Until you post a photo, and check "store original" every thing about your lens is just conjecture. A lens that you say does not AF as sharp as you expect, could have a easy fix, or you may have to send it in for repair. The problem could be as easy as a front focus issue, or a back focus issue, which can be cleared up by micro adjustment. An other problem could be a internal lens is out of alignment, which will need a technician to fix. YOU have been REPEATABLY ASKED to POST a PHOTO to help the members determine YOUR PROBLEM. Why not cooperate, and help your self.

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I've been shooting Tamron lenses for quite a few years on both my 7D MII, and classic 7D. But mine is a prior model the 18-270mm. For travel it is a great lens, light weight, large zoom from wide to tele, and a great warranty of 6 years. The 18-400 will follow the same route as the 18-270 since there will be a lot of bending of light going on inside the len, and just that will distort and soften the images. The images will not be as sharp as a prime, but acceptable.

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My experience in shooting feeding bears is extreme caution. I would only take the Canon, with the Sigma 150-600, with either a 1.4, or 2X teleconverter. I'd also look into a good guide familiar with the area you are going to be hiking, and shooting the bears. Remember, the bears may be transitioning between streams, while you're hiking, and you may become prey for these bears. Be prepared to abandon your equipment at any time to flee a attacking bear. You can always return to retrieve you equipment, but not your life. From experience, and seeing how these bears work, I would leave the bear spray home, and carry something in the .44 to .45 caliber range.

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Depending on how far apart the subjects will be, you may need more than on flash, definitely two off camera flashes. Otherwise, some of the features of the people will shadowed. You'll need light stands, two flashes, with modifiers, three radio transmitter/receivers. (transmitter on the camera, receivers on the flashes.) Don't forget to practice with the setup before the big day.

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I've been shooting digital for some time now, and find the actual time for a lens to achieve focus varies from time to time. The time period has to do with the conditions you may be shooting in. I know my Canon 5D Mark IV focuses faster in brighter light, with lots of contrast than my old 50D does with the same lens. That is the nature of the two cameras electronics. Most cameras, using optimal lighting, contrast, color reflection, and settings will focus in mil seconds, and drive the lens. So, if you're using a 50mm f1.2 wide open in dim light, on your 7D body it will take a few more mil seconds to achieve focus. Use your 5D Mark IV, it will snap in focus faster. Of course the human eye can focus almost instantly in any light as long as it is not completely dark, but how do you time the cameras function? In reality, you may confuse the time of focus, with how accurate your camera is focusing. Some of the things that will cause a lens to focus slower than normal, is battery charge, distance the motor has to rack or move the lens to achieve focus. The cameras focus system can be the culprit too, since that is where the condition of focus is determined.

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In the 1970s, I was in several P-3, and VQ Squadron. Many times we were assigned photo recon of shipping in the Pacific, near Vietnam, and later in the Med. I took many of those Soviet Ships, and other Nations ships. We used Canon equipment aboard most of the flights. I even used my own camera at times. I had no Navy training in photography, just a bit a amature shots while stationed in Subic Bay, and Rota. So, I was elected photographer on the P-2s and P-3s I flew on. So, the Navy didn't use designated photographers in every instance when gathering intelligence.

B

The Wife and I took the Rhine River Cruise with Viking just a few years ago. It was a really wonderful cruise, but the airline (Delta) lost our luggage for the entire trip. It never showed up until we arrived in Amsterdam. We had to use our shore time to buy clothes.

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I've had a bit of experience with Tamron repair, and they do a great job. If you bought the lens new, not used, Tamron my repair the lens just by disassembly for a estimate, and reassembly. The cost, depending on parts used will be fair. But the lens will be fixed and will be returned with a warranty. KEH, is also a great company to deal with. KEH is a reseller of used photographic equipment, and does have a repair facility. They will also provide a free estimate for a quality repair. You'll have to make up your mind, now you're able to use your lens.

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I've shot with both of these lenses. Comparing the two would be an injustice. The 100-400mm would serve you well on a tripod in a blind, or handheld while strolling in the forest. The 600mm is a large heavy prime, and would be best used in a blind on a heavy duty tripod. I used for only one or two shots hand held, but it was to heavy to hold steady enough for the shot. The 200-400mm lens has a built in converter, which adds to the weight and your ability hold on the target, so it needs a sturdy tripod. The common word between all these suggested lenses is tripod.

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I never keep a lens mounted to my camera bodies. After every shoot I remove the lens and install both rear and front caps, and place them in a protective padded lens bag. I also place a body cap on the lens mount on the body, and wrap the body in a protective padded wrap with velcro closures. Everytime I go to a shoot I take the lenses that I'll be using for the shoot. I do keep a ready bag, with spare batteries, lens cloths, and Zeiss wipes. I also have a variety of CPL, and neutral density filters and a set of adapters. When I return from a shoot I check each lens I may use for dust, lint and wipe down the lenses and the body I use. Everything has its own special spot on the shelf, which is bubble wrap padded. Of course I test my lenses fairly often for micro adjustment using the program FoCal. I feel when you make money off your photos, keeping your equipment in top condition is essential.

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I'd like to chime into this sales tax discussion. I did not read all the posts in this thread due to the amount of pages. But, it is important for all you folks read up on the United States Constitution. Specifically, the Section dealing Interstate Commerce. This makes it illegal for States to impose a tax on interstate commerce. One of the reasons companies like Amazon will collect sales taxes is that a deal was struck between Amazon and the States to allow Amazon to keep a portion of the collected sales tax to pay for the cost of collecting the tax. Companies, and individuals will not take on these States for their illegal taxing over State lines, because of the legal fees, since the amount of money involved would make these State to take the challenge to the U.S. Supreme Court. You could move to equally beautiful State as Colorado, like New Hampshire, no sales tax, no State income tax.

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Every time I read such a post that always try to compare two or three lenses, and of course include the pricing of the lens, I get a knee jerk reaction. I shoot Canon cameras, and mostly Canon lenses. Canon prices its lenses only for the R&D involved, and the cost of higher grade glass, and special optical glass. Build quality, and resilience to bumps and shocks over time is also considered. Photo quality is also the prime objective, and also repeatability of quality is Canons standard. Personally I shoot full frame (5D Mark IV) and shoot cropped sensor (7D Mark II) professionally. I always select Canon lenses when going to a "paid" shoot. I do shoot with a Tamron SP 24-70mm f2.4 VC USM lens when the shoot dictates. All my Canon glass is "L" quality of course. You'll find if you are more worried about the cost of the lens, rather than the results, your photography will suffer. The OP, or other responder mentioned a 18-400mm lens. This I would consider a totally amature quality lens. Going from 18mm to 400mm magnification really bends the light and the image, this brings into the photo a lot of distortion, no matter the quality of the glass. Photography is one of the most expensive hobbies

B

I moved there right after I graduated from college. It was my first engineering job. I lived in Courtney, Fl, just miles from the Apollo launch pad, and could see the bird on the pad. The Titan IIIC was launched from Cape Canaveral, on the pad beside the old Vertical Integration Building (VIB). The Saturn V was built on the KSC side in the Vertical Assembly Building (VAB)

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It looks like the old Titan IIIC. Brings back memories when I worked on the Saturn Project, at KSC.

B

CR is a country with vast areas where animals and birds thrive, both in towns, and in the country side. These animals can be very mobile, or like the sloth rather still. The monkeys in CR vary between the "white face" and the "howler". Both come in quantities of individuals. You will hear the howlers towards the evening hours, with loud howls. The white face will be heard almost all day long as a tree top chatter. These troops of monkeys move fast through the forest, and are smaller than the howlers, a good shot would be when they stop to feed on fruit. You 70-300 lens would be just Ok for the white face, and be right on for the howlers if you can get close enough. When I was there I hired a guide for the parks to shoot monkeys. For the birds, your 70-300 will be Ok but remember some birds sit tighter than others. Toucans tend to be rather flighty, but can be baited with fruit. Other birds are also better baited with some orange, banana or other local fruit. There are lots of roadside fruit stands to buy your bait. I stopped at one stand and it was surrounded by coatimundis, and racoons. I got some excellent shots of these animals with a 24-70mm lens since they had been fed by the shop owner with spoiled fruit. Don't try to hand feed these animals, they will get very aggressive and bite. Try to get some shots of Caiman along the river on your cruise. Caiman are much like the American Alligator, but are smaller. But don't get close they can run pretty fast and like the alligator, there bite is bad. You may want to buy some high octane bug repellant, with about 70-90% deet. In the jungle the mosquitos are really bad, and carry a variety of very infectious diseases. On your river cruise, you may want to use a longer lens than the 70-300. The river limits your ability to get closer to some of the animals, like the sloth. Even with 300mm it may just look like puff of fur high up a tree off in the distance. At the time of my visit I had a Tamron SP 150-600mm lens. I shot two different sloths that were both well over 100 yards into the canopy. I hope this helps, and have a good trip.

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