mstuhr Loc: Oregon

If you dont want to buy perhaps a camera shop nearby would rent you the lense(s) you need.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

Well, you stuck your foot into it this time. You really do not understand what your getting yourself in for. My only suggestion is this, meet physically with the bride and groom (to be) and ask them for MUST HAVE PHOTO's. These are the photo's that they really want. Tell them to have their parents come up with a list. Use these lists and make sure you get every shot they put down. That way you have PROTECTED them and your self from later bad feelings. Make sure to shoot two or three or four shots each of the MUST HAVES so they have a selection. Good luck and god bless you for you are about to enter the lions den. Thinks I'm kidding, just wait. My only other suggestion is that on the standard alter family shots make sure you make clear to the other dozens of photographers that YOU SHOOT FIRST. Then them. If not, you will have many, many, blinked eye shots. At the reception (better before) talk to DJ, if they have one, usually they help run the reception, make sure he/she understands that you need to know ahead of time what will happen when. Work in conjunction with he/she, it will make your job easier in the long run. In conclusion, please promise everyone here that you will not make this mistake again.

JimG1 Loc: Waxahachie, TX

The sigma 17-50 F2.8 is a great lens and I believe they have dropped the price on it to 399

jeep_daddy Loc: Prescott AZ

Don't buy an EF-s lens. Why would you when you have a nice selection of lenses that will all work on your 7D. Give the wife the 50mm lens to put on the 7D and tell her to get close to the nuptials and start shooting. You can use something else like the 24-105 and your 70-200 for other pictures. You have plenty of focal lengths to choose from no matter a crop sensor or full frame sensor body.

SharpShooter Loc: NorCal

Rent the 17-40(cheap) and BUY a good flash!
SS

Bill Emmett Loc: Bow, New Hampshire

You've left out a lot from your original question. The main one is lighting. If in a church, how will it be lite up for the shoot? This will determine your lens choice, speed, and ISO. You may also want to look at the site of the reception too. If outdoors, look at the rain options. This will effect your shoot. The suggestion about the "must have" shots is right on target. You may want to look at some books about wedding photographing. One thing I learned that if you want to loose a friend, photograph their wedding.

B

amfoto1 Loc: San Jose, Calif. USA

Instead of the EF 17-40L, if you only want to use the lens on your 7D I'd suggest you get the EF-S 17-55/2.8L IS USM instead. It's a much better lens in many respects. New or used, the 17-55mm only tends to cost about $100 more, and is worth it.

DaveSLR Loc: Lancashire

Thanks everyone. It's certainly given me something to think about. I have done a friends wedding before but it was very informal and they were pleased with the results. This ones a full on one and my nephews trying to save costs I think. He's tight as a submarine door. It is some pressure and I don't intend doing it ever again.
Thanks again. I didn't expect such great advice.

dar_clicks Loc: Utah

I absolutely agree. Enjoy the event and let a pro worry about the photos.

Gifted One Loc: S. E. Idaho

Rather than use a 17-40 I would poke a hole in a body cap and use the 7D like a pin hole camera. The only lens worse than the 17-40is the 28-135. I am somewhat biased. Look used if need to. Borrow beg or wel not steal but buy used and if not happy re sell.

J. R.

TriX Loc: Raleigh, NC

Based on your personal experience or professional testing and reviews? (because they don't seem to agree with you).

http://www.the-digital-picture.com/Reviews/Canon-EF-17-40mm-f-4.0-L-USM-Lens-Review.aspx
http://www.kenrockwell.com/canon/lenses/17-40mm.htm
http://www.thephoblographer.com/2011/11/15/long-term-review-canon-ef-17-40mm-f4-l/
http://www.dxomark.com/lenses/brand-canon/mounted_on-Canon_EOS_7D-619/focal-from-16-to-50/aperture_max-from-4-to-4/lens_use_case-lens_wide-lens_superwide/lens_zoom-zoom/sensor_brand-Canon#hideAdvancedOptions=false&viewMode=list&yDataType=global

I'll grant I'd prefer the 16-35 f2.8L, but that's a bit harsh, especially considering the price difference.

williamlepoer Loc: IRELAND

I don't know why you would use a 70-200 mm. lens for a wedding, but maybe it could be used in certain circumstances. My daughter got married recently and I used a Sigma 17-50mm. f2.8 lens for over 200 shots. This is a super lens with great image quality and the price is very reasonable. I compared the quality with the official wedding photographs (made with full-frame Canon cameras and lenses) and there is little difference to be seen. I also have a second-hand EF-S 15-85 mm. F3.5 - f5.6 lens which I would probably have used for the wedding but I only bought it afterwards. Someone on the forum suggested that the maximum aperture might be a bit slow, but most wedding work is done using flash anyway, so it shouldn't be a major problem. Both lenses are good but I would rate the Sigma as being marginally better for image quality, despite the fact that it is significantly cheaper. Although bear in mind that it does have a shorter focal length. The cameras I use are the EOS 70D and EOS 700D. As someone already suggested, it could be an option to rent a lens for a day or two. Hope this is helpful.

Gifted One Loc: S. E. Idaho

5.89 USD EF body cap https://www.amazon.com/Canon-RF-3-Body-Cap-Cameras/dp/B00007E7K1/ref=sr_1_1?ie=UTF8&qid=1470361043&sr=8-1&keywords=EF+body+cap

I said I was biased. Seriously UWA 16-35 f/4 Canon.

Temp for 7D would be cheap 18-55 EFs. But mine is sharp. You can pick one up 50 USD and sell for 70.

J. R.

TriX Loc: Raleigh, NC

Agree the 16-35 f2.8 is a better lens, but DXO (if you believe them) shows the 16-35 f4 performance very close to the 17-40's admittedly older design. here are some shots in this thread taken with the 17-40. Not showing these as an example of good composition, but they will provide a feel for the sharpness and distortion, especially at the corners. These are SOOC: http://www.uglyhedgehog.com/t-395011-1.html

Merlin1300 Loc: New England, But Now & Forever SoTX

Find a used Tamron 24-70 f/2.8
AFAIK, it's the only lens in it's class that has image stabilization (VC)
It is an EF equivalent lens - so you can use it on your 7D as well as your 1Ds