Boo Rocks

Which Fisheye Lens for the RX100?

Recently I have started building my RX100 Mark II photo rig and as part of this I had to choose a wet fisheye lens.

For video I do not like the barrel distortion of a fisheye lens, and on top of that you can’t attach a push on filter to a dome so for me those are two big no when it comes to the RX100 and its white balance error woes.

For still instead I shoot only RAW never white balance in the water and a fisheye lens is required so that I can have human size strobe arms when shooting close focus wide angle at distances between 0 and 16”.

I will focus my discussion on the Nauticam housing starting off with a 67mm thread and go from there.

Currently there are 3 options on the market for the RX100 and come from 3 difference manufacturers. I will go through each one briefly and then we will look more in detail at the two I consider best.

The first lens is the FIX UWL-28M52R, this lens is the smallest of all and was originally design to nicely complement the form factor of a Canon S100 in a fix housing, hence the 52mm thread. The lens has a magnification factor of 0.41x and a diameter of 126mm including the hood, the lens is actually much smaller at around 90mm.

Fix has introduced this lens in 2011 as a replacement of the previous UWL-04 model for two reasons, the first is to have a smaller lens as the UWL-04 was a too big in comparison of the housing, second probably cost though this was never declared. However other people tests and plenty of in water images show that this lens is actually worse than its predecessor. It is also smaller making split over-under shots more difficult.

When Fix withdraw the UWL-04 the manufacturer of the lens continued the production and finally put it back on the market under the i-divesite brand. This lens is the same as the Fix except the label.

Both lenses the old and new fix are pretty much a copy of the old Inon UFL-165, both made of 4 glass elements and an acrylic dome with hard anti scratch coating.

Here is a set of shots for the UWL-04 and the various parts in the box.

UWL-04 Box
UWL-04 Box
UWL-04 package contents
UWL-04 package contents
UWL-04 Hood Cover
UWL-04 Hood Cover
UWL-04 with ring
UWL-04 with ring
UWL-04 back lens
UWL-04 back lens

The last lens on the market is the Inon UWL-H100 with dome. This lens is available with an M67 mount and with an LD bayonet mount. Due to the size and weight of those lenses in water (100 to 500 grams weight and diameter between 125 and 152 mm) a bayonet mount is my preferred choice.

The Inon lens is actually made entirely of glass, the dome is the biggest at 115mm for the lens with an overall diameter of 132mm. This lens is the more suitable to split over under shot and promises a better contrast and less flare than the other lenses with plastic domes. Inon had some concerns about plastic domes and flare following the performance issue of their UFL165 so went for 100% glass for all next generation lenses.

Vignetting with RX100

In certain conditions all those lenses actually have some vignette in water. Despite what you read on shop websites if you look at real pictures there is a bit of that.

The Fix and Idas lenses have an issue with the lateral hood, the shots look clear of vignette on land but in water the magnification of the hood petals makes them show in the picture, we are talking a minimum crop required around 1% and usually on one side. The Inon UWL-H100 has a different issue and it gives in specific situations a tiny bit of vignette in the corners, around 2% of the image needs to be cropped. Both lenses will not vignette when image stabilization is deactivated, the image stabilizer tends to aggravate the issue so if you are obsessed switch it off and try to be steady shooting at speeds of 1/125th of a second or faster. For example on the amount of vignette see the following

UWL-04 note the vignette left center
UWL-04 note the vignette upper left center
DSC02620Corrected
UWL-28M52R again vignette on the left upper side
SONY DSC
UWL-H100 vignette in left corners

I would like to thank Alex Tattersall, Tamas Plotek and Troy Williams for those in water pictures.

Inon UWL-100 28AD

Inon has another lens that is suitable for the RX100 and is the UWL-100 28AD a lens originally introduced in 2005. This lens has a smaller rear element than the UWL-H100 and it is not suited to many cameras with a very large lens aperture. The RX100 however works fine with this lens and contrary to the newer UWL-H100 this lens does not vignette in water or on land. The reason is that the de-magnification of this lens is less than the newer lens 0.63x vs 0.6x. This is the lens I have chosen for my RX100 Mark II and I will compare it here with the UWL-04 I have recently bought for my Canon S95. There are no substantial differences between the UWL-100 28AD and the UWL-H100 in terms of optical quality.

Here are few pictures to compare the lenses, take into account that whilst the weight on land is comparable, once in water the Inon lens is heavier at 400 grams versus 160 of the UWL-04.

UWL-04 UWL-100
UWL-04 UWL-100
UWL-04 UWL-100 profile
UWL-04 UWL-100 profile

 

Image Quality

There is no need to take the lenses in water to compare image quality generally things get worse in water not better so it is sufficient to take a shot on land and see how that goes to have a relative comparison between two lenses. In this example the cameras are on a table exactly in the same position when the shots are taken and use the same settings of ISO, aperture and shutter speed.

The first impression is that the UWL-04 is a tad wider but more rectilinear, the Inon lens has definitely more barrel distortion and is more a fisheye than the UWL-04 is. Looking at mid upper frame you can see that at diagonal level the UWL-100 28AD is actually wider than the UWL-04 that remains wider horizontally. This means looking at the specs can be misleading and results depend on the camera lens combination.

So how do these lenses compare when it comes to corner sharpness and flare?

This is a shot with the UWL-100 in very harsh conditions with sun-rays hitting the lens directly on the dome, you can clearly see the ghosting that comes from it.

UWL-100 Sunlight
UWL-100 Sunlight

This is the same shot in the same place taken with the UWL-04 you immediate notice that the ghosting has a green color. This is most likely due to lack of anti-reflection coating inside the dome and to the color of the inner lens mount.

UWL-04 Sunlight
UWL-04 Sunlight

Looking at the image the picture taken with the Inon has a clearer ghosting but then is sharp in the rest of the image, the UWL-04 image has flare around it with comparable less contrast as we move from the center to the corners.

The other two images are a crop in the corner, you can see that despite the high level of distortion you can still distinguish some detail of the small grass bush in the Inon image, the UWL-04 instead is softer and the bush is basically a uniform green shape with no detail at all.

UWL-100  Crop
UWL-100 Crop
UWL-04 Crop
UWL-04 Crop

Update 28 Feb I have taken some shots with the UWL-H100 and the UFL165AD here are the overviews

Inon UWl-H100
Inon UWl-H100

The UWL-H100 is actually wider than the UWL-04 with the Sony RX100 despite the advertised 144.5 degrees versus 165 of the UWL-04. Has the same level of detail of the UWL-100 28AD

Inon UFL-165 AD
Inon UFL-165 AD

The UFL165AD flare issue is obvious in this shot both lower corners are compromised, this confirms why the UWL-04 is the best option for the Canon S series in terms of flare or vignette.

Looking at the UWL-H100 crop you can see the vignette more apparent in the upper corner and the image sharpness, it is possible that with an M67 mount there is no vignette with a Nauticam housing in most conditions, with LD mount you need to turn image stabiliser off or crop. Considering this is the widest lens it is not a big issue. Once cropped the UWL-H100 gives still the widest field of view but someone maybe be annoyed by this. Zooming in results in the same field of view of the UWL-10- 28AD

Ergonomics

The Inon lens presents the benefit of a bayonet mount, although the lens is heavy it can be removed in water quite easily, the UWL-04 has some issues whereby the adapter ring would unscrew instead of the lens, this can be avoided fixing the adapter on the lens but then there is no lens cap that would fit the larger M67 screw in the box so you need to buy one yourself, generally the size of the petals make this lens impossible to handle in water and is more like diving with a dome port. It has to be noted though that you can zoom through with both lenses so still continue and take portrait shots and close ups. Obviously for real close or macro you do need to take the lens off which with the UWL-04 you can basically forget.

Cost

The UWL-04 costs $460 in US as shown here with dome cover and step down ring, and £362 in UK. The Inon UWL-100 28AD with dome costs $907.80 including an M67-ADF adapter in US and £775 in UK. All in all the Inon is around near to double the price of the UWL-04. The UWL-H100 is even more expensive at $970 for the M67 version and $942 for the LD bayonet, you then need to add $160 for an adapter for a total of $1,102 that is a lot of money another reason for the 28AD version.

Conclusion

The Inon is the best lens for the RX100 and there is no doubt, however it costs more than double the UWL-04 not everybody will be able to afford it. The UWL-04 is a somewhat basic lens that lacks sophistication and is essentially not removable in water but comes at a great price. In terms of field of view the lenses are very similar with the Inon lenses having more fisheye distortion and a wider diagonal field of view. The UWL-04 is more rectilinear and as consequence has less field of view diagonally. Only one lens has zero vignette at the wide end and this is the UWL-100 28AD with dome.

In Water Shots

I don’t have shots in water yet pending my next trip but two galleries that give an idea are here:

For the Inon UWL-100 28AD with dome look at my Red Sea Gallery https://www.flickr.com/photos/interceptor121/sets/72157645375379256/

For the UWL-04 instead this is an excellent one

http://www.flickr.com/photos/13930495@N06/sets/72157636133030726/

The second shooter has got rid of the UWL-04 to buy an Inon as not happy with corner sharpness!

My perspective is if I look at the pictures I can barely tell the difference however looking close the Inon lens is sharper at one f/stop less, the UWL-04 requires stopping at f/8 or smaller, you can happily shoot f/5.6 with the Inon which means you need less light and less strobe power.

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6 thoughts on “Which Fisheye Lens for the RX100?”

  1. Hi there, I read through your info but I still don’t understand why you use different WW converters for still and video?
    If you were geeting a WW-converter with the intention to be used without Dome first (maybe with dome later) for the RX100II, for someone doing 80% photography and 20% movie – which one would you recommend? The UWL-10028AD? Does it also work well without Dome? Thanks a lot, Paratom

    1. A dome lens is predominantly for close wide angle or wrecks or schooling fish. A flat lens is better for turtles or shark that don’t come that close. So really you need both for photos. For video I don’t use fisheye lens as the image is distorted and I don’t like it

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