YW , but would like to mention this . As mentioned you will be very limited to use with that 600mm . The majority of objects (DSOs') can be very well captured with your 70-200mm F/4L lens . I've used mine for a lot of my imaging of nebulaes but for objects like Globular Star Clusters which are my favorite I just attach my camera at Prime Focus my Celestron C8 (8") SCT . I manually guide cause I have a 97' scope and EQ5 mount with tracking motors . Not the best but back in 97' or todays time I don't have all the money in Texas , otherwise i'd have some of the best equip money can buy and i'm not college educated . I learned from friends on forums of astronomy only . Retiring from imaging now but still have the erge and interest to stay updated on things and love seeing DSO images that are produced everyday . One forum I visit regularly includes ppl from all over the world and some are top pros that all I do is read there comments but never get involved cause it's sometimes way over my head but interesting reads . https://stargazerslounge.com/ . If I really needed to and you were really deeply interested in getting into astro work and you were physically able and of any age concern i'd probably mention a mount of minimum cost $2500.00 and up and instead of your lens i'd suggest you get a good APO Refractor , a good CCD camera , laptop and editing software but to invest in all that I would be suggesting you spend approx. 8k-10k or more but if that turned out to not be your thing then you'd have to go through the process of selling all your equipment and maybe paying off any debts you accumulated . But that's the reason I don't go into deep detail on things cause it's a hobby to enjoy and share with others and personally I think unless you have a big bank roll as some i'd start out small and build up cause as I said if it's not really your thing and you wanted to get out it's a lot easier to get rid of less equip than high $$$ equipment . SO just sayin I agree make sure it's what you definitely want to get into before you start investing big $$$ . You'll be happier in the long run .
I don't have that kind of money. Good to know that reasonably good results can be had with more modest equipment. Going to do some more research. Can't thank you enough for your help