21

This is really simple when you think about it. The additional element changes the focal length of the lens, without changing the apparent size of the aperture. That means that the relative size of the aperture decreases, so the f number does in fact actually change. (If this is unclear to you, see the bit about f numbers in this other answer.) This is also ...


14

The blue halo is often referred to as purple fringing. It is caused by chromatic aberration. According to Wikipedia: There are two types of chromatic aberration: axial (longitudinal), and transverse (lateral). Axial aberration occurs when different wavelengths of light are focused at different distances from the lens, i.e., different points on the optical ...


11

With any lens of greater than 300mm focal length on a full frame camera you're probably not going to get results you're happy with shooting handheld. On your 1.6X APS-C camera, the same angles of view are provided by any lens 188mm or longer. It is true that lenses such as the Sigma and Tamron 150-600mm telephoto zooms are weakest at their longest focal ...


10

I have used the exact setup you are using. I found that the 2X Teleconverter iii worked wonderfully with the 70-200 f/2.8 IS II on the 5D Mark iii. I actually tested it in far harder conditions (shooting a wedding in a relatively dimly lit gymnasium) and it worked quite well. Particularly since you will be using the shorter focus distance setting, I ...


10

You will have to manually focus by moving the focusing ring on the lens. Using the center focus point to focus and then recompose is still considered autofocus. Even if you have manually selected which autofocus point the camera uses, the camera is still focusing the lens, not you. You'll also lose more image quality with a 2X than with a 1.4X. This will ...


8

Well, the main thing is that crop factor doesn't really affect focal length. It just affects the field of view by making it narrower. So, what you really have is a 400x1.4x => 560mm lens combination on a crop body, which has the same FoV that an 896mm lens would have on a full frame body. So, unless you shoot full frame enough to translate focal lengths to ...


7

The Canon extenders will not physically mount to an EF-S lens. Even if you defeat the keying the front part of the EF 2X (any of the three successive versions) would extend into the rear of the EF-S 55-250mm and almost surely contact and damage the rear lens element or the front element of the extender or both, at least at certain focal length and focus ...


6

With a ideal 2x teleconverter, you will be 2 f-stops down from what the lens is set to. Think about the basic physics and this should be clear. A 2x teleconverter makes the dimension of anything in the image 2x larger. Something that would result in a 1x1 mm square with the bare lens results in a 2x2 mm square with the teleconverter. That 2x2 mm square ...


6

Your basic assumption about teleconverters is right. But you haven't done the math: 1/2" is 6.4mm x 4.8mm—doubled is still only 12.8mm x 9.6mm. OTOH it's not unheard-of for tiny format lenses to have image circles well larger than their specification.


6

It depends on how you define "work". And it depends on the lens with which you are working. If it means everything will work the way it does as you are now shooting with only the EF-S 55-250mm f/4-5.6 lens the answer is no. Autofocus: Because your T3 limits your auto focus system to lenses with maximum apertures of f/5.6 or wider, even a 1.4x teleconverter ...


6

How can I modify my NIkon D5500 so I can make a vintage lens auto focus? You can't. I learned that using a TC-16A AF Teleconverter 1.6X might help ... Whatever you learned is probably wrong. From my googling it looks as if the TC-16A was designed to turn AIS lenses into AF lenses (i.e., an interim step to add electronic communication and the physical ...


6

From Nasim Mansurov, the author and founder of Photography Life. Teleconverters do not affect optical characteristics of lenses – they only magnify the center portion of the frame. This means that if one were to use a telephoto lens with a short minimum focus distance, it could be used as an excellent option for extreme close-up / macro photography as ...


6

Theoretically, optically, it would work (for low-quality values of "work"). Yes, the focal reducer would give an extra stop of light. But because the 2x teleconverter is responsible for 2 stops of light loss, you'd still net 1 stop of light loss. Aside from the optics math, there are some real practical problems with this approach. Depending on exactly ...


6

Although very little (single digit percentages) light is lost to a teleconverter, the ratio of entrance pupil to focal length grows proportional to the magnification of the telecon. For example, if a 100mm f/2 lens has a 2x teleconverter attached to it, the lens will effectively become a 200mm f/4. This is because the lens will always have a 50mm entrance ...


5

Yes: Remember that the f-stop is a relation between your aperture and the focal length. In theory if you have a f/1.0 50mm lens, that means that you have an aperture of 50mm. If you double the focal length (2x) the relationship reduces to half, so it will be a f/2.0 aperture. There can be some other factors as the quality of the lens elements, the ...


5

I don't think it would work with the first party teleconverters from Canon simply because of how they are constructed. There is a rubber ring that sticks out into the lens which helps prevent bleeding from rays that aren't being used, but it also won't fit in the backside of the teleconverter. There also isn't any correction profiles for the electronic ...


5

Yes. 5.6 becomes 8.0 If you add a 1.4x extender (teleconverter) you will now have a 140-560mm f/6.3-f/8 lens. Keep in mind that most cameras will only autofocus to a limit of f/5.6 and f/8 will be too dark for the AF to work. Newer high end cameras like the 7D Mk II and 5D Mk III will attempt to AF with f/8 lenses. Even if AF works (as in "the camera will ...


5

Any teleconverter/extender made for the Canon EF mount will work with your camera. Your question should be, "Which teleconverter would work with my lens." The short answer: It depends on what you consider as "working." You'll probably think, "No." Here are the main reasons why: You lose maximum aperture and thus auto focus. A 1.4X converter costs you one ...


5

None of them. Here are the reasons why: Teleconverters are designed to be used with telephoto lenses. Most makers of teleconverters state that they are intended with lenses of 70mm focal length or longer. But many teleconverters are designed to ideally work with lenses 135mm or longer. Even if they will physically fit on wider angle lenses, and often they ...


5

I will assume no. The first one seems to be a filter mounted converter and you need to have a lens with the specific diameter to fit it. By the looks of it, I don't think any DSLR camera lens are that small. It looks like something you mount on a GoPro or similar. The second lens seems to be as cheap as they get, https://www.amazon.com/Xit-XT5837XTL-58mm-...


5

tl;dr — Keep the Sigma and learn to shoot it rather than buying a prime instead. From your post, it's tough to tell if you've simply read about unsharp photos with zooms or if you're actually disappointed with the Sigma. At the end of the day, the choice is completely yours and gear only helps so much. Photographer skill should be talked about more than ...


4

Yes you could put reversed TC optics into a tube and use it as a focal reducer for shorter registration distance systems, in the process sharpening and intensifying the field. You could even give it a silly name like "lens turbo" or "speed booster" and sell loads of them! The quality obtained by re-purposing an existing teleconverter for the task would be ...


4

No it is not going to work with the EF-S 18-135mm. I don't know of any EF-S lenses that the 2x extender works with. The lenses are too close to the body and would interfere with the area that the extender takes up. More info on why only certain lenses work with the extenders can be found here: Why can only certain Canon lenses be fitted with an extender? ...


4

I'm not a moon photographer, but your examples are just about as impressive as I've seen taken with a DSLR and standard camera lens. Some of the things you're looking at may help, but I think they're just going to be incremental. Additional sharpening is only going to get you so much, and the teleconverter is only giving you a less-than-50% increase in each ...


4

Unfortunately, I can't recommend using a teleconverter with the Tamron 70-200mm f/2.8 at all (Update in 2020: The most recent Tamron SP 70-200mm f/2.8 Di VC G2 takes a TC better than the older Tamron 70-200mm lenses do - it's pretty much the equal of the Canon EF 70-200mm f/2.8 l IS II). The lens is pretty good for most of its range, but the weakest image ...


4

Teleconverters are designed for use with longer focal length lenses. Many are optimized for a specific focal length range of telephoto prime lenses. There are both marketing reasons why this is so, but there are also technical reasons. Just as it is the case that zoom lenses with very wide focal length ranges must make compromises in image quality to allow ...


4

A teleconverter is basically a magnifying lens used between the camera body and the existing lens, it is also called an Extender. Physical compatibility with a teleconverter depends on the lens being used and not the camera, but of course they need to be the same mount. A lens with a protruding rear element, which would mesh with the teleconverter front ...


4

The lens you have that goes on the front of another lens is not, technically, a a telephoto lens. That's a specific kind of lens design made to give a narrow field of view. Usually, when we use the term "telephoto lens", we mean any lens with a narrow field of view (a focal length of 100mm or higher, give or take.) What you have is a "secondary" lens, ...


4

How much an extender affects image quality is dependent upon both the quality of the lens and the quality of the extender. In the case of the EF 1.4X III and the EF 70-200mm f/2.8 L IS II, both the lens and the extender are of very high quality and for most shooting situations will probably not affect image quality in any noticeable way unless you are ...


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