There's quite a lot of amateur wedding photographers both canon and nikon using an 18200. Of course you can use it especially if you're doing it alone & with only one camera body.
Some people might disagree and say normal lenses "
can't bokeh enough" & that the famous Tamron 1750 2.8 is a better "wedding" lens than the Nikon 1855VR / 18105VR or 18200VR. Been there done that.. got so pissed at my Tamron 1750, I sold it off after just a few months. I got the built-in-motor version before the VC came out..the motor is damn slow to achieve focus, even the cheap 1855VR is faster to get a focus lock.
For me, the ability to take interesting camera angle, pose, capturing important & memorable moments etc2 are more important than bokeh. I got a friend who used just an 18200 but his wedding shots are so nice it can easily beat most amateurs with 1750 2.8. The 1750 has constant f/2.8 but dont be fooled to think you can shoot wide open at f/2.8 for portraits/weddings. Bokeh is nice but the sharpness is not enough. You want bokeh? Get a prime lens.

A 50mm at 2.8 is much much sharper than 1750 at 2.8
So my suggestion would be :
1. Sell the 1855VR if you can & get a 2nd hand 18105VR & also get a cheaper ultrawide like the Sigma 1020 f/4-5.6 or Tokina 1224 f/4 (built in motor version)
---OR---
2. Sell the 1855VR if you can and get an 18200VR.
I just wanna share my experience, opinions and a bit of researching through the internet about the famous Tamron 17-50mm f/2.81. Tamron 17-50 f/2.8 (without motor) - 1st version
- This lens is the fastest focusing lens among all three versions.
- It has no motor and only can focus on bodies with built in motor like D80/D90/D200 etc.
- Some are made in china and some are made in japan. Japan versions are somewhat better optically.
- Quite a lot of this lens version have back/front focus problems especially the built in china ones.
2. Tamron 17-50 f/2.8 (with motor) - 2nd version
- This lens is the slowest among all three versions.
- It has a motor and can focus on all bodies like D60/D5000.
- Afaik, all are made in Japan.
- A small number suffers back/front focus problems.
- The lens electronic contacts sometimes fails to connect to the body. This usually happens because it's still new. Try cleaning it with a clean cloth.
3. Tamron 17-50 f/2.8 (newest version with motor & VC)
- This lens is 2nd in terms of focusing speed.
- Slower than 18-105VR focusing speed but still acceptable.
- It has a motor and can focus on all bodies like D60/D5000.
- From what I've heard, just a small number of people suffer from problems with front/back focus issues.
Now the question most will ask me. Why does the built in motor ones are slower than the one without motor?1. Tamron still uses micro type motor in all it's lenses and this slows down the focusing speed and thus making it longer to achieve focus lock which is a b***h when taking wedding pics or other fast paced photography jobs. Been there..done that.. Really hate it because my friend's Nikon 18-55VR can have a faster focus lock than me. Sold it off in just a few months...
2. Sigma's 18-50 f/2.8 HSM is really fast because of the HSM motor but IQ and colour wise, Tamron wins. It's a toss between speed and overall IQ.
3. I'd like to note that the newer 1750VC has a faster motor than the 2nd version but it still uses a micro type motor and not a ring type motor.
4. Micro type motor are used in Tamron lenses with built in motor & cheap Canon lenses which usually dont have the words "USM" on it.
- This type of lens is cheaper to produce
- Slower in focusing speed
5. Ring type motor are lenses like Nikon SWM (stated as AF-S on it's lenses) , Sigma HSM, Canon USM, Sony SSM, Olympus SWD.
- This type of lens is more expensive to make
- Fastest focusing compared to micro type and non motor.
- Do note that pro lenses like the canon L lens and nikon's tele lenses have a faster SWM motor compared to normal/cheaper SWM lenses.
* This is why there's a lot of people selling the non motor tammy 1750 at a higher price than newer version (2nd hand).
* This is also why there's a lot of people selling their 1750 built in motor (some just 1 month old) or swapping it with a 1750 without motor.
* Most if not all sellers of the built in motor versions will just say they wanted to upgrade to other lenses, needed money, selling on behalf of friends etc etc...but now you know what the main problem is. It is slow!!!..at least for me where i really need a faster focus lock. The 1855VR, 1870 and 18105VR has a faster focus lock...yeah..
* The older non motor version is nice and fast but be careful if u wanna buy a 2nd hand NON motor version of the tammy 1750 because a lot of em has a front/back focus issue. U need to test it out yourself using a focus test chart here:
http://focustestchart.com/chart.htmlthanks for the review. hmm think twice about tamron now. but 18-200 for wedding, not really good in low light, unless using flash.. any suggestion on settings?