JayHT Loc: NorthWest Washington

When using a telephoto lens with an extender attached (i.e., 100mm - 400mm with a 2.0 extender) will the results in clarity of the photo be degraded to any degree by keeping the extender on the lens when taking a photo within the 100mm - 400mm range? In other words, would it be advisable to remove the extender from the lens when it will be of no assistance in exceeding the 400mm range of the lens by itself?

Best holiday wishes,
JayHT

rmalarz Loc: Tempe, Arizona

Keep in mind, a 2 power extender doubles everything. That includes flaws in the lens' optics.
--Bob

wdross Loc: Castle Rock, Colorado

Your 200 - 400 range is best shot without the teleconverter. But the teleconverter is obviously needed to generate the 400 - 800 range.

davidrb Loc: Half way there on the 45th Parallel

Jay, the answer to your question is yes. An extender is going to degrade any image it renders, it's the nature of the beast. For that reason it is advisable to remove the extender from the shot. It is simply an additional piece (s) of glass that is unwanted if unneeded. Some photographers refuse to add any glass to a lens for any reason but this is a personal decision.

jim quist Loc: Missouri

Remove it when you don't need it.

CHG_CANON Loc: the Windy City

Jay - I have the 1.4III and the 2.0III. First, you need to pay attention to both your camera and your lens(es) when selecting an extender. If your camera can't autofocus an extender + lens combination, then don't bother. You mention the 100-400 with a 2.0. This is an example that won't autofocus on any Canon EOS body and likely never will.

Selecting to use an extender with a valid lens & camera combo, there are some considerations. The new 100-400L v2 with the 1.4III is considered as sharp as the old v1 100-400L with no extender. I add the 1.4x when I know I'll need it or don't mount. But, if mounted, I don't remove. Instead, I pay attention to the aperture while shooting manual or in aperture priority. The extender changes the properties of the lens in the sense the 'sweet spot' isn't going to be the same as without the extender. So if I have the extender mounted, I don't shoot the lens wide open regardless of the focal length. The old 100-400L with the extender, keep it at f/11 to f/13 for best results. The new 100-400L, it's good at f/8 but better at f/10 or f/11.

Yes, the extender impacts the image quality. If you manage how it changes your lens characteristics, that change can be marginal to negligible when balanced against the extended focal length. Today's mega MP cameras are starting to allow for cropping a sharp image sans extender where possibly the extender isn't needed, particularly the 1.4x that is only a 40% increase. The 2.0 'doubler' works almost exclusively on Canon's long focal length primes that are already pin sharp ...

Sharp enough with 1.4x?

Chicago area Dragonflies by Paul Sager, on Flickr
http://c8.staticflickr.com/8/7577/27357692983_b36c924717_b.jpg

jim quist Loc: Missouri

That is an amazing photo.

bull drink water Loc: pontiac mi.

it depends on the primary lens. I have a 200mm f2.8 G lens and a 1.4 and 2.0 tc. the tc's are the same brand as the lens. fabulous I.Q. with both and full auto focus. I also have a 500mm f8.0 auto focus reflex that I use with a 1.4 tc. the auto focus still works and the I.Q. is good. I took a chance, matched them up and gave them several good shakedowns. lastly I have a 70-200mm G zoom that gives great I.Q. with both tc's.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

You lose 25% of your sharpness, your viewfinder is really dark (you lose two stops), and only the newest cameras can autofocus at F8. The lens you described is F5.6, which makes it F11 at 400mm. While you may be able to shoot something in bright daylight, if you manually focus, you won't be happy at all with the results.

If you use a 200mm F2, 300mm F2.8 or a 400mm F2.8, you will be able to AF, track focus, and actually see things in the viewfinder without too much trouble. You still lose the 25% image quality, but all the lenses I listed are extremely sharp when used wide open, and do a very nice job even with the 2X attached.

So yes - if you have to use the 2x on that lens, make sure you take it off when you don't need it.

jerryc41 Loc: Catskill Mts of NY

So it must also double the lens's goodness. A Canon L lens would become an LL.

DirtFarmer Loc: Escaped from the NYC area, back to MA

Another point:
A teleconvertor also reduces the aperture by the same factor as it increases the focal length. A f/4 lens becomes an f/8 lens with a 2.0 TC. F/5.6 becomes f/11. On many cameras this will impact the autofocus speed negatively. So you will want to remove the TC when it's not needed for the focal length conversion.

wotsmith Loc: Nashville TN

use the teleconverter or extender as you need it. Yes, it raises the f stop, yes, your body may not focus at the higher f stop, BUT THE ASSUMPTION THAT THE QUALITY WILL BE DEGRADED IS TOTAL HORSESHIT! Don't believe me? check out the "proud eagle" shot listed today in the photo section.. Shot with a 400mm f4 and a version iii 2X extender. Absolutely razor sharp. BTW was also hand held, so much for the crap that you HAVE to use a tripod. It just may be that the photographer has better technique than you have. Still believe quality will be degraded. go to Art Morris's website and look at his wonderful photos shot with a teleconverter.

Yes you need a really good lens to start with, and yes the older versions of teleconverters were not so good, but you can get perfect photos with an excellent lens and a new version of the teleconverter if you have a body that will focus at that f stop. Come on, quit repeating stuff you heard 25 years ago. Look and see what others are doing with good teleconverters.

DirtFarmer Loc: Escaped from the NYC area, back to MA

In my experience, the stronger the teleconverter, the higher the probability is that the image will be degraded.

That's not to say that the TC is not usable. The TCs that I've used are just fine for most wavelengths, but with my old 70-200, the old TC2.0 gave images that were just fine up to about 380mm. Above that, I could see a bit of softness in the images. But the images were still usable. I did not see any problems using the TC1.4 and TC1.7.

Whether you have degraded images or not will depend on just how much OCD you have in pixel peeping and which lens/TC combination you use.

Lorendn Loc: Jackson, WY

If you are talking about the Canon 100-400L, it is notorious for problems with converters. You will likely have auto-focus problems with the 1.4x converter and it will not auto-focus with the 2x on any Canon body that I know of. The 100-400L is great by itself but be very cautious of expectations with a tele-converter.

Regis Loc: Coeur d' Alene, Idaho

That's not true about extenders degrading any image. Just look at my recent posts where I use the Canon 2.0x III extender.