Another Tokina 10-17 / teleconverter question

I've never used a teleconverter and I'm trying to get a better understanding. I've read a number of post discussing the advantages of a teleconverter when using the 10-17 with a full frame camera. What about with a DX like the D7000? Are there advantages / disadvantages in using say the Kenko 1.4 with the Tokina?

Steve

Hi Steve,

From my understanding the Tokina 10-17mm on a DX camera is like a 15-25.5mm on a FX Camera (1.5x cropping factor). So what people are doing is adding the 1.4x TC to the Tokina when mounting onto a FX camera to turn it into a 14-23.8mm, which makes it very close to how the Tokina 10-17mm looks on a DX camera like the D7000 (slight zoom required on FX camera to remove vignetting at its widest end).

Using the 1.4x TC with the Tokina 10-17mm on a DX camera like the D7000 turns the Tokina into something like a 14-23.8mm Dx lens but with 1.4x image size. They are then mounting the Tokina 10-17mm with TC behind a mini dome (4inch/100mm) which allows the shooter to get closer to the subject and filling the subject more in the frame making it appear more magnified.

The ability of the Tokina 10-17mm to focus very close by itself and when used with the combination of 1.4x TC and mini dome makes it a very versatile lens. Shoot the Tokina at 10mm with Manta's on the first dive and use it behind a mini dome and TC and take CFWA and WAM on the second dive.

But to give the Tokina 10-17mm and TC combination justice on DX format Cameras you really need to mount it behind a mini dome. Then again the Tokina 10-17mm by itself is a completely different lens when behind a mini dome and might just be all you need or a good place to start.

Here is a Alex Mustard's review on mini domes which kind of ties into this topic: http://wetpixel.com/i.php/full/thoughts-on-mini-domes/P1/

Regards Mark

It's not simply that the focal length changes, but that the perspective is altered in a way that emphasizes the foreground in close-focus wide-angle compositions. That can be useful when creating a dramatic image of a small, but non-macro, subject: frogfish.

Tim

Thank you Mark & Tim, that was very helpful.

Steve

I too am still trying to get to grips with this.

Allowing for correct exposure in both images am I correct in thinking, if you use the teleconverter (1.4x) with the lens at 10mm it will produce a similar image to the tokina lens without a teleconverter at 14mm? The picture may be less distorted with the teleconverter because you are magnifiying the centre portion of the image which is less distorted than the periphery on a fisheye. Minimum focus distance will stay the same in both instances so you won't be able to get closer/further away in either situation.

Does this mean that most of the benefit of the teleconverter comes at the longer focal end of the tokina where the teleconverter will produce a longer focal length that is not possible by simply zooming (ie >17mm)?

What are the advantages of using a teleconverter with the Tokina over an imaginary native 14-24mm fisheye lens? Is it just that the minimum focusing distance of the Tokina is preserved at the expense of a stop of light?

Thanks, trying to understand all this and make an informed decision before buying.

The picture may be less distorted with the teleconverter because you are magnifiying the centre portion of the image which is less distorted than the periphery on a fisheye.

The overall effect of the teleconverter is to emphasize the foreground, with less effect on the background. In that sense it introduces an additional distortion. It's that change in the visual properties of the image, particularly behind a small dome port, that makes the technique interesting. To get a bigger image of the subject, it's usually much better just to get closer; to get a less distorted image, a rectilinear rather than a fisheye lens.

Tim

Okay, thanks for that. I think I'm trying to think of it a bit too simplistically.

This thread includes what I think is Alex's master image using the technique:

wide-angle macro

It's about getting close, but controlling the field of view.

Tim

Hi all...

In response to a question I posted regarding adding a 1.4 tele behind a Tokina 10-17 (on a D7000, Aquatica, 8" dome), I got hunting around for more info.... and I too am having trouble understanding what to expect.

I also have a Nikon 12 - 24, which I rarely use since I got the 10-17. From what I can gather, adding the 1.4 converter to the 10-17 does NOT make this lens behave like the 12-24, correct? Rather it emphasizes a centre-frame subject at the expense of the background?

Does the minimum focussing distance change with the addition of the converter?

I am going to take my camera to the shop today to peak through the lens with the converter, but I don't think that this will give me a great idea of what to expect behind the dome.

Your learned replies appreciated!

The addition of the TC gives the user the option of better using the 10-17 fisheye lens for Wide Angle Macro shots. The TC 'sucks' the image in closer

so you get more working space for lighting on smaller subjects in the foreground. The 8" dome you have isn't as suitable for the WAM technique as its

size won't allow for placing strobes in tighter positions like the 'çar headlights' position close to lens. The larger dome also stops you placing the housing

as close and low as you often need to as well.

The 12-24 is a rectilinear WA lens with a tighter field of view. Even with the addition of the TC to the 10-17 fisheye, it still has a distorted image, more so at

the wider end. I'm not so good with the tech side so not sure what exact change there is to minimum focus. However the closer you get the harder to light the

area right in front of lens without blowing out everything else. This is where the extra magnification helps you to back off a little and light the frame in a more

balanced way with greater ease.

It is a style of image I must do more work with myself but here are a few examples, good and bad, that I've taken.

Hope this helps a bit more.

Cheers,

Jim.

On 9/22/2012 at 4:33 AM, JimSwims said:

 

It is a style of image I must do more work with myself but here are a few examples, good and bad, that I've taken.

Thanks Jim, that's really helpful to see! Have you done any more since? I'm just about to get the TC as I've got everything else