Piggyback setup or not?

[haldafluke]

Assalamualaikum & Salam Sejahtera,

While imaging with my setup, I wonder if piggybacking a camera on top of the OTA will be worth it.
My primary imaging setup will be a 60D + Flattener IV + Megrez 90. While this has provided some zoom to the sidereal objects, I would also like to explore the widefield by piggybacking a 5Dii on top of the tube + 50mm lens.

1. My question now is that, how bad will this 50mm on a fullframe be affected by this field curvature + severe light falloff ? I haven't had the chance to try that yet. I am just trying to find out whether that is worth a try technically.

2. This brings me to my next question on what are the option to shoot from a full frame without having to accept the fact that stars on the edge are oblong and vignetted?

Terima Kasih Daun Keladi...

[mymoon]

you mean similar to this

but then you need a guider scope. if you don't have better try with a piggy back 50mm guider scope. you can take many 30 sec shots like saudara redzuan's M42 and stack them. More bang for the buck. 

maybe you are thinking like this . The black mount is a clone of  EQ6.

Full frame Canon 5D2 with  50mm. Most agree than best performance to price for 50mm is the Sigma f1.4 followed by Canon's from 1.8 to 1.4 to 50mm f1.2L. Nikkor's wide angle are superior so best if you seek Nikkor Ais and get EOS adapter

I have seen images using Sigma lense. Google and here is one.

 If there is coma and corner softness I don't see any.

Canon 50mm f1.8 is cheap. So why not try. Add to total sum of knowledge in amateur astronomy. 

cheers

[redzuan]

Waalaikumussalam,

Piggyback-ing a camera on top of the OTA shouldn't be much of a problem, considering ur using quite a heavy duty mount. Just make sure the balance is done prior to imaging with the complete full gear attached.

I am not so sure about Canon's Full Frame but from Nikon, you do see small falloff as you reach the edges when wide open. But stopping it around 1 stop or more makes it better. And to make it even better you can do FLATS to cure it (stacking helps too). Or use GradientXterminator (shortcut), if u don't have the time. To be honest, I wouldn't worry about it at all. Minor flaws like that most of the time are not so obvious, and can always be fixed.

And I do agree with Pak Aziz that the lens is cheap, but worth every penny. The Nikkors are good options too. Samyang makes some good manual lenses as well, like its 85mm F1.4.

And my personal experience, don't shoot too wide angle when piggybacked. It is hard to frame things especially when you will get some minor obstruction and done in the dark.

Lets do some sessions together shall we? Maybe the Planetarium is a good place.