Extraneous light

[Guest]

I was just trying some things out on my SW 200PDS in my shed in the daylight with the cap on the scope. I had a canon 450d camera fitted and using APT to take some pictures. I noticed that there was a fuzzy light patch in the pictures. So I covered the viewfinder on the camera, disabled the LCD display but still there was this fuzzy light patch. I put a coat over the end of the scope, covering the camera too. Still the fuzzy patch. Eventually I took the camera out and looked through the focuser tube.  It turned out that the light was spilling around the main mirror at the bottom of the scope. So I wrapped something around that, tried again and  my fuzzy patch was gone. I don't know if this has ever caused a problem when I'm actually observing at night but I do wear an LED headlight which is normally pointing down. I'll be more careful in future.

[Clarkey]

I think this is a common problem on the newtonians. I have a piece of expanded polystyrene cut into a disc which fits perfectly in the 'hole' and blocks out the light. It also holds in my home made primary dew heater, so does 2 jobs. A flowery shower cap might look nicer though🤣

[Guest]

Yes I'll try that. I did wonder if it might have spoilt my bias and flat frames since I made those in daylight. Obviously for the bias the scope was covered but not at the bottom.

As an aside - I have an HEQ5 and I've got my eyes on a Stella Lyra RC8. How do you find them in combination?

Steve

 

 

[Clarkey]

To be honest I have never used the RC8 on the HEQ5 - I use the AZ-EQ6 for it. I think the total weight of the scope, camera and other kit would be too much for the HEQ5. I think the RC8 ships at 11Kg which is the limit for AP on the HEQ5.