If your considering one of these cheap ebay wide angle adapters from ebay here is some reading material!
There have been other threads about this. But then there have been other threads about nearly anything you find here. So I wanted to give my personal experiences.
I watched a series of youtube videos on these $18 super wide angle adapters. Most of the youtube videos I saw supported them as a good idea. One video in particular showed how you need to get a SHORT adapter to keep the dreaded black barrel look from your pictures. It showed that there were many models on ebay. And the lengths varied. MOST were longer with 2 "lenses" (more like filters) on either end of a machined tube. Supposedly you could remove one of the lenses and it became a macro adapter.
I watched several of these videos. I went to ebay and found the longer adapters all over ebay, and the shorter ones were VERY difficult to find. Fee-bay has successfully ran off all the old timer sellers, and replaced them with chinese importers. Heck ebay in general has basically become one giant Harbor Freight. So even when I found what I was looking for it was difficult with stock photos to determine if it was a short tube or long. Because with the chinese based sellers "actual product may vary form picture".
Then I came here and read horrible reviews about these on the forums. I figured... "Ehhh 18 bucks... lets have some fun!"
So I bought one for my Pentax K-x.
I tried the famous youtube trick where you look through the viewfinder of your camera and then while looking slide the adapter across the front of your lens revealing a much wider picture.
Did it work? YES!!! I now had more of my tiny little office in the picture than I had with my 18mm stock lens. I tried the macro trick. Did it work? Not for me. It didnt really look any worse. Or any better.
So I screwed this adapter onto my stock 18-55mm Pentax lens and took it to Disney World for a fun filled week in the 97 degree heat.
I took approximately 2000 pictures that week. I rare ever preview pics, as it eats batteries. On the rare occasion that I previewed them they seemed to look great. I got all the super wide fisheye shots that I wanted. I was quite pleased with my purchase.
TILL I GOT HOME!!!
Upon closer observation i had about 1800 pictures that I would consider "3MP point and shoot" quality. Were they useable? Yes. Were they pictures I'd post on a forum and say "Look at this!"? HECK NO!
I had about 20 pictures that were simply amazing. Here's the funny part. One one particular day I slipped the adapter off to get some tele shots and forgot to put it back on. EVERY ONE of the pictures that were "great" were during that evening.
EVERY ONE of those pics were taken WITHOUT the super wide adapter!
Ok so I messed up and lost a whole week of vacation pictures. We do Disney like 3-4 times a year, almost every other year. Its no biggie. We already have THOUSANDS of disney pics as well as DAYS worth of camcorder footage. IF however, this had been my first trip I would have been DEVASTATED!
So in closing here is my review. Should you buy one?
Yes and no.
If you just want to squeeze everyone in at the family reunion, and the pictures will probably be used on some low resolution website or lo-res screen presentation, then YES!
If your wanting to snap a picture to post a picture of your house (that actually includes your ENTIRE house, as well as your yard) on a standard sales magazine or website, then YES! It WILL do the job!!! It will give you the wide angle shot your after.
If you want to use this for wide angle shots that you can show to friends or post on forums as "spectacular" or even "decent", then NO!!!!!!!!!
These adapters, no matter how clean. No matter how well used will give mediocre pictures at BEST! They WILL do what they say, but don't expect the quality of even the most generic kit lens. This adapter will NOT give you better macro. At least it doesn't for me. And even though I shopped excessively and I specifically bought a short lens adapter, as advised on youtube, I still had the dreaded black barrel shadow distortion. When I toned it out with a twist of the lens, I still had a much wider picture than with stock lens alone, but at full wide, it was black on all 4 corners and it was NOT minor.
So I will not tell you not to buy one. I will however tell you they will offer a wide angle picture at the sacrafice of the picture's quality. they WILL degrade even the cheapest kit lens.