 533MC. I haven't experimented with different combinations of gear though.

robert-j-strain

wvreeven Have tried it both ways - adapter and screws. Still present. Have tried a different brand filter wheel, as well. I have eliminated every light leak I can find with tape or be changing hardware to narrow it down.

I have changed enough and tried enough different combinations that the only common hardware has been the 2600.

Corsair It does not. Not visible in darks or flats. Flats are usually 2-4 sec with a Flatmaster, but have tried sky and regular LED panel.

hyiger I have the rings. Still present.

Corsair

Does it show up on your calibration frames (darks, flats, flat dark/dark flat)?

Kevin_A

Make sure there are no open screw holes on the filter wheel. Put electrical tape over any unused holes to check.

hyiger

The newer EFW ships with black gaskets that are supposed to go between the EFW and the camera and well as the EFW and the OAG-L. You can purchase them separately from ZWO (or other places like Agena)

Kevin_A

I have only seen this type of artifact with optics.

robert-j-strain

Kevin_A I've done two different scopes and it's been in both.

Mapleleaf

Block the exposed motor housing on the back of the EFW (except for the end of the motor spindle itself). It is known to be a source of light leaks as well as the screw holes.

robert-j-strain

Mapleleaf Did that a long time ago.

Kevin_A

Have you tried without all the filterwheel etc… straight to scope flattener? Can you even try a different camera or borrow a friends. In reality a sensor cannot do that, the sensor glass could but not the sensor unless you see that circle when looking at the camera directy. Check any spacers you have kept while swapping the scopes as maybe one tube is internally shiny. I spray all my 21 and 16.5mm spacers with matte flat black on their insides as I have had internal reflections from them.

robert-j-strain

That's my concern ... that it's the sensor glass.

I haven't tried it with no filter wheel, but I have used two different brands, which are internally different, and two different brands of filters.

I have changed every spacer though.

Tech@ZWO

robert-j-strain The left image is a master light that has been calibrated, and the right one is the single light frame without any calibration, right?
If so, can you please do this test? as the ring seems only to appear in the master light from the screenshot.
1 Stack all light without any calibration fields to see if the problem appears.
2 Check the master flat, does it have the ring?

Y5EGDT6T

This is interesting as I am seeing something similar with my new ASI2600MM Pro + 36mm X 7 position wheel. Here is a single 120s light frame, a single flat, and a calibrated master. Ignoring the dust motes, you can see a ring where it is brighter on the outside than inside the ring.

I suspect a light leak, but have not tested this directly with any experiments (will this weekend when I am near my rig). Note that it is largely corrected in calibration (the gradient that remains is probably light pollution) so is not the kiss of death, but it does not seem like it should be there.

Tech@ZWO

Y5EGDT6T Do you use unmounted filter? if so, check the filter mask first.