How much of a difference is the T/3.8 vs your traditional f/3.8?
1729410
The t/3.8 has de clicked apature blades. This basically means that you can adjust the iris (f-stop) smoothly. It's best used for video purposes so that you can darken or lighten the video smoothly. With regular lenses they will click between f-stops making the video get darker and lighter very choppy. Other than that they're pretty much the same!
923956
I don't know. I have an FT7. It would be worth an e-mail to Polar to know what difference is. George
1130016
I have both. The f/4 has only two advantages: it's much more portable, and it's much cheaper. But if you can afford the f/2.8, and if you can bring it where you want to use it (it's big, and you will probably want at least a monopod)--well, it's an amazing lens. Haven't regretted buying mine for an instant.
1196603
Here's the deal:F8-older model==> NON wide lens, better quality photos, faster sensor resulting SLIGHTLY better pictures in low lightF18-newer model==> Wide lens, good pictures but slightly less sharper than F8 due to wider lens and more crammed pixels onto the same sensor.And the reason wht the FZ8 get better reviews than the F18 for the points mentioned above.SS
2067572
There is no difference. If you order one, when it arrives, on the back of the unit it will show the model as a 560BTS. There is a difference between a 560BTS and a 560BFS model. T= throttle controls on tube, F= throttle controls on frame.
853453
If you shoot sports or any other fast moving objects (such as small children), get the 7D. 8fps (7D) can really get you the shots that 5 fps (T4i) might miss. Don't expect big differences in image quality (dynamic range, etc), they are very close. I have a 40D (2007 vintage) myself, and rented a 7D last weekend to see how it performs. With the same 70-300L lens, there really wasn't much difference in image quality. T4i with it's tilting touch screen could be very useful. I have no comments on its focusing accuracy or speed though.
1578620
I am not aware of a review that compares those 2 configurations, but I would be amazed if the 400 f/2.8 AFS with converter was as sharp as the 800. I have read a review that might shed some light on the question, but cannot access it without my laptop.
1837117
It is not a "fixed" F/2.8. It is a "constant" F/2.8 which does not change when zoom from 24 to 70. It still has the smallest aperture of F/22 that you can use to gain all the DOF you want.
1578624
In my experience, the 800mm is noticeably better, at least with my copy of the 400mm. The TC option is a lot lighter way to get to 800mm, though.
678604
The f4 is a super good all around lens and pretty nice for wildlife etc. More of an outdoor lens. If you're more indoor, portrait, etc, go for the 2.8. It is much larger however. I went with the f4 first because it gives more range of use.
46389
i am not sure about the tj performance gains, but i imagine it would be equivqlent to my jk 3.8. i am very happy with the performance gains, still better than stock, even after adding 35" tires. i would definitely recommend it.
1069243
I own both. This is sharper and faster to focus than the 70-300. With either lens, "faster" is not a consideration. Both lenses are sharpest at f8 and require plenty of bright light. BTW, the lens hood from the 70-300 works on this version for those wondering...
449840
Besides the longer zoom, the lens on the "9" is also slightly faster [f 3.3 vs the f 3.5 on the "7"]. Therefore, it should [theoretically] have better IQ in low light situations.
666201
The difference is larger than "adding an image stabilizer" to the IS model. In other words, the internal lens elements are not identical (in design or in quantity) between the f/4L and f/4L IS. Perhaps some of the glass elements are shared between the models, but the addition of IS technology requires the addition of more lens elements. Look at the Canon site and compare the number of "elements" and "groups" internal to each lens to see what I am talking about. If you poke around the internet you should find a graphic demonstrating the optical arrangement internal to each lens. I have owned the f/4L, the f/4L IS, and the f/2.8L IS II. If I had to rate these lenses on a scale from 1-100 for image quality: I'd rate the f/4L at 85 because it lacks a little sharpness and has a small amount of chromatic aberration. I'd rate the f/4L IS at 95 because it has a small amount of chromatic aberration toward the corners. I'd rate the f/2.8L IS II at 98 because it is almost perfect with no real flaws to speak of. The f/4L IS is noticeably better than the standard f/4L (but doesn't "blow away" the f/4L model). If you can afford the f/4L IS model it is definitely worth the price premium. If you can only afford the f/4L you won't find a better lens at the price point.
254048
Yes you can tell the difference. The f7 is bigger and the color and shape is different.
108982
The Contemporary version according to "http://www.dpreview.com/lensreviews/sigma-17-70mm-f2-8-4-os-hsm" is smaller, lighter, and uses revised optics compared to the old version which is why I choose this contemporary version. I use it on a Rebel T3i and I am very happy with the results.
575774
Well I think 1.8 is ultra fast (vs 4), so I would use it in a particular situation if I had that lens.