3 replies to this topic

[Aljo2345]

Hi,

Requesting advice from anyone that may be able to assist me. I am getting severe coma-like halos, off centre when trying to image with my Mak 90mm coupled with my Nikon D750 at primary focus via the native T-adapter. Any advice that may assist in resolving the problem would be greatly appreciated. Please excuse the poor focus and tracking in the attached image-test pics.

thanks very much Alex.

Attached Thumbnails

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Edited by Aljo2345, 29 March 2024 - 05:17 PM.

[RichA]

Hi,

Requesting advice from anyone that may be able to assist me. I am getting severe coma-like halos, off centre when trying to image with my Mak 90mm coupled with my Nikon D750 at primary focus via the native T-adapter. Any advice that may assist in resolving the problem would be greatly appreciated. Please excuse the poor focus and tracking in the attached image-test pics.

thanks very much Alex.

I've got the same thing with an Orion Mak.  You don't see the flaring with the eye on astronomical targets (but a camera would show them up for sure), but you clearly see it at night on terrestrial lights.  Because it only impacts "land" objects, I've ignored it, but it could be due to some kind of issue with the inside of the baffle tube.  Though it is blackened, you can see (if a bright light is coming into the scope) the ribbed bands of the inner part of the baffle tube reflect/refract light as glances off the sides.  They may have been better-off leaving the inner baffle smooth so the "peaks" of the ridges wouldn't do what they are doing.  Mind you, this is just a guess.  I might fit the baffle with some black paper to see if it has any impact.

Edited by RichA, 29 March 2024 - 07:48 PM.

[Aljo2345]

I've got the same thing with an Orion Mak.  You don't see the flaring with the eye on astronomical targets (but a camera would show them up for sure), but you clearly see it at night on terrestrial lights.  Because it only impacts "land" objects, I've ignored it, but it could be due to some kind of issue with the inside of the baffle tube.  Though it is blackened, you can see (if a bright light is coming into the scope) the ribbed bands of the inner part of the baffle tube reflect/refract light as glances off the sides.  They may have been better-off leaving the inner baffle smooth so the "peaks" of the ridges wouldn't do what they are doing.  Mind you, this is just a guess.  I might fit the baffle with some black paper to see if it has any impact.

Thanks for your reply Cosmos. I am thinking the same

[DAVIDG]

  Look at the diameter of the baffle around the secondary spot on the corrector. I have seen them be smaller then the spot itself. This leaves a ring of the reflective surface outside the baffle.

 

 

                         - Dave