Teleconverter - math and opinions.

[SnappingShark]

OK, starting out basic, Is it worth me getting a 1.4 teleconverter for $400?

Next up, the math.

Shooting DX, would this make the following staments true?

55-300mm * 1.5 (crop) becomes 82.5-450mm * 1.4 (teleconverter) = 115.5-630mm ?
70-200mm * 1.5 (crop) becomes 105-300 * 1.4 (teleconverter) = 147-420mm

Hmm, just need clarification.

 

[amolitor]

Shove the word "equivalent" in all over the place and you've got it.

The equivalent focal length will slightly more than double, and you'll lose one stop of light.

 

[SnappingShark]

hah yeah, I was going to use equiv, but figured there's too many repeated words

but phew - sounds like it may be worth getting if it makes my 300mm a 630... equivilently

 

[Braineack]

it'll make your 300mm f/5.6 a 420mm f/8.0. add whatever equivalent you want to that.

 

[Overread]

Will any teleconverter actually fit your 55-300mm?
Teleconverters all have a protruding front element which physically restricts what lenses they can mount to. Many zooms often have very little if no recess at the back and thus physically won't fit even a Kenko Pro series teleconverter (which have the smallest protruding front element).

Check out to see if the TC will physically fit your lenses before you purchase one. Kenko Pro series have the smallest protrusion and often will mount to lenses that own brand TCs won't. Also make sure if you do get Kenko that you get the pro series - their other line of teleconverters are lower grade.

And yes a TC simply increases focal length by the factor of the TC.
1.4TC increases focal length by 1.4 times and reduces maximum aperture by one stop
1.7TC increases focal length by 1.7 times and reduces maximum aperture by one and a half stops
2*TC increases focal length by 2 times and reduces maximum aperture by two stops.

 

[SnappingShark]

Seems the Nikkor 55-200 is not compatible, but the 55-300, and 70-200 IS!

Huzzah!

 

[Derrel]

Well, a 1.4x TC does cost the one stop of light transmission, so the 70-200 f/2.8 loses effective aperture value down to f/4 when wide-open. Also, consider that the f/2.8 might actually only be f/3.1 or so in T-stop, and the loss is even more painful. Consider that the 1.4x TC compromises both effective f/stop, effective T-stop, AND compromises optics on every single picture made except at the longest focal length settings. The TC is only a focal length benefit on the LONGEST few settings; anything that can be had "natively" on the zoom, without the TC, is best shot without the TC on. But, that's a rigorous and demanding route, and many people will not bother to take off the TC, and will instead just zoom and shoot at whatever length suits the image.

The very NEWEST Nikon TC, the Mark TC14e-III , the 1.4x model, which is the world's first aspherical element teleconverter design, is somewhat of an exception when it is paired with the newest, high-end Nikkor AF-S lenses. Canon's new Mark II 70-200 f/2.8 also has a sterling reputation with Canon's 1.4x TC. But for the majority of converters on the market, with the majority of lenses, I think it's actually a net benefit to shoot without the converter and get: 1-higher shutter speed and 2: the full quality that the optics can deliver and thus get 3: the highest-quality pixels possible and then 4) use a HIGH-resolutiuon, pixel-dense sensor like that in the D7100 to....CROP-IN at the computer, on a BETTER-quality image.

 

[robbins.photo]

OK, starting out basic, Is it worth me getting a 1.4 teleconverter for $400?

Next up, the math.

ARRGGHH!!! Math.. I must avert my eyes... Math.. the dark and terrible nemesis.. the bane of my existence...

lol

Shooting DX, would this make the following staments true?

55-300mm * 1.5 (crop) becomes 82.5-450mm * 1.4 (teleconverter) = 115.5-630mm ?
70-200mm * 1.5 (crop) becomes 105-300 * 1.4 (teleconverter) = 147-420mm

Hmm, just need clarification.

Ok well somebody will eventually weigh in with a high end deal about how a 300 mm on a 1.5 crop sensor isn't actually 450 mm and how adding a teleconverter doesn't make it the same as a 630 mm and there will be a much long winded debate over the subject, but yes with a 1.4 teleconverter your looking at the same angle of view as you would get otherwise. Thing to remember about teleconverters of course is that all of them will reduce image quality, even the more expensive ones though the more expensive you get generally the less of a hit you'll take in IQ.

Also they reduce your F-Stop of course, as I recall I think a 1.4 will drop you by one Fstop.

 

[table1349]

Frankly, if you are not putting the TC on absolutely TOP QUALITY, TOP Optical glass, then I think you will end up finding that it is not worth it. TC's are not the be all, do all on a budget. They will magnify the optical flaws of the lens you put it on.

 

[Ysarex]

OK, starting out basic, Is it worth me getting a 1.4 teleconverter for $400?

Next up, the math.

ARRGGHH!!! Math.. I must avert my eyes... Math.. the dark and terrible nemesis.. the bane of my existence...

lol

Mathematics, rightly viewed, possesses not only truth, but supreme beauty -- a beauty cold and austere...yet sublimely pure and capable of stern perfection such as only the greatest art can show.
--Bertrand Russell

Joe

 

[Derrel]

Frankly, if you are not putting the TC on absolutely TOP QUALITY, TOP Optical glass, then I think you will end up finding that it is not worth it. TC's are not the be all, do all on a budget. They will magnify the optical flaws of the lens you put it on.

Exactly. About 10 years back, Thom Hogan and Ron Reznick were both talking about how incredible the then-new Nikkor 70-200 AF-S VR-G lens was when paired with the TC 14e converter. Reznick sold his 300mm f/3 AF-S, since the converter + zoom he felt was so,so close in terms of results. He went so far as to talk about how the converter had basically no penalty... What a load of B.S.. Now, keep in mind, THAT was way back in the early 2000's, in the Nikon D1h (2.7 megapixel) and Nikon D1x (5.4 megapixel) and Nikon D100 (6 megapixel) era.

I later bought a 1.4x TC 14e, and tried it on my 70-200 VR-G with the 6 MP Fuji S2 Pro, and later the Nikon D2x, which is 12.2 MP. I had no idea WTH those guys were talking about; The first NIGHT I had the TC unit, I did a test and determined that the lens had to be closed down AT LEAST 1 full stop for the corners of the frame to even approach the center quality, and my 300 f/4 was wayyyyyyy better.

Now, OTOH, the same 1.4x converter with the 300 f/4 AF-S prime, or 300/2.8 AFS-II or 200/2 VR-G is actually...pretty good. Not "perfect", but farrrr better than when it's on a zoom lens. I think now, as we've crossed the 16-megapixel barrier, and hit 24Mp to as many as 36 MP, converters are less-needed, and if they are needed, we need the absolute newest and best zooms. Nikon AF-S tele-primes are all basically excellent optically, better than the zooms by a good margin, and TCs work better on their primes than on Nikon zooms. Marianne Olund did some serious tests of the new TC14e-III, the aspherical converter, with the new VR-II 70-200, the 200/2, and the 300/2.8 VR models, and on those lenses, that new 1.4x is pretty darned good. But that is one expensive TC unit, and when SHE did her tests, 24MP was the tippy-top camera in Nikon line, and most of the consumer cams were 12.2 MP.

 

[coastalconn]

I think it would be a big waste of money to even consider a 1.4x on the 55-300. AF would be more painfully slow than it already is. I would wager a bet the 55-300 would be sharper without a TC than the 70-200 would be with a TC. I use a 2x TC on my 120-300 F2.8 all the time, but I do pay the penalty of 2 stops and IQ drops quite a bit, the tradeoff is I can put more pixels on a bird at 600mm and get more detail and have more perceived sharpness than just cropping from 300mm. I went down that road with many lenses I have tried in the past and the only time a 1.4x really works is on a f4 or faster lens... just my humble opinion...

 

[robbins.photo]

OK, starting out basic, Is it worth me getting a 1.4 teleconverter for $400?

Next up, the math.

ARRGGHH!!! Math.. I must avert my eyes... Math.. the dark and terrible nemesis.. the bane of my existence...

lol

Mathematics, rightly viewed, possesses not only truth, but supreme beauty -- a beauty cold and austere...yet sublimely pure and capable of stern perfection such as only the greatest art can show.
--Bertrand Russell

Joe

"Bertrand Russell is a nit. A complete knee biter" -- Former classmate of Bertrand Russell turned ditch digger thanks to "grading on the curve"

Lol