Collimation, sct, some advice for improvement welcome

[Erquy]

Hi!

I have a C8 for 8 months and already did a collimation when i received it (slight correction was needed, not much). Tonight i checked it up at *250 8 mm EP, slightly defocuse, could see it being again slightly off (i hardly see it at *100, only after indeed realized it was off looking at *250). I did not push using my barlow as anyhow seeing was not that good and the ota was not cool enough.

Now it sems next week may be great conditions (best i think since i have the C8): clear skies, low temp, low humidity, no wind, no jetstream,....the moon, jupiter and mars are awaiting!!! (i think i will take my chance to get up early one morning to see mars for the 1st time) and hopefullymy best images (i use a dslr + 2,5 barlow, it works great).

My question is related to the method to get best collimation: would it be at the highest magnification i can through the eye piece (* 625 with the 8 mm ep + barlow if seeing permits or at least at*250 with the 8 mm EP) or would it be using dslr/liveview on laptop (using live view digital zoom + 2,5 barlow and using al's collimation tool is pretty good and convenient and i did use that way successfully in the past). The main issue i can see is that with the laptop, the mag is roughly *190 at max in my set up (the liveview zoom *5 or*200 help furthe, but of course remains purely 'digital' mag, not bringing up sensitivity)

I like the laptop approach as it avoids running around to the EP (especially that i do the collimation visually without diagonal, as i could notice my diagonal induce miscollimation - i have 2 basic diagonal of same design and both give me different patterns , , even at low mag, one is better than the other but still bring some error (same error using different EP). A good diagonal is on my coming purchase list). Also without diagonal, this way also corresponds better to my imaging set up, more critical/sensitive to misscollimation.

I would think it may be more accurate and robust to go visual and highest magnification possible 250 or even higher) rather than being limited to my max imaging magnification (190) for collimation. Also beside collimation, that will give me the occasion to look more on optic quality looking at diffraction pattern at higher mag (i have not been fully satisfied with my planetary images with the C8 as compared to my little wonderful mak102 so i suspect some other issues like spherical aberrations or other). Even collimated and decent conditions, cooled ota etc i sometimes have difficulties to get easily sharp focus on the moon for examples (i never managed to get as good close up pictures of the moon with the C8 as with the little mak (see my galleries with the mak and what i managed on saturn the moon close up but this was good to excellent seeing i have not had chance so far to get with the C8... Hopefully i will know next week!).

As another topic, i may simply have an almost 'perfect' mak102 and a low average c8 quality?

Input welcome, so i go for working out directly the best way possible to finetune my collimation and not wasting my time in experimentation of collimation set up methods (personnaly this is not the part i have funwith in the hobby, i prefer enjoying watching or imaging than tweaking my equipment!)

Thanks for input!