I have had the idea for this thread for a long time. After weeks of lockdown, I am ready to clear my conscience. Before we get started, let me state that none of the gear under discussion is for sale. My buyer's remorse do not go that deep. Not yet...
My biggest regret is a Samyang 85mm f/1.4 in Samsung NX mount. Nothing wrong with the lens, it is near new condition and works exactly as it should. But that is where the rub lies. Let me explain. Before this one, I bought a Rokinon 85mm f/1.4 in KA mount. That works perfectly on my Pentax bodies. The aperture ring has an A position. It does everything that a Pentax KA lens can do. All of the automatic exposure modes work. I could have used it on my Samsung bodies with an adapter but I wanted more.
When the (used) Sammy showed up on the website of a large American website, I pulled the trigger. Shipping was a little slow in the Christmas rush but it arrived in perfect condition. Everything was there, in the original box. The flimsy hood I left in the box. The lens cap was nice, but sadly I have managed to lose it since.
The problem is that there is no communication between lens and camera. Nothing at all. It functions as a manual focus, manual aperture lens. For critical focusing, the drill is the same as the Spotmatic/Takumar combo of old. Open aperture all the way, focus, stop down, adjust shutter speed, take picture. Do not move the camera backwards or forwards during the process or focus might go out. Half a century, where is the progress?
I tried to research the lens before buying, but could find no information specific to the NX mount version. Even the manufacturer's website just stated that NX mount was available and nothing further. I expected it to integrate with the camera as a manual focus lens like the KA version, with all auto exposure supported. As it is, shutter priority and full program modes are off the table. Manual and aperture priority works fine. If you set auto ISO, shutter priority can be used. Focus aids, i.e. magnification and focus peaking, have to be activated manually. How to do this took some internet searching to figure out. It is quite simple. Just press the OK button in the middle of the four way controller. A bit fiddly when one is using the EVF but it works. Focus aid goes away when you half press the shutter button, an old habit that now gets in the way of the work flow.
When I place the Rokinon with K/NX mount adapter next to the Samyang, they are exactly the same size. As it should be, of course. I would have posted a photo, but as this is written during lockdown it would be tricky to take such a picture. There will be a lot of explaining to do about two identical lenses on a table. Let's just leave it at that.
So what have I gained? Not much. I believe that the Samyang has slightly improved coating, being a later version of the design than my Rokinon. This is only a hunch and I don't really know. The Rokinon was bought used and so I do not know when either was manufactured. The Samyang has a depth of field scale that the Rokinon does not have. The latter fits on full frame and crop frame, so they couldn't really put it on.
Now I have two identical lenses. I could liquidate one of them but which one? The K mount is more versatile and works on my Pentax and Samsung bodies. I could sell the NX mount, but demand for dead mount lenses is not great. The K mount might fetch a better price. I just can't make my mind up, so I have not moved on this. For the moment both them serves a purpose. I'm much better at buying than selling anyway.
Please share your tales of buyer's remorse. I have a few more but want to hear from my fellow Pentaxians first.