ronichas Loc: Long Island

Thanks so much for your support.

Canisdirus

One cannot just look at aperture and say the glass is better...it's just brighter...and just slightly.

They are pretty much a push image wise...which is not surprising coming from the same company.

imagemeister Loc: mid east Florida

The higher cost, GM designation, and MOST reviewer's opinions makes me think it is "better glass" ! - until I see some definitive evidence otherwise ! Just like the OP, I am open to definitive evidence .....I don't have either - so no dog in this fight ....

Nalu Loc: Southern Arizona

I have both and they both produce excellent results and I also find no significant image degradation with a Sony 1.4x converter on the 100-400. I find the 200-600 more convenient when wanting more reach simply because I don't have to put on the converter, but on the other hand, the 100-400 is lighter and easier to manage. I was skeptical of the 200-600 for some time because I was not getting tack sharp images, but I think it was due to operator error, perhaps because of the weight. But I have to say, during a recent trip to the Falkland Islands, I used it a bunch and got some excellent results. There is talk by some however that some of the copies of the 200-600 may "off" a touch so should you decide on this lens, it would be a good idea to put it through its paces to verify it is a good copy, which you should do with any lens. Anyway, they are both good lenses and I find the Sony teleconverter excellent. You can't go wrong. Here is an example of and image taken with the 200-600 but keep in mind this is relatively low quality jpeg. The original processed raw file is better.

(Download)

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

Both have the same quality glass, both are weather sealed.

imagemeister Loc: mid east Florida

Thanks for weighing in Frank ! .....What bird is this ?? Thanks

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

I use both lenses for Florida wildlife photography. I do not ever use a 1.4 teleconverter. Just have a thing about them. I prefer having the 200-600 on my a9 or a1 because it offers me more choices especially if the bird is at a distance from me. I do not like to have to add teleconverters to lenses or changing lenses in the field. The a1 does have a shutter to help keep out dirt, but I prefer, once I am in the field, to only have one lens on my camera at a time.
The 100-400 is lighter and has two focusing motors to one on the 200-600. Both are weather sealed. Both deliver the same amount of sharpness which was my main reason to switch from Nikon cause they promised the 180-600 for years and did not deliver. Sony had their 200-600 on the market 3 years before Nikon finally delivered.
I regress, sometimes I carry two camera's and I have the 100-400 on the a9 and the 200-600 on the a1. I have not noticed any difference in focusing speed between the two even though the 100-400 has two focusing motors.
If I were you I would continue to use the 100-400 with the teleconverter although the lens becomes slower by a stop and low light focusing could be a problem with it attached.
Below is an grab image of a Snowy Egret in full mating colors, the lure around the eye turns a deep red and feet to match, shot at 600mm f6.3 wide open with the 200-600 on the a9. This bird is very hard to expose properly due to the brilliant white colors.
The Sony a9 and 200-600 delivers.
You will be happy with whatever you choose to do, just keep using native Sony lenses with your Sony camera's.
Good luck and keep on shooting until the end.

UTMike Loc: South Jordan, UT

This is not rocket science. I have both lenses and use both with 1.4 and 2x tcs. They both produce sharp results when used properly. I have no "lag time" issues with either. The 100-400 is lighter, but the 200-600 has a really good reach. It all depends on your needs and what you are willing to go through to get your shot.

I also have a 600 f/4 that I use with both tcs that produces great results, but it requires more support.

bwana Loc: Bergen, Alberta, Canada

Are we to the point of discussing the original question or are we still in conflict mode!?

bwa

Nalu Loc: Southern Arizona

Hey Larry, it's a Striated Caracara. Relatively common in the Falklands.

bwana Loc: Bergen, Alberta, Canada

I have the FE200-600 and note it does not reach infinite focus on either my A7 III or A7R V when it is really cold, i.e.: below about -10C; otherwise a great lens.

bwa

SuperflyTNT Loc: Manassas VA

Better build quality, not better glass. No major lens manufacturer is gonna use inferior glass in any of their lenses.

ORpilot Loc: Prineville, Or

check out the Images posted by gwilliams6 using the 200-600 with 1.4x and 2.0x. I think it will answer most more your questions.

Artcameraman Loc: Springfield NH

I use Sony lenses on my Nikon (D and Z's) , I found that they are not as sharp as Nikkor lenses. Could this because of the different manufactures?
Cheers.

zug55 Loc: Naivasha, Kenya, and Austin, Texas

I assume that you are talking about old Sony lenses for the Sony/Minolta A-mount--which has been defunct for a number of years.

Sony E-mount lenses (like the 100-400mm and the 200-600mm under discussion here) cannot be used on a Nikon "D" (presumably F-mount) because the Sony E-mount requires a flange focal distance of 18mm while the Nikon F-mount has a flange focal distance of 46.5mm. You can put a Sony E-mount lens on a Nikon Z-mount body, however, as the flange focal distance is 16mm--which gives an adapter 2mm to work with.