how much 'wide will I lose'

The Q ... is that the camera zoom effectively creates a cone of light that is received by the camera .... unfortunately that is given in mm not in degrees, so I am trying to figure out what 36mm equites to in terms of 'angle of view'

I consulted my lens chart and it said the angle of view of a 24mm lens on my D300 (36mm full-frame equiv) was 61 degrees.

I then tried DaveLew's equation using an online arctan calculator, and I got 61.69 degrees.

DaveLew, thanks for the equation - it was very easy to use!

Scott

but going back to my original post my zoom has max wide setting of 36mm so 28mm is not in the equation.

To be honest, it was never 100% clear to me whether you were talking about zooming in a 28mm to 36mm, or if your camera was actually 36mm.

Since you don't have a 28mm camera, there's no reason whatsoever to even consider the UWL-100 28 AD.

I consulted my lens chart and it said the angle of view of a 24mm lens on my D300 (36mm full-frame equiv) was 61 degrees.

 

I then tried DaveLew's equation using an online arctan calculator, and I got 61.69 degrees.

 

DaveLew, thanks for the equation - it was very easy to use!

 

Scott

Out of curiosity... is that 61 degrees an in-the-air measurement or is that what you get in the water?

I don't dispute that ... that is what I said ... strobe is stated as 80 degree, i.e. the cone of light coming out of strobe head is 80 degree ... fully understand that.

 

The Q ... is that the camera zoom effectively creates a cone of light that is received by the camera .... unfortunately that is given in mm not in degrees, so I am trying to figure out what 36mm equites to in terms of 'angle of view'

I had some time to run my equation through an excel spreadsheet to answer some of the questions here.

A lens system with an equivalent focal length of 36mm in air, or in water with a dome port, or in water with optics equivalent to a dome port will have:

vertical angle of view of 36.9 degrees

horizontal angle of view of 53.1 degrees

diagonal angle of view of 62 degrees

(see the equation in my post above)

If using a flat port in water and a 36mm equivalent lens, those numbers change to

vertical angle of view of 27.5 degrees

horizontal angle of view of 39.3 degrees

diagonal angle of view of 45.6 degrees

(see the equation in my post above, plus use Snell's Law to account for diffraction at the air-water interface)

Also note that all of these numbers (and angle of view numbers in general) apply at infinity. AOV is actually a little bit smaller at finite differences, although it doesn't really become significant until you get to macro distances. At really close distances, the fact that your camera's sensor is smaller than your flash's diffuser becomes more important than angle of view.

I had some time to run my equation through an excel spreadsheet to answer some of the questions here.

 

A lens system with an equivalent focal length of 36mm in air, or in water with a dome port, or in water with optics equivalent to a dome port will have:

vertical angle of view of 36.9 degrees

horizontal angle of view of 53.1 degrees

diagonal angle of view of 62 degrees

(see the equation in my post above)

 

If using a flat port in water and a 36mm equivalent lens, those numbers change to

vertical angle of view of 27.5 degrees

horizontal angle of view of 39.3 degrees

diagonal angle of view of 45.6 degrees

(see the equation in my post above, plus use Snell's Law to account for diffraction at the air-water interface)

 

Also note that all of these numbers (and angle of view numbers in general) apply at infinity. AOV is actually a little bit smaller at finite differences, although it doesn't really become significant until you get to macro distances. At really close distances, the fact that your camera's sensor is smaller than your flash's diffuser becomes more important than angle of view.

To check if I'm following correctly (and thanks for the help)

with camera zoomed out to 36mm

In standard housing (flat plate) in the water I'm going to get vert angle of 27.5deg and horiz angle of 39.3 degree

Which aligns with what I expected of about 1/3 reduction in wide angle compared to 'in air'

If I fit for example a Big Eye lens this returns the effective horiz coverage to 36mm .

As my Remora strobe is 80 degree angle ... then it would work happily with or without the Big Eye ? ................... am I right so far.

If I fit the Inon UWL105AD - what is the effective horizontal angle if that was used with the 36mm zoom ?

This is the bit that I think I am losing the plot on .......... I know it states 105mm, but what is effective coverage when used with 36mm zoom

Finally .. what is the diagonal angle of view ? ...... don't know what that is.

To check if I'm following correctly (and thanks for the help)

with camera zoomed out to 36mm

In standard housing (flat plate) in the water I'm going to get vert angle of 27.5deg and horiz angle of 39.3 degree

 

Which aligns with what I expected of about 1/3 reduction in wide angle compared to 'in air'

 

If I fit for example a Big Eye lens this returns the effective horiz coverage to 36mm .

 

As my Remora strobe is 80 degree angle ... then it would work happily with or without the Big Eye ? ................... am I right so far.

 

If I fit the Inon UWL105AD - what is the effective horizontal angle if that was used with the 36mm zoom ?

This is the bit that I think I am losing the plot on .......... I know it states 105mm, but what is effective coverage when used with 36mm zoom

 

 

Finally .. what is the diagonal angle of view ? ...... don't know what that is.

Inon UWL105AD states 105 degrees. Not 105mm. See http://www.inon.jp/products/uwl_lens/uwl_1.../uwl_105ad.html

If your strobe is putting out 80 degrees, and your lens is delivering 105 degrees (which is what it delivers to all standard 35mm equiv cameras it is connected to... by design... it is not made to work with cameras that aren't 35mm (36 is close enough)), then NO, your single Remora will not deliver adequate coverage.

I could swear we went over this like 6 posts ago.

Inon UWL105AD states 105 degrees. Not 105mm. See http://www.inon.jp/products/uwl_lens/uwl_1.../uwl_105ad.html

>I could swear we went over this like 6 posts ago.

But I am not understanding things hence my Q.

The Inon 105 is 0.51mag 105 degree angle.

What I don't underatnd is what will be the angle when used with my camera at zoom setting underwater ?

On the Inon page it just states 105 degree ... but when attached to what ?

Whether the camera is 36mm or 28mm or whatever is bound to have an effect on the effcetive angle of coverage of camera + lens combination ? ... or am I missing something ?

>I could swear we went over this like 6 posts ago.

 

But I am not understanding things hence my Q.

 

The Inon 105 is 0.51mag 105 degree angle.

What I don't underatnd is what will be the angle when used with my camera at zoom setting underwater ?

 

On the Inon page it just states 105 degree ... but when attached to what ?

Whether the camera is 36mm or 28mm or whatever is bound to have an effect on the effcetive angle of coverage of camera + lens combination ? ... or am I missing something ?

You don't "zoom" when using a WA lens. It defeats the purpose. Cameras are left at their native, max wide, 35mm position. (36mm in your case, close enough)

With very few, very specific exceptions, all WA lenses (for P&S cameras) are made for cameras with 35mm equiv lenses. The only exception I'm aware of, frankly, is the Inon UWL-100 28 AD, which is designed for 28mm cameras. It's the first one created for that class of camera, so people are very excited about it. You can't use lenses like the Inon UWL105AD on 28mm cameras without severe vignetting, so there's no point in discussing 28mm cameras (which you don't have anyway) in conjunction with the UWL105AD (which is only designed for 35mm cameras).

The Inon UWL105AD should deliver 105 degrees of FOV attached to ANY 35/36mm camera (or close enough), including yours. If you zoom in on the subject, you may as well take the WA lens off, but that would dramatically reduce the FOV delivered, and is a very different calculation regardless.

There's lots of great information in this thread and its well worth a 'sticky' I think...

You don't "zoom" when using a WA lens. It defeats the purpose. Cameras are left at their native, max wide, 35mm position. (36mm in your case, close enough)

 

With very few, very specific exceptions, all WA lenses (for P&S cameras) are made for cameras with 35mm equiv lenses. The only exception I'm aware of, frankly, is the Inon UWL-100 28 AD, which is designed for 28mm cameras. It's the first one created for that class of camera, so people are very excited about it. You can't use lenses like the Inon UWL105AD on 28mm cameras without severe vignetting, so there's no point in discussing 28mm cameras (which you don't have anyway) in conjunction with the UWL105AD (which is only designed for 35mm cameras).

 

The Inon UWL105AD should deliver 105 degrees of FOV attached to ANY 35/36mm camera (or close enough), including yours. If you zoom in on the subject, you may as well take the WA lens off, but that would dramatically reduce the FOV delivered, and is a very different calculation regardless.

Thnaks your comments have helped.

Interesting I phoned an Inon dealer today, he was steering me away from the UWL105 ... his advice was that the UFL-165 AD was the one to get, and to use camera zoom to move it away from max zoom position when using Strobe if I encountered light drop off at edges.

Although he did not think the 80 spread of strobe would be an issue it I fitted it above camera, rather than to the side.

Advised that the 80 degree is not the point at which light stops, but the point at which light has reduced by 1 stop .... and it falls off after that in linear relationship.

I guess I need to try 105 & 165 out and see the result.

Depends on what you're looking for in a WA lens. The 165 is a fisheye, which I personally really like (and I would choose over the 105 as well), but some people don't like the curvature/distortion a fisheye lens brings in. Much wider field of view than a flat WA lens like the 105, but again, curvy photos. Depending on what effect you're going for, this can be good or not so good.

I don't know if you're a member on DecoStop or not, but was an excellent thread recently covering this (from a DSLR point of view, but the theory is the same), with many examples: http://www.thedecostop.com/forums/showthread.php?t=41094

Good info on Scott Gietler's UW Photography Guide here as well: http://www.uwphotographyguide.com/fisheye-lenses-underwater

Thnaks your comments have helped.

 

Interesting I phoned an Inon dealer today, he was steering me away from the UWL105 ... his advice was that the UFL-165 AD was the one to get, and to use camera zoom to move it away from max zoom position when using Strobe if I encountered light drop off at edges.

Although he did not think the 80 spread of strobe would be an issue it I fitted it above camera, rather than to the side.

 

Advised that the 80 degree is not the point at which light stops, but the point at which light has reduced by 1 stop .... and it falls off after that in linear relationship.

 

I guess I need to try 105 & 165 out and see the result.

I don't use the UFL-165 as, unfortunately, its incompatible with the G9. So my w/a is the UWL-100 and dome which offers 130 degrees FOV u/w. However, sometimes, when shooting pelagics I find this lens combination too wide and I think I would prefer to use a UWL-100 on its own. Using the zoom with a UWL-100 and dome combination is not an option as corner distortion becomes unacceptable. I'm not sure how this may manifest itself with the UFL-165 and your camera but you may wish to check. If I were shooting a UFL-165 I may have a UWL-100 or 105 as well.

Hope this helps, Tim

I don't use the UFL-165 as, unfortunately, its incompatible with the G9. So my w/a is the UWL-100 and dome which offers 130 degrees FOV u/w. However, sometimes, when shooting pelagics I find this lens combination too wide and I think I would prefer to use a UWL-100 on its own. Using the zoom with a UWL-100 and dome combination is not an option as corner distortion becomes unacceptable. I'm not sure how this may manifest itself with the UFL-165 and your camera but you may wish to check. If I were shooting a UFL-165 I may have a UWL-100 or 105 as well.

 

Hope this helps, Tim

Thnx for the things to check out

As I'm going to get an INON lens ... anybody have any particular recommended resources for buying INON ?

The price for UWL-105 in the UK is high 299 gbp ( $498) and 75gbp ( $125) for the adapter.

If anybody knows of a good reliable on-line source US, Asia ? ... please let me know.

I can have it delivered to a US address if necessary.

I buy all my Inon stuff from Reef Photo.

I know a few people who have purchased from DiverVision overseas and saved a few bucks in some cases, but I trust Ryan more.

Ryan at Reef is excellent.

Just consider the cost implications of VAT, import duty and customs clearance charges though...

Probably the most competitive INON dealer in the UK is KMR / Aquaphot. I'd recommend giving Kevin a call...

Ryan at Reef is excellent.

 

Just consider the cost implications of VAT, import duty and customs clearance charges though...

 

Probably the most competitive INON dealer in the UK is KMR / Aquaphot. I'd recommend giving Kevin a call...

I can avoid postage etc. .... I work for a US company, and can get it sent to a colleague, who will hand carry it to UK for me.

But thanks for link to KMR / Aquaphot ..... I'll certainly look them up.