6d/T4i telephoto zoom

Why is there a difference in closeness of image between a 6d and T4i when using the EF 70-300mm f/4-5.6 IS USM lens. When zoomed out to 300mm object appears a lot closer in T4i than in 6d. All settings on each camera identical. I am confused?

You're comparing a full frame with a cropped sensor. Field of View (FOV) is wider on a full frame when compared to a cropped sensor using the same focal length. To achieve the FOV of 16mm on a full frame on a cropped sensor, you'll need to shoot with a 10mm. Cropped bodies use the center of the lens, the edges are cropped, hence "crop body."

Wow, so if i understand correctly I am losing ability of lens to bring objects as close with 6d as I can with T4i I want to achieve same FOV on my 6d as is on my T4i using lens I mentioned To achieve the 300mm like image on the T4i on 6d what size lens would I need?

We know that as "reach." You will need a 480mm lens on your 6D to achieve a similar FOV of your T4i with the 300. In order to do this, you will have to consider new glass and teleconverters. Focal lengths 400mm and above are not very budget friendly. Longer lenses such as the 500, 600, 800 can still be bought brand new but they are very expensive. You can also achieve a similar FOV using teleconverters on compatible lenses but maintaining auto focus becomes an issue depending on various teleconverters. I've only mentioned Canon equipment but there are third party options to bring cost down as well.

3Rotor wrote in post #18243329
We know that as "reach." You will need a 480mm lens on your 6D to achieve a similar FOV of your T4i with the 300. In order to do this, you will have to consider new glass and teleconverters. Focal lengths 400mm and above are not very budget friendly. Longer lenses such as the 500, 600, 800 can still be bought brand new but they are very expensive. You can also achieve a similar FOV using teleconverters on compatible lenses but maintaining auto focus becomes an issue depending on various teleconverters. I've only mentioned Canon equipment but there are third party options to bring cost down as well.

What would be teleconverter you would recomend?

Converters/extenders are not a good idea on this lens even if you can find one that will fit. They cost both light and image quality - unless you have the sharpest lenses (read most expensive!) then it is better to do without them.
Getting closer to your subject will give you much better results. It is more difficult but much more rewarding in the long run.

If you aren't printing large, just edit the 6D photos and crop out the same view you are getting with the rebel, that is what the rebel sensor is doing for you (if we ignore the loss in resolution after the crop).

Other than cropping the image you're only relatively budget friendly option is going to be non Canon products. The Canon 1.4× extender won't fit on your lens, in 70-300mm lenses it only fits the L series lens, and it will make the maximum aperture f/8 at 420mm, so that AF would not work. The same limitation would apply to a non Canon converter, the extra stop of light you lose will stop the camera from either AF'ing at all if it reports it's presence, or will make the AF basically unuseable if it doesn't report. This is not to do with the amount of light, or contrast, getting to the AF sensor, but with the angles that the light rays follow. If cropping over 50% of your horizontal and vertical pixels is not leaving you with enough resolution for your needs then you will need to look at third party lens options. Both Tamron and Sigma make very good budget friendly 150mm to 600mm telephoto lenses. Both companies now have two options in their lineups. The original MK I Tamron is optically at the bottom of the list, although it is still better than most consumer grade 70-300's, and it also has issues with it's optical image stabilisation system that means you need to turn it off, or it is turned off automatically if the firmware update was done, when you pan with the lens. If you are using fast shutter speeds, say 1/1000s and faster this is not much of an issue. If you need to use much slower speeds it is pretty big for a lot of folks. This is especially true for those of use who shoot aviation, you really need to shoot slower than 1/200s to get good blur on aircraft propellers, and for a large helicopter that can come down to 1/60s for the main rotor. I rented the Tamron for an airshow when it came out, before the Sigma was available, and left the VC turned on, I got very few keepers! Even when comparing to comparable focal lengths with my Sigma 28-300 without stabilization, so it was the VC issue. Then there is the Sigma 150-600mm Contermory, this lens is optically better than the Tamron, most people putting it on a par with the original Canon 100-400 L, which is about where I would put it, having used both. The Sigma lens has a panning mode for the OS, and it is also fully compatible with the Sigma dock, which allows you to update firmware yourself, as well as to adjust the performance of the OS and do the full range of in lens micro focus adjustment at four distances, and four zoom settings, for a total of 16 MFA points. Here in the UK both the Tamron MK I and the Sigma C are the same price at most dealers, selling between about £700 and £750 including all our taxes, usually they are £739. Sigma has a Sport version of the 150-600mm and although there is as I understand it a marginal improvement in optical quality over the C, most of the differences are in build quality, with a full brass chassis and additional weather sealing etc. This does add both to the cost and the weight of the lens, with the Sigma S at about £1100 now in the UK. Tamron recently announced a MK II version of the 150-600 that uses Tamrons equivalent of the Sigma dock. I don't know what it allows you to adjust with regards to lens performance, or if it is firmware update only. The new Tamron is supposed to be about the same optically as the Sigma S, but other than the launch announcements I haven't seen much about the new lens, but I haven't been looking either, I'm much more than happy with my Sigma C. Without looking it up I think the new Tamron is about £1700. The other option being the Canon 100-400 VII, which is a much superior lens, and although only 400mm it apparently strikes that balance between focal length, image quality and the ability to crop and resize the image to pretty much match the performance of the 150-600mm lenses, but then at about £2200 it is three times the cost of the cheapest options.

Although it depends on the actual camera bodies you compare, if an APS-C body has about the same total number of pixels as a 35mm format then there is an advantage to the smaller sensor in that the number of pixels in any area will be greater. When the total number of pixels is significantly different then you have to do some math to make a comparison. For a 35mm format sensor to have the same number of pixels in a unit of area it has to have 2.56× as many pixels in total. So if I compare my APS-C sensored 50D (since I know the specs for it) to the 35mm format my 50D has 15 mega pixels, so a 35mm format camera would need to have 38.4 MP to have the same resolution when cropped to the same Field of View. My old 20D on the other hand only has 8 MP, and so has the same resolution as a 20.5 MP 35mm format camera. So with your 6D I would have an advantage in resolution using the 50D, so cropping the 6D to match would leave you potentially short in pixels. Comparing the 6D and the 20D though you actually end up with more MP from cropping the 6D image down rather than using the 20D. So the results of the comparison are body specific. One final comparison is that the APS-C 7DII at 20 MP has almost exactly the same resolution as the 35mm format 5DS/5DSr when cropped, since 50 / 2.56 = 19.5. You will need to look at the specifications of your cameras to decide if cropping might work for you.

Alan

chiefdeck wrote in post #18243527
What would be teleconverter you would recomend?

Kenko as it will fit more canon lenses. Also, you can have AF in very good light, ie. daytime, as long as you tape the last 3 pins on the converter itself (the pins that connect to the body), and that stops the reporting of the TC to the body, allowing the body to try to AF. In good lighting, AF will happen most of the time. This is how you can AF with f8 lenses on non f8 AF bodies.

http://www.michaelfurt​man.com/taping_the_pin​s.htm