Second Thoughts !?!

[craig 0]

I have just put my housing, camera +14-42 + PT-E03 port basically everything except the strobes on my bathroom scales 2.9kg or 6.4 lbs and I am sure that the Ike and D70 with port and 105 macro weighed over 4kgs.

What do you mean you are "sure"?

 

Why are you comparing only a subset of a ready-to-dive rig? What does that matter? Is that all you carry around with you all day? Is the 14-42 your go-to lens? If so, why don't you use a digicam instead?

 

There is nowhere to hide in terms of obsolecents in the digital market and that is one of the reasons I decided not to spend 5k on a system the other being my mean nature and my self funded retirement plan.

Somehow I doubt an Oly setup is the cheapest available.

 

I also didnt want to drop down the quality slope as I have enjoyed my film years with a Nikon and Aquatica, the total $ with lenses cost me a fortune at the time. I didnt want to make that kind of investment again for what is essentially a hobby.

How do you know you didn't drop down the "quality slope"? Compared to what?

[Drew 0]

Well I can't speak for obsolescence in equipment but I'm using two 5 yr old cameras and see no real need to switch as yet. One still has more resolution than all but 3 cameras in the market and the other is still faster in fps than all but 2 cameras in the market. It does pretty much everything I want it to do well except improve my skills as a photographer, which is really why I bought them!

 

As for the camera and lens weight differences, if I remember the 10.5 nikkor is lighter than the 8mm zuiko by 150g, the nikkor 10-24 is about 300g lighter than the 7-14 Zuiko. Once you start buying the better lenses, the weigh savings becomes less and less. I do like that the Zuiko lenses are dust/splash proof like the Canon L series, something Nikkor lenses should have as well.

 

Still I think the Nikon D90 and Olympus E620 weight difference isn't that wide after you start buying the better lenses and ports. One has to compare apples to apples. Comparing a Canon 5 D2 which is 3 price classes away is not going to be useful. The D90 nikon does a lot of what the E620 does and then some. Each has strengths and weaknesses and EVERYONE has to buy according to their needs.

 

Some like to have a lot of headroom while others just get what is needed. I know at least one shooter who doesn't have the top of the line camera and housing, and he still does a "decent job" (;P) with his shots. Worst of all, he doesn't even have a backup body, although he has enough body to be backup Some guy named Le Moutarde.

[ce4jesus 1]

No, it's not a reasonable estimate and there's no reason to pull something like that out of thin air. Moving a camera back and forth 3 times a day isn't the same as carrying it around all day and it's irrelevant when weight differences are made up anyway. If someone suffers from a disability that significantly limits their diving, should they be using a DLSR instead of something radically smaller?

 

 

No, I got it right. He didn't talk about enjoyment, he said the differences would have zero impact.

 

Technically, micro 4/3 is not a DSLR. It is more of a conventional digicam with interchangable lenses.

 

 

I don't think so. All these vague arguments could also be made on behalf of a Canon G9 being preferable to any DSLR rig. All you have to say is that the advantages of a DSLR are meaningless and the advantages of the G9 are important. If you make up some facts it gets even easier but no more compelling.

 

Okay maybe he should have said, carry to and from dive location, carry to/from boat, carry camera to/from dive site, dive with camera all day ... so I guess you're parcing the term "lug"

He stated that for the majority of us, or 90% in his words, there would be zero impact. We can argue semantics all day but he's right. The majority of us will never need anything more than what a 4/3 system offers. Finally yes you are correct about the 4/3 micro however if image quality is solid and performance is DSLR-like then I'm not sure many folks will marry themselves to the SLR mechanics just to stay in a club. As far as the G9 goes, I don't think it applies. There still is no point and shoot with the focus speed, write speed and interchangeable lenses. As far as image quality, it was a G9 that won best of show in the Scuba Diving Magazine last year.

Edited May 18, 2009 by ce4jesus

[ce4jesus 1]

What a great thread! I'm glad that there has been so much factual info posted as it clears up a lot of misconceptions. Thanks for doing the research Drew.

 

In my opinion, what I think it comes down to is that you can't just consider the weight and cost of the camera - as you are buying into a SYSTEM. Looking at the comparisons, an aluminum housed Nikon vs the Oly+Oly housing was only a one pound difference. That's just not significant really. The size of the camera and lenses isn't relevant either as you'll be interfacing w/ them through the housing.

 

Comparing the 5DII to the Oly there is a bit more difference, but in return there is a LOT more you get back in features from the Canon because it's a "pro" type camera w/ HD video capability and extremely good low light performance.

 

Cheers

James

 

I agree completely. I think when you purchase a camera you are essentially marrying yourself to the glass and ports because the bodies and housings will change over time. That's a big committment that each individual has to weigh.

[ce4jesus 1]

Discarding price, image quality and the camera/lenses weight differences, the housings are not that much different in weight. The PTE06 is 5lbs without arms. The PTBK-E02 arms bracket is about 1kg... which brings it right back up to 7lbs again. Arms and strobes are the same for any setup (except one has to look for optical strobes only vs sync cord capable housings).

Looking at the dimensions of the housing : PT-E05= 212.5 x 170.5 x 147 mm vs the aquatica 5D2 230m x 195mm x 145mm. Again not much savings against a camera which is bigger and heavier. An aquatica D90 housing (which is closer in performance class) is 216 x x 171.5 x 133 mm and weighs 6.25lbs/2.85kg with grip. That's aluminum vs the "lighter" poly construct.

The weight savings is only significant on the camera and lenses. A few hundred grams on the camera and whatever lenses, I'd say you'd save about 2-2.5 lbs or about 1kg if you have a many lenses and 2 bodies. I absolutely agree every bit of weight counts in these times but there isn't such a significant savings in the magnitude of 30-50% overall.

I'm not advocating either systems as people have to choose what works for their budget/needs/whims. I just want to reiterate that research is crucial in making the right choice. I spent 2 mins in Google to find that info and 7 mins to write this down. That's more than I should've really

 

Okay, maybe you can tell me where you fould the statistics for the PT-E06 because I couldn't even find them for the PT-E05. I'll weigh mine when I return home but I think 5lbs without a port is very generous. I was thinking about 3. I don't think brining in trays and arms is relevant since no one is locked into a particular brand. Olympus will actually do both sync cord and optical for firing some strobes and needs converters for handling others with a wired setup. What would be interesting is to have someone with a D80 sign up to weigh their D80 in an ikelite with a standard kit lens. I could do the same for the E520 which would be very similar to the 620. Anyway,

[TheRealDrew 0]

Okay, maybe you can tell me where you fould the statistics for the PT-E06 because I couldn't even find them for the PT-E05. I'll weigh mine when I return home but I think 5lbs without a port is very generous. I was thinking about 3. I don't think brining in trays and arms is relevant since no one is locked into a particular brand. Olympus will actually do both sync cord and optical for firing some strobes and needs converters for handling others with a wired setup. What would be interesting is to have someone with a D80 sign up to weigh their D80 in an ikelite with a standard kit lens. I could do the same for the E520 which would be very similar to the 620. Anyway,

 

 

On the PT-E06 amazon has shipping weight of 7 lbs, weight of 5 lbs PT Housing

 

Trays and arms can be somewhat locked in, for instance the Aquaticas come with handles, but no need for tray. As to the Ikelite numbers, I posted some numbers for the D80 and a guesstimate above for the 620 (no lenses though).

[Drew 0]

Okay, maybe you can tell me where you fould the statistics for the PT-E06 because I couldn't even find them for the PT-E05. I'll weigh mine when I return home but I think 5lbs without a port is very generous. I was thinking about 3. I don't think brining in trays and arms is relevant since no one is locked into a particular brand. Olympus will actually do both sync cord and optical for firing some strobes and needs converters for handling others with a wired setup. What would be interesting is to have someone with a D80 sign up to weigh their D80 in an ikelite with a standard kit lens. I could do the same for the E520 which would be very similar to the 620. Anyway,

 

You have to add handles arms for the housing otherwise you can't have strobes unless you handhold them (which is fine for one strobe but impossible with 2). Actually I don't know why we need to go through all that. Obviously if the aluminum Aquatic housing + camera weight is known via simple extrapolation, then once you weigh your E520 rig, the comparison will be done. This is assuming manufacturers are accurate about their product weight... unlike people.

Adding lenses etc just convolutes the issue as there are different grade lenses in Olympus and Nikkor, plus the focal lengths differ. A fisheye setup is as basic as a 100mm macro (35mm equivalent). After all that, I'd be pretty surprised if the differences overall were over 2lbs. for housing and camera for a WA setup.

[GoinDown 0]

For weight measurements maybe we should be comparing a 'real world' setup to include body, 3 x lenses, housing, ports, handles/trays but minus strobes (strobes being the obvious item with varied options), so...

 

An E-620, Oly housing, FE lens, Macro Lens and WA zoom

 

A 5D2, xxx housing, lenses as above

 

A xxx camera, xxx housing, lenses as above

 

 

 

As for residual values.....

 

Residual values of obviously popular premium cameras such as the original 5D are high which bodes well for future resale of the 5D2. This appears to be true for premium housings such as Seacam/Subal retaining 30-50% or more after 3 years ??? Not sure about the lower end Ike's.

 

How well would residual values of Oly kit hold up when they replace models on a more frequent basis? And is the upgrade cycle shorter because the 4/3 technology is less mature, my guess is that micro 4/3 upgrade cycle will be as frequent (e.g. Panasonic G1 to GH1 about 3 months !!!). The G1 is obsolete and relatively worthless within 6 months !!

 

An obvious advantage of 4/3 is its low bulk, but will this matter too much in the underwater world? Packing is a definate advantage. But 5D2 housings are very tailored (Ike aside) to the camera providing low volume anyway.

 

Another advantage of Oly is the lower price - depending on the price of the 5D2 housing chosen and options, the price difference could be up to 40% cheaper for Oly, quite a difference, but then this could be equalled by better residual values of the 5D2 at second user sale time (a recent sale of a seacam 45 viewfinder on ebay fetched 75% of list price) !

 

So after analysing the weight price and residual values we come back to quality of output and underwater handling. Based on high ISO noise reduction, the 5D2 clearly wins, this is a definate advantage for green water (read UK) diving. Underwater handling I guess could be a personal choice, but after using an Canon 20D Ike housing for 3 years I really long for something better with a better viewfinder.

 

I have left Nikon out of this post as I believe most people would judge Nikon alongside Canon and I am trying to compare high end Canon with perceived lower end Olympus (as per my OP). Adding Nikon would only add another para to this already long post !!

[AndyK 0]

What a great thread!

Yes, indeed. Thanks to everyone for their contributions.

 

GoinDown's made a good point on residual values as well (tho' I'm not good at getting rid of things ...)

 

I'll weigh mine when I return home but I think 5lbs without a port is very generous. I was thinking about 3

For info .. my PT-E05 seems to come in at about 3lb / 1.2kg. Good estimate.

 

All of this hardware is really a means to an end, and we should each choose the kit that'll work best for the sort of photos we want to take.

I'm happy with my decision, given the factors that are important for me at the moment. These were the initial outlay, airline carry-on weight (my arms/tray can go in checked, so they don't really factor in), quality (vs high-end compacts, as much as other DSLRs) - and the cost of replacement when nasty things happen.

The trade-off for that meant compromises - the most significant are probably in terms of depth capability (which doesn't really bother me) and noise at high ISO (which does, sometimes, a little bit).

But ... that was my choice to make.

[GoinDown 0]

For info .. my PT-E05 seems to come in at about 3lb / 1.2kg. Good estimate.

 

That would appear to make the Oly plus lenses plus a couple of ports around 3.5-4Kg, against a 5D2 in a 2.5Kg housing plus ports guesstimate around 6Kg so a 30-40% weight saving around 2-2.5Kg saving. An Ike housing would be double the weight of the Oly setup.

Edited May 18, 2009 by GoinDown

[Steve Williams 0]

If all you care about is weight, get yourself some of that new waterproof paper and a wood pencil. It's a nice system, it floats so it's easy to find when you lose it and spares don't take up any room on a plane at all! It's real inexpensive, (golf courses give the pencils away). It does take a little more time to make an image but it's worth it if weight is the primary concern. Image quality is highly variable however.

 

Cheers,

Steve

[TheRealDrew 0]

If all you care about is weight, get yourself some of that new waterproof paper and a wood pencil. It's a nice system, it floats so it's easy to find when you lose it and spares don't take up any room on a plane at all! It's real inexpensive, (golf courses give the pencils away). It does take a little more time to make an image but it's worth it if weight is the primary concern. Image quality is highly variable however.

 

Cheers,

Steve

 

I am not sure if that is true, have you weighed the system you have proposed?

[craig 0]

Okay maybe he should have said, carry to and from dive location, carry to/from boat, carry camera to/from dive site, dive with camera all day ... so I guess you're parcing the term "lug"

I'm pointing out the wild exaggeration to emphasis a point that doesn't, for the most part, exist. If weight above water were critical beyond function or travel issues, no DSLR should be considered. The difference between an OLY camera ready to dive with strobes is not that much different from other DSLRs.

 

He stated that for the majority of us, or 90% in his words, there would be zero impact. We can argue semantics all day but he's right. The majority of us will never need anything more than what a 4/3 system offers.

No, he's not and the majority of us don't need an underwater camera at all so that point is meaningless. Perhaps many don't feel the extra performance is justified but that's not the same as claiming it has "zero impact". It's another exaggeration.

 

Finally yes you are correct about the 4/3 micro however if image quality is solid and performance is DSLR-like then I'm not sure many folks will marry themselves to the SLR mechanics just to stay in a club. As far as the G9 goes, I don't think it applies. There still is no point and shoot with the focus speed, write speed and interchangeable lenses. As far as image quality, it was a G9 that won best of show in the Scuba Diving Magazine last year.

We don't know what the focus speed is, in general, for cameras that don't exist yet so be careful about claiming that point and shoots can't match them. Basically, a micro 4/3 camera is a point and shoot with a large sensor and interchangable lenses and a 4/3 format sensor will always have 1/4 the sensor area of full frame.

[AndyK 0]

If all you care about is weight, get yourself some of that new waterproof paper and a wood pencil. It's a nice system, it floats so it's easy to find when you lose it and spares don't take up any room on a plane at all! It's real inexpensive, (golf courses give the pencils away). It does take a little more time to make an image but it's worth it if weight is the primary concern. Image quality is highly variable however.

 

Thanks, Steve.

I actually did try it, but the ISO went negative

[GoinDown 0]

If all you care about is weight, get yourself some of that new waterproof paper and a wood pencil. It's a nice system, it floats so it's easy to find when you lose it and spares don't take up any room on a plane at all! It's real inexpensive, (golf courses give the pencils away). It does take a little more time to make an image but it's worth it if weight is the primary concern. Image quality is highly variable however.

 

Cheers,

Steve

 

Even better - shave a few pixels from the full frame sensor, saving a bit of weight, also increasing DOF (for a given aperture) and corner sharpness- bonus !!!

Edited May 18, 2009 by GoinDown

[TheRealDrew 0]

Thanks, Steve.

I actually did try it, but the ISO went negative

 

 

But the noise is pretty good in that event, no?

[craig 0]

That would appear to make the Oly plus lenses plus a couple of ports around 3.5-4Kg, against a 5D2 in a 2.5Kg housing plus ports guesstimate around 6Kg so a 30-40% weight saving around 2-2.5Kg saving. An Ike housing would be double the weight of the Oly setup.

It makes no sense to compare only a portion of the rigs. If you care about travel weight then you need to consider everything. If you care about lug-around weight then you need to compare the rigs ready to dive. By comparing only a fraction of the rigs you falsely inflate the percentage difference between the two systems (as is intended). Since 4/3 doesn't offer any advantage in IQ and doesn't offer the lens selection of DX or FX, it appears that dive weight is it's only argument. It's a shame it has to be exaggerated to even seem significant.

 

My Seatool D300 with a 60mm macro, Nexus port, Inon 45 degree finder and Seatool dual grip tray comes in at 4.4 kg ready to dive (no strobes or arms). The D300 is a heavier camera than the 5D2. The Seatool tray and grips are 450 grams of that so the system without grips is only 4 kg.

 

What is the weight difference between the two setups when the 4/3 one doesn't even offer the lens that I need for a dive?

[GoinDown 0]

It makes no sense to compare only a portion of the rigs. If you care about travel weight then you need to consider everything. If you care about lug-around weight then you need to compare the rigs ready to dive. By comparing only a fraction of the rigs you falsely inflate the percentage difference between the two systems (as is intended). Since 4/3 doesn't offer any advantage in IQ and doesn't offer the lens selection of DX or FX, it appears that dive weight is it's only argument. It's a shame it has to be exaggerated to even seem significant.

 

My Seatool D300 with a 60mm macro, Nexus port, Inon 45 degree finder and Seatool dual grip tray comes in at 4.4 kg ready to dive (no strobes or arms). The D300 is a heavier camera than the 5D2. The Seatool tray and grips are 450 grams of that so the system without grips is only 4 kg.

 

What is the weight difference between the two setups when the 4/3 one doesn't even offer the lens that I need for a dive?

 

I wasn't aware that I had 'exaggerated' the weight differences, just stated them as fact for a typical setup (body, housing, 3x lenses and ports, without strobes) as I mentioned in an earlier post. And I have made no judgment about weight whether it is a good or a bad thing, just trying to eek out the facts so that personal judgment can be made based on different system setups with a typical set of lenses and ports for a baseline comparison.

 

You are free to make your own judgment on weight, which is significant for transportation above water and becomes academic underwater, IMO of course !

 

I thought I had presented a few balanced arguments for and against either system througout all my posts, so weight is certainly not the only issued to be discussed, I have no axe to grind here, just trying to get the collective opinion so I can make a better informed choice at purchase time.

 

It's interesting you think the 4/3 system does not have the full compliment of lenses for underwater use, which ones would be missing that you might like to use that are missing?? (I am genuinely interested?)

Edited May 18, 2009 by GoinDown

[rtrski 20]

...Somehow I doubt an Oly setup is the cheapest available.

 

For a housed, ported, lensed, strobed DLSR to cover a couple different shooting ranges (macro to reasonable WA), with reasonable IQ for a hobbyist although clearly not the equivalent of FF...Why not?

 

You've shot down other arguments based on lack of numerical accuracy, but I don't see any numbers offered to support (or deny) this statement. There's a $1k difference in current body price alone, D300 to E620 right now (B&H). Considerably more between the 5DII and 620, which was the OP's original 'what if' comparison. That's a pretty big start. I can find other bodies in the sub-$600 range from all manufacturers, but only Oly has OEM housings as an additional option. Haven't priced them out - I'm still strictly a bottom-feeder myself (used gear).

 

Tell us what the OP should be thinking a "complete rig" is to compare with and the total dollars will fall out pretty quick. Assuming "cheapest" was ever the intent, vs. looking for guidance of where on the cost vs performance slope he should be looking to go.

 

You're not an Oly fan though...we get it.

Edited May 18, 2009 by rtrski

[james 0]

You think comparing an D300 to an E620 is apples to apples though? How about comparing a D90 or a Rebel Xsi to the E620 instead - even though that wasn't what the original poster was looking at - it's a much more valid comparison.

 

Cheers

James

[GoinDown 0]

You think comparing an D300 to an E620 is apples to apples though? How about comparing a D90 or a Rebel Xsi to the E620 instead - even though that wasn't what the original poster was looking at - it's a much more valid comparison.

 

Cheers

James

 

So where's the math(s) ?

Edited May 18, 2009 by GoinDown

[rtrski 20]

You think comparing an D300 to an E620 is apples to apples though? How about comparing a D90 or a Rebel Xsi to the E620 instead - even though that wasn't what the original poster was looking at - it's a much more valid comparison.

 

Cheers

James

 

 

I don't disagree - I didn't bring the D300 into it, I just rolled with what was already provided with the weight discussion. But neither was the 5DII a 'valid' comparison to the E620 per the OP's question. Not to put words in his mouth, but he wasn't apparently ever after a pure apples to apples based on any one parameter, but asking for advice on relative merits and demerits on several sliding scales - weight, cost, and IQ.

 

I was certainly exhibiting a little bit of obfuscation of my own. There's no doubt in my mind that a roughly equivalent* "complete" rig between D300 and E620, which would be 'cheapest'. Any more than I doubt which would be 'cheapest' between the 5DII and the E620. Then again that was never the OP's question, was it? "I doubt it's the cheapest" without #s - is a bit of a straw man, thrown out idly in response to an "I decided not to pay 5k for a rig" defense, and in its own way just as ill-numerated as the weight discussion being slammed elsewhere.

 

Not the cheapest - for WHAT set of parameters? That's what I was pointing out. Or trying to.

 

That, and craig really isn't a fan of Oly. Or at least not of Oly fans. Doesn't take a lengthy history search to draw that conclusion. I can ennumerate posts later if anyone wants.

 

 

[*roughly equivalent meaning similar lens, strobe, and port setups in this case, as IQ difference is already at least partially forced by the bodies mentioned unless a really crap lens or port decision obviates it. Also obviously between 4/3 and other sensor sizes the exact 'same' macro focal length, wide angle focal range, etc aren't going to be found. They're still going to fall into typical usage categories though.]

 

One last P.S. While I still agree with you that there's a world of difference between the 'higher end' and 'lower end' cameras, if you look at specs, and ignore things that don't strongly influence UW shooting (like FPS) and obvious line differences (sensor size), there's not a huge gap between the D300 and E620: http://www.dpreview.com/reviews/compare_po...20&show=all Aside from the LCD pixel count, but people aren't supposed to want to LV with DSLRs anyway. Watch that spin people up!!

Edited May 18, 2009 by rtrski

[craig 0]

I wasn't aware that I had 'exaggerated' the weight differences, just stated them as fact for a typical setup (body, housing, 3x lenses and ports, without strobes) as I mentioned in an earlier post. And I have made no judgment about weight whether it is a good or a bad thing, just trying to eek out the facts so that personal judgment can be made based on different system setups with a typical set of lenses and ports for a baseline comparison.

 

You are free to make your own judgment on weight, which is significant for transportation above water and becomes academic underwater, IMO of course !

My weight judgement would be entire travel weight. That would include all my photography gear. Ready to dive weight isn't important to me because any still camera is within reasonable range. The weight of a few arbitrary components isn't interesting but it sure can be misleading.

 

Size of the rig is of some importance since it effects what shots you can get. A housed 4/3 isn't really all that different than smaller Canon or Nikon offerings.

 

It's interesting you think the 4/3 system does not have the full compliment of lenses for underwater use, which ones would be missing that you might like to use that are missing?? (I am genuinely interested?)

It lacks the variety of macro lenses available in Canon and Nikon mounts and lacks the 10-17 fisheye. The Oly 50mm macro lens provides similar field of view to a 50mm on DX or 100mm on FX but to get more you have to resort to teleconverters. If I had to use nothing but a 60mm/DX and a 1.4x I'd be unhappy.

[craig 0]

For a housed, ported, lensed, strobed DLSR to cover a couple different shooting ranges (macro to reasonable WA), with reasonable IQ for a hobbyist although clearly not the equivalent of FF...Why not?

 

You've shot down other arguments based on lack of numerical accuracy, but I don't see any numbers offered to support (or deny) this statement. There's a $1k difference in current body price alone, D300 to E620 right now (B&H). Considerably more between the 5DII and 620, which was the OP's original 'what if' comparison. That's a pretty big start. I can find other bodies in the sub-$600 range from all manufacturers, but only Oly has OEM housings as an additional option. Haven't priced them out - I'm still strictly a bottom-feeder myself (used gear).

If you define the argument so that anything less than the Oly can't be considered then it will certainly be the cheapest, but by what standard do you assume that only 4/3 can provide a low cost, reasonable alternative to DSLRs?

 

Tell us what the OP should be thinking a "complete rig" is to compare with and the total dollars will fall out pretty quick. Assuming "cheapest" was ever the intent, vs. looking for guidance of where on the cost vs performance slope he should be looking to go.

 

You're not an Oly fan though...we get it.

I don't need to offer advice in order to counter bogus arguments in favor of one particular system. I believe both Nikon and Canon offer compelling entry-level gear. I believe a new buyer should consider cameras, lenses, ports, and housings together when making a purchase. I don't support the idea of buying the cheapest housings in order to control costs.

 

No, I am not an Oly fan. It's main claim is its reduced size but that is hardly realized at all underwater. Everything else about it is a loser compared to the competition except, perhaps, its price. No doubt they are capable of good quality results. So are digicams and even a used D100. If someone wants a new system with interchangable lenses at the lowest price, a 4/3 may appeal to them and it wouldn't bother me. I just don't like specious arguments and we've seen a lot of them here regarding Oly 4/3. Right now it's weight savings but in the past it's been other things like superior macro lenses.

[craig 0]

You think comparing an D300 to an E620 is apples to apples though? How about comparing a D90 or a Rebel Xsi to the E620 instead - even though that wasn't what the original poster was looking at - it's a much more valid comparison.

That depends on your perspective. I brought up the D300 because it was a divable system that I could weigh and it is actually heavier than a 5D2. I believe the weight of the Seatool D300 (aluminum BTW) is pretty competitive. This is the quote I have been responding to:

 

The money compared to buying an almost obsolete D80 and a housing was 40% less and would have still weighed 50% more.

 

Taking Drew's numbers for the Oly housing and body, my D300/Seatool combination is comparably light at 3000 grams vs. 2800. Of course, a D90 or Rebel would be smaller and lighter than a D300 and that would make the claims of 50% heavier even less likely.