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hedonist222

should I get 5d mkii aquatica housing?

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hello,

 

I've quoted the posts about apprehension of whether the 35 L would work.

Based on the, admittedly mediocre quality, photographs, does it work?

I mean technically?

 

 

 

On 5/23/2021 at 11:42 PM, atus said:

And anyway you should check the focus distance for that 35mm, the lens must be capable to focus the virtual image done inside the dome, and if not check if you can achieve that with an extra diopter lens

 

 

 

On 5/24/2021 at 1:18 AM, ChrisRoss said:

UW housing manufacturers only test popular lenses for UW use and then only list those that can actually function in a port, main criteria is they focus close enough.  Just because you like a lens on land doesn't mean it is a good idea to take it UW.   You also don't benefit from using fast lenses UW as you need to stop down for use in the dome.  Nautica for exa,ple has an extensive port chart but does not list either the 35mm 1.4 or f2 apart from the f2 lens for use with the WACP.  In general zooms are much more convenient UW as you are trying to get as close as possible to a range of creatures and still frame them properly.

If you still want to take the 35/1.4 UW you could work out what is required, but it's not a particularly useful focal length UW.

 

On 5/24/2021 at 1:31 PM, ChrisRoss said:

The dome produces a virtual image that is 3 dome radii from the dome surface for an object at infinity.  This is what the lens behind a dome needs to focus on.  A lot of lenses can't reach focus - particularly older designs and can't e used behind a dome without a diopter.

The virtual image is curved and concentric to the dome which means the corners of the image are much closer than the centre.   You need to stop down to get both the centre and edge of the image in focus.  If you don't stop down the corners are soft.  It becomes more of a problem the wider the lens and for rectilinear lenses it starts to be a losing battle as you drop below 14-15mm full frame equivalent focal length.  The problem is worse for fullframe cameras.  On full frame a 16mm focal length is shot at f11-16 and even then the corners are not perfect. 

This link has some details:  https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwiQy4qv_-HwAhVU83MBHX-nCg4QFnoECBEQAA&url=https%3A%2F%2Foceanity.com.au%2Fblog%2Fview%2Funderstanding-flat-port-and-dome-port-theory&usg=AOvVaw3Z4dn07Qbhosq60gj6J2lk

 

 

 

On 5/26/2021 at 1:26 AM, ChrisRoss said:

How did you determine the back plate is sealing?  Did you use a vacuum test?  It is flat contact o-ring and the back plate needs to be able to move in to seal properly so it can compress the o-ring.  It's your housing and expensive L- Lens but I would not dive with it like that.

BTW the reason for the correct extension is to get the best optical quality from the lens - it seems counter intuitive to me to want to use a lens because of the optical quality but compromise on the dome placement.

 

On 5/27/2021 at 2:23 AM, ChrisRoss said:

It's quite variable, you want the entrance pupil to coincide with the centre of the radius of curvature of the dome.  You can measure the nodal point your self or even estimate by looking at the apparent location of the aperture blades.  Once you have that you can compare it to nodal points of other lenses here:https://wiki.panotools.org/Entrance_Pupil_Database

If yu find a lens on that port chart with the same nodal point distance  you need the same extension.  You also need to know the radius of curvature of your port it - this can be calculated if the port is not a hemisphere- or if it is, then radius is half diameter.  Formulafor radius is here:  https://sciencing.com/radius-arc-7846775.html

 

 

On 5/27/2021 at 3:40 PM, ChrisRoss said:

that's right they don't, but the chart I linked does - if you can approximate where the entrance pupil lies and measure the distance from th lens mount to that point - you can estimate what extension is required.  Look down your lens and place your finger on the lens barrel at the depth it looks like the aperture blades are located.  Measure from the lens mount to this point .  This will get you in the ball park for the correct extension.  You just look for a lens with the same nodal point distance that is also in the Aquatica lens chart and use the extension recommended for that lens.

 

On 6/12/2021 at 9:26 PM, Barmaglot said:

Those are taken in air. With air on both sides of the glass, it does not modify the image aside from some very minor loss of sharpness and potential flare. It's when you place it underwater that different refraction indices come into play, and the dome starts acting as an additional lens element. If you google 'dome port theory', you'll find plenty of articles explaining the effect.

 

On 6/14/2021 at 12:57 AM, adamhanlon said:

It is also not simply a question of getting a similar extension in terms of the overall lens dimensions. Some lenses simply do not work well behind a dome port. The only way to know whether a given lens works or not is to experiment (or find someone else that has!) To reiterate, this is to do with lens design, and is not related to the lens's physical dimensions. 
 

 

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What are your concerns with the photos?  They are reasonably sharp I guess, but seem to have limited depth of field.  Typically I would think I'd using 35mm equivalent focal length for fish portraits  and single subjects rather than scenes unless they were rather small.  Lighting using a torch is also a little limiting, nowhere near the light output of a strobe. 

It's a little hard to judge scale not knowing the size of the subjects but it seems to me one of the issues is you are too far away and needed to back up to frame the subject with the 35mm lens.  This is why wide angle lenses are used underwater - to get close. 

What settings did you use for the shots (shutter/aperture/ISO)?

Note that I was trying to get across that the lens probably would not be that useful,  not that it straight out would not work, there's always a chance a lens may not play well underwater , but for the most part they'll form images that are usable and sharp at least in the centre of frame if they focus close enough.

 

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Posted (edited)

exif data over each photograph:

 

22 hours ago, hedonist222 said:

1/100 f/2.2 ISO 100

wrkc2pV.jpg

 

1/200 f/14 ISO 400

LtFIhEo.jpg

 

1/40 f/9 ISO 400

Iu77xhA.jpg

 

1/100 f/9 ISO 400

1Yoe41R.jpg

 

1/125 f/9 ISO 400

gwMtaWv.jpg

 

1/320 f/9 ISO 400

CfxTs9a.jpg

 

1/100 f/18 ISO 1000

natural light

wFEMoMO.jpg

 

 

 

Edited by hedonist222

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Posted (edited)

shooooooooooooot

I just realized - all these photographs were sans port haha

8" dome directly appended to housing -

I was pressure testing the housing in phases:

Phase I: Housing/Dome sans camera

Phase II: Housing/Dome/Camera in

Phase III was supposed to be Housing/Dome/Port/Camera

But I never got to Phase III.

 

Edited by hedonist222

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So...as others have said, does it do what you want it to do? If it does, I would suggest it seems fine...

Technically, it's close focus seems very limited, corner sharpness is not great (which may be the lack of extension), and focal length seems to be too narrow for most wide angle subjects, and too wide for portrait type shots.

The latter is the biggest issue. Take the image of the divers for example. In order to get the a field of view that allows you to capture the divers, you have been forced to back away, which has meant that you have no way of getting your lighting on too the subject. A wider lens, will allow you to get a field of view and to light your subjects...

 

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4 hours ago, adamhanlon said:

So...as others have said, does it do what you want it to do? If it does, I would suggest it seems fine...

 

 

I don't think this is a fair question.

If someone asks me if McDonald's is good, if I say, does it taste good to you?

I Imply that their taste ultimately dictates their fate and I actually added no value to them.

Maybe they've never tried anything better than McDonald's. So they have nothing to compare to.

My response would be, try something a bit higher end than fastfood and then you can decide for yourself.

Also, that wasn't my question. I honestly never asked if the photographs looked good.

I ask, and reiterate, has the apprehension you all had about untested lens dynamics & setup remain?

I suppose its a moot point because I did not use Aquatica's setup advice.

I intend to test again with port+dome.

 

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Yes they do. With the exception of the second image, I think none of the images you posted are really up to the results that most people here strive for. After people generally don't spend thousands on a setup to get reasonable results. They better be good...

Generally though, the Wetpixel Forums are unfortunately not a place where it's easy to judge the image quality of any setup, because the forum software downsizes images to the point where you might as well take a phone underwater...

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Quote

I've quoted the posts about apprehension of whether the 35 L would work.

Based on the, admittedly mediocre quality, photographs, does it work?

I mean technically?

I think I answered: 

7 hours ago, adamhanlon said:

Technically, it's close focus seems very limited, corner sharpness is not great (which may be the lack of extension), and focal length seems to be too narrow for most wide angle subjects, and too wide for portrait type shots.

The latter is the biggest issue. Take the image of the divers for example. In order to get the a field of view that allows you to capture the divers, you have been forced to back away, which has meant that you have no way of getting your lighting on too the subject. A wider lens, will allow you to get a field of view and to light your subjects...

On the basis of the images you have posted (with the proviso that the port set up was probably incorrect) would I say that this lens combination works for underwater photography works?

My answer would be: No, it does not. I would not chose or use this lens combination.  BUT, and this is the point we are all trying to make to you, if YOU are happy with them, that is largely all that matters. 

In underwater imaging terms, I freely admit that I prefer Michelin starred!

Adam

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