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Titanium is a real Hillary! to work with...

Hillary - that one went straight over my head - care to expand ?

 

Paul C

 

A picture is worth a thousand words...

 

hillary_soldier_finger_duress.PNG

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Ok - I get the general idea......

 

Ta,

 

PaulC

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Somewhere I've read that Titanium doesn't like high pressure oxygen (perhaps it becomes slightly reactive) but I'm not sure if there is any substance in this. Can anyone confirm or deny? (It does seem odd that Titanium isn't used more in housings as it should be an excellent material unless it has a drawback other than cost/machining).

 

AFAIK Titanium may ignite in presence of high pressure O2 (or high fO2s) at as low as 70 deg C.

 

Tha is not a problem when dealing with a 1 atm camera housings, unless you have a habit of filling the housing with pure O2. -_- Why we're not seeing titanium housings has more to do with the not-so-nice machining properties of Ti.

 

Titanium regulators, however, are a bit scary...

 

//LN

Edited by lauri

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Interesting, given that Ti might be a viability for fittings (ok, so at a higher cost) I was actually wondering whether it might have beneficial electrolytic properties if used on an aluminium housing as its the stainless steel fittings which eventually cause some degree of corrosion on most housings. Although given the duration (as opposed to life) expectancy of most digital cameras (dSLRs included) I'm not sure that this is the problem it was with film camera housings!!!

 

Yes, I did see that there was a Ti regulator made......... specification and technology defeating itself perhaps?

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Techniques for medium format differ from their smaller (35mm & APS) cousins, with MF techniques being closer to large format.

Let's make this quantitatively clear. This H3 sensor is 48x36. Full frame 35mm is 36x24. That means the sensor is 4/3 wider and 3/2 taller. It's not magic. Any "technique" differences aren't due fundamentally to the larger format, they're due to the nature of the bodies and lenses that offer them. These differences in technique are PRECISELY what I'm discussing. Glad you're interested in joining in.

 

BTW, FF 35mm has a greater difference in size compared to DX than MF does to it, yet NOBODY claims there are fundamental technique differences there. There is less inherent quality difference between MF and FF 35mm than there is between FF and DX, at least due to sensor size. Other factors are precisely what's worth discussing.

For starters, extension rings are commonly used, and Yes, even stacked, in order to simulate how bellows work on a view camera.

 

Also, actual bellows are used in MF for lens movements (shift/tilt/swing) -- Another set of LF techniques -- as well as macro.

Extension tubes are VERY restrictive underwater, they increase the port sizes (dramatically for larger formats) and they reduce light required for focusing. They may or may not degrade image quality depending on the lenses.

 

In any event, extension tubes do NOT change perspective (the most glaring problem with only having a portrait macro lens), they offer only modest improvements in magnification on such short lenses, and they sacrifice maximum working distances. Extension tubes are not a substitute for teleconverters. Any mythical benefits attributed to MF do not change fundamentally how the optics work.

 

Teleconverters are generally not used as often in MF, except out in the field with Very Expensive Lenses, since MF glass (like this lens I own) has higher aperture numbers, due to the fact the lens has to spread the light out over a larger film (or CCD) surface area without fall-off, yet still be manageable.

 

Teleconverters are more common in the 35mm world, because even if you add 1-2 stops (1.4x & 2x), good glass with decent gathering power (larger apertures) is relatively inexpensive, such as an 80-200 f/2.8 zoom: Pop a 1.4x TC on it and you just bought a 120-300 f/4, which is still quite good.

 

On the other hand, I'd never put even a 1.4x on my 645AFd using my 300mm f/4.5 lens, as that would take me up to f/6.3 at only 420mm, dimming the viewfinder quite a bit... In that case, I simply mount my 500mm f/5.6 MF lens instead.

Chalk another one up in favor of 35mm then. 35mm has available high quality teleconverters that are usable not only because of their minimal IQ degradation but because the macro lenses are bright enough that one can afford the light loss. MF, on the other hand, by your own words, Dan, doesn't because of their macro lenses lack the brightness. Sad that's the case, since MF sure needs good teleconverters for macro.

 

Considering that 35mm has a 150mm macro offering f/2.8, it's a bit sad that MF can't do better than f/4 at 120mm. After all, everything else about MF is larger and heavier, what's the problem with making a bigger lens? Fact is that MF shooters don't value macro or else the lenses would exist. 35mm macro solutions consistently get down to half the size of MF, or better, with greater working distances. We NEED that capability underwater.

 

Subjects underwater don't change just because the camera is no longer capable of taking shots of many of the macro opportunities. If you look on a boat with a number of experienced macro shooters, you don't see them constantly shooting 50s and 60s even if they are shooting DX. Sadly, that lens is ALL that's available in MF. I have never shot a macro lens with as wide a perspective as the 120mm and have no interest in doing so. For those shots I use a midrange zoom which offers me greatly more flexibility and nearly the same frame sizes as this 120mm offers to a MF shooter. I wouldn't criticize someone who prefers a 50/60 for that purpose, but it underscores the fact that, with 35mm, we have real, useful choices.

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Craig

 

Having shot on everything from 35mm to 5" x 4" including a variety of 'medium formats' I can honestly say that there is a REAL difference between using different formats. As the film size (sensor size) increases so the the exacting nature of the format. It really isn't all about the camera size ergonomics (I had a Contax 645 which handled exceptionally well) but move away from the 'simple' photography of landscapes and the like and everything becomes magnified in its exactness. DX format has a great deal to recommend it for underwater use and is also at the end of the day probably the easiest format to use underwater.

 

The comments you make in your post illustrate just why its easier to use a DX style camera; close-up abilities and the use of teleconverters on DX still produce relatively acceptable results. To use similar gear on MF requires precise technique and pre-consideration of the potential subject and/or exceedingly good teleconverter optics. On the other hand, there are differences between DX and '35mm' and '35mm and 'MF', some subtle and appreciable only be the visually 'educated', others to do with their inherent physical size differences.

 

As you will see from my posts, I'm perfectly satisfied that by using the '35mm' format I can achieve the images that I set out to take. I assume that Troy considers MF in the same light, but MF is most certainly not the route I'd want to take! But don't be fooled into thinking that formats are all the same, they really are not.

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I know you feel that way, Paul, and we've have discussions to that end. I accept that there are differences in the qualities of various systems, but I don't accept that those qualities should be attributed consistently to the size of the format itself.

 

I'm as big a fan of large sensors as anyone but I firmly believe that different lenses and camera bodies can contribute greatly to image quality. The fact that MF uses entirely different lenses and is optimized for different applications means that there are factors other than imager size that contribute. Put a 36x24 sensor in an H3 and you will still get IQ differences compared to a 1Ds.

 

I think comparing DX to FX (if I may use the Nikon branding) is interesting in this context. Paul, you value the shallow depth of field that FX offers compared to DX in wide angle applications. Similarly, people consistently comment that MF offers a dramatic advantage over FX in this regard. The fact is that the size ratio between DX and FX is quite similar to the MF/FX ratio. FX is 2.25 times as big as DX while MF is 2 times as big as FX. People don't generally consider the difference analogous even though it is (in fact, MF is less of a jump). I consider that to be because people romanticize MF systems and attribute magical rather than technical qualities to them. As good as FX is, there are occasions where DX is better. Same is true for larger formats.

 

No doubt this H3 system offers capabilities that set it apart from other systems, but these capabilities are the sum of all the engineering that goes into the product, not simply the chosen size of the imager. As underwater photographers, we have to consider not just the appealing IQ it's capable of but also the limitations imposed by the system, and I don't think anyone can argue that small lens selection isn't a huge disadvantage.

 

Imagine, hypothetically, that one could quantify the IQ advantages of MF over FX. What would that quantity be? 10%? 50%? 100% 500%? Depends on what you value.

 

In my mind, and I know this will be greeted with substantial disagreement, just such a quantitative judgement is possible and it is done all the time. That's what is done by objective testing and review sites, and because of those efforts we have a really good idea what the resolving power and IQ differences are between a 1Ds2 and a 5D or D2x is, just to name an example.

 

If you accept that such a quantitative judgement is possible, then you can decide objectively whether a system is more desirable after you factor in all its cons in addition to its pros. I believe that when someone objects to that type of analysis it's because he fears the results. All SLRs work the same way; with the H3 you get to use a different camera box, different shutter mechanism, and different lenses in addition to a different imager. Ultimately, this camera captures images the same way as a Canon or Nikon does.

 

All the benefits of the larger imager in an H3 are easily squandered when the system doesn't have the lens you need for the job or if it requires you to use an IQ-robbing teleconverter to get the shot. If the only kinds of UW photography you are interested in happen to be the strengths of the H3, then I'm sure it would be a fantastic solution. That kind of photography would be limited to rectilinear wide primes and portrait-style low magnification macro. Considering those are clearly limits of MF itself, I don't see how that could be argued.

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Troy,

 

I'm here at Splashlight Studios in Manhattan, where Hassy is introducing the H3D-II in a few minutes. Everybody who has seen your shark photo is quite impressed, including Christian Poulson, the president of Hasselblad.

 

Great work!

 

Thank you for the welcome. Out of water is 95 degrees. But u/w it sure looks alot wider. Here is a shark photo shot 3-4 ft away. shark was 8ft.

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Troy,

Do you have any plans to take the Hasselblad fisheye lens underwater? Macro aside, that will surely get everyone's attention. (It's only $7339 at B&H)

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Good Morning Dan,

 

That's awesome! Ask him if he would be interested in some images for next years PMA for display purposes for the H-series cameras. Doing something for a display panel would be great. Ask them what is the noise improvement over the H3D by their improved cooling or is it done by software. The noise level is already virtually non-existant. Flexcolor has no real sign of noise but the same file in CS3 does show some in low light conditions. I'm sure the new Hasselblad software will only get better. One more thing, ask if the GPS option can be applied to the H3D w/o a full upgrade.

 

Enjoy,

Troy

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Somewhere I've read that Titanium doesn't like high pressure oxygen (perhaps it becomes slightly reactive) but I'm not sure if there is any substance in this. Can anyone confirm or deny? (It does seem odd that Titanium isn't used more in housings as it should be an excellent material unless it has a drawback other than cost/machining).

 

Paul, I have been using an Atomic Ti2 regulator for over two years with Nitrox up to 40 percent. I seem to remember you also persuaded me to sell all my Hasselblad lenses!

 

(Ah well... I met an old art director in the street today. He reminded me that my first advertising shoot featured a model called Rona Newton-John, who had a little sister called Olivia who wanted to be a singer. I'm getting too old for all this!)

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Good morning Loftus,

 

At this point no. The 28mm underwater can get very close to subjects u/w and plenty, plenty wide. No distortion etc. Maybe next year with the H3Dll upgrade or the following year with who knows what they will come up with. January will tell me how I can turn a profit with u/w images then I will let u/w profits dictate repeat investments. By the way in practical terms the majority of professional photographers own alot of lenses but only use a few of them most of the time. Sounds ideal to have alot of lenses but how many times out of every year will we use all of them.

 

Intensly enjoying what I have already,

Troy

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But John, is it just in the name.......?

 

I'm not sure I 'persuaded' you to sell them (I think that I suggested that the sooner they were sold the better the price you might get for them, and looking a current 500 series prices I may well have been right).

 

But be honest, would you still be using them? And would you take a 'blad underwater?

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If you follow a bunch of threads here, you'll see the fisheye lenses, 10.5 Nikon and 10-15 Tokina mostly, have become huge workhorses underwater for close focus wide angle reef and wreck stuff etc without much concern about distortion underwater. It might be worth trying to rent one if such a thing is possible from Calumet or someone.It would definitely lay to rest one of the arguments against MF.

Just my two pennies worth.

Jeff

Good morning Loftus,

 

At this point no. The 28mm underwater can get very close to subjects u/w and plenty, plenty wide. No distortion etc. Maybe next year with the H3Dll upgrade or the following year with who knows what they will come up with. January will tell me how I can turn a profit with u/w images then I will let u/w profits dictate repeat investments. By the way in practical terms the majority of professional photographers own alot of lenses but only use a few of them most of the time. Sounds ideal to have alot of lenses but how many times out of every year will we use all of them.

 

Intensly enjoying what I have already,

Troy

Edited by loftus

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Jeff, if you look at the MTF curves of the lenses -- Especially zoom lenses; and as you venture from the centerline -- you'd throw up when you see the loss of contrast.

 

FWIW, last night at the H3D-II launch, they put up on the screens the MTF curves of their new 28mm MF lens... It was so flat, I thought I was looking at the 50mm Leica curves.

 

[MTF: Modulation Transfer Function]

 

If you follow a bunch of threads here, you'll see the fisheye lenses, 10.5 Nikon and 10-15 Tokina mostly, have become huge workhorses underwater for close focus wide angle reef and wreck stuff etc without much concern about distortion underwater. It might be worth trying to rent one if such a thing as possible from Calumet or someone.It would definitely lay to rest one of the arguments against MF.

Just my two pennies worth.

Jeff

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Loftus

 

If you are referring to the 30mm V series fisheye which can be fitted to an H series via an adapter, I looked into this some time ago (it can be adapted to Canon too). The problems are that you'd need custom gears for both aperture and focus and it has a very large diameter (it couldn't be used with Seacam's ports for example). These problems aren't impossible to get around though, and the good news is that these lenses do crop up at very good prices especially the slightly older ones (I was offered a used one for ~$2400 (US dollars) not tat long ago). It has the reputation of being pretty good although possibly not up to 'blad's best - hardly surprising it must be a pretty difficult optic to design, and as far as I remember has a pretty good close focus.

 

Dan

 

MTFs are great but put a port in front and they will plummet!!! Tricky to test (I think a student on my course back in the early 80's did some lens testing underwater) and few people ever do try much in the way of really objective testing underwater. Thick flat ports and concentric domes are the optical evil necessities of underwater photography

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Here's what I think the problem is. Dan Schwartz is 100% unproven in underwater photography, so all of his arguments here are met with skepticism. Troy has taken a MF digital camera underwater, but has thus far not shown any interesting images. If the Hassy folks were truly impressed by that shark image, something is wrong.

 

There is a sub-thread of MF vs 35mm somewhere in this thread, but it's clouded by Dan's attempts to talk about shooting underwater, which is he not qualified to do. Furthermore, Craig is being very specific and unambiguous in his arguments, while arguments from Dan and Troy talk about things like producing "film-like images -- without the noise!".

 

This is all really great discussion, but I'm personally tuning out until I see some images -- and until Dan gets his ass in into the water with ANY sort of camera. -_-

 

.. and when someone starts showing some good images taken with MF digital, the conversation will really start getting interesting. We all know that it's possible, but until we see some results, this is all theoretical. :wub:

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Eric, you're skepticism is dead-to-nuts... But when I do get my ass back in the water and start shooting, I intend to do it right. In my case, it's the tail wagging the dog: I already have a lot of MF gear; and since I ditched most of my Nikkor lenses,* I have no desire to go back.

 

Besides, there's a certain pleasure I get when I pull a roll of 120 or a 4x5 chrome out of the processor drum, which I just don't get with postage-stamp-sized frames... But I digress.

 

Here's what I think the problem is. Dan Schwartz is 100% unproven in underwater photography, so all of his arguments here are met with skepticism.

[cut]

This is all really great discussion, but I'm personally tuning out until I see some images -- and until Dan gets his ass in into the water with ANY sort of camera. -_-

 

* FWIW I only kept 4 Nikon lenses and my S2 Pro for my NCTS work.

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MTFs are great but put a port in front and they will plummet!!! Tricky to test (I think a student on my course back in the early 80's did some lens testing underwater) and few people ever do try much in the way of really objective testing underwater. Thick flat ports and concentric domes are the optical evil necessities of underwater photography

 

Paul, you're quite correct about taking a great lens and shooting through the bottom of a coke bottle. Fortunately, my fiancee has a swimming pool in our backyard, so I can actually test the rig I choose, with a laminated version of this chart.

 

If I'm going to take vacation time & spend the $$$ for a trip, why not do it right the first time?

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Hasselblad's HCD 4/28 MTF charts can be seen by downloading it's spec pdf from Hasselblad's spec page. Nikon's 14-24 f/2.8 zoom lens has a published MTF chart viewable here.

Jeff, if you look at the MTF curves of the lenses -- Especially zoom lenses; and as you venture from the centerline -- you'd throw up when you see the loss of contrast.

I'm not sure what Dan's referring to by "the lenses", but if you compare MTFs of the HCD 28 and the Nikon you'll wonder what he's talking about. I didn't throw up. In fact, I giggled. ;-) Canon's 16-35 f/2.8LII looks pretty good in comparison as well.

 

Of course, MTF doesn't tell us all there is (though it's as good as we've got) and Paul is absolutely right that lenses are only part of the optical equation underwater. A big problem with zooms underwater is that they are doubly hard to make work well behind a dome.

 

One of the downsides of having a glorious, huge imager is that the optics have to be superlative that much further off center. Introduce an unmatched dome (is UK Germany doing custom domes too?) and you could be in a world of hurt. One technique that Canon FF shooters use involves bumping ISO in order to use smaller apertures. The H3D isn't nearly as good at that as a Canon (or now, Nikon) is.

 

If there's going to be MF advocacy, speaking in generalities about MTF charts isn't useful. Rectalinear wide angle should be the strength of a MF system, so how about we see images with EXIF data and 100% corner crops to prove that the optics are actually good? It won't do anything for the deficiencies in fisheye or macro, but at least we can see one application where MF excels. So far we've seen one shot that didn't impress photographically nor tell us anything about optical capability. We can get good tonality out of 35mm, too.

 

Fortunately, my fiancee has a swimming pool in our backyard, so I can actually test the rig I choose, with a laminated version of this chart.

If you plan on shooting test charts underwater then that might tell you what you need to know, Dan, but you'd be well served to study how Stephen Frink tests wide angle optics underwater. He has the knowledge, experience and ability to conduct real world tests that help him, and us, understand how wide angle solutions really work. He uses charts, too, but he uses them in ways that tell us something! He doesn't need a chart anything like you've linked to, either.

 

If I'm going to take vacation time & spend the $$$ for a trip, why not do it right the first time?

Indeed :-) It might cost you a small fraction of what you are planning, as well.

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Do you have any references to Stephen Frink's work? It sounds like what I need to look at, not only for wide angle but also normal & telephoto. [more]

 

If you plan on shooting test charts underwater then that might tell you what you need to know, Dan, but you'd be well served to study how Stephen Frink tests wide angle optics underwater. He has the knowledge, experience and ability to conduct real world tests that help him, and us, understand how wide angle solutions really work. He uses charts, too, but he uses them in ways that tell us something! He doesn't need a chart anything like you've linked to, either.

 

Actually, using a chart helps diagnose issues you can't quite put your finger on just looking at a photo, such as the effect of astigmatism on the contrast.

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Hello Rod,

 

Pressed at work but I will sure post over the weekend. Crapy weather right now but I will try.

 

Thanks,

troy

 

 

Good point. I will check it out depending how much they rent for.

troy

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Hello everyone,

 

What a busy week for me. Conditions have not been that good. I was able to go out on another shark dive and although not much macro I was able to test the 120mm for the first time. Not much subjects for interesting macro at all.

 

Here is my opinion with just my first experience:

Not as difficult as one would suspect with all the concerns about limitations.

Not a super macro set up at all. However, the cropability of such a huge format can allow an enlargement of a very small area of the image

Very sharp capture and good color detail

Nova strobes had to be turned way down, so light is definately not an issue

 

So up to this point if anyone wants to get super macro shots for a very large print then wait for the

Canon 1ds mk3. For me to talk tech talk of mf vs. 35mm when it comes to macro then tech talk would win. However, the quality of capture this camera can produce is stunning. There is just so much potential to grow in. Here are just a few images since I promised I would post something. When conditions permit and I have a day off I will go out in my own boat to find some critters. Everyone, I must say I am really enjoying myself. I feel very fortunate to have such a set up. I think there is room in this forum for mf, so don't knock it too much.

 

Dan, since you already have a mf it makes sense for you to consider taking it u/w. For someone who is not a professional and does not alread own a mf I would think twice before sinking 50k into a set up. It just does not make sense espcially when it has been proven that there are so many options in 35mm at half the price and less. In my case it was cheaper for me to put my mf u/w @ 13K .

 

 

Just wanting to share,

Troy Aitken

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Edited by Troy Aitken

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