In my previous blog Bird Photography Equipment Lens and filters I compared two telephotos which I use regularly, the 300 f/4 IS USM which is an excellent prime lens, and the 100-400 f/4.5-5.6 IS USM is the best zoom lens commonly used for bird photography. I also tried the Canon Extender EF 1.4X II and found that the 300 f/4 worked well but the image quality was never superior that the 300 f/4 by itself.
Recently I tried the Kenko C-AF 2X Teleplus Pro 300 DGX with my Canon 7D and the 300 f/4 lens. To my utter surprised it worked! I had read that this was not possible since the 2X raised the f stop by two-stops making it a 300 f/8. In this particular case this combination raised the f stop to 8, as expected, but the camera was able to focus. I tested this combination extensively and found that the 7D would focus but only under good light conditions. But… after some more testing , I found that the 7D focusing system has more sensitive focusing points on the right or left sides of the 19 point AF system. After multiple test I found that the 7D will focus under all normal conditions with the Kenko 2X by using the Zone AF set to the right or the left sides as show below:
So now I have a 600 mm f/8 lens with autofocus and Image Stabilization. How good is the image quality? Here are two images (cropped) taken at the same distance and you can be the judge:
Dont try this with a Canon Extender, the camera will not focus!
Note: I thought this would be an interesting post since Canon has now priced the new 600 mm f/4 at $13,599.
To top it all, I am now a proud owner of the the new 5D Mark III and it too works with the 300 mm f/4 + 2X Kenko. It focuses perfectly well even at reasonably low light conditions at f/8! Again Canon says this is not possible..
Here is a shot with the new Canon 5D Mark III at an amazing ISO 8000 and 1/400 sec with Kenko 2X + 300 mm f/4 = 600 mm f/8 AF and IS:
Sword-billed Hummingbird at my garden taken with Canon 5D Mark III with a 300 mm f/4 L IS USM telephoto and a Kenko C-AF 2X Teleplus Pro 300 DGX. 1/400 sec, f/8, ISO 8000 Focal lenght = 600 mm
I stack the canon 1.4x ii and Kenko 1.4x on my canon 300mm f2.8 (588mm) Focus speed on my 7d with the combo is just as fast as the single 1.4x, where as using then canon 2.0x ii is slow… Still haven’t tried a 2.0x iii model on my 300mm f2.8…
Ever since birding with you and your generously allowing me to use your 7D/100-400 rig, I have lusted after it because it put my Minolta w/ the 500 catadioptric to shame. The writing was on the wall,and the focus was way too soft.
A few months ago I finally upgraded, and got the 60D and the 100-400 lens. Thanks for letting me ‘test drive’ it!
ps the “Bottomless Pitta” also has recently gotten the lens; Canon may owe you a royalty!
@Dan, Thanks for the tip, I tried the 300 f/4 plus the kenko 2x plus the canon 1.4x and the Canon 5D mark III actually focuses is situations with good light. I was also surprised at the IQ, it is actually very good and it is f/11!
Hi Arie, Great to know that you switched! That is a great camera and lens. I tried the teleconverter on the 100-400 lens but it does not work. I will order a Kenko 1.4X soon and will report back the full story of the TCs for 7D and 5D MIII.
I´ve been researching a lot lately about what lens to use with my 5D Mark III. I previously had a 7D (i sold it) that was great with my 70-200 f2.8 (Non IS Version) but the evolution to full frame reduced a lot of my 70-200 abilities.
So right now I´m really wandering what to do.
Option 1. The old 100-400 f/4.5-5.6 IS USM
Option 2. The 300 mm f/4 L IS USM with a Canon 1.4x Extender III
Option 3. The 400mm f5.6 (Non IS)
Option 4. Another Canon APS-C body with my 70-200
But now with this article about the Kenko´s working at f8 I´m even more confused.
I already tried Canon 2x (version 1 and 2) but the quality loss is way too much (or i got two very bad copies).
I´m wandering what will be your recomendations!
I have a canon 5d mkiii with a 300mmf4 l is with a canon 1.4x tc attached with mind blowing results. The image quality with this combo is far superior than my 7d with the 300 mm f4 attached. I am doing some research on the Kenko 2x at the moment for the auto focus ability as I wear glasses and dont trust my manual focusing. I dont use my 7d now as the new 5d mkiii is so far ahead in Image quality. I am not sure of how the image quality will be with the Kenko 2x. Even with light drop off the 5d mkiii produces sharp images with high iso so the only problem with the Kenko i see will be how good the image will be.
I use the Sigma 800mm Prime F5.6 with a Kenko 1.4x on a 5DMkII and it autofocusses every time. Brilliant image quality as well
@Byron: The image quality is so good that I always leave the 2X Kenko on my 300mm lens. I only take it out if the bird is too close or the light is so poor that my ISO is above 10,000
@Richard: I cannot walk around with a 800mm prime lens so the 300mm with a 2X+1.4X (840mm) is a viable option form me. I am sure that the 800mm + 1.4X must produce amazing photos.
I have a Tamron 2X TC and just ordered the 300mm F4 for my 6D.
The TC and autofocus actually works normally with 24-105 F4L but only in very bright and average light conditions. If it does the same with the 300mm F4, I’m happy. Thanks.
Hi Renato I just want to say that because of your report with 2x kenko I bought one. And I am enjoying. I saw your report early last year I am glad I stumbled with it when I am planning to buy teleconverters. I have 300mm f4 IS USM and 7D. Now with the report on 5d3 I might scratch the idea of buying the 500mm f4l and buy the 5d3 instead. Thank Renato and everyone.
Hi Renato.. great report. I use a 5DM3 with a canon 300 f/2.8. I tried the Kenko 2x teleplus pro with the lens and was surprised to get 600mm at f-4 when it should have been f-5.6. It focused very well and I took a few bird shots. Was very happy with the results. Thanks
Thanks for your input. I just buying it in online without the proper knowledge of it that AF dont works with 7d+300mm f/4.But after seen the article m very much pleased.Though I have Canon 1.4x vIII and it works very well under low light conditions bt some times feel 2x would better bt financial it would me a worry things rather kenko supply me it within the half budget.Hope it will focus under good conditions..
Hi there, I use a Canon ^D with a tamron 150-600 for bird photography. The tamron is f/6,3. Normaly i use no extender, but last winter i made some experiments with the extender 2x from kelko. I auto focus it was not working, but in live view it is working. I found ot that in live view, with flexi zone AF, the focus will be done by the picture sensor and not by the AF sensor. I made some nice pix from a king fisher with 1200 mm. Of course on a tripod. The 6D has built in wifi. So you can make a connection to a cell phone, apple or android with the canon connect app. Now you can hide your camera with extender and 600 mm or whatever lens and make pictures with your cell phone on a save distance from the camera. The point is, that your object has to ake place on the right position in opposit of the lens.