Prime focus vs. Eyepiece projection

[anigakid]

Hello!

My telescope is an 80mm refractor on an Alt-az mount (not go-to). My telescope came with a smartphone adapter, so I have tried some astrophotography. I have attached a photo I took of the moon with my telescope and smartphone. I have a Nikon D5200 and have read that it is possible to do some astrophotography, so am planning to buy an adapter for it. I did some research on the topic and saw that there are two different types of adapters - prime focus and eyepiece projection, each with their pros and cons (One has more magnification, while the other gives brighter images).  However, I need help to choose between these two. I am not fully sure if I want to focus on planets or DSOs. I have done a good deal of planetary observations with my telescope, but have never managed to observe a DSO (except M45 - Pleiades). That could be because I live in a city (Oslo, Norway). It would also be helpful to know how to calculate the magnification and FOV in each of these methods.

My equipment:

1.  Celestron Inspire 80AZ with 20mm and 10mm eyepieces giving x45 and x90 magnifications respectively. Focal length and focal ratio of telescope: 900mm and f/11. 80mm refractor on an Alt-az mount without go-to.

https://www.celestron.com/products/inspire-80az-refractor-telescope

2.  Nikon D5200 DSLR

Hope you can help me with this decision!  

Regards,

Aniruddha