In a previous post I described the use of the Canon 8-15mm as a zoom fisheye using the Kenko Teleplus HDpro teleconverted.

I had the opportunity to try this set up in Malpelo although in a situation that was not ideal for it.

I put this lens on expecting some wide angle school shots and instead it ended up being a dive with Galapagos sharks coming fairly close.

With the imminent launch of the Nauticam Fisheye Conversion Port many users will ask if they shoud invest in that or they can get decent quality at more affordable cost spending less then £800 for a teleconverter set up. I assume any Sony full frame E-mount shooters own both the Canon 8-15mm and the Sony 28-60mm.

Edit 9 March 2024

Studio Shots

I found some time to do some tests at f/16 distance 25cm which is typical of wide angle in a dome.

As you can see the kenko 1.4 TC does not loose any quality compared to the bare lens and looks more magnified at same focal lenght in the centre.

Why is the quality the same? Probably the Canon 8-15mm is a better lens at 10.7mm that it is at 15mm and therefore even with the teleconverters result match. This corroborates my in water results.

Malpelo Shots Analysis

The dive was early in the morning and topside overcast resulting in a fairly dark dive.

The sharks came fairly close however as soon as the strobe fired they turned on their back. My impression was that this was more due to the noise of the strobe firing then the actual light.

All my shark shots are at f/8 1/30 ISO 500. As the shutter speed is quite low you have situations where the subject is sharp but some of the fish at the edges has some motion blur this is unrelated to the lens.

If you open the above image on a separate tab and zoom 100% you will see that the shark is pin sharp and so are the small fish on the same focal plane and the one behind. The reef on the left bottom corner is soft.

This has to be expected as the focal point is further back from the shark so the camera is out of depth of field on that corner.

The situation repeats in other shots like this one where the shark is even closer however the edge improves due to the reduced distance gap with the reef.

Again shot after shot the fact I was focussing on the shark that was deeper in the frame resulted in the left edge being soft, this has to be expected and there is nothing wrong with the set up the dome or else.

I took some shots really close on the reef at f/16 to make the point here the muray eel is sticking out of the reef so the edges look much better.

This other shot has an hawkfish in the edge you can still see the coloration and the eyeball of the fish.

Conclusion

In general terms shooting f/8 on full frame is not an example of small aperture in fact this is a setting for distant subjects almost and wide angle scenes. In the environmental situation I was in I could have increased the ISO to achive higher shutter speed and smaller aperture however this would have resulted in more noise and loss of resolution across the whole frame. My view is that for general wide angle where there is no clear subject you can try to focus closer to have the edges sharper however this is not always a possibility with sharks and things moving and furthermore there is rarely anything of interest in the edges.

This was my second time with this combination and I remain of the opinion that the teleconverter does not take anything away in the center of the frame and deteriorates the edges only just slightly and is therefore a worth addition. The nauticam FCP is not yet released and combined with the 28-60mm will for sure produce a more flexible set up because of the increased zoom range compared to the teleconverter however if this produces better image quality on the overlapping range remains to be seen. I expect it will cost considerably more than the £800 required to add the teleconverter to your Canon 8-15mm.

Since many years Canon and Nikon full frame users are able to use their respective 8-15mm with a teleconverter underwater, however this is not a very popular configuration.

In this article I will look at the Canon 8-15mm with the Kenko Teleconverter 1.4x for Sony full frame cameras.

First and foremost a teleconverter is not cropping the image it has optical elements. Cropping means reducing the resolution at sensor level while a teleconverter induces a deterioration of the image and possible defect but does not affect the sensor resolution. Generally 1.4x TC is much better than 1.4 crop. If you find yourself cropping a lot your fisheye shots or even using the 8-15mm in APSC mode the teleconverter may add some real value to you so read along.

Parts Required

In addition to the set up required to use the Canon 8-15mm you need 3 additional items:

• Kenko 1.4 Teleconverter
• Canon 8-15+TC zoom gear
• Extension ring N120 20mm

The benefits of this set up are clear:

1. Unique field of view
2. Smaller additional bulk
3. Relatively low cost

Some readers have emailed asking if the Kenko is compatible with the Sigma MC-11. I do not recommend using the Sigma MC-11 with the Canon 8-15mm because it only supports single AF and it is unclear if the Kenko will work or not and how well. I have tested with the Metabones smart adapter and this is the one I recommend.

Field of view

The 8-15mm lens with teleconverter will give you access to a zoom fisheye 15-21mm with field of view between 175 and 124 degrees. This is a range not available with any other lens of water contact optic that stop normally at 130 or 140 degrees.

Additional Bulk

The additional items add circa 370 grams to the rig without teleconverter and make is 20mm longer due to the additional extension. The additional fresh water weight is circa 110 grams.

Cost

The latest version of the Kenko Teleplus 1.4X HD DGX can be found in UK for £149.

The 20mm extension ring II is £297 and the C815-Z+1.4 Zoom gear is £218. Note this is in addition to the 30mm extension required for the 8-15.

With a total cost of £664 you are able to obtain the entire set up.

The rig looks identical to the fisheye except is a bit longer. You have a choice of 140mm glass dome or 4.33″ acrylic dome see previous article.

With the rig assembled I made my way to the pool with the local diving club.

Pool Session

The 8-15mm with teleconverter was my first pool session with the A1 on the 3rd of February I was very much looking forward to this but at the same time I had not practiced with the A1 underwater previously and did not have my new test props. I think the images that follow will give a good idea anyway.

15mm Tests

At 15mm (zoom position somewhere between 10 and 11 mm on the lens) the image is excellent quality in the centre and I find very difficult to tell this apart from the lens without TC except for the color rendering. I believe the Kenko takes a bit away from the Canon original color rendering.

At close range you get the usual depth of field issues depending on where you focus but this is not a teleconverter issue.

For comparison a 15mm image without TC.

Zooming In

Obviously what is interesting it that you can zoom in here a set of shots at 16, 18, 21 mm.

Finishing up with the required selfie.

Conclusion

I enjoyed the teleconverter with the Canon 8-15mm and in my opinion in the overlapping focal length this set up provides better image quality of the WWL-1. I shot for most at f/8 as I was not very close and this actually shows the TC does not really degrade the image much.

You need to ask yourself when you will need 124 to 175 degrees diagonal and the answer is close up shots of mantas and whalesharks where a fisheye may be too much and 130 degrees may be too little. The set up also works if you want to do close up work and zoom in however I reserve the right to assess more in detail using my new in water props when I have some time.