Inon UWL-100 off center out of focus and weird streaking look

[DazedAndConfuzed]

The reason for zooming in is when I encounter passing marine life, it is much easier to zoom in on the WA lens and accept the fact that I have a moderate telephoto setting than unscrew the lens and put it in a safe place before taking the picture. The marine life might have already swam away or went into hiding.

Also, even if I use the WA lens for its close focusing capability, if I put it in WA setting, coming to within a inch of an subject will almost likely cause whatever I wanted to shoot to run off. The closer one gets to a critter, the more likely they will run off or go into hiding. 4 inches is usually the minimum distance that camouflaging critters will think they have not been spotted and will not run off.

As for using multiple lenses, the WA lens could be tethered, but not the diopter lens, so chance of dropping that during a wall dive is great, especially with a threaded mount. Maybe I can use a smaller diopter lens and attach it to a flange where I then velcro attach to the camera housing's lens port, since there seems to be plenty of metal between the lens port and filter thread (camera lens/lens port/filter thread diameter are 28/47/67mm. Don't know why such a filter is needed for such a small lens.) This way, there will be one less lens to thread on/off. Wish I can do it for the WA lens, but its weight will pull it loose from the velcro.


Will a Type 1 mount be better? Since it mounts closer to the camera's lens?

 

[DazedAndConfuzed]

Did a little test on land on subject consisting of white page with alot of writings on it. With camera's lens zoomed all the way in and varying the f-stop between 2.6 and 8.0. 2.6's image starts blurring 1/3 the way out from the center of the image, while 8.0's image only starts blurring on the outer 1/4.

Also, tried it at different focus distance. It seems that the closer the subject, the less blurring toward the edge. It is hard to tell since the test pattern's lines are finer when shooting from farther away, thus easier for it the white color to blend completely into the black lines, while when subject is at close range, then lines are much thicker, thus not as easy for complete blending of the black lines. Plus, focusing on a closer subject should provide a much shallower depth of field, worsening the problem.

Too bad this camera has a min aperture of f8. I could use a f32 now.


On further inspection of the camera's zoom lens, it seems that the main lens group shifts toward the camera when zooming in, thus shifting the nodal point farther away from the outer lens/lens port/wide angle lens adapter. And when looking thru the Inon wide angle lens, the farther you pull your eyes from the end of the lens, the more distorted the outer edge the image becomes. Thus a lens zoomed in with a nodal point farther away from the wide angle lens will encounter increased aberration of all kinds toward the edge of the image.

 

[Nemrod]

Did a little test on land on subject consisting of white page with alot of writings on it. With camera's lens zoomed all the way in and varying the f-stop between 2.6 and 8.0. 2.6's image starts blurring 1/3 the way out from the center of the image, while 8.0's image only starts blurring on the outer 1/4.

Also, tried it at different focus distance. It seems that the closer the subject, the less blurring toward the edge. It is hard to tell since the test pattern's lines are finer when shooting from farther away, thus easier for it the white color to blend completely into the black lines, while when subject is at close range, then lines are much thicker, thus not as easy for complete blending of the black lines. Plus, focusing on a closer subject should provide a much shallower depth of field, worsening the problem.

Too bad this camera has a min aperture of f8. I could use a f32 now.


On further inspection of the camera's zoom lens, it seems that the main lens group shifts toward the camera when zooming in, thus shifting the nodal point farther away from the outer lens/lens port/wide angle lens adapter. And when looking thru the Inon wide angle lens, the farther you pull your eyes from the end of the lens, the more distorted the outer edge the image becomes. Thus a lens zoomed in with a nodal point farther away from the wide angle lens will encounter increased aberration of all kinds toward the edge of the image.

Bingo.

N

 

[DazedAndConfuzed]

I would use the super macro mode of the camera instead of a diopter, but the camera disables its internal flash, TTL or slave mode, so no way to optically sync with a external strobe. I wish they hadn't done that.

I guess that's why some people uses video lights instead of strobes, or one of those ikelite UW housing that could take a flash sync signal from the hot shoe.