D300 with Tokina 10-17

Hi,

With the following configuration it's necessary the use of the EXR 18?

Nikon D300 with Tokina 10-17 + Subal ND30 housing, DP-FE2 dome port.

I put that question, because only with the dome port the lens don't touch the glass, but the SUBAL recomend the use of the DP-FE2 with the EXR 18 for this lens.

Somebody with the same rig can tell me what do in this situation and why?

The use of the EXR 18 is mandatory, necessary, better or it's possible work well only with the DP-FE2 with less opportunity to flood the camera without the use of the additional extension ring?

Best regards,

Tigershark

I've just been through this with Ryan from Reef Photo & Video. The EXR 18 extension ring has only just been introduced to the Subal line for use specifically with the Tokina 10-17 (I use a Canon 40D but the port/extension ring recommendation is the same). Previously some people have been using the EXR 20 (with the odd report of the vignetting caused by the shade) or the EXR 15 (which I use) with the 10-17 . I've been happy with my results using the EXR 15. The only reason I'm updating to the EXR 18 is that my EXR 15 is one of the old versions that used the smaller 2.6mm O ring and I want to standardise on the same sized O rings with all my ports and extension rings.

I think that as long as you use an extension ring in the 15 to 20 range you should be happy with results. Not using an extension ring at all may result in loss of image quality.

Hi,

Thanks Gudge for your answer.

Also the explanation from Subal:

yes, the EXR-18 IS neccessary! It is needed to have the glass of the port in the optical correct position. This has nothing to do with the space inside - the lens does not conact the port without the EXR but you will be not abel to have the image in focus becuse the 'zero' point of the lens can be not reached by the light beam trough the glass (where it has been 'broken').

You know that the light beam will be 'broken' (or bended) when it passes water, air or glass but the angle of of that 'break' is different in water, air and glass. The target is that the light beam reaches the lens of the camera as 'straight' as possible. To reach that the glass has to be set into the most exact position and therefore we need the EXR.

Understandable?

Best regards,

Rolf

Best regards,

Tigershark

Previously some people have been using the EXR 20 (with the odd report of the vignetting caused by the shade) or the EXR 15 (which I use) with the 10-17 . I've been happy with my results using the EXR 15. The only reason I'm updating to the EXR 18 is that my EXR 15 is one of the old versions that used the smaller 2.6mm O ring and I want to standardise on the same sized O rings with all my ports and extension rings.

Gudge,

What diopter, if any, have you been using with this lens and the 15mm extension?

I'm just getting this set up.

[Edit: Never mind, I see that there are no front filter threads to mount a diopter, so everyone is doing without! I have not received my lens yet, so didn't realize...]

thanks,

Linda

What diopter, if any, have you been using with this lens and the 15mm extension?