I rented all three lenses from a local camera store here for one week each. I went to the same places each week so I could get the same type of pictures: San Diego National Wildlife Refuge, San Diego Zoo, San Diego Zoo Safari Park, SeaWorld, Lake Murray, Santee Lakes, Sweetwater River, Ramona Grasslands, and La Jolla Cove. I'm not particularly interested in the sharpest pictures because whatever pictures I get are taken into various editing programs and messed up significantly until they no longer look like a picture to begin with. Photoshop, onOne, Nik, Redfield, Photo-Paint, Paintshop Pro, etc., etc., etc. I sell my Photographic Art to Realtors, escrow agents, title agents, and loan agents as close-of-escrow gifts. Thus, I'm more interested in getting the picture, something to play with, rather than getting the sharpest picture.

Initial research online indicated that I wanted the Sigma Sport 150-600mm. After real-time use, not so much.

Camera: Canon 760D

Prices:
Sigma Sport, $1,999
Tamron G2, $1,399
Sigma Contemporary, $1,089

Weight:
Sigma Sport, 101 oz
Tamron G2, 71 oz
Sigma Contemporary, 68 oz

All three had a rotatable tripod mount, and since I don't use monopods or tripods for still pictures, only videos, I rotated the mount 180° so that it became a carrying handle on top of the lens. Quite convenient.

Note that all three of these lenses were rentals, and we all know how people treat rented stuff, so some of my problems noted below might be due to previous mistreatment of the lens rather than an actual problem with the lens.

Throughout the range, I actually thought that the Tamron provided the sharpest pictures, followed by the Sigma C and then the Sigma S. Interesting.

The Sigma S had a propensity for taking significantly underexposed pictures. I can work with those in Photoshop, but why? Retaking the picture provided a normal exposure but the picture I wanted already was gone. For the price, surely the focusing algorithms should always provide me with a properly exposed picture that is easiest to work with in Photoshop.

On the Tamron, there are four controls on the barrel of the lens: Focus Range, Auto Focus/Manual Focus, Vibration Compensation On/Of, and three Vibration Compensation custom modes. Due to how I was holding my camera and supporting the lens, I had a propensity for turning Auto Focus to Manual Focus, so the next time I went to catch a quick shot of some scampering squirrels or flying birds, well, the shot wasn't there. Towards the end of my 7-day rental, I had successfully altered my holding style so that I was never switching Auto to Manual.

The Tamron wasn't working in AI Focus or AI Servo mode initially. I eventually did get it to work in those burst modes, kid of critical for BIF pictures, but inconsistently. I demonstrated the problem to the camera store when I returned the lens, and got a credit from them.

One of the reasons why it has taken me so long to get a lens of this size is because I'm don't like using neck straps, shoulder straps, monopods, or tripods. I just like to carry my camera around and take what they call "hand held" pictures. That usually means that I need a fast shutter speed to get good pictures. Fast shutter speeds mean I need lots of light. Lots of light means that I need big aperture openings. These comparatively inexpensive zoom lenses typically have maximum aperture openings in the 4.5 range. Both the Tamron and the Sigma are f/5 at 150 mm and f/6.3 at 600 mm. Would those maximum apertures let in enough light to let me take good hand-held pictures? My unequivocal answer is, "Yes!"

The Tamron 150-600 appears to let in more light than my walkaround Tamron 28-300 at equivalent focal lengths of 150, 200, 250, and 300, and it was truly rocking at 600mm. I had not a single problem with light. Granted, technology changes, and my Tamron 28-300 is about eight years old, so that might be a factor.

Another difference I have noticed between these two lenses is the quality of the bokeh. Tamron was giving me absolutely stunning pictures of tiny flowers with much better background blur than either of the two Sigma lenses.

I find it interesting that the direction the zoom ring rotates is not standardized. Canon and Tamron lenses rotate to the right. Nikon and Sigma lenses rotate to the left. I have a Canon camera and have been using a Tamron 28-300mm lens for eght years. I guess you know which direction I like the zoom ring to rotate although I was willing to be convinced otherwise. I ended up not being convinced because of the fact that I do hand-held pictures exclusively. If I'm at 150 and want to zoom to 600, with the Tamron, I'm already supporting the lens with my left hand so it's an easy and natural rotation. With the Sigma zoom, I would have to terminate my lens support and move my hand up to the top of the camera to rotate the zoom ring to the left. Trying to rotate the zoom ring while still supporting the lens with my left hand resulted in discomfort as I tried to rotate my wrist out of its natural range. I almost dropped the camera and Sigma lens a couple of times because my right hand (and mind) wasn't prepared to try to support that kind of weight by holding on to just the camera.

The picture below is of a wild rose at the San Diego National Wildlife Refuge. This rose is about a half inch in diameter and the background is a bunch of wild grasses, bare dirt, and pebbles.

Although I am familiar with Adorama, B&H, and Cameta, I chose to see what else was out there, excluding imports from Canada, Japan, Hong Kong, England, Germany, etc. A Google search for a Tamron 150-600mm G2 lens sent me to eBay. The price was good so I went to check on seller reputation. With a 99% rating over 447,963 sales, and reading through a hundred of the comments, I was satisfied with that. I went to check out and eBay asked me if I wanted to use PayPal or apply for PayPal credit. I have been using PayPal since 2004, so what the heck. Let's see what PayPal credit has to offer. Well, they offered me a $3,000 credit line. For the lens, I could choose to pay it off in 6 months with no interest or 24 months with no interest. Decisions, decisions, decisions. I chose 24 months with no interest to get the nice low payments, which will allow me to buy a new computer; this one is ten years old. Lens should be here in a week with free shipping from Edison New Jersey from Buydig. Now if only Adorama, B&H, and Cameta would do PayPal.

Cost was $1,399 and the bundle included "Console Lens Accessory, Memory Card Reader, Card Wallet, Mini Tripod, Cleaning Kit, [64GB] Memory Card, Microfiber Cleaning Cloth, Backpack, Tripod, Dust Removal Blower System, Lens Cap Keeper, Filter(s)." Since I don't use tripods, I messaged the seller to let them know they could keep the tripod, save postage, save resources, etc.

Just a few hours after I purchased the lens from eBay via PayPal, I got an email from Consumer Priority Service (CPS) offering me an extended warranty. I was offered an extended warranty when I check out, but it was $144. The CPS extended warranty totaled $37.49 and provides a 2-year extension after the manufacturer's warranty has ended, including accidental damage from day of purchase and no deductible. Such a drastic difference meant checking ratings and complaints for CPS. I was satisfied with what I found there so I purchased the extended warranty. My confirmation email offered me an addition 30 days if I would like CPS on Facebook. No problem.

Hope my actions, experiences, and choice can help someone else, but I would highly recommend renting something like this before you buy. I was lucky because I have a local camera store that rents all sorts of stuff. If you don't, try borrowlenses.com or lensrentals.com or lensprotogo.com.

I don't have a problem with somebody choosing a lens for their own particular reasons even when those reasons go against what I think I know about photography. I just hope that new folks skimming the post are not lead to believe that the chosen lens is the 'best'. Since sharpness is not a consideration, the rest of the 'review' in my mind is not very helpful to somebody looking for a lens to buy but if the goal of the post is to just tell the story, so be it. Maybe the moral of the story is you don't need sharp photos ?

My only real quarrel with the post is how a lens can be said to have a 'propensity to underexpose' shots. Was the meter not used and the exposure guessed from 'experience' ? I don't understand how a 'focusing algorithm' has any impact at all on exposure. Glad the OP found something that makes then happy. Maybe I just don't need to understand the un-followable 'logic'.

One last comment - not sure how you purchase any photo's from the OP's website - I could not find anything using the search feature (response was 'Sorry, no results...). Same results looking at the collections, newest or most popular. Hmmmm - assuming sales are from somewhere else ...? When evaluating experience posted, I like to see their work to determine if we share similar aesthetics. I am guessing no on this one.

Glad you found something that works for you.

I don't have a problem with somebody choosing a lens for their own particular reasons even when those reasons go against what I think I know about photography. I just hope that new folks skimming the post are not lead to believe that the chosen lens is the 'best'. Since sharpness is not a consideration, the rest of the 'review' in my mind is not very helpful to somebody looking for a lens to buy but if the goal of the post is to just tell the story, so be it. Maybe the moral of the story is you don't need sharp photos ?

My only real quarrel with the post is how a lens can be said to have a 'propensity to underexpose' shots. Was the meter not used and the exposure guessed from 'experience' ? I don't understand how a 'focusing algorithm' has any impact at all on exposure. Glad the OP found something that makes then happy. Maybe I just don't need to understand the un-followable 'logic'.

One last comment - not sure how you purchase any photo's from the OP's website - I could not find anything using the search feature (response was 'Sorry, no results...). Same results looking at the collections, newest or most popular. Hmmmm - assuming sales are from somewhere else ...? When evaluating experience posted, I like to see their work to determine if we share similar aesthetics. I am guessing no on this one.

Glad you found something that works for you.

My whole purpose for posting this is so that "new folks" can see that there is more than one way to do things. I realize that a lot of folks don't read the whole post--that's already been proven here with several comments--but if one actually WERE to read the whole post, one could, IMHO, see why I chose the lens. In fact, the title of my post is "Why I chose Tamron 150-600 over Sigma Contemporary & Sigma Sport." I is first person. I didn't title it, "Why you should choose Tamron 150-600............." I'm hoping that people reading the post can apply their own analysis, logic, and reasoning. Heck, if they want the best lens, they can read all the reviews online and come to the same conclusion I came to: "Sigma Sport." If all one wants is the sharpest picture for the most money.

When I'm out shooting birds in flight and scurrying ground squirrels, I use the P mode with either AI Focus or AI Servo burst mode, I'm going to let the camera do as much of the work as possible. All I want to do is find the subject hiding out in the grasses and push the shutter button. So if I do all that, and the pictures are underexposed or overexposed, all else being the same, then I have to say that the lens has a propensity to underexpose shots. If the lens doesn't focus on the subject, my 760D won't let me push the shutter. So there is some sort of focusing algorithm making that determination. After all, these cameras are run by computers.

After reading your comments, I'm 100% certain we don't have the same or similar aesthetics. I have no problem with that because you are not in my target market.

I'm over at Fine Art America.