I think what you are looking at are not actual lenses, but adapters that screw onto the filter threads of a lens. The sizes are the filter thread sizes of the lens that the adapter fit.
The decimal numbers are "Multipliers". A 2x telephoto adapter would magnify the lens focal length by 2.
The numbers you show essentially tell you the effect that you get if you reduce the lens focal length to that factor. So a 0.45 adapter on a 50mm lens, change the field of view to what you would get with at 22.5mm lens (in theory).
As a general rule, these adapters don't produce very good images. They are promoted as an inexpensive way to get a wide angle lens, and are frequently included in kits from stores selling a lot of junk with a camera.
Tue 25-Jun-13 11:23 PM | edited Tue 25-Jun-13 11:24 PM by four eighty sparky
>As a general rule, these adapters don't produce very good >images. They are promoted as an inexpensive way to get a wide >angle lens, and are frequently included in kits from stores >selling a lot of junk with a camera. > >You get what you pay for. >
Agreed. You'll find out pretty quickly you bought a high-priced paperweight.
As for the multipliers, many are grossly exaggerated anyway. They may SAY it's 0.42x, but it's really more like 0.75x. So instead of turning a 50mm into a 21mm, it turns it into a 38mm.
Save your pennies and get good glass. You'll never regret it.
I hate when people ask me what I see myself doing in 5 years...... I don't have 2020 vision!
I think you are right going back over them there seems to be "macro" adapters in the description that are not in the images.
I'm fairly set on a 24MM f/2.8 nikkor, but I don't know exactly how the focal length plays with the wide angle. I have a 35mm f/1.8 standard DX lens, so i don't really know where to go for a wide angle. it will be used primarily for cityscapes.
I've never used it but the tamron 10-24 but it seams well loved. It is about 500. I've had the nikon version in the past it was about double that. It wasn't without flaws but a good lens. Looking at your setup, I wouldn't be looking at the 24d. You have the 18-55. Go out and shoot with it and get a feel for 24. There is a world inbetween 10 and 24. As far as city scapes go, it really depends on you subject, camera position, and your style. Most the time 10 mm is a whole lot of real-estate to controll, but I'm not saying you won't use it. My ultra wide zoom is one of my favorite lens and doesn't come out of my bag as much as others. The 18-55 you have may be the cheapest kit lens nikon makes but that's not saying you can't make great pictures withit.
I use a Nikon 20mm 2.8 AF lens on my D7000 and am pleased with the results; seems when it drops into the teens images appear more stretched out than I like... sure you can correct in post but that just means less time to get pictures. I would urge you not to spend your money on adapter/screw on lens pieces, at least in my experience, I have had less than stellar results and eventually purchased other equipment.