Sigma 17 70 or tokina with tc

Hi community..i own a canon 7d in an aquatica housing with an 8" dome port..and i want to buy me a new lens..and i was thinking about the sigma 17 70mm for mid range , and fish portraits maybe..i know its not a properly macro lens..but i would like to have a more close up for mid to a little smallest subject....or..i heard as well that maybe its better to buy a kenko 1.4x tc to add to the tokina..but i dont know  if that work well in my big dome or i will have to buy a 4" dome..anyone any suggestion or adviced?..thanks a lot in advanced.

hi juanmag

I can't say much about the Sigma (which I have never used) other than I didn't like the Nikkor mid-size zooms with my Nikon APS-C cameras. They were neither Man nor Beast.

My suggestion would be to go for a 60mm macro paired with the Tokina 10-17 and, sure, why not get the Kenko 1.4TC too. You then have great range and lenses which will do a good job of macro, fish portraits, wide-angle and CFWA.

As important as using the right lens - rather than hybrid-one-size-does-sort-of-anyting - it effects on your mind set and the way you see photo opportunities on the reef. If you are using a macro lens you will naturally look for the best macro opportunities. Same thing with WA, CFWA.

For the last few years, the Tokina 10-17 has been pretty much the go-to WA/fisheye lens for APS-C users. I had it for my Nikon D300 and now the Nikon D500. It's horrible topside, but underwater, it really is excellent: sharp, flexible, close-focussing, easy to use, good colour rendition, relatively inexpensive.  Adding the 1.4TC then gives you very good CFWA. The only downside, I think, is it's a slightly fragile lens and you have to be a bit careful with handling. 

You can use it with pretty much any dome. I use it with both an 8" and 4" dome. The 4" is much better for CFWA; the 8" is good for splits.

Thanks tim for the answer.the thing is that for the canon 60 mm ill have to buy the lens plus the port..and for the sigma just the lens since i can use it behind my 8 inch dome..and to see the versatility of this lens as a mid range lens..quality etc..

Of course i know at one point for macro i will have to purchase de 60mm

I use the nikon 16-85mm in my aquatica housing. Works with 6inch port and 8inch port. I do 1:2 macro to mild wide angle. The only time i do 1:1 macro or smaller is pygmy seahorse. For 1:1 macro or smaller i add a +4 diopter to the lens inside the housing. To see sample of what this lens does. I like the ability to use one lens and just change the zoom. Easier for travel as less gear and underwater your not locked into either small or large subjects   . I use the 18457 extension. The 48457 is the same size as my 18457 but has the lock    The sigma 17-70 would produce similar shots as my 16-85mm. I have seen this lens on a friends housing and he is very happy and the shots are excellent.  https://reefscenics.smugmug.com/Underwater/Komodo-Indonesia/i-Swr6KZ6

No worries, juanmag.

I don't know what the Sigma costs but if it's significantly more than the Tokina, I'd be tempted to buy the Tokina, use it with your 8" dome - and save the cash towards the Canon 60mm/port

I have already the tokina tim..its the one a use most of the time..i just was wondering is to buy the sigma or the 60mm.

Oh right, sorry I misunderstood. Wow, if you have that, I wouldn't go for the Sigma - get the Canon 60mm 

The issue with the sigma lens is it' not very wide on 1.6x crop (28mm equivalent) and while it says you can get 0.36x, this would be achieved at a working distance of 94mm from the front element (when the lens is at it's shortest, it gets longer as you zoom and this eats into working distance) but to work effectively the front element will be towards the back of the dome which has a 100mm radius.  This means minimum focus is right on the dome or pretty close to that so you need to get the dome in right on top of whatever you are shooting to achieve 0.36x which may not be possible for a lot of subjects.  

I would think you might be better served  by a 4" dome on your Tokina - you can demonstrate the benefit for your self on land, get a small target and get as close as you can with the dome and take a shot.  Then take the camera out getting  about 50mm away  with the camera out of the housing and take another shot for comparison.  that little bit closer you get makes a surprising difference to subject size in frame.

Or get the 60mm - it will be much more flexible allowing more working room, significantly more magnification.  at the same working distance as the Sigma 17-70 (at max magnification) you get 1:1 and the much smaller port means it easy to get in closer and to light the subject.  at 0.3x - 0.5x magnification the working distance will be quite comfortable.  Note that the 60mm Canon is discontinued, but you should be able to pick up a nice second hand.  

In UW work it's not just if the lens takes nice picks, it's the handling in combination with port you need to consider.

Thanks a lot chriss for your answer..yes i think i will go with 4" dome  and then the 60 mm..thanks!!