Although they appear bright to the naked eye, planets are really very small compared to most DSOs. Saturn is only about 25 arc seconds compared to the many arc minutes that we typically see with DSOs. My Newtonian has an aperture of 210 mm and a focal length of 1,623 mm but even at 100X visually it is very small, I have to go to 235X with my Pentax XW 7 eyepiece before I get an image large enough to really start seeing detail. While imaging DSOs we normally use prime focus which works well on objects that are 20 arc minutes in size.
I have had my best results imaging planets using eyepiece projection which I realize is generally advised against. It can work with right equipment and sometimes a little trial and error, You need to take an Avi video which can be processed using Registax software to remove the effects of the atmosphere. You need an adapter that is specifically designed for eyepiece projection which is available from High Point Scientific at a reasonable price. Well corrected eyepieces are crucial. The Pentax XW 7 and similar eyepieces from Tele Vue will not fit in the adapter and can not be used. I use old Vixen orthoscopics of either 12 mm or 18 mm focal length, When ever you put a refracting element in the optical train there is the risk of chromatic aberation but good quality eyepieces like the Vixens minimize this risk, particularly if you are using an all mirror telescope like a Newtonian or RC.
I have always used a tracking GEM which makes image acquisition much easier but I suppose it can be done with a Dobsonian with a large aperture, particularly if it has some kind of powered alt-az tracking capability, The OP's image of Saturn is very good one obtained with a non-tracking mount.
This is an image I obtained several years ago of Saturn using an eyepiece.
Edited by Stephen Kennedy, 23 September 2019 - 02:13 PM.