RRS Loc: Not sure

Don't know from where you are coming from but Bozeman Camera is a fine place with very competitive pricing and I do believe that they do rent too. As for your 70-200, is it an f/2.8 version, then a 2x will give you 400mm f/5.6. Now as for a tripod, be sure that it will be steady with whatever longer lens you bring. Another thing that is most helpful to have is a bean bag, many shots taken right from the car. You should also take good binoculars, you'd be surprised at how many people seem to forget them. My first wolf shots were done with a full frame and a 70-200mm and I was able to get some "first time "shots, not bad and I was able to crop. I now take a 600 f/4.0 with a 1.4 and a 2x converter. We shoot both full frame and crop and we take a 300mm f/2.8, 70-200mm f/2.8, 24-70, 18-135 and a 17-40. We also take 3 tripods with a gimbal head, ball head, pan and tilt and a fluid head for our spotting scope. What I am saying is if you are driving take all you can, we use it all. We go at least twice a year and sometimes three times if we can fit it in. We stay for 10 to 12 days in early Summer due to taking grandchildren after they get out of school and stay for over two weeks and again the last week of September and the first week in October or until the snow forces us out. I was sitting in the car at Fisherman's in a pull out in Lamar Valley checking the focus on a road sign and looked up and about 20' away there was a wolf looking at me, anything longer then a 200 would have been too much. Early morning, still dark is when we leave our motel in Gardner because it can take almost an hour to get to where we want to be in Lamar Valley. Early morning light is beautiful, dress warm as it's not unusual to have temps of below freezing early morning in both June and July. If you do drive it would be best to buy your bear spray and carry it with you as you will pay a premium price in or close to the park and know how to use it! Have a great time!

via the lens Loc: Northern California, near Yosemite NP

I use the 1.4 Nikon tele with the same lens and it worked fine. Using a teleconverter though will impact your aperture. I shot with the same setup in Africa several years ago and as the animals were actually fairly close got some nice shots. So, the setup can work out fine. The best approach, however, is often just getting a lens with longer reach, so put that on your list of things to get in the future.

RRS Loc: Not sure

Hi Steve, I see that you are from Texas and what is close for you may be different then someone from a smaller state. MT Shooter is in or very near Billings MT and unless you happen to be driving in from the east it's a long, very long drive from Yellowstone. You are right that he would be very knowledgeable and helpful for info about Yellowstone and what gear could be most beneficial.

rparthas

Bozeman Camera rents lenses. Bozeman is about 90 miles from West Yellowstone and about 80 miles from the North Entrance.

jaycoffman Loc: San Diego

I second that suggestion--I know there are a couple of good camera stores just outside Yellowstone and they are experts on the area so could best advise you what you want to rent (Montana Shooter has a store there and he consistently makes very helpful suggestions on this forum). I think it may depend on what you're shooting--like wolves will require a much longer lens but much other wildlife can get by with a bit shorter lens.

RRS Loc: Not sure

MT Shooter is at least a 3 hour drive from Yellowstone, I'd call him first, he's not just outside the gates of Yellowstone. It will make a big difference from which direction you are coming from. MT shooter is good if coming in from the East and Bozeman Camera is better if coming in from the West.

Unclehoss

Not ALL wildlife in Yellowstone is arms reach from the car. MANY will be where you will have to reach out at snap the photo. My best grizzly images the bear was just a moving dark spot across the meadow before magnifying with a camera lense. On a budget, the most versatility that you can take with you will give you the best results.

Unclehoss

Second that information. Bozeman Camera are great guys.

SteveR Loc: Michigan

Thanks. I thought he was closer.

Unclehoss

If you already know where you are staying, some of the lens rental companies will ship to the hotel/motel and you can pick the lens up at the office and then drop the lens back in the mail when you are finished, saving you a full 3 week rental. There are post offices in several different locations inside the park. Having been to Yellostone a few times, it would be well worth the time to drive to Bozeman to rent the lens and again to return it. Especially if this is your once in a lifetime trip to Yellowstone. Also, very worthwhile to get up early, get to your destination for the golden hour light and siesta in the midday and get out again in the evening, hard to do with non-photographers in the group maybe.

imagemeister Loc: mid east Florida

I would consider a 1.7X with the 70-200 - but mostly only in good light ( 340mm @f4.7). Maximize your IQ using appropriate support and shutter speed and crop if need be.

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Toolking Loc: Pacific Northwest

I'm going to assume that you are aware that in a 7100 (DX) the effective range of that lens is roughly 108 to 300. IMHO you won't need any thing longer than that in the Stone. We were there last year and I used my 28-300 on my 610 (FF). I didn't need anything longer and shot many with my F-4 wide angle.