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

[SawMaster]

HID's + white coloured cars in front darkens the image, don't think it's due to the CPL. I remember experiencing similar darkening with the A2.

The wider FOV seems to be the culprit, appears to be More susceptible to such darkening, never experienced such behaviour with 8 and 12mm lenses.

The lens takes in everything, then the metering decides what adjustment to that raw image is needed, so having a wider FOV would give that resulting problem unless metering was done in a manner to minimize that.

HID's and LED's have a different color spectrum range then incandescent lights do. That too needs to be figured into the metering, but currently all you can adjust is the output, not the input, of the color difference that the sensor sees. It would likely take a supercomputer to mitigate this in every circumstance. But the point I wanted to bring up regards this is that if you adjust to your headlights, then you may be reducing the visibility of things being illuminated by other lights around you. Since that can be other headlights, streetlights,or whatever the best you can do is compromise to get the best overall performance.

Another aspect of modern headlights is their sharper cut-off at the edges. What is in the beam is better lit at a cost of seeing things outside of the beam. This makes them seem brighter and better, but since we tend to look at what we can see, you see a lot less with them since your eyes are now adapting to their bright light only, and not to the general darkness all around you. We'd be far better off with the cut-off fading gradually like the older sealed beams do, but that won't sell. A cam will act similarly in losing that which is not being illuminated, or in washing out what is well-lit to get the darker areas. Up close, my old halogens give me more of light and dark both, but at father distances the newer headlights show things I miss. For general dashcams purposes, you want to capture as much view as you can, but with a telephoto lens and smaller FOV as we have here, there might be an advantage to the newer lights and their higher intensity, but only if they will tune the color range to be more like the general illumination being used where you are. As in your image, washout will still be a problem, but at that range your main wider angle dashcams should give sufficient details to cover for it.

Everything in life is a compromise of one sort or another.
Phil

 

[SawMaster]

It's just a shame that many proprietary polarisers can't be adjusted.

I've noticed this seeming to occur with quite a few folks using some highly-regarded cams. The images they post lack the sharpness they should have. Though I've never used a CPL, the need to be able to adjust it for each situation just seems obvious, but cannot happen with cam designs using slide-on filters. Doing things the easy way doesn't often give the best results.

Phil

 

[SawMaster]

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

Nah, all you need is a bigger hammer. Back to saner solutions, a "stepped drill" bit makes cutting concentrically easy, and for plastics turning it by hand or with it held in vise-grips ( mole grips) is a breeze. Best the hold the grips steady, then turn the object being cut to lessen any wobble. Cost less than a half pint of your chosen brew for the cheap ones and that's as good as you need for plastics and soft metals.

Phil

 

[Dashmellow]

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.

As it says on the package of the VisBella UV cement I have here in front of me: "May not work with polyethylene or polypropylene plastics".

 

[Lola]

I'm going the step up holder and 37mm lens. It's a little more professional looking and makes for a tight fit with the ability to take off or add different filters with ease fast. Still waiting for the VisBella to come in from Bangood though!
I've been reading up on polarizers though and Radius8 is right about the Hoya filters, at least as far as the major reviews of filters and comments from people in the know.

I wish I had waited on buying the FOTGA but at the time from what I had learnt it looked like a good thing since it has 16 layer coats, but with my luck they used a paint brush to put them on! Almost every review article I've read warns about Chinese polarizer filters not being up to the quality of just about all other manufactures.

 

[Dashmellow]

I'm going the step up holder and 37mm lens. It's a little more professional looking and makes for a tight fit with the ability to take off or add different filters with ease fast. Still waiting for the VisBella to come in from Bangood though!
I've been reading up on polarizers though and Radius8 is right about the Hoya filters, at least as far as the major reviews of filters and comments from people in the know.

I wish I had waited on buying the FOTGA but at the time from what I had learnt it looked like a good thing since it has 16 lawyer coats, but with my luck they used a paint brush to put them on! Almost every review article I've read warns about Chinese polarizer filters not being up to the quality of just about all other manufactures.

16 lawyer coats! OMG!! That doesn't sound good at all! Often, even one coat of lawyers is too much.

Anyway, all seriousness aside for the moment, FWIW, the cheap Chinese CPL I've been using with this lens has been performing quite nicely, as you can see. Sure, it would be nice to have less of an exposure factor penalty but at more than 5 times the cost for the Hoya HD CPL and ten times the cost for the HD2 version, plus the cost of the step up filter, I'm not quite ready to make the leap.

 

[Lola]

LOL, I didn't notice that till you saw it (corrected), I've been doing a lot of that lately.
You are right, I know it, but being a gadget freak is really awful, it's like having a little kid pulling on your leg saying buy it for me pleaseeeee! However I intend to stick with what I've got till I get everything ready and together. If it comes close to what you are getting with the 6-22 I'll be happy.

 

[TonyM]

I re-fixed the CPL to the lens cap using a different glue position - effectively a fillet weld on the outside edge rather than a spot weld underneath the CPL. It is still holding firm after a week.

 

[TonyM]

I regularly drive along country lanes where I'm at risk of being swiped by an oncoming vehicle. I suffered a minor accident on this same road last year when someone knocked off my wing mirror but failed to stop at the scene. Being able to identify the other vehicle in that incident has helped bring about a court summons to recover costs from the other party.

This is the main reason why I like to run a telephoto (or in this case, a varifocal at a telephoto zoom setting) alongside a regular dashcam. The wide-angle A129, fitted with a CPL, records the general scene but ultimately falls short in preserving critical details. The 6-22mm lens at approx half-zoom mounted on a Mobius Maxi (without CPL) does a much better job for my intended purpose of capturing details.

A129 - 1080p 30fps with CPL 16.4Mb/s

Mobius Maxi with f1.6 6-22mm - 2.7k 30fps 60.1Mb/s

A129

Maxi

Unfortunately there is a trade-off when using a telephoto lens, that it misses objects to the side such as this car coming around the bend

A129

Maxi

I'm reluctant to put a CPL on the front-facing telephoto because the increase in exposure time makes a noticeable difference in situations like this. Perhaps I will go back to using the original wide-angle F1.5 lens in the Maxi, plus this 6-22mm lens with a CPL on a Mobius 1.

 

[Harsh]

I re-fixed the CPL to the lens cap using a different glue position - effectively a fillet weld on the outside edge rather than a spot weld underneath the CPL. It is still holding firm after a week.

Did something similar with the lens cap that came with one of my fixed telephotos and the 24mm CPL.

 

[TonyM]

I checked the footage from my front & back varifocal-equipped cameras tonight. I'm glad I did. Both of them need fixing!

The view through the 6-22mm attached to my front-facing Maxi is rotated. The camera must have been knocked without my knowledge, although I had not noticed that it is so badly mis-aligned from within the car which puzzles me. I suppose such things can happen after a two week holiday with kids in the car. It's also focused too close. I was going to remove the 6-22mm and put the original Lens B back in the camera soon, so now seems as good a time as any.

The rear 2.8-12mm lens on a Mobius 1 has gone completely out of focus!

I'm glad I didn't need the video footage from either camera for an incident. This is a reminder to me that I should check my cameras frequently. And perhaps the varifocals need checking more often to ensure they're still in focus.

 

[Dashmellow]

The same thing happened to me yesterday but to a lesser degree. The camera was slightly askew. I've also had the focus go out on me (also not quite that bad). I've since learned to make certain that I've really cranked down tightening the focusing knob after getting the focus where I want it. I think that's why the focusing knob even includes a slot for a screwdriver.

 

[TonyM]

I did not want to risk damaging the lens by turning those screws so tight, but as you say they do have slots so maybe I'm being too careful with it.

 

[c4rc4m]

This is one reason why I like primes for Dashcam use. Telephotos are great for establishing the most appropriate focal length, however they can be more prone to focusing issues as they're heavier and so apply more force to focusing screws in vibratory environments. With a small light prime lens, there's less of an issue.

BTW do Treeye still exist? Their Aliexpress store seems deserted - no products for sale.

 

[TonyM]

BTW do Treeye still exist? Their Aliexpress store seems deserted - no products for sale.

You're right that none of their products appear to be for sale at the moment, including the lens discussed in this thread.


There are other vendors with similar lenses, including fulekan who include an IR-cut filter with their lens:
https://www.aliexpress.com/store/pr...-5-inch-Manual-Focus/1862644_32860939063.html

 

[Dashmellow]

I noticed the other day that the Treeeye store was still there but empty of products. I sent Sophie a message asking what's going on. If I get an answer I'll report back.

Unfortunately, the Fulekan version of the varifocal doesn't use the fail-proof IR-cut filter install method I championed. If I were to buy another varifocal, I think I would install my own filter and recommend the same for others. It's easy to do.

 

[TonyM]

This is one reason why I like primes for Dashcam use. Telephotos are great for establishing the most appropriate focal length, however they can be more prone to focusing issues as they're heavier and so apply more force to focusing screws in vibratory environments. With a small light prime lens, there's less of an issue.

I agree with you, up to a point. We have found that the telephoto prime (i.e. fixed) lenses can be very difficult to focus correctly, and they seem to drift in/out of focus at times - perhaps being more sensitive to temperature changes than wide angle lenses. One benefit of the varifocal lenses is that they can be re-focused quickly in-situ within the car, without having to take the camera case apart and undo the tiny locking screw or nut. I hope that once the screws are tightened enough the zoom and focus will not change over time.

 

[TonyM]

Unfortunately, the Fulekan version of the varifocal doesn't use the fail-proof IR-cut filter install method I championed. If I were to buy another varifocal, I think I would install my own filter and recommend the same for others. It's easy to do.

Are you sure? This is taken from the fulekan listing:

 

[Dashmellow]

Are you sure? This is taken from the fulekan listing:
View attachment 41512

No, I'm not sure, so maybe it's OK. Hard to tell for certain from their photo. Guess we would need to ask.
Also, we don't know if it's even the same exact lens. There are a lot of look-a-likes and clones out there in the Chinese CCTV lens market. They number in the billions and not all come from the same manufacturer.

 

[Harsh]

I agree with you, up to a point. We have found that the telephoto prime (i.e. fixed) lenses can be very difficult to focus correctly, and they seem to drift in/out of focus at times - perhaps being more sensitive to temperature changes than wide angle lenses.

Not as per my experience. The 3MP ones I didn't apply any glue or use a locking ring and even with the bumpy roads here, none of them went out of focus. Been using a locking ring with the new 8 and 12mm, no focus issues whatsoever.

You're probably referring to the 4 and 6mm f/1.2 some of us got from Treeye.