gvarner Loc: Central Oregon Coast

Can extenders do an adequate job on tele zooms or should they be limited to primes? I have a
Promaster 2X that seems to be pretty soft on my Nikon 18-200. Is it the brand quality or is 2X pushing it for an extender? Are 1.4's that much better?

CWGordon

Stick with the 1.4. Even the 2.0 Nikon isn’t that good. I like having it, just in case, but almost never use it.

CHG_CANON Loc: the Windy City

Depends on extender, depends on zoom

olemikey Loc: 6 mile creek, Spacecoast Florida

Rather than a tele-extender, try using the "in-camera" crop feature, it will give some extra reach without light loss (f-stop change). You can crop in PP, but this method allows you to fill the frame, or at least increase perceived zoom reach, while taking the pic. Your standard view on sensor is 24 X 16 MM @ 24 megapixel, the in camera crop is 18 X 12 MM @ 15.x megapixels. You will find it in the shooting menu under image area. It does not compress the pixels either. Not perfect, but useful to help reach without light loss.

You can use it with a tele-extender, but I would limit that to a 1.4 or 1.5 to to cut light loss. They (tele-extenders) work, but also magnify any shortcomings of the zoom, and you lose a stop, or more depending on the extenders magnification factor. They are better with primes. I use it when I need it, and am happy with the images.... give it a whirl, doesn't cost anything, I have another button set for it so I can hit the button and toggle between DX and 1.3x crop. It will also cut vignetting if you have a lens that has that unwanted side effect, since it reduces image size to the sensor. Hope this is helpful.

speters Loc: Grangeville/Idaho

No, its the lens your trying to use with it! Zooms are in generally just fine with TC, just as primes, but there are some lenses one should never put a TC with and that is usually the cheapest of the cheapest kit lenses, the bottom of lenses. They usually don't perform worth a damn, if at all with TC's!

GEEPOPS

The Nikon 18-200 was not designed to work with a TC. It's not on the Nikon list of compatible lenses, in some case it could make contact with the rear element and do damage. Here's the link to the compatibility chart https://cdn-5.nikon-cdn.com/Assets/Common-Assets/Images/Teleconverter-Compatibility/EN_Comp_chart.html

sidpearce

Nikon Extender with compatible Nikon lens. But only use with a 1.4

David in Dallas Loc: Dallas, Texas, USA

I have the Nikon 18-200VR2 (and an older VR) and was told that it was not compatible with a telextender.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

I see you own a D7200. Which means that auto focus at or above f8 is not possible. The 18-200 is a 3.5 to 5.6. If you put a 2X on that lens on your camera it would no longer auto focus. I would think even a 1.4 may give you problems with auto focus, ie. either it would slow you focusing way down or not focus at all.
Facts about extenders.
1. their has not been a extender made that IMPROVES image quality.
2. the higher you go, 1.4 to 1.7 to 2.0, the greater the Degradation of the image.

imagemeister Loc: mid east Florida

Much of this depends on your definition of "adequate" ! I think the latest extenders from Tamron and Sigma may have a design bias towards long zooms but most longer zooms are aperture challenged for good AF WITHOUT a further light loss extender anyway ! The Canon, Nikon, Sony extenders are optimized for PRIMES. The third party extenders are usually a design compromise for shorter zooms and primes to give decent performance with ALL but not outstanding performance with any - except for the occasional happen stance.

Yes. 2X is really pushing it with any zoom and even the "best" extenders ! Yes, 1.4's are much better !

IMO, slower consumer zooms will give better ultimate performance by using a high MP sensor, stopping down 1 stop at the aperture, backing off 15% on the maximum zoom, using a low ISO, and minimizing any motion blur before CROPPING and using well applied pixel enlargement software for larger printings.
At least this will maintain your best focusing abilities.
.

Architect1776 Loc: In my mind

Depends on the lens and tele-converter.
The Canon 100-400mm MII L and the 2X III and 1.4X III are as good as 99% of the primes on the market.
All other brand lenses, including Nikon, lose quality, and even more so zoom lenses, that is visible according to Nikon users.
The Promaster is not the best of converters and would NOT be matched to any lens and would most likely produce visibly inferior photos compared to decent primes.
This is one area where paying less definitely does make a difference.
If absolute sharpness is not needed, more than likely very acceptable results can be had if the converter happens to like the lens. It is a crap shoot though.

LFingar Loc: Claverack, NY

Despite arguments about whether it is the gear or the photographer there are times when having the "latest and greatest" offer a distinct advantage. I have had a Canon EF 1.4x III extender for some time now. I bought it to use with my EF 100-400 f/4.5-5.6 L II. With my previous cameras, a 6D, I lost all auto focus. Bummer! With the 7DII I lost all except the center 5 points. Also a bummer. With my current 5DIV I have all of my focus points, but, had I bought the 2x extender I would have lost all auto focus. My f/4.5-5.6 lens becomes an f/9-11 with the 2x and the 5DIV will only auto focus at f/8 and larger. I recently did buy a EF 2x III because I had bought an EOS R not long ago. It will auto focus at f/11, so, my 100-400 and 2x work just fine on it.
As far as image quality the 1.4 does a fine job on the 5DIV. There is some slight deterioration, but, to me, it is hardly noticeable and I am tough on myself in that aspect. The 2x and the 100-400 are a great combo on the EOS R. Again, there is some slight loss of IQ but I don't see it to be any more then with the 1.4 on my 5DIV. The EOS R does a better job in that respect and I believe it is because it has the more accurate and consistent auto focus.
Extenders do slow the auto focus. It is noticeable with both of mine on both cameras but that is not a deal breaker. It's just something you have to learn to work around at times.
Extenders also limit light, of course. This can be a big factor at times. Fortunately, in my case, the EOS R does very well at higher ISO.
IMO,If you want the best results from extenders go with components that are made to work together. Component communication, optical profiles, and the camera's capabilities all have to be at their best to get the best, or, for that matter even acceptable results. Otherwise, I would think it would get very frustrating in a hurry.

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

A 1.4X will lose about 5% sharpness
A 1.7X will rob 15%
A 2.0X will take up to 30%

So, if you have a tack sharp zoom, like a 70-200 F2.8 or a 200-400 F4, you'll be able to use a 1.4 without issue, and with the F2.8 lens, the 1.7 and the 2.0 will be fine. with the 200-400, it's a little dodgy with the 1.7, and not worth the expense with a 2.0X.

Some lenses are so spectacularly sharp that not only could you use any TC but you could stack them - like a pair of 1.4Xs - to get a little more focal length - the Nikkor 200mm F2, 300mm F2.8 and 400mm F2.8 come to mind.

You should NEVER use a TC with any lens that starts off wide, like an 18-200 - you could end up crashing the rear element of the lens into the front element of the TC.

amfoto1 Loc: San Jose, Calif. USA

It's both...

Promaster appears to be a low quality, low price brand. I wouldn't expect much from them.

A 2X teleconverter magnifies any lens faults more than a 1.4X.

In general, teleconverters work best on prime lenses, instead of zooms.

The zooms that work best with teleconverters are those with modest ranges such as 70-200mm (3X) or 100-400mm (4X).

Extreme range "do it all" zooms such as an 18-200mm (10X +) are unlikely to work very well with teleconverters.... even expensive, high quality TCs. That type of lens simply has a lot of compromise, trying to cover such a wide range. Adding any telecoverter will magnify those short-comings.

bwana Loc: Bergen, Alberta, Canada

Teleconverters (TC's) work best on high quality primes and zooms but are better with primes.

I have several TC's (Canon, Sigma, Sony and Kenko). Never had much luck with 2x TC's; a 200% enlargement in PhotoZoom, Affinity Photo, Photoshop, etc. is probably just as good an image quality (IQ). 1.4x TC's offer some advantages and, in most cases, acceptable IQ.

It is not only IQ you have to consider when using a TC. Focal ratio is also impacted!

bwa