piggy back or T-ring?

[danccat]

Soon I'll be getting a mod Canon EOS 1100D for use with my Nexstar 8se... I've already ordered a t-ring which arrived today but I've seen some people take pics without attaching the camera to the scope via the ep bit instead, piggy back on top on the scope? Any reason to this? Are the pic quality better or worse?

[happy-kat]

The camera is not using an EP, if it is piggy backing the telescope it is using the telescope as a mount, so the camera has a lens atatched.

Eyepeice Projecton is if the camera with lens is looking down the eyepeice but that is different again.

[danccat]

Yes, that's right... What I'm asking is, is there a difference to the qualify of photo? I initially thought using the t-bar method would be best, but now I'm unsure. It's for DSOs

[Uplooker]

Depending on what lens you are using you will generally get a wider FoV using the camera a lens, rather than using the telescope as the lens. The quality and speed of your lens will also dictate distortion that you will get. This distortion, known as coma and or flatness of field can be addressed in scopes with a coma corrector, not so easily when just using a lens and camera together.

Ian

[danccat]

Thanks mate

[astrosathya]

Ok, I dont think anyone here has actually explained the procedure correctly. I see that you've modded the camera, but you are quite unfamiliar with DSO imaging in general.

Eyepieces aren't used in DSO imaging. The camera, along with the t-ring is attached to the 8SE telescope at the rear (after removing the mirror diagonal) using an SCT to T-ring adapter. This adapter is necessary because if you use a regular 1.25" nosepiece with the T-Ring you will get severe Vignetting in the edge of the frame.

However, the 8SE is on an Alt-Azimuth mount. You will need to put the telescope on an Equatorial mount if you want to take long exposures of DSO's and do guided astrophotography without any "field rotation" which is a common problem with mounts like the one you have. One other issue is that the legs of the tripod you have are very thin. A small tap on the telescope makes the image vibrate badly. I would recommend a mount no less than the EQ5 GOTO. Specially if you want to do piggyback photography where the camera lens adds additional weight to the already overloaded system. I mentioned above that alt-az mounts have "field rotation". The sky moves east to west in a circle centered around North Celestial Pole(NCP) which is at an angle to us depending on our latitude. The alt-az mount only mimics this "arc" rotation in a combination of minute step like motion. This way, if a galaxy starts off in one orientation in your camera or eyepiece at 8PM, then at 2:00AM it may be in the field, but its orientation would have changed. Equatorial mounts dont have this problem because they have one axis aligned to the NCP. It is nice that you are starting off with astrophotography, but I would advice you read up on all required procedures before you start so that later on while you are actually in the field, you are not confused or even misled. I believe "making every photon count" is a great book to start with. All the best.