Tried photographing the Earthshine today.
This is a stack of 5 frames, each with a shutter speed of 6 seconds and ISO100. No dark frames. Aligned them manually in Photoshop and edited in Lightroom.
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Hi @siva great shot. I was also spending 3 hours observing moon. I was unable to shoot the full disk of moon using the 8" dob. I’m connecting my Nikon dslr with 2x barlow only to view magnified view but not the whole disk. Any suggestion on how I can get full view?
Tried without the Barlow?
Yes, but I’m unable to focus anything without barlow. When I spoke to tejraj they said I need to try reducing the focal length either by reducer or by moving the primary mirror further in. When I spoke to @Venkatesh_Rajamani he said he uses a phone adapter which can be placed on top 2" eye piece.
Okay, what’s happening here is that the light from the primary mirror is coming to focus at a point below the minimum draw length of the focusser. Normally when you use an eyepiece this would work but since your DSLR has no focusing elements (as you are mounting only the camera body) this is causing issues. When you use a Barlow, the effective focal length of the telescope changes(2x Barlow means twice the focal length as normal) and as a result the light rays come to focus in a way it works for your DSLR. This is a common issue with dobsonians and reflectors in general. I can give three suggestions:
- Continue using the Barlow and sacrifice wide FOVs
- Push the mirror inside as Tejraj suggested. I wouldn’t really recommend doing this to a brand new telescope.
- Get a new focusser that has a low profile. Something 2-3 inches shorter than your existing focuser could work.
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Appreciate your detailed explanation. I see what is going on here. Interestingly I found these in tejraj site. Please let me know if any of these options work.
- Focal length reducer
- Eyepiece with T adapter to connect cameras
- Prime focus adapter (guess I can connect camera without barlow for photography)
Prime focus adapter
I don’t think this will be helpful. You need to connect this with a T-ring and then to the camera and drop it in the focusser. This is just an adapter so the backfocus is going to be the same. You will not be able to achieve focus even if you remove the 2 inch to 1.25 inch adapter that’s attached to the focusser as it’s only about 5mm thick(at least in my case). I would recommend you to remove the 2 to 1.25 inch adapter, push the focusser as downward as possible and just hold the DSLR next to it. If you are able to achieve focus(I don’t think you will), you can consider investing in this.
Eyepiece with T adapter to connect cameras
Why not just get a phone adapter? Unless you get a tracking platform for your telescope, you will not be able to take anything other than planets and the moon anyway.
Focal length reducer
I am not sure why Tejraj recommended this for your case. Your issue is because of the light rays getting focussed at 20 inches(for example) and your focuser being 23 inches(for example). If you use a .5x reducer, they will get focussed at 10 inches which means the focus is now more inside your scope than before. This will only make your issue worse, not better. I would suggest talking to Tejraj about this and see if there was some miscommunication here.
Got it. I’m not a big fan of clicking images on cell phone (I prefer my camera). Let me talk to Tejraj and explore what other options I have. Thanks @siva
Hi @siva. I found in youtube about attaching eyepiece adapter and then connecting camera. Will that work ?
