1.4 Extender Image Quality Question

Donde · Oct 26, 2018

Can images taken with a 1.4 extender on a 400mm lens be equal in sharpness and quality as images taken with out? Or should some loss be expected.

jcdeboever · Oct 26, 2018

Donde said:
Can images taken with a 1.4 extender on a 400mm lens be equal in sharpness and quality as images taken with out? Or should some loss be expected.

Good one for @Derrel

tirediron · Oct 26, 2018

A good, name=brand (eg Nikon or Canon) TC paired w/ a 400 2.8 prime is going to cause VERY little image degradation.

john.margetts · Oct 26, 2018

You are bound to get some image degradation. Just introducing the extra glass surfaces will ensure that. Will it be enough to see? Depends on the lens, extender and the size of the final image.

Gary A. · Oct 26, 2018

I've used extenders on both zooms (which are not really made for them) and primes (the better option) ... with very good results. Any degradation, while measurable, was not significantly visible. I've used Canon and Fujinon extenders.

Overread · Oct 26, 2018

A 1.4TV on that lens will cause so little image degradation that you won't notice it in the field, esp after sharpening for output. You might notice it in side by side test shots done before any sharpening is applied, but yeah otherwise the performance drop is totally negligible. You are more likely to see more image degradation if you cropped a photo and enlarged it to simulate a longer focal length; as opposed to using the Tc in the field

The TC that causes more of a drop is the 2*TC, yet a 400mm f2.8 can take one of those and whilst the drop can be noticed, it will still produce very sharp results that are perfectly usable (at 800mm with that you are more likely to get blur from increased handshake or atmospheric issues as you can shoot further)

Donde · Oct 26, 2018

Thank you for those replies. I should have mentioned the lens I'm using is the Canon 400 5,6 not 2.8. I don't know if that affects the answers.

Derrel · Oct 26, 2018

One comment about extenders: on "some lenses", the rear element of the main lens can make contact with the front element of "some" extenders! So...one has to make absolutely sure that the main lens and the extender are compatible.

With an f/5.6 main lens, adding a 1.4x extender will cut the effective maximum aperture down by one, full EV value. So, f/5.6 becomes f/8, and f/8 becomes f/11. So...you'll be shooting at f/8, with a very long lens; THAT is where image quality issues can begin. In less-than-full-sunlight, f/8 and a lens that is effectively 400mm x 1.4x, and you have an _actual,measured_ focal length of 560mm. When you multiply the 560mm focal length by the Canon 1.6x FOV factor, you have a very dim 896mm effective focal length.

The effective focal length of 896mm, with an f/8 absolute MAXIMUM aperture value, and a slightly slower T-stop with the addition of seven more glass elements in a high-grade extender, and you're losing maybe 1/3 of an EV value below f/8....so, you have what is basically an f/9 lens with a very high-magnification

How does an f/9, 896mm lens sound? In the forest, this lens will need to be shot at HIGH ISO levels, in order to prevent multiple image quality problems from subject motion blurring, camera shake, mirror slap, shutter shock at slow speeds,etc..

Adding a 1-stop extender to a 400mm f/5.6 lens is NOT the same thing as adding one to a $10,000 400mm f/2.8 or a $7,000 300mm f/2.8 lens. You do NOT end up with the same options, but much,much less in the way of shooting envelope options.

tirediron · Oct 26, 2018

Donde said:
Thank you for those replies. I should have mentioned the lens I'm using is the Canon 400 5,6 not 2.8. I don't know if that affects the answers.

Makes a pretty significant difference as Derrel notes above.

Donde · Oct 26, 2018

Very thorough analysis Derrel thank you very much.

photoflyer · Oct 26, 2018

You decide. 6D Mark II. 300 mm F4 L and with version one 1.4 Canon TC.

photoflyer · Oct 27, 2018

Here is a link to the original JPGs in my last post so you can pixel peep. Both are shot wide open (F4 and F 5.6).

My Cloud

JoeW · Oct 27, 2018

I have a Kenko 1.4 extender/teleconverter. I will agree with what Derrel posted. On a really good lens that is not in extreme situations (like really low light or a fast moving object like a small bird), it will do reasonably well so that you'd have to compare side by side with something shot without the teleconverter to notice a difference. The biggest issues are when there is low light or you're shooting subjects (athletes, wildlife) that are moving and at a distance so f8 just isn't going to allow you to have any kind of shutter speed to capture most shots in those situations.

If it's a great lens. Or it's great light (very bright). And the subject isn't moving fast--any of those 3 conditions, then I think an extender is a good way to boost your zoom. If your zoom is mediocre and/or slow, don't bother using a teleconverter. I'm very happy with mine. I've sometimes taken it to sporting events where I don't have a press pass and a 200mm lens is the max they'll allow (so I bring a 200mm f2.8 and my 1.4 teleconverter). But then I also limit what I try to shoot with it--I don't treat it as a 350mm zoom. Instead, it's a slow zoom that requires good light and little movement at a distance.