how much 'wide will I lose'

[Osprey 0]

I use the zoom on my compact camera set to 36mm wide setting when on underwater duty.

 

Allowing for water diffraction, I obviously lose effective wide angle capability.

 

Just read that I will lose 30% .... making my camera effectvely close to a 50mm standard lens when in the water.

 

I'm considering buying an add-on supplementary lens (Fantasea Big Eye), the blurb states that it will correct any 'wide capability' loss when underwater and return it's full wide angle range ... to the same as when it's out of the water.

 

 

is what I'm being told correct ?

[Timmoranuk 10]

Yes, the Fantasea Big-Eye restores the field of view of the camera's lens to its above water capability and IIRC, is designed for the new generation of compacts which have 28mm (equivalent) lenses.

 

Frankly, I'd look at wide angle offerings from INON, Epoque or Sea & Sea which increase the field of view. If you own an older generation of compact (with a 35mm equivalent lens) a good place to start would be the INON UWL-100 and dome unit or the UWL-165. If you have a 28mm lens, then the INON UWL-128 and dome is a candidate.

 

HTH, Tim

[CompuDude 0]

Yes, the Fantasea Big-Eye restores the field of view of the camera's lens to its above water capability and IIRC, is designed for the new generation of compacts which have 28mm (equivalent) lenses.

 

Frankly, I'd look at wide angle offerings from INON, Epoque or Sea & Sea which increase the field of view. If you own an older generation of compact (with a 35mm equivalent lens) a good place to start would be the INON UWL-100 and dome unit or the UWL-165. If you have a 28mm lens, then the INON UWL-128 and dome is a candidate.

 

HTH, Tim

What is the UWL-128? Do you mean the UWL-100 28AD?

Edited November 5, 2009 by CompuDude

[Timmoranuk 10]

What is the UWL-128? Do you mean the UWL-100 28AD?

 

You are absolutely correct. My mistake! Interestingly, I am told that fitting the dome unit to the 100 28 AD results is a wider FOV than provided by the lens on its own in air.

[CompuDude 0]

You are absolutely correct. My mistake! Interestingly, I am told that fitting the dome unit to the 100 28 AD results is a wider FOV than provided by the lens on its own in air.

 

Per Inon's website ( http://www.inon.jp/products/uwl_lens/uwl_1...l_100_28ad.html ):

 

- Maximum view angle 100 ° (u/w), 179 ° (air), x0.63.

- Maximum view angle 150.8 ° when attaching optional [Dome Lens Unit for UWL-100]

 

I presume the latter refers to underwater, which means specs are not given for topside use with the dome. If the bare lens already gives 179 degrees (in air), though, I have a hard time seeing how it's going to get higher than 180 degrees! Is that even possible without some crazy 360 camera?

Edited November 5, 2009 by CompuDude

[Timmoranuk 10]

I'll check with Steve Warren from Ocean Optics, the INON distributer in the UK. I'll see him this weekend at 'Visions in the Sea'

[epicrondo 0]

i am not very clearn abou tthis

[Osprey 0]

My compact has wide setting of 36mm .............. (F31fd) so looking for a supplementary lens to use with that.

 

Need to consider that I am using a Remora Strobe... one head only, so no point in going to a super wide fish eye lens, if strobe can't illuminate it effectively... and I do not want to go for twin strobe heads.

Not sure what the actual angle of coverage is ...

 

Hence the use of INON lens has a Question mark against it, will strobe give wide enough coverage.

 

The following links have been supplied by Fantasea ... may be of interest to some

 

How Big Eye works -

http://fantasea.com/Dealer Packages/Fantasea Eyes/Big Eye Chart.html

 

Video of it in use:

https://system.netsuite.com/core/media/medi...03&_xt=.bin

[Osprey 0]

I'll check with Steve Warren from Ocean Optics, the INON distributer in the UK. I'll see him this weekend at 'Visions in the Sea'

 

I had been looking at the 105AD lens from INON

 

It states the angle is 105 (in water) and a 0.51 magnification.

 

but isn't the angle dependant on what lens is on camera (or in my case what zoom is) ?

 

I have a 36mm zoom ... if I attach this lens won't it give a different result than if attached to a camera with 28mm zoom ??

[CompuDude 0]

I had been looking at the 105AD lens from INON

 

It states the angle is 105 (in water) and a 0.51 magnification.

 

but isn't the angle dependant on what lens is on camera (or in my case what zoom is) ?

 

I have a 36mm zoom ... if I attach this lens won't it give a different result than if attached to a camera with 28mm zoom ??

 

The issue is you have a Fantasea Remora strobe, which, according to Fantasea's website has a "Beam angle 80 degrees horizontal".

 

Your strobe will not light up the full range of a 105 degree lens. You'd need two strobes or a different strobe with wider coverage (like the Inon strobes).

 

There is only one wide angle lens made to work with the 28mm lens compact cameras, the Inon UWL-100 28AD we discussed above. The other ones, as I understand it, will not work with cameras with a 28mm lens, so that's not relevant to the discussion.

 

If your camera is 36mm (which can be treated as 35mm for this discussion), you have more options, such as the UWL-105 you mentioned.

[Osprey 0]

The issue is you have a Fantasea Remora strobe, which, according to Fantasea's website has a "Beam angle 80 degrees horizontal".

 

Your strobe will not light up the full range of a 105 degree lens. You'd need two strobes or a different strobe with wider coverage (like the Inon strobes).

 

There is only one wide angle lens made to work with the 28mm lens compact cameras, the Inon UWL-100 28AD we discussed above. The other ones, as I understand it, will not work with cameras with a 28mm lens, so that's not relevant to the discussion.

 

If your camera is 36mm (which can be treated as 35mm for this discussion), you have more options, such as the UWL-105 you mentioned.

is there a simple way of relating angle to zoom capability ...

 

 

i.e strobe is quoted in 80 degrees lens is 36mm ?

be nice to have a common unit so I can see maximum angle of lens I can use with this strobe

[CompuDude 0]

is there a simple way of relating angle to zoom capability ...

 

 

i.e strobe is quoted in 80 degrees lens is 36mm ?

be nice to have a common unit so I can see maximum angle of lens I can use with this strobe

80 degrees is the strobe's measured output, not the lens. Lens has nothing to do with the strobe... the strobe outputs the same spread whether there is a camera there or not.

 

Not sure what the naked FOV is with a 36mm lens. Small... something like 40-50 degrees comes to mind? (Could be way off there, I'm not sure where that figure popped into my head from.)

 

You're talking about adding a wide angle lens to the camera, though, so you have to look at the WA lens' FOV, which is in the lens specs: 100 degrees or more, for the ones we've been discussing. Any way you look at it, the Remora doesn't have enough coverage with an 80 degree spread.

[Osprey 0]

80 degrees is the strobe's measured output, not the lens. Lens has nothing to do with the strobe... the strobe outputs the same spread whether there is a camera there or not.

 

Not sure what the naked FOV is with a 36mm lens. Small... something like 40-50 degrees comes to mind? (Could be way off there, I'm not sure where that figure popped into my head from.)

 

You're talking about adding a wide angle lens to the camera, though, so you have to look at the WA lens' FOV, which is in the lens specs: 100 degrees or more, for the ones we've been discussing. Any way you look at it, the Remora doesn't have enough coverage with an 80 degree spread.

 

 

Maybe I stated it wrong ... I know the Remora has a fixed horizontal spread ... i.e. the cone of light that emits out of it.

Likewise he zoom setting of my camera affects the cone of light that 'comes into it'

 

What I am trying to figure out is how to equate these ... for flash to be successful it needs to be equal to or greater spread than that of lens, so illuminating all tha the lens can see.

 

Now the in built flash of F31fd works at full wide zoom so must have a horizontal spread that matches wide angle setting, I'm assuming that Remora will equal or exceed that.

 

 

When I used to use 35mm film it was much easier ... lens quoted in mm ... and flash coverage was quoted the same.

 

The Remora comes with a diffuser but I don't know if that spreads the light or just softens it .... I have had flash guns in the past which had clip on diffuser that you added when using 28mm lenses.

[CompuDude 0]

If it helps any, using the diffuser on the Inon strobes adds 5-10 degrees to the spread.

 

As to the rest, I think it's safe to say that the remora strobe should give full coverage to the naked lens. And safe to say it will give insufficient coverage to an added wide angle lens. If you zoom in a bit with the WA lens, you may get back into the coverage area of the Remora, but that somewhat defeats the point of adding a WA lens, doesn't it?

[Osprey 0]

If it helps any, using the diffuser on the Inon strobes adds 5-10 degrees to the spread.

 

As to the rest, I think it's safe to say that the remora strobe should give full coverage to the naked lens. And safe to say it will give insufficient coverage to an added wide angle lens. If you zoom in a bit with the WA lens, you may get back into the coverage area of the Remora, but that somewhat defeats the point of adding a WA lens, doesn't it?

 

 

it certianly would defeat the purpose :-)

 

does anybody know the math of relationship .... if lens is 36mm at wide angle setting, what angle that equates to ? assume there must be a way of working it out

[Timmoranuk 10]

I'll check with Steve Warren from Ocean Optics, the INON distributer in the UK. I'll see him this weekend at 'Visions in the Sea'

 

 

I've just heard back from Ocean Optics. The FOV of the UWL-100 28 AD is 179 in air and 150 (with dome) u/w. For 28mm compact camera lenses is the w/a INON glass to get. HTH, Tim

[davelew 4]

is there a simple way of relating angle to zoom capability ...

 

That depends on your definition of simple... Here's the basic equation:

 

 

where alpha is the angle of view,

d is 43mm for a full-frame 35mm equivalent (this give you the diagonal angle of view; d is 36mm for horizontal AOV and 24mm for vertical AOV)

f is the focal length (ie 28mm)

[CompuDude 0]

I've just heard back from Ocean Optics. The FOV of the UWL-100 28 AD is 179 in air and 150 (with dome) u/w. For 28mm compact camera lenses is the w/a INON glass to get. HTH, Tim

Right, that's what the Inon site says, too.

 

Now I just have to find a housing that will let me mount this puppy on my new S90!

[Osprey 0]

I've just heard back from Ocean Optics. The FOV of the UWL-100 28 AD is 179 in air and 150 (with dome) u/w. For 28mm compact camera lenses is the w/a INON glass to get. HTH, Tim

 

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

[Osprey 0]

80 degrees is the strobe's measured output, not the lens. Lens has nothing to do with the strobe... the strobe outputs the same spread whether there is a camera there or not.

 

Not sure what the naked FOV is with a 36mm lens. Small... something like 40-50 degrees comes to mind? (Could be way off there, I'm not sure where that figure popped into my head from.)

 

You're talking about adding a wide angle lens to the camera, though, so you have to look at the WA lens' FOV, which is in the lens specs: 100 degrees or more, for the ones we've been discussing. Any way you look at it, the Remora doesn't have enough coverage with an 80 degree spread.

 

 

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'

[sgietler 1]

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

[CompuDude 0]

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.

[CompuDude 0]

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?

[davelew 4]

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.

[Osprey 0]

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.