Mobius 5MP Varifocal Zoom 6-22mm ƒ/1.6

[Dashmellow]

I may invest in something better than a craft knife and a small sheet of sandpaper.

You need a cutting laser with a 24mm beam!

 

[Dashmellow]

I may invest in something better than a craft knife and a small sheet of sandpaper.

Actually, if you have a craft knife blade or other knife you are willing to sacrifice, heating the blade with a torch or candle can facilitate doing a job like this by hand if you are careful when cutting on an outline you've drawn.

 

[c4rc4m]

I used to use a polarizer on my primary dash cam but I gave up on them primarily because I didn't like the way they detract from night time capture. I discovered that a good quality dash mat is so effective that a polarizer is not needed.

Out of interest, is the photo above dash mat + polariser or polariser alone?

 

[TonyM]

I put together my DIY CPL for the 6-22mm varifocal this morning. Despite a cut finger (!), it turned out rather well.

I began by holding a circle drawing template up to the front of the lens to get an idea of what size aperture to go for. It looked like 17mm would be fine.

I started by cutting a hole in the 28mm lens cap supplied with the lens. The actual hole is just 16mm diameter, which I checked for vignetting on both my 6-22mm and 2.8-12mm varifocal lenses at their current zoom settings before continuing.

I extracted the 22mm diameter CPL for the SG9665GC from its holder, and glued it to the front of the lens cap with 4 small dabs of UV glue. The edge of the filter sits on the slightly raised ring you can see around the hole, so there is a small gap behind the filter where I could place the spots of glue and not worry too much about it spreading when in contact with the filter. The CPL could have gone on the inside of the lens cap and JUST fit inside the 23mm front aperture of the lens barrel, but it did not look so neat & tidy from the outside.

This is the finished product on a 2.8-12mm lens, which I use rear-facing with a Mobius 1:

And here it is on the 6-22mm lens, which I use front-facing with a Mobius Maxi:

From the front it has a fairly discreet profile

 

[TonyM]

I did a quick test in the car with the CPL fitted on the front-facing 6-22mm lens attached to a Mobius Maxi. The effects are noticeable in this static scene with a parked car. Reflections are reduced, and contrast is improved by reducing glare.

 

[Dashmellow]

Out of interest, is the photo above dash mat + polariser or polariser alone?

I have a dash mat permanently installed in my vehicle, so the varifocal photo is dash mat plus polarizer.

 

[Radius8]

Here's another example of what I mentioned above. Note that the polarizer has eliminated most reflections from virtually every windshield within the camera's FOV in this parking lot regardless of the angles the lens is observing them from. This effect seems to work for the most part regardless of the angle the sunlight is coming from as as well, as long as the polarizer is dialed in for other car's windshields. Note that the polarizer is not effective for the other vehicle's side windows or the puddles on the ground.
View attachment 40590

That picture looks almost HDR like. Pretty impressive.

 

[Dashmellow]

That picture looks almost HDR like. Pretty impressive.

Yeah, this lens, especially with the polarizer really transforms what the camera is capable of. As I've mentioned here and there, the lens seems to have the unique ability to open up the exposure range under challenging lighting, especially when compared to simultaneous captures from my SG9665GC. Careful tweaking of the advanced exposure controls enhances the results.

 

[Dashmellow]

That picture looks almost HDR like. Pretty impressive.

Your post prompted me to revisit and repost an image from this thread that I posted a couple of months ago. The capture was taken when I was backing out of a parking space in town. These were early days with this new lens and what struck me about the image at the time (aside from being an interesting photo) was how well the exposure held together despite the intense glare right in the middle of the image. Most every other dash or action cam I've owned would have completely blown out the image trying to deal with such lighting but here all the shadow detail is still there, even in the deepest recesses behind the wooden parking shelter in the background, directly adjacent to the glare. It's quite remarkable, especially for the Mobius which is not known for it's stellar control of bright highlights. Of course, this was before I decided to try the polarizer on the 6-22mm ƒ/1.6, so in theory this image could have even been better exposed than it is.

BTW, the rural town in Vermont I live near has a uniquely diverse and international population along with our usual assortment of farmers, rednecks, hippies, preppies, bikers, urban tourists, festives, tattooed and pierced characters with man buns and lawyers in suits. About 15 seconds after encountering this Muslim woman wearing a niqab I turned the corner and came across a Buddist monk in flowing blue robes walking with a guy who looked part hippy and part redneck, heading towards a popular sandwich shop.

 

[Lola]

Here's another example of what I mentioned above. Note that the polarizer has eliminated most reflections from virtually every windshield within the camera's FOV in this parking lot regardless of the angles the lens is observing them from. This effect seems to work for the most part regardless of the angle the sunlight is coming from as as well, as long as the polarizer is dialed in for other car's windshields. Note that the polarizer is not effective for the other vehicle's side windows or the puddles on the ground.
View attachment 40590

I take it this is the new windshield, awesome, I can't even tell you have one! The quality of the shot looks way better by far then any M12 lens I've ever seen, absolutely Awesome!!

 

[Dashmellow]

I take it this is the new windshield, awesome, I can't even tell you have one! The quality of the shot looks way better by far then any M12 lens I've ever seen, absolutely Awesome!!

Actually, that's still the old windshield. Most of the time you couldn't see that much of a difference on dash cam videos except when the sun hit the windshield from certain angles and then you practically couldn't even see through it because of all the millions of tiny pockmarks from years of driving around on dirt and gravel roads.

The new windshield (the third one ) is really nice and clear (and not distorted). I love it and I do in fact think it makes a difference in the clarity of my dash cam videos. This third replacement windscreen also made it obvious that my claim that the defective ones had a haziness to them was accurate.

 

[c4rc4m]

That picture looks almost HDR like. Pretty impressive.

Yeah Polarisers are known for saturating images as well as reducing glare, most notably in scenes involving skies where the effect is more prominent.

Would be interesting to see someone use a Hoya HD Circular Polariser either in it's own right or as the basis for a polariser build, because HD filters have the distinction of letting an extra stop of light through which potentially makes them better at night.

 

[Radius8]

Yeah Polarisers are known for saturating images as well as reducing glare, most notably in scenes involving skies where the effect is more prominent.

Would be interesting to see someone use a Hoya HD Circular Polariser either in it's own right or as the basis for a polariser build, because HD filters have the distinction of letting an extra stop of light through which potentially makes them better at night.

Here's one taken through that Hoya filter from my old trusty Canon 20D. It was a super sunny day with temps in the 110F (40+ C). Picture was downsized but you can still see the effectiveness of a top quality circular polarizer filter with multi coated surface. It even reduced the glare from the windshields of other cars facing other angles than the main subject. Downside is that that piece of glass was $$$ at the time. Looks like B&H has the 37 mm version now for ~ $32. Pretty reasonable, but mounting to Mobius is still going to be a challenge.

 

[meanie2]

https://www.lenstip.com/139.25-article-Polarizing_filters_test_2015_Results_and_summary.html


polarizer review

 

[Dashmellow]

Mounting a 37mm filter onto the front of a 28mm diameter lens bezel could be achieved easily with the use of a step-up ring.



And the Hoya HD polarizer filters have been superseded by the HD2 version yielding even greater light transmission. AFAIK, the current stock of HD1 CPLs may be the last available. There's even an HD3 version that has 16 layers of nano-coatings which provide a 2/3rds stop increase in exposure over the previous version although I'm not aware if it is even available in the 37mm size. Of course, the HD2 is about twice as expensive as the original HD and I have no idea what the HD3 sells for.

While it's nice to fantasize about installing ridiculously expensive filters (and lenses) on a camera like the Mobius there's an extremely steep slope of diminishing returns in spending what could ultimately amount to nearly the equivalent cost of the camera itself on the results you'd achieve. I'm happy stickin' with my 6 buck CPL from eBay for now.

 

[c4rc4m]

Did a bit of research:

HD3 - 92% Transmission - smallest size 49mm @ $99

Evo Anti-static - 92% Transmission (same as HD3) - anti-static coating (ideal for dashcams no doubt as cars are dusty) - smallest size 37mm @ $80

As you say, diminshing returns.

Personally, I'd probably go for a Hoya NXT Plus. They don't state the transmission but at $27, great value for what should be a top filter.

If of course you can get the HD1 still for around $30, it would be rude not to!

 

[Dashmellow]

Rude not to? So, spend 30 bucks to install a giant filter, larger than the width of the camera itself along with the added cost of a step-up ring onto a lens that costs 14 bucks on a 70 dollar camera?

 

[Radius8]

Just to clarify, the listed % transmission on the Hoya spec sheet is for light that is parallel to the axis of the polarizer. It still will cut > 50% of the original light, assuming that it was completely unpolarized (that just how polarizers work).

For the geeks, check out Edmund's into to polarization here:
https://www.edmundoptics.com/resources/application-notes/optics/introduction-to-polarization/

I suspect that a great deal of the efficiency is also due to the anti reflective coatings that the expensive filters have. Applying anti-reflective coating to a transparent surface will effectively increase the transmission. I've had looked into possibly applying an anti reflective film to my windshield to reduce/eliminate the glare. Though, there is a company that sells such a product (and I have it here at work for scientific purpose) it's really $$$ and the film is not very flexible.

For the curious see these products:
http://www.mecanusa.com/polarizer/AR-film/AR_roll.htm
http://www.mecanusa.com/polarizer/AR-film/AR_sheet.htm

 

[TonyM]

DIY CPL update:
After just two days in use, the CPL fell off overnight. It appears that the UV glue does not form a secure bond with the particular plastic used to make the lens cap.

 

[Radius8]

DIY CPL update:
After just two days in use, the CPL fell off overnight. It appears that the UV glue does not form a secure bond with the particular plastic used to make the lens cap.

Have you tried lightly sanding the area to be glued to make it a bit rougher? It will give a bit more "grip" for the glue.