Canon S90 w/ lenses Pool Practice

[dogdrjohn]

If I measured accurately? What are you implying - that I measured it with a tape measure? OK< I did measure it with a tape measure, although the previous measurements were with a little stainless steel ruler. So, none of my measurements are going to be perfect. Now on to more imperfect measurements. I measure 3.25 inches from the back of the camera to the front of the AD mount - I thought this might equalize things a little for comparison between housings. The Canon housing does have the thick bezel around the front glass, but the back of the lens projects behind the back of the mounting plate so it is very close to the front of the glass. Another imperfect measurement suggests that the front of the camera lens when set at 28mm will be about 1/2 inch from the back of the INON lens. I suspect that the greatest difference between the Canon and FIX housings will be the double glass port (no fogging). I may make some similar measurements with my old Sony P150 and Sony housing and INON adaptor and see what I come up with as far as lens-to-lens distances go, but I have to go to work today and then off to New Orleans for Jazz Fest this weekend. Diving in Philippines in less than 2 weeks. Woo Hoo

 

[Nemrod]

If I measured accurately? What are you implying - that I measured it with a tape measure? OK< I did measure it with a tape measure, although the previous measurements were with a little stainless steel ruler. So, none of my measurements are going to be perfect. Now on to more imperfect measurements. I measure 3.25 inches from the back of the camera to the front of the AD mount - I thought this might equalize things a little for comparison between housings. The Canon housing does have the thick bezel around the front glass, but the back of the lens projects behind the back of the mounting plate so it is very close to the front of the glass. Another imperfect measurement suggests that the front of the camera lens when set at 28mm will be about 1/2 inch from the back of the INON lens. I suspect that the greatest difference between the Canon and FIX housings will be the double glass port (no fogging). I may make some similar measurements with my old Sony P150 and Sony housing and INON adaptor and see what I come up with as far as lens-to-lens distances go, but I have to go to work today and then off to New Orleans for Jazz Fest this weekend. Diving in Philippines in less than 2 weeks. Woo Hoo

I will try to get some more "imperfect" measurements also, lol. I don't think he was trying to insult us, I think he is just implying, as we have, that these numbers are approximations and not absolutes.

If we know the distance from back of the camera to front of lens port (face of lens) and then the back of camera to the face of the AD mount then we should be able to solve for distance between rear of AD lens element to front of camera lens of both housings.

I can then get that same "solution" for an Inon engineered mount for my Oly and Canon 570 as a benchmark and we should be able to see how they stack up to each other.

N

 

[skynscuba]

I don't think he was trying to insult us, I think he is just implying, as we have, that these numbers are approximations and not absolutes.
N

Absolutely! I could have said "based on." Anyway, I was trying to see the comparison in the distance from the back of the camera (which implies the position of the front of the S90 lens) to the outside of the port for the two housings. If it were the same, the Canon housing could, with similar close mounting, get the good results that Nemrod has demonstrated with the UFL-165AD. Nemrod has said that even the ~1mm difference of his DIY adapter and the 10bar ring makes a small but noticeable difference in the photos. So, if the back of the camera to front of the port is several mm more for the Canon, it doesn't seem that likely that the fisheye will work that well with it.

 

[dogdrjohn]

Some more measurements, some more questions. On my old Sony P150/MKP-PHB/INON AD mount, the distance from the front of the port glass to the back of the UWL-105AD lens is significantly greater than on the S90-WP-DC35/INON AD28 mount. I can place three pieces of 1mm cardboard and mount the lens and the cardboard is loose, while I cannot even mount the lens with only ONE piece of 1 mm cardboard on the Canon. This is not surprising as on the Sony AD mount, the back of the lens is nearly flush with the back of the mount, while with the Canon AD28 mount the back of the lens projects a good 3 to 4 mm behind the mount, closer to the port glass. I bought a little caliper at True Value and measure/calculate that the distance from the the front of the lens to the front of the port glass on the Sony is ~22mm, while the same distance on the Canon is ~12mm. On the Sony the lens is fully extended at wide, unlike the Canon. Which brings up the next point. If as INON claims as little as 5mm difference in the lens (camera) to lens (WA) distance can have such an impact on picture quality, how does one lens such as the UFL-165AD work well with so many cameras? Do they all have the same distance from lens to lens? Does INON somehow compensate for this with the design of their AD mounts. These measurements also confirm something I have long suspected - that the big difference between AD and AD28 mounts is the that AD28 mounts the lens CLOSER to the lens port. This was suggested by the fact that INON says the UCL-165AD Macro lens only works on AD28 mounts with the AD spacer they sell, placing the lens farther away from the port. And what about other lenses such as the Ikelite WA 20 or FIX UWL-04 - is the lens to lens spacing as critical with these lenses? After determining that I could relatively easily replace the AD mount on my new INON mount with a 67mm threaded ring, I seriously considered buying a FIX UWL-04 instead of a UFL-165AD, but the extra size and weight and slightly narrower FOV (130 vs 165) deterred me for now. I will have to wait for my Philippines trip in two weeks to try my friend's UFL-165AD. ALso, I just tried another quick test. I had noticed that the arrows on the lens hood on my 105AD did not align with the arrows on the mount and realized the hood was moveable. So I just took it off completely and greatly reduced the vignetting at 28mm, slightly at 35mm. This post is getting long but one more question - which is better: to zoom and narrowly crop (or not crop at all if zoomed enough), or just crop form the widest possible picture? That's all for now.

 

[Nemrod]

Wow, not sure I can answer all of that.

But I can tell you that it is always better to not crop your sensor or image. I would rather zoom than crop unless the crop is essentially nothing (greater than 95%).

The lens spacing thing, without going into serious investigation which would require more info from Inon and a multitude of cameras, cannot be done.

Yes, Inon individually engineers their mounts for best results.

My experience, the AD lenses are more sensitive to mounting position than are the larger UWL100-67mm lens.

Regardless of what the Inon catalog says with the 5mm thing, there is an acceptable zone of mounting position relative to the camera lens within which satisfactory results can be obtained. Beyond that "zone" quality deteriorates rapidly with corner blurring, reduced FOV, vignetting, unequal exposure/light etc.

When people interchangeably refer to the AD and 28AD as AD it gets very confusing to me.

FIX90, Inon UFL165AD, dual Inon D2000, zoom at 35mm, no crop required:

N

 

[under water]

- which is better: to zoom and narrowly crop (or not crop at all if zoomed enough), or just crop form the widest possible picture?

Depends what you are going to do with the picture. If you are going to resize a 13 MB RAW image to a 800* 600 jpeg to make it smaller for the web, you are going to lose resolution and definition, so crop first, then resize.
Optical zoom is better than cropping, if you don't have to give up anything, like focus range, DOF, Fstop, etc. Often you do have to give up at least one of those.


In order of preference (mine)

• Get as close as possible
• frame the best shot you can
• use the highest resolution possible and
• crop if it makes sense.

 

[swee sin]

• Get as close as possible
• frame the best shot you can
• use the highest resolution possible and
• crop if it makes sense.

Agree ...

 

[Nemrod]

I think what was being asked was with a lens that vignetted potentially, was it better to zoom to eliminate the vignetting or to post crop the image. I say it is better to zoom in slightly and keep the sensor operating at 100% effective area than to crop after and loose sensor size.

The example is with the 165AD on the Ikelite housing apparently requires about a 45mm focal length zoom to eliminate vignetting, is it better to zoom the camera to 45mm or to shoot at 28mm and then crop the image. My answer, zoom to 45mm. Fortunately with the FIX90 that much zoom is not required to produce full field, no crop images.

Another example, 165AD with 10Bar adapter on the FIX, this combination and the UWL100-28AD with dome on any camera requires about a 98% crop to eliminate minor corner darkening. Is it better to zoom in further than 35mm or crop after, in this case, I would crop after.

Another example, my DIY adapter, my FIX90 housing, the UFL165AD lens, Canon S90, shoot at full open 28mm and have significant vignetting and crop after or zoom to the natural operating focal length the lens was designed for, 35mm, and have 100% effective sensor area, no crop. In this case, zoom to 35mm is the best answer, as the images above are.

N

 

[under water]

I think what was being asked was with a lens that vignetted potentially, was it better to zoom to eliminate the vignetting or to post crop the image. I say it is better to zoom in slightly and keep the sensor operating at 100% effective area than to crop afterwords and lose sensor size.
...Another example, my DIY adapter, my FIX90 housing, the UFL165AD lens, Canon S90, shoot at full open 28mm and have significant vignetting and crop after or zoom to the natural operating focal length the lens was designed for, 35mm, and have 100% effective sensor area, no crop. In this case, zoom to 35mm is the best answer, as the images above are.

N

Makes sense N, I was reacting a bit to your previous statement "But I can tell you that it is always better to not crop your sensor or image. I would rather zoom than crop unless the crop is essentially nothing (greater than 95%)"
Just didn't want someone scanning and seeing that and thinking cropping is a bad idea. I'm sure you didn't mean it as a generalization.

It does make sense to zoom in to accomodate a lens designed for 35mm on a 28mm camera. I stayed with my G9s because they work really well with all the wet lenses since they are 35mm not 28mm, so zooming underwater to me is something I don't do hardly ever. I probably should try it a bit more, but I find it rather difficult to control zooming accurately with the Ike housing and the short port. For all the reasons you mentioned, going to a 28mm, at this time, was not an upgrade in my eyes.

Photography is a bit like cooking. The raw ingredients (what you shoot) are important, but it is so much fun to use all the ways to prepare the images. The end result is what hits the brain of the observer.

To the OP.
I really like the idea of practicing on little plastic creatures rather than waiting until you get to the real thing.

 

[Nemrod]

Zoom for the S90 to 35mm can be set in custom settings or controlled from them front ring. Once set to 35mm (or whatever required for the wet lens and housing) it is left alone. I am not talking about zooming in and out, I mean to zoom to the required setting to eliminate vignetting and leave it alone.

Other generalizations, I dunno, I am talking about the accessory lenses being discussed on the three housings being discussed with the Canon S90 in this thread, other applications and other threads or such, don't know. Not what I am talking about.

N