FOV for 570 investigated

[Nemrod]

Being as I seem to have recorded over the SD card with my pool experiments from last fall I shot a few in the spa for comparison.

1. Canon 570 with DC-12 and Inon 165AD fisheye, full wide:

2. Canon 570 with DC-12 and flat port at full wide:

3. Canon 570 in Ikelite with Inon 165AD fisheye at 16:9 aspect, full wide:

4. Canon 570 in Ikelite with 165AD fisheye zoomed to no vignetting:

5. Canon 570 in Ikelite with Inon 100WAL and dome port full wide:

6. Canon 570 in Ikelite zoomed full in, flat port:

Please forgive the horrid quality, shot with no strobe, dim light, inches below the surface with a lot of refraction going on inside a bathtub, hand held so don't fuss over the halos and reflections and all that, just look at the FOV. Shooting distance to tape, about 1.5 feet.

N

 

[Nemrod]

I had the F stop wide open or nearly so therefore the light fall off on some corners, stopping down a bit or a slight zoom in mostly eliminates that in photographs were it is objectionable or noticeable. Clearly the FOV is far improved over a plain flat port. Also note that I was told repeatedly by the experts and a well known camera housing manufacturer that it was impossible to use the Inon AD lens with their housing to any advantage and you might notice who is right and who was wrong. Using the 165 AD in the Ike housing at 16:9 is very usable and using the 165AD zoomed to no vignetting with the Ike yields a HUGE improvement in FOV over the flat port alone.

The top photo above, the dark edge along the top is the result of air inside the lens adapter, like I said, I was not completely submerged in a bathtub so take the quality as stated as not representative of anything, the only important info is the tape measure in the FOV--that is real.

N

 

[Nemrod]

With the ultra wide dome port wet lenses I use manual focus and then just preset the focus. This speeds up the camera shutter response considerably. Ultra wide lenses have such depth of field that I can just prefocus the camera much of the time. Thus the reason the zoomed flat port pic was blurry, auto focus was turned off.

N

 

[maged_mmh]

I see it has the same vignetting as my G9; only in G9 it is much more pronounced

 

[Nemrod]

What vignetting? Which pic? Only the third pic has noticeable vignetting in the lower left corner due to the f stop being wide open. I am shooting the bottom of a bathtub, it is not evenly lighted, especially the bottom edge of the shots.

Those were shot with two different lenses and housings and two different cameras and then flat port wide and zoomed. The top shot as I said, the lens adapter gap is not fully flooded, that is an air line, not vignetting.

The main purpose is to show how much wider you can shoot compared to a native lens behind a flat port, even if one were to zoom in another notch it is still multiple times more FOV.

I did not set exposure, I did not focus, quality was not the intent, FOV demonstration was. The pic shot with flat port and native lens wide zoom, the picture measures 16 inches horizontal. The pic shot with the Inon 100WAL and dome converter measures about 46 inches horizontal from the same 1.5 foot shooting distance for a nearly tripling of horizontal field.

N

 

[maged_mmh]

#3,4,5,and 6; not sure though if this was due uneven light and/or fisheye lens.
nice FoV stretch for the Inon fisheye compared to native port of the WPDC12 though

 

[Nemrod]

#3,4,5,and 6; not sure though if this was due uneven light and/or fisheye lens.
nice FoV stretch for the Inon fisheye compared to native port of the WPDC12 though

I don't think so.

Pic number 6 is full zoom through flat port so it would not vignette due to corner interference of the port or a wet lens--there is none--and the pic is only four or five inches across .

The number 3 does vignette in the left lower corner, the rest is uneven light.

The number 4, you are seeing the bottom of the bathtub curve back up on the lower edge and is not as well lighted.

Number 5 may have slight vignetting but again it is the bottom of the bath tub curving up in all four corners which is contributing to the light drop off. A slight zoom in would eliminate if it is vignetting or stopping down the lens from full open.

The two curved lines that appear in photo 1 and 5 are detail lines molded into the side of the spa, they are not optical aberrations or vignetting.

Again, I did not shoot these for lighting or focus or exposure or anything other than demonstration of horizontal field. If I had shot against the flat side of the swimming pool with light behind me and my strobe the weird light patterns go away, they are being caused by the curved sides and bottom of the spa and indirect and dim lighting.

I will have to wait for warmer weather to shoot in the pool with a color chart again. I figured these would just confuse more than help, oh well.

N

 

[apaka]

Hi Nemrod! do you have a photo with the Ikelite housing and the Inon WAL 100 with no dome port, just to see what's the difference? Thanks

 

[Nemrod]

Sorry, I did but they are gone. Last fall I shot a bunch of experiments in the pool but somehow I managed to get my SD cards confused and shot over them. Since then I have added the dome port. Soooo, basically no, I stupidly erased them by accident. I cannot get back in the pool 'till warmer weather. I guess I need to get another lens now but I may get a Ikelite W20 to save some money. The Ikelite of course will not accept the dome.

FYI, the dome adds about 30 degrees more FOV over the 100WAL alone and causes a semi fisheye effect, barrel distortion (lines are curved unless they pass through the center of the field).

The bottom of the spa I photographed, lol, is curved and not a good subject for investigating exposure and vignetting, it was only good for my intent, horizontal FOV comparison.

Is the 725 dollars for the 100WAL and dome port converter worth it vs 325 for the 100WAL alone, yes, beyond all doubt, it is an amazing combination. The FOV is wider, the view is brighter and I like the semi fisheye effect. I can also zoom to about the same equivilent as the 100WAL alone and still get good results with no distortion from over zooming.

Cameras Underwater: Olympus PT-015 underwater housing and C-5050 camera. Test pictures.

The above link may have some interesting info helpful to you. Also hit their home page and look over all of the optical subjects. The cameras they are using are obsolete but the lens info is useful still and current.

The bathtub shots were shot through the flat port, full wide and full zoom and with the Inon 165AD fisheye lens and the Inon 100WAL Type II with dome port corrector.

JFYI, at anything less than full wide open lens aperture the minor corner vignetting in the 16:9 shot will disappear and the slight light drop off seen in one photo will go away as well. IMO based on my experiments and use of these lenses with these housings and cameras vignetting will not be an objectionable problem and can be fully eliminated by either a slight zoom in or use of a stop down from full open on the aperture. Those photos, lol, should represent a worst case scenario.

N