24 replies to this topic

[Alex_Mustard]

I took these test shots yesterday with the FITpro external dioptres. They are dual element, underwater close-up lenses that come in +5 and +8 powers. Although they are at the cheaper end of the scale, I have been impressed with their sharpness, but more so with their lack of fringing and other optical aberrations that can effect corners in this sort of setup.

These shots are all with Nikon D7000 and 105mm VR and 1.4x teleconverter (all on minimum focus, all uncropped). So they are already at high magnification before the addition of the dioptres (dioptre used noted on image). They are close up details on the small polyps of star coral (each polyp is approximately 1-3mm across).

But I thought I'd share these tests - as I actually managed the photograph the same polyps with each setup!



If you want a general purpose close-up lens then I'd favour the +5. Whereas if you want something for super-macro to use in conjunction with a macro lens and teleconverter then I'd go for the +8.

They do work stacked together - but Depth of Field is razor thin and only suited to certain subjects.

Alex

p.s. There are many, many external dioptres on the market. I was lent these for my trip - and had not seen any test shots from them before - so thought was worth sharing.

[Aussiebyron]

Alex Do you have a link where you can purchase these dioptres?

Regards Mark

[Alex_Mustard]

Alex Do you have a link where you can purchase these dioptres?

Yep, here.

Alex

[derway]

Very cool Alex! But the link is broken.

What kind of mounting do they use?

[ckchong]

I get from here
http://www.fun-in.co...hp?cPath=33_219

It is using 67mm screw in.......

[Otara]

Ooo meow on the lmgtfy!

Otara

[howeikwok]

I've been using the FIT +5 Diopters for about a year now. No complaints about the IQ and like what the good Dr says, pretty good sharpness and little fringing compared to the Inon and UN diopters i've tried before. I have used it with my Canon 50D and 100mm macro lens and triple-stacked the +5 diopters. Now i'm waiting on the subsee +10 to see the difference. Sample of a shot taken with the above mentioned set-up, no cropping. Not sure if it was at minimum focal distance though. At minimum I think i can probably do a full frame or even a half body portrait of a pygmy if it's adult sized.

Edited by howeikwok, 17 January 2011 - 05:22 AM.

[Alex_Mustard]

I have shot these a lot more now and I'm very impressed with the image quality. This rough head blenny is taken with the +5 and +8 dioptres stacked together and in front of a 105mm VR and 1.4x teleconverter - on minimum focus (for those who have not dived the Caribbean, like pygmy seahorses, rough heads are much smaller than people expect).

Whole frame:


100% crop (straight export from lightroom - not sharpened):


This is really impressive detail and very well controlled fringing (no CA or other corrections applied in RAW conversion), considering it is with stacked dioptres.

Alex

[loftus]

Alex, are these D7000 or D700?

Edited by loftus, 24 January 2011 - 04:48 AM.

[Alex_Tattersall]

Very good detail Alex. What a fantastic little fish!

[Alex_Mustard]

Alex, are these D7000 or D700?

These are D7000 - can't see any point in doing super macro with a D700 (when you have a D7000 in a housing)! The ones at the top are D7000 too. I have lots more - just too busy (with the workshop) to post at the moment.

Alex

[Alex_Mustard]

We went out again yesterday afternoon to photograph the golden blennies on the workshop - and many people were really shocked by how small they were - so I shot a sequence again - as this gives a better idea of the performance of the external lenses and performance we're discussing.

A - my fingernail taken at minimum focus with Nikon D7000 + 1.7x TC + 105mm VR (no external dioptres).
B - blenny taken at minimum focus with Nikon D7000 + 1.7x TC + 105mm VR (no external dioptres).
C - blenny taken at minimum focus with Nikon D7000 + 1.7x TC + 105mm VR and FIT + 5 diopter.
D - blenny taken at minimum focus with Nikon D7000 + 1.7x TC + 105mm VR and stacked +5 and +8 diopters.

All images are uncropped:



Alex

[buceo]

Very great pictures and test
What is the distance to the blenny to take this pictures ?

[Alex_Tattersall]

For info, there are plans to produce a +16 diopter in the near future.

[Timmoranuk]

I'm wondering how the stregths of the INON UCL-165 and 330 compare with the FIT diopters. Can anyone advise the equivalents?

[SlipperyDick]

It is important that underwater shooters understand that the strength of a given lens is not absolute. Let me explain:

The dioptric strength of a lens (+5, +8, +16, etc.) is relative to the medium that the lens' refractive surfaces contact (air, water, jello, etc.). So, while these FIT lenses have strengths of +5 and +8 in air, they appear to be water-contact lenses (correct me if I'm wrong!). If so, they are not +5 and +8 underwater, because typical glass achromats lose around 60-70% of their power underwater.

Timmoranuk - By direct measurement from the photos that Alex has provided, the magnification ratio achieved by the +5/+8 combo relative to the shot with no diopters is about 1.5:1. That's what you would expect from an underwater +5 diopter lens. This is consistent with the loss of strength due to water contact mentioned above. If this is true, then the FIT +8 is an underwater +3 (same power as the Inon UCL-330), and the FIT +5 is an underwater +2. A similarly constructed +16 would be an underwater +6 diopter lens (same power as the Inon UCL-165).

The MacroMate and SubSee are examples of sealed optics which retain their power both above and below water, since the lenses are always in contact with air.

All of this being said, Alex's results speak for themselves - they seem to produce sharp images free of chromatic aberration.

Just my two cents!


Keri

[Alex_Mustard]

Thanks for the explanation, Keri. Very helpful.

For those interested in the techniques and kit options you should read Keri's article on DPG.

Alex

[howeikwok]

It is important that underwater shooters understand that the strength of a given lens is not absolute. Let me explain:

The dioptric strength of a lens (+5, +8, +16, etc.) is relative to the medium that the lens' refractive surfaces contact (air, water, jello, etc.). So, while these FIT lenses have strengths of +5 and +8 in air, they appear to be water-contact lenses (correct me if I'm wrong!). If so, they are not +5 and +8 underwater, because typical glass achromats lose around 60-70% of their power underwater.

Timmoranuk - By direct measurement from the photos that Alex has provided, the magnification ratio achieved by the +5/+8 combo relative to the shot with no diopters is about 1.5:1. That's what you would expect from an underwater +5 diopter lens. This is consistent with the loss of strength due to water contact mentioned above. If this is true, then the FIT +8 is an underwater +3 (same power as the Inon UCL-330), and the FIT +5 is an underwater +2. A similarly constructed +16 would be an underwater +6 diopter lens (same power as the Inon UCL-165).

The MacroMate and SubSee are examples of sealed optics which retain their power both above and below water, since the lenses are always in contact with air.

All of this being said, Alex's results speak for themselves - they seem to produce sharp images free of chromatic aberration.

Just my two cents!


Keri

Hi Keri,

could you clarify what it means by sealed optics? from my understanding it's the lens elements sealed in air? Aren't the FIT and Inon diopters dual element lens that are also sealed?

Many thanks for any clarification.

Alvin

[pdemaagt]

I have shot these a lot more now and I'm very impressed with the image quality. This rough head blenny is taken with the +5 and +8 dioptres stacked together and in front of a 105mm VR and 1.4x teleconverter - on minimum focus (for those who have not dived the Caribbean, like pygmy seahorses, rough heads are much smaller than people expect).

Whole frame:


100% crop (straight export from lightroom - not sharpened):


This is really impressive detail and very well controlled fringing (no CA or other corrections applied in RAW conversion), considering it is with stacked dioptres.

Alex

Great shot Alex!!

[SlipperyDick]

No problem, Alex - thanks for giving that article a shout-out

could you clarify what it means by sealed optics? from my understanding it's the lens elements sealed in air? Aren't the FIT and Inon diopters dual element lens that are also sealed?

When I say "sealed optics", I mean that the lens' refractive (curved) surfaces are permanently sealed in air, so they never come in contact with water. This is how the MacroMate and SubSee are constructed - underwater, they perform exactly as they do on land. I'm not sure about the MacroMate, but the +10 diopter SubSee is actually a 4-element lens system.

The FIT lenses are most likely dual-element achromats, but are not sealed optics (again, someone correct me if I'm wrong!). Water directly contacts their refractive lens surfaces, so they lose most of their power underwater.

The Inon lenses are a combination of sealed optics and water-contact optics. They have 2 curved internal surfaces which are permanently sealed in air, but their external surfaces are also curved... so, a much smaller portion of their power is lost (the Inon UCL-165 goes from a +7.4 on land to a +6 underwater). However, they are not achromats (so are prone to chromatic aberration), and have much more edge distortion than others.

I hope that cleared things up for you, Alvin!

Keri