Originally posted by Lake Good picture of the moon and I really like the explanation of your setup. Please share more, this sounds fun. I should try something similar.
I have a post or two about the technical details. Essentially I've built an adapter out of metal that slides into my 2" focuser. The lens side of my adapter has a repurposed old ring flash part. It's essentially a small piece of aluminum with 52mm filter threads on one side. I epoxied that to my 2" pipe and I can attach my 18-55mm lens directly to it. I also have a 49mm-52mm step up ring and I have a 55mm-52mm adapter as well.
I've ordered a 77-52mm step down for my 14mm. That's where I'm unsure if it'll be ok; quite a large step down, but might be able to get it working. We shall see in a few days.
It's not enough to just attach the camera though. While this works visually the camera ends up seeing a huge portion of the tube and the image circle is small. So i had the idea of using extension tubes to push the focus distance of the lens waaaayyy forward, and it worked. If I had more extension I wouldn't need the 2x converter. But essentially I found that the further forward the focal point was pushed, the less the vignetting was visible but also got more magnification from it as well.
If you did the math, 72mm of extension tubes on an 18mm lens would probably push the focal point near the camera body. It wouldn't work if you were to try this as a macro setuo because the subject would come to focus inside the lens tube. I figured though as light is the subject in this case, it can come to focus behind the front element of the 18-55mm lens. Im sure I'll hit a limit of what's possible. I'm sure too wide will push the focus point beyond the sensor. But it's been a fun experiment.
Oh, if you do use a 2x converter, it has to be at the body of the camera. Anywhere else and it causes the image circle to be waaaayyy smaller.
---------- Post added 02-04-2020 at 07:59 PM ----------
Originally posted by SSGGeezer Edge sharpness versus center of the frame for one! At least if an older 14mm.
It's more the fact that I have to step it down from 77 to 52mm. And then being 14mm, it might not be able to come to focus. There is a chance that my focus point will be pushed past my sensor.