Planetary Imaging Barlow Problems

[Andy ES]

Thursday  night I was out trying out some more planetary photography (second time actually). I managed to get some good data on Jupiter and Saturn using firecapture. The problems started however when I tried to use the 1.25” x2 Barlow.

I would centre the planet with a high power EP then insert the Barlow and the camera but I could never find the planet again.

Things I tried were:

ensured all the adapters and Barlow and camera were fully locked in the 2” diagonal , using 1.25 adapter.

moved the focuser fully back and forth

ensured the mount was tracking properly

ensured all dust caps removed 🤪

increased the gain in firecapture 

made sure view was MAX not ROI in  firecapture

When I put the EP back in the planet would still be there!

Hope  someone can suggest what might to happening?

Thanks

Andy

 

 

[Cornelius Varley]

The problem is that the eyepiece has a greater field of view than the camera, the planet "looked" centred in the eyepiece but was probably just out of frame with the camera. Instead of using a normal diagonal try a flip mirror diagonal. The camera is attached to the rear of the flip mirror and the eyepiece in a way similar to a diagonal. Using a high powered eyepiece with cross hairs will help you to centre the planet more accurately and then the mirror is flipped up to allow the camera to be used.

[vlaiv]

Use higher power EP and center planet in the field of view. Longer FL eyepieces and wide field eyepieces have large field stop - larger than sensor and you can easily miss sensor if you don't get centering exact. Use short FL ortho to center the planet - that will be much better match to sensor size.

Another trick that you can use - is to defocus planet.

When you start defocusing planet - it gets bigger and at some point it will start appearing on chip - then center it and refocus again.

 

[Stickey]

Hi. This might be teaching granny to suck eggs and apologies if it is,  but you never actually said you inserted the barlow and then used an e/p to centre again. Did you try that? 

Alternatively,  is it possible that the extra length of the barlow and the weight of the camera are slightly misaligning the optical train, such that the target is too far outside the field of view?

Just a couple of thoughts.

[Andy ES]

Thanks for the advice all I’ll try all these suggestions

[Peter_D]

I haven't got around to buying a recticle eyepiece. In my flip mirror, I use a zoom eyepiece and I can progressively zoom in on the planet and have it centered in the camera when I flip the mirror.

[Andy ES]

Do you think it’s worth getting an illuminated cross hairs EP, I think the FLO one is 12.5 mm?

or what is a good flip mirror to use?

cheers

Edited October 23, 2021 by Andy ES

[neil phillips]

17 hours ago, vlaiv said:

Use higher power EP and center planet in the field of view. Longer FL eyepieces and wide field eyepieces have large field stop - larger than sensor and you can easily miss sensor if you don't get centering exact. Use short FL ortho to center the planet - that will be much better match to sensor size.

Another trick that you can use - is to defocus planet.

When you start defocusing planet - it gets bigger and at some point it will start appearing on chip - then center it and refocus again.

 

 

19 hours ago, Andy ES said:

Thursday  night I was out trying out some more planetary photography (second time actually). I managed to get some good data on Jupiter and Saturn using firecapture. The problems started however when I tried to use the 1.25” x2 Barlow.

I would centre the planet with a high power EP then insert the Barlow and the camera but I could never find the planet again.

Things I tried were:

ensured all the adapters and Barlow and camera were fully locked in the 2” diagonal , using 1.25 adapter.

moved the focuser fully back and forth

ensured the mount was tracking properly

ensured all dust caps removed 🤪

increased the gain in firecapture 

made sure view was MAX not ROI in  firecapture

When I put the EP back in the planet would still be there!

Hope  someone can suggest what might to happening?

Thanks

Andy

 

 

Put exposure to 1/30 secs and wack gain up to 80%. After centering with a high power eyepeice. Very carefully insert the barlow and camera. You should see it out of focus. If not keep repeating untill you do. the slow exposure and high gain will show it even if its way out of focus

[Pete Presland]

I do pretty much what Neil has said. I have one of the "filter tabs" with the settings for exposure and gain very high, that way when you add the Barlow you should usually see a out of focus "doughnut" shape in or on the edge of the field of view. I also leave the ROI at max until i have added the Barlow.