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Ikelite N90 conversion and questions

Ikelite N90

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#1 ruckusman

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Posted 18 January 2018 - 12:05 AM

Hi Guys,

 

first post here, so I'll give you some background. I used to shoot professionally, film, medium and large format etc - but haven't in quite few years. D2X was he last camera body I purchased.

 

Anyway my local beach Narrabeen has nice clear azure water on occasion with distinctive red sand but awful waves for surfing where I am.

 

I've never dived, though I've spent many many years in the water and I suppose under it when I've got a wave on top of my head, if that counts.

 

I've tried various gopros with stock and different rectilinear lenses - their image quality is awful, colour space is tiny and surprisingly they were not holding my highlights - so they are basically ruled out. That's the film snob in me...

 

So I've decided to convert an Ikelite N90s housing I got for cheap - $60.
It has what I suspect is an 8" diameter dome port.
It needs both the port and back o-rings before it gets anywhere near water.

First up it's getting an older Canon Kiss X4 (550D) inside. Reason being is that this camera was going to be thrown out and my Nikon D2X doesn't physically fit into the housing nor will it align with the centre of the port.

 

The 550D goes surprisingly close to fitting with only a new mount plate needed to lower it approx 2mm to centre the dome port and lens optics. I may need to remove the popup flash to move the body minimally forward.

 

I've got 3 lenses to test for optical alignment with the dome port EFS 17-85mm f4-5.6, EFS 10-22mm f3.5-4.5 and the kit lens EFS 18-55mm f3.5- 5.6 - again nothing exotic.

 

I've got a fair understanding on what to look for with lateral chromatic aberration and will test the lenses with some tiles in a pool to see how good/bad the lineup is with the lens aperture/dome centre.

 

Realistically though, swirling water and sand isn't going to demand much of  the optics, though I don't want it looking like it was shot with a potato.

After that depending on the success/failure of my ideas that may change to a 5D MkIII or similar.

 

For simplicity I've removed all but three dials, focus/zoom and shutter and the other holes will be plugged.

 

Now the plan is to basically put myself right in the impact zone - literally, there will be no opportunity to change setting, that will have to be achieved by going back onshore and opening the housing. There is no image preview because the housing back is black.

 

That's why I've made housing single use shutter and possibly focus/zoom only.
Almost everything will be done with a hyperfocal focus distance settings likely.

 

So quick questions...

 

Given that I'm going from normal air pressure to underneath waves breaking the pressure gradient will be quite severe, is it worth getting one of the vacuum devices to securely seal the housing?

 

Does anyone know if the lens focus and zoom rings are universal between the Ikelite housings, so if I get them for these lenses they will mesh with the gears correctly?

 

I will likely be looking for a flat port at some stage - some reading suggests they are standard across the Ikelite SLR/DSLR range - is this correct?

 

any tips appreciated also

 

thanks

 

Glenn



#2 ChrisRoss

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Posted 18 January 2018 - 01:43 AM

Depending on the age you may want to service the o-rings on controls you have left. How do you plan to plug the other controls?  You would need to find some way that was watertight.  As for the lenses positioning them properly requires use of different length extension rings.  To get a starting point I would think that using Ikeliyes recommendations would not be too far out.  For that you need the port chart:

 

http://docs.ikelite....t-fl-system.pdf

 

this seems to recommend the 8" modular dome for the lens you list, it may already have an extension on it?  I don't know if yours would be the same style given the age.

 

As far as the vacuum system goes it would certainly make leaks due to being bumped around in the surf less likely as it pre loads all the o-rings.  O-rings require water pressure to seal and the most likely place for a flood is probbaly the rinse tank   I would also suggest the fact you are modifying the housing means you would want some good way to test that what you have done is watertight.

 

It's not exactly clear what you are shooting, normally you are trying to get close as you can when diving hence recommendations for diopters to allow the lens to focus on the virtual image.  If you are above water this may prevent you taking a photo for example of a surfer.   If you are not sure what I'm talking about google "dome port optics".

 

Also to be clear UW you focus on a virtual image which is really close to the dome so hyperfocal focus does not work.   Above the waves it works no problem.   This is why the 17-85 says it needs a close up diopter so it can focus close enough for the virtual image to be in focus.  Also note there's no zoom gear for the 17-85mm. 



#3 ruckusman

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Posted 18 January 2018 - 04:32 AM

Hi Chris,

 

I'm considering getting some short 316 stainless bolts with belville washers to compress the o-ring inwards to seal the holes and a thin nut on the inside.

 

Thanks for the lens port info - I had browsed that lens port chart briefly, however you are correct my dome port is much older and already has an extension permanently attached.

I will contact Ikelite and see if I can get the specs so that I can make a correlation between them., though looking at the modular port and the extension it seems it will be in the ballpark.

 

A simple test pointing down into a pool will be my first test, so I will know more once I've done that.

 

I've just check the 17-85, it's got the dreaded aperture ribbon cable problem and isn't worth repairing at this stage.
I'll concentrate on the 10-22 for now.

 

At the 10mm wide end I am hoping that depth of field on the virtual image below the surface and have above focused also for split shots.
Minimum focus on the 10-22 is 24cm, with any luck a set focus distance will cover most of what I need and I'll use a small aperture and sharpen in post.

 

To clarify, the waves at the end of the street can be perfectly formed, almost impossible to surf, but you can have more than overhead breaking into knee deep water.

I've tried surfing it for long enough, sometimes it's a very quick trip from the top to the bottom.

I haven't taken photos just for the sake of it for quite a long time, and I think it's got photographic potential from right in the impact zone, both above and below the surface.

 

If that works out I may then venture amongst some surfers and shoot it from behind and below the waves



#4 Cerianthus

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Posted 18 January 2018 - 06:24 AM

your old port will be a six inch port (those come with a hood for stray light), although there is a 'super wide port' from the film era that might be a bit wider without any hood. I dont think there are any numbers on the old ports. the Oring will be the same as newer ones, the port size has not changed. Orings for the housing will also still be available.

 

I'm not sure if I would remove all the controls, unless you need the room inside.

 

As for the vacuum : that might be worthwhile to beef the system up a bit: the 2 lock system will have a slight wobble, although that doesnt mean it will leak when wobbling (if that makes sense). I have jumped of boats with that port system (without vacuum), but I took care to minimise the force on the housing by leaving it on top of my head. My current housing has the 4 lock port system and I use a vacuum.

 

I think there are 2 focus gears available, one is a bit thinner then the other. They are quite cheap and simple. https://www.ikelite....ions/zoom-gears(well there are more, but 2 are the main ones)


Gerard

My photo's on flickr
Crop the world ! (Using Canon 70D, 60mm, 100mm, 10-17mm FE, Ikelite)


#5 Roger-Botting

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Posted 18 January 2018 - 12:25 PM

I hate to put a damper on your ideas but I think you would be further ahead by either getting a wet proof point and shoot like an Olympus TG-5
or 

get a waterproof cover like an Outex for your camera.
If you had to get your housing serviced it would be several hundreds of dollars if Ikelite would consent to doing it.
And, you might find the dome port awkward for focusing if you are trying to do the over/under types of shots. A flat port would work better in many cases.
And take a good look at the types of housings that surf photographers use. I don't know the brand names, sorry. They might be what you really need.



#6 ruckusman

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Posted 19 January 2018 - 10:15 PM

Gerard - well spotted on the port radius/diameter - I did a crude measurement of the outside and it is indeed a 6" port on the internal image forming surface.

 

That had double benefits a now the sphere centre is located within the extension tube and coincides with a distinct line on the extension.

Now that this line is visible outside the housing body itself, I can check the sphere centre co-incidence with the lenses easily.

 

Just got to find my macro slider so I can make the measurements easily...

 

I noticed the wobbling also - there is no o-ring on this system as yet, however I tightened the slider screws for the port locks incrementally in minute amounts till there was no more wobble even without an o-ring installed.

 

I will likely install a schrader valve vacuum system and use a hand pump to pull vacuum.

 

I've removed all superfluous controls because each is a potential leak source, the plugs will be 100% secure, plus they served no functional purpose not meshing with any camera controls.

 

Triggerfish - you may be right, I may be crazy ;) I'm borrowing a Panasonic waterproof point and shoot to test just that solution.

 

A surf housing is going to be in the vicinity of at least $2K - not money I'd splurge on this at the moment.



#7 Undertow

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Posted 20 January 2018 - 01:53 PM

Yes alining the lens behind the dome is very important for UW. 

 

I would indeed suggest a vacuum valve especially as dive housings are designed to seal with pressure - they're weak on the surface. I'd consider surf impact to be extreme flood risk. Surf housings are different for a reason. 

 

The focus difference b/w the dome's virtual image and above water with a 6" dome will be huge. The post above however is wrong that a flat port would be better for over/unders. Only better for over (for wide lenses) and hence why surf housings use them.