Polar Pro Red Filter vs UR/PRO Analysis

[Marty Cerven]

Just a few quotes on some of the claims made by Interceptor and the last quote is his definitive proof lol.

I thought that it would have been useful to all gopro users to understand how a filter really works and what it can or not do for you

Underwater Video Tips: Using filters with your GoPro or Compact Camera « Interceptor121 Underwater Video

Next issue we look at the polarpro filter vs SRP and why is on better than the other

Marty you lack the understanding of the physics behind and now try to climb on some things that do not relate trying to put them together
The reason why that dome SRP does not perform well (am not saying anything compared to polarpro) is because there is a design flaw similar to the one of the SRP tray (no point comparing it to a video housing where the positioning or arms depends on other design decisions and also a camcorder has different field of view)
The gopro is a small camera with around 110 degrees field of view in water, video lights are designed for cameras with 65-80 degrees fov, in order to illuminate the subject at the distance the gopro can focus the arms need to be further away. Why would someone spend more money for a tray that needs longer arms than need to be?
Anyway this is pointless maybe you can stop hijiacking the thread and just wait until you see what the issues with this dome are? Hint it is not that difficult just look at all the other filters on the market place and how they are designed. Were they all waiting for the genius of SRP?

I am surprised about the lack of knowledge about what a filter is and how it works, there will be some reasons why this filter performs better than the SRP and have to do with physics I am going to put some content on my blog so far I have not bothered with gopros but I think it is time

And here is the conclusive proof from your blog.

The SRP dome has a design issue as there is a layer of water between the lens and the filter that may absorb color and can’t be recovered

Care to give any reasoning behind this as you promised so much yet delivered so little. It may absorb colour? thats far from definitive proof of a design flaw that you are showing there. If you cant find an issue with the design whats the point of that comment?

I have doubts about your background as it doesn't show through in how you are coming to your conclusions, making claims based on physics should be proved explaining your theory and then proven in a practical test. Otherwise the claims are completely pointless and show little more then someone trying to make their opinion appear more valid, once you look into it all credibility of the claim is lost if that is all you have to back up such claims.

Just please stop claiming to be any more then just a general user with an opinion, its fine everyone has one just no need to pretend to be more then that. If you claim physics and science as a basis for your opinion show it! and if you cant show that then dont make such claims.

 

[Interceptor121]

Still hanging on I see
Do I need to show water absorbs color? I thought that was covered in your open water dive course?
As you have the whole lot of SRP products try the blurfix vs the dome next time and see it by yourself that there is a tiny difference especially as you go at depth then you let me know
Till then....Byeee!!

 

[flareside]

Do I need to show water absorbs color?

No, you just need to show how that that extra 1/4" of water behind a curved lens magically behaves differently than having that same 1/4" of water on the outside if the filter were flat. Discounting the filter thickness of course, if your housing is 6 feet from the subject, there is the same 6 feet of color absorbing water between you and it regardless of where the filter is.

 

[Interceptor121]

Because the water on front of the filter is taken care by the filter
The water between the filter and the port is not taken care by anything
How does it feel when your mask is full of water?
Why do you think ikelite when got push up filters with URPRO material has a rubber ring to push right on the lens?
Every design tries to minimise water in between as the effect is never positive

Did you buy the srp dome?

 

[Marty Cerven]

Because the water on front of the filter is taken care by the filter
The water between the filter and the port is not taken care by anything
How does it feel when your mask is full of water?
Why do you think ikelite when got push up filters with URPRO material has a rubber ring to push right on the lens?
Every design tries to minimise water in between as the effect is never positive

Did you buy the srp dome?

Feels like a mask full of water, how that's relevant I have no idea. Do you know what a mask is for? Does it do anything if its flooded? Or is it then just the same as if you didn't have a mask. Does wearing a mask have any effect on colours you see at depth? If not I don't get your point there sorry.

Still hanging on I see
Do I need to show water absorbs color? I thought that was covered in your open water dive course?
As you have the whole lot of SRP products try the blurfix vs the dome next time and see it by yourself that there is a tiny difference especially as you go at depth then you let me know
Till then....Byeee!!

Tried both can't say I have noticed this, care to show your videos shot with the dome that lead you to this conclusion? Have you got a dome filter? Have you ever used it underwater?

 

[toozler]

The water between the filter and the port is not taken care by anything

Your physics is exactly correct, water will absorb color. However, a layer of water few millimeters thick will cause this effect to such a infinitesimal extend that it can not be accounted for - maybe only if you're using fancy precision instruments, which is not the case, is it? I tried to point this out before. Does your glass of water look darker or bluer at the bottom? Theoretically, yes. Can you tell?

May I ask what is your background? By that I mean, what do you do professional and what is your academic area of expertise?

 

[flareside]

Because the water on front of the filter is taken care by the filter
The water between the filter and the port is not taken care by anything
How does it feel when your mask is full of water?
Why do you think ikelite when got push up filters with URPRO material has a rubber ring to push right on the lens?
Every design tries to minimise water in between as the effect is never positive

Did you buy the srp dome?

OK, one at a time.

Because the water on front of the filter is taken care by the filter. The water between the filter and the port is not taken care by anything. The filter does not change the properties of the water. Using the dome in the 6' example above, 287/288ths of the color loss occurs on outside of the dome and last 1/288ths happens behind it. With a flat filter all 288/288ths happen outside the filter. The light is passing through the same amount of water either way. Sure the filter adds a finite amount of red back in but as there is less color loss leading up to the dome, that which takes place afterward balances.

How does it feel when your mask is full of water? Not much of a diver are you... I don't let my mask fill with water.

Why do you think ikelite when got push up filters with URPRO material has a rubber ring to push right on the lens? Flat lenses are far easier and much less expensive to manufacture. It is very easy to get high optical quality from cell casting acrylic and cutting circles in that acrylic and dropping them into rubber rings is very economical. Having to press that same acrylic into a formed surface and achieve high optical quality is extremely difficult, requiring absolutely perfect molds which don't come cheap.

Did you buy the srp dome? No. I was able to achieve a far better system for a fraction of the price building my own.


Ultimately I don't expect you to acknowledge that you are wrong on this, but it really doesn't matter. Everyone already knows.

 

[Interceptor121]

Toozler I am a trained engineer I think I have said this before somewhere

Also when you were saying that polarpro do filters for the normal dive housing I was curious
Actually the marketing people of this company must be a bit thick but the filter goes inside the housing so fits the dive housing
I guess as they also have a polariser that is only in the housing so they called them standard housing filters however the red filter is only worth going in the dive housing
They already used the term dive housing filter and snap on must have run out of words and came out with standard housing poor choice

Re srp
So as we agree that the water does not do good we are already in a good place
Now how good or how bad is not that important in a wide angle lens leaving those few mm means around 8% loss on focal length (I should say gain as it makes the lens longer)
I would think that if in terms of optical distortion that is something under 10% for colour it will be similar with more pronounced effect as you go at depth
I think this is not that interesting to be frank the key question is why bother with a dome shape when the gopro lens is not rectilinear so can't be corrected by a dome?? Surely that puts the price up a notch in addition to decreasing the performance of the filter itself
As an engineer you may agree that the design effort was not actually needed
I believe srp have worked it out themselves as they have abandoned the dome concept
To give you an idea the dome is not even sold in UK just the blurfix standard

Because the water on front of the filter is taken care by the filter
The water between the filter and the port is not taken care by anything
How does it feel when your mask is full of water?
Why do you think ikelite when got push up filters with URPRO material has a rubber ring to push right on the lens?
Every design tries to minimise water in between as the effect is never positive

Did you buy the srp dome?

OK, one at a time.

Because the water on front of the filter is taken care by the filter. The water between the filter and the port is not taken care by anything. The filter does not change the properties of the water. Using the dome in the 6' example above, 287/288ths of the color loss occurs on outside of the dome and last 1/288ths happens behind it. With a flat filter all 288/288ths happen outside the filter. The light is passing through the same amount of water either way. Sure the filter adds a finite amount of red back in but as there is less color loss leading up to the dome, that which takes place afterward balances.

How does it feel when your mask is full of water? Not much of a diver are you... I don't let my mask fill with water.

Why do you think ikelite when got push up filters with URPRO material has a rubber ring to push right on the lens? Flat lenses are far easier and much less expensive to manufacture. It is very easy to get high optical quality from cell casting acrylic and cutting circles in that acrylic and dropping them into rubber rings is very economical. Having to press that same acrylic into a formed surface and achieve high optical quality is extremely difficult, requiring absolutely perfect molds which don't come cheap.

Did you buy the srp dome? No. I was able to achieve a far better system for a fraction of the price building my own.


Ultimately I don't expect you to acknowledge that you are wrong on this, but it really doesn't matter. Everyone already knows.

I can't acknowledge that I am wrong if I am right
Now tell me why is it necessary to have the shape of a dome that as you say is expensive instead of something flat?
Also what is your solution if I can ask?

 

[toozler]

Also when you were saying that polarpro do filters for the normal dive housing I was curious
Actually the marketing people of this company must be a bit thick but the filter goes inside the housing so fits the dive housing
I guess as they also have a polariser that is only in the housing so they called them standard housing filters however the red filter is only worth going in the dive housing
They already used the term dive housing filter and snap on must have run out of words and came out with standard housing poor choice

I said the stock housing (domed lens). Those circulars filters will not work on the dive housing (flat lens) as they won't cover the whole frame or stay put in place, as the glass sits a couple mm away from the camera lens itself.

Here is a picture from their website, I don't believe it is a naming issue, it's a lack-of-knowledge-of-what-they-are-doing issue:

Similarly, they sell a "polarizing filter" for the dive housing (flat port). Curious to know how that benefits diving or it's another great business opportunity to sell stuff to people that like colorfull packaging

 

[flareside]

Now tell me why is it necessary to have the shape of a dome that as you say is expensive instead of something flat?
Also what is your solution if I can ask?

As for the necessity of a dome, ask SRP. I have no involvement in their decision process. Probably something to do with vignetting.

Prior to the flat lens housing, rather than spending $180 on SRPs Blurfix system, a more than cost effective substitution could be achieved with a properly glued up combination of a 37mm-55mm step up ring, a cokin A filter holder, a 55mm-60mm step up ring, and a 62mm UV filter glass placed in that order over a bubble housing. Adding a urpro filter cut from an ikelite 6441.43 ($27 ebay) to fit the filter holder lead to a system with a removable filter, no vignetting, and no dessicant beads to deal with for around $75. If I can find a photo I will post it but here is a test image through the lens taken back when I still had it:



Sorry no good water images because water conditions were crap on that trip. Wrong time of year to be in Destin.