Ok, I actually own a GoSky smartphone adapter and I really don't like it. I think you may get better results if the hole in the adapter was bigger. In fact, if you look closely at the adapter hole, it may look like it has some room to be milled out at the factory, but they never did. I haven't tried doing it yet myself.
I own another adapter and it works much better, but the viewing hole is bigger, and it's a friction fit, as opposed to the rotolock-style on the GoSky adapter. That adapter came with my Vivreal monocular, but you look like you need a better universal adapter. I haven't used one of these, but this looks better: https://www.amazon.com/dp/B07JW9KHZ2/ref=cm_sw_r_cp_apa_fabc_P3SbGbA9MQFBS?_encoding=UTF8&psc=1
Also, try zooming in on your phone to get rid of the vignette, which is the circle you see around the image. You may need to use a 3rd party app, such as PhoneSkope, if the iPhone gives you zooming problems, but that is moreso for the iPhones with multiple cameras. Good luck!
Most adapters made for a microscope or telescope will probably work, as long as your phone size is within the supported range. I guess its possible for there to be incompatibility due to camera position, but most of them are adjustable to fit many different phones.
This is the one I have and it works well for me despite its relatively low rating: https://www.amazon.com/Vankey-Cellphone-Telescope-Universal-Microscope/dp/B07JW9KHZ2
At far as getting a live view of the phone camera through your computer, I've never done it but it looks like there are apps to use a cell-phone as a web-cam which would probably work for this case
I just got a cheap cellphone mount from amazon for my 6mm hd Meade eyepiece and it seems to do the trick. Vankey Cellphone Telescope Adapter Mount, Universal Phone Scope Mount, Work with for Spotting Scope, Telescope, Microscope, Monocular, Binocular, for iPhone, Samsung, HTC, LG and More https://www.amazon.com/dp/B07JW9KHZ2/ref=cm_sw_r_cp_api_i_-hGlFb9JQ9Q6Y
Edit: just saw your most recent comment. I also have that issue on my solar telescope eyepieces. Seems the phone is too far from the eyepiece.
I use this one. It works great for me:
https://www.amazon.com/dp/B07JW9KHZ2/ref=cm_sw_r_cp_apa_i_1EXgFb7PK2851
About ten bucks to solve your problem:
https://www.amazon.com/dp/B07JW9KHZ2/ref=cm_sw_r_cp_apa_i_1EXgFb7PK2851
For a phone there are adjustable clamps to hold it to the eyepiece. see here
For a DSLR there's a few options. You could do the same thing as with the phone but that would be unwieldy, though there are adapters and eyepieces that can screw into the front of a DSLR lens. The simplest and probably best for image quality would be just using a 1.25" nosepiece adapter so that the camera is at prime focus of the telescope. here's a Nikon one
This is the one I used. Works well and was dirt cheap
I have this one which honestly is a pain in the bottom to use: https://www.amazon.com/Vankey-Cellphone-Telescope-Universal-Microscope/dp/B07JW9KHZ2/ref=sr_1_4?crid=2CF1UZG3CETZV&keywords=telescope+phone+mount&qid=1642559250&sprefix=telescope+phone+mou%2Caps%2C97&sr=8-4
And this one which is much better to use but larger and more expensive:
Yeah for under 100 you'll be best off with a smartphone adapter I think. If you have a regular 12, you want to use the wide cam (not ultrawide) and if you have the 12 pro you want to use the telephoto cam.
I don't have a ton of experience with different adapters (I'm hoping to do a comprehensive review some day) but I think this style looks decent.
If you feel like splurging some time, I've heard good things about these bad boys but they're fairly pricey.
Glad I could help! I'm going to be making many beginner microscopy tips and whatnot on my youtube channel so pop a sub on that if you're so inclined and you might see something useful for you in the future!
Check out this gadget to clamp your phone to your telescope/binoculars/microscope.
I'm glad to hear you're having fun. Now, get yourself one of these and start showing us what you found.
https://www.amazon.com/dp/B07JW9KHZ2/ref=cm_sw_r_cp_apa_i_nEnvFbPTTHHVB
I've read a lot on this sub that the best camera for amateur microscopists is usually your cell phone. I have a Google Pixel 3.
I purchased this cell phone adapter and it works great: https://www.amazon.com/dp/B07JW9KHZ2/ref=cm_sw_r_cp_apap_zJWxNfzGYSEmO
My setup looks like this: https://photos.app.goo.gl/3EF8h16CA4hm2Jz26
Thanks! I've read a lot on this sub that the best camera for amateur microscopists is usually your cell phone. I have a Google Pixel 3.
I purchased this cell phone adapter and it works great: https://www.amazon.com/dp/B07JW9KHZ2/ref=cm_sw_r_cp_apap_zJWxNfzGYSEmO
My setup looks like this: https://photos.app.goo.gl/3EF8h16CA4hm2Jz26