5 replies to this topic

[safinsd]

I've been wandering through the Internet for days looking for an answer, no joy. I am taking lunar images with an 8SE using an A7III connected to the rear cell via a t-adapter and t-ring. I want to introduce a TeleVue 2x Barlow into this imaging train.
Two questions:
1. Will adding the Barlow in this case work?
2. If yes, exactly how can I do it and what do I need, other than the Barlow itself?
An image would be greatly appreciated.

[Porkkala]

You need to use the visual back.
Camera: remove the lens, put a camera specific t2 adapter on.
Buy a t2-1.25 " nosepiece, connect that to the camera
Put the visual back into the scope
Put the barlow into the visual back
Put the nose piece into the barlow.

[safinsd]

Thank you! Do you by any chance know if I can use the Televue 2X this way - will it achieve focus with a DSLR? Also, do you have a recommendation for a good Barlow 2X?
Thanks for your help. 🙂

[Borodog]

The A7III is a full frame camera and the 8SE is not coma corrected. You may have noticeable coma, although depending on your presentation scale it may not bother you. Also I'm not sure I would use 1.25" components rather than 2". Depending on the Barlow it may induce chromatic aberration as well; I'm not familiar with the TV 2X.

Edited by Borodog, 16 January 2022 - 09:48 AM.

[Porkkala]

I'm sure you will reach focus, an SCT is very adaptable because the main mirror moves. I don't see any reason why you wouldn't reach focus.
But Borodog is right, with a full frame sensor the result may not be what you expect. Only a portion of the frame may be good enough for you.
If you're considering a barlow, you are probably trying to image details rather than the full disk of the moon. Instead of investing in a barlow, consider investing the same amount in a small planetary camera, with a pixel size of maybe 2.4 or 2.9 microns. The image scale with no barlow will be equivalent to what you'll achieve with the Sony + barlow, but the result will probably be better.

[safinsd]

Thank you. I'm considering both an ASI224MC and a Barlow.