[astro744]

You have a good spread of magnification if you include the Barlow. What do you feel you are missing with the eyepieces you have? Perhaps a larger apparent field than Plossls provide or do you want a larger true field of view?

I would presume you have a 2” focuser so perhaps a long focal length 2” eyepiece between 30 and 40mm with an apparent field 60-70 deg. to give you both a larger apparent field and maximise your true field of view. Note exit pupil is 8mm with the 40mm at f5 so only good for dark skies. As a low power finder eyepiece do not be too concerned about the large exit pupil but it will give low contrast under light polluted skies. Something around 30mm is better for your telescope to keep the exit pupil down a bit but you lose out on true field unless you go to say 80 deg apparent field. A few years ago the cheap 30mm/80 deg eyepiece was very popular (may still be) but note none of these cheap offerings come close in performance to something like a 31mm Nagler but of course none come close to the cost of the Nagler (yes the Nagler is worth it). I’m not familiar with what cheap offerings are available in 30/80 these days so perhaps someone else can help you here. This will give you greater apparent field and greater true field to complement your current selection.

Note eyepieces are not required for prime focus photography but are required for eyepiece projection (high power for planets) which just about no one does anymore favouring video capture with Barlows or Powermates and small chip cameras. You can use longer focal length and long eye relief eyepieces for afocal photography (digiscoping) but again this is not normally done with a DSLR but rather a mobile phone.

Your Skywatcher may have come with a 2” adaptor with T-thread in which case you only need a T-ring to match your camera brand. If not yes you need a T-adaptor with a 2” nosepiece one end and T-thread the other end and then a T-ring to match your camera brand. Don’t bother with a 1.25” T-adaptor if you have a 2” focuser as it will only vignette.

Edit. If your telescope is f6 then 40mm eyepiece for low power finder would be fine, (dark skies still better for contrast). Exit pupil=eyepiece focal length/telescope focal ratio.