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

Dashmellow

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#1
I just took delivery of a new lens to play with on the Mobius, a 5MP Varifocal 6-22mm ƒ/1.6 zoom in a 1/2.5" sensor format purchased from Treeye on AliExpress. I understand that @TonyM purchased one of these as well. Here is a new thread where we can discuss our results.

treeeye.jpg

Even though I had a lot to do today, like a kid on Christmas morning I couldn't help but take a little time to check it out. I did a few quick tests without changing any of the existing settings from my Variofocal 2.8-12mm zoom lens. The results were very promising considering and will likely see improvements when optimized for this new lens. The lens is set to "B" in mSet up but may be better when set to "C".

Here the lens is set to the widest 6mm setting.
min.jpg

Here the lens is set to 22mm.
max.jpg

For comparison here is an original Mobius A lens view.
a_lens.jpg

Here I randomly set the focal length somewhere in the middle of the range.
zoom2.jpg

Interesting telephoto parking lot coverage. Click for full rez, as with all of these.
zoom1.jpg

Here's another one only one second later. Interesting to observe other drivers this close. Good detail so far considering only a quick down and dirty first focusing attempt. I can already see the need to carefully consider and calculate hyperfocal distance like on the 2.8 to 12mm varifocal, which can be challenging.
parkinglotdriver.jpg

More to come.
 
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Dashmellow

Dashmellow

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#2
Looks like my down and dirty quick focus is still a bit off. Like the 2.8-12mm varifocal I can see that optimizing the hyperfocal distance will be a challenge except that this lens seems so far to offer greater depth of field.
focus.jpg
 

TonyM

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#3
Like another kid at Christmas, I've been up late setting up my 6-22mm too!

IMG_20180515_013515-01.jpeg

It's now ready for a test run alongside my 6mm F1.2 and a standard Lens D Mobius.

IMG_20180515_022739-01.jpeg
 

TonyM

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#4
My initial results suggest that towards the wide end of the 6-22mm varifocal lens' range, the performance is similar to the fixed 6mm F1.2 lens.

This is a mostly static scene, where the varifocal renders a good amount of detail.

6-22mm


6mm F1.2


Lens D (2.66mm F2.8)


I have the Lens D camera set to lens profile 'B', whilst the two Treeye lenses are using profile 'C'. All other image adjustment parameters are at default.
 
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Dashmellow

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#5
@TonyM, I think this the first and only time I've ever seen you post dash cam images that were shot on a sunny day! I was beginning to think the sun never shines in the UK. Or maybe this was a one-off? :);)

The 6-22mm looks good but as I think you'll soon discover, if it's anything like my experience with the 2.8-12mm, there's a sweet spot in the hyperfocal distance where you can optimize the near/far range of focus for your desired dash cam use. That's the beauty of using a varifocal on a dash cam. This can take a fair amount of trial and error and can also depend on the kind of driving you usually do but in your above image for example, you may find that you can achieve better focus on the truck out ahead of you while still capturing the approaching car in the other lane. It remains to be seen how this new 6-22mm ƒ/1.6 performs but my initial impression is that it offers a somewhat longer depth of field than the 2.8-12mm ƒ/1.4.
 
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Dashmellow

Dashmellow

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#6
The whole idea behind using a secondary telephoto dash camera is that it gives you a degree of souveillance capture that simply can't be achieved with a single wide angle camera. The combination of a telephoto and a wide angle dash camera brings things to an entire new level.

I didn't have time yesterday to illustrate this but here is a re-post of one of the images I posted last evening along with the corresponding identical frame from an SG9665GC. As I've mentioned elsewhere, I started out using a varifocal equipped Mobius as an interesting experiment but now I don't like to run without it.

Street Guardian SG9665GC V2
gc.jpg

6-22mm ƒ/1.6 varifocal zoom Mobius
zoom2.jpg
 
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TonyM

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#7
Last night I noticed some out of focus areas on my videos taken with the 6-22mm f1.6.


Initially I thought it was bug splats on my windscreen. However I also noticed similar patches on videos taken indoors. I removed the lens to check for dust on the sensor, and found the IR cut filter had fallen off the lens and was resting on the sensor!


The loose filter has a bit of glue remaining around its edge. Unfortunately that has left glue marks on my sensor, which match the out of focus areas I noticed in my video.
EDIT: The marks on the sensor appear to be graphite lubricant from the lens threads.


I have contacted the seller Treeye via AliExpress. They have already offered to send out a replacement lens.
 
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Dashmellow

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#8
Unfortunately, my 6-22mm ƒ/1.6 varifocal suffered the same fate; the IR-cut filter came off. Careful examination explains why.

Treeye started offering more types of M12 CCTV lenses with IR filters after many people (especially our little cabal here on DCT) started requesting them. They realized that many people wanted to use their CCTV lenses on action cameras. Most CCTV lenses, especially varifocals are intended for use on cameras that have a separate mechanically operated day/night IR cut filter and are therefore always shipped without them.

In this case, they simply mounted an IR-cut filter on the back of the lens just the way they do for fixed focus M12 lenses. Unfortunately, the method they chose is problematic with a variable focus lens where it wouldn't be on a fixed focus lens.

Apparently, if you operate the variable focus mechanism so the rear element of the lens is as far back as it can go, it can press up against the filter just enough to dislodge it.

Treeye uses a 10.5mm IR filter that is cemented onto the very thin lip of the M12 threaded barrel which doesn't provide much a bonding surface to begin with and of course, when the rear element presses up against it, it will pop right off.

6-22.jpg


When I installed an IR-cut filter on my very similar 2.8-12mm ƒ/1.2 lens I used a different approach that apparently is a much better method.

The method I used was to install a 9.5mm IR-cut filter inside the lens tube on the internal retaining ring directly on the back of the lens, just above the rear element. This provides a thin gap between the glass lens element and the filter while allowing the rear lens elements to move freely back and forth within the lens tube without hitting any obstacles.

I plan on sharing my method with Treeye when I hear back from them since reporting this issue to them this morning.

lens2.jpg

As you can see there is a decent sized retaining ring around the rear lens element which creates a nice lip for cementing a filter in place with good adhesion.
You can also see where the ring creates a gap between the glass lens element and the IR-cut filter which is desirable.
lens3.jpg
 
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Dashmellow

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#9
Last night I noticed some out of focus areas on my videos taken with the 6-22mm f1.6, which can be seen in the examples I posted earlier:


Initially I thought it was bug splats on my windscreen. However I also noticed similar patches on videos taken indoors. I removed the lens to check for dust on the sensor, and found the IR cut filter had fallen off the lens and was resting on the sensor!


The loose filter has a bit of glue remaining around its edge. Unfortunately that has left glue marks on my sensor, which match the out of focus areas I noticed in my video.


I have contacted the seller Treeye via AliExpress. They have already agreed to send out a replacement lens.

I hope you understand where I'm coming from Tony, but I've been thinking about some of what you have to say in this post some of which I find puzzling and even a bit perturbing and so after two days of kicking it around I finally decided, somewhat reluctantly mind you, to ask some questions as well as to express what is on my mind.

Firstly, I'm not at all clear how the cement from the IR-cut filter could have left such "glue marks" on your sensor. For one thing, there is such a tiny, tiny amount of cement on the filter itself I can't see how it could cause such extensive marking of the sensor. Additionally, they use UV optical cement that is completely dry, solid and inert after it cures. There is no way it could possibly cause smudges on your sensor unless it caused actual physical damage but you've told me that you intend to clean the sensor with Eclipse methyl alcohol solvent which would seem to indicate that you do have smudges on the sensor and not actual physical damage. When you told me that you fished the IR filter out with tweezers at first I thought perhaps you damaged the sensor in some way but that makes no sense really.

When my IR filter came loose, it too ended up down inside the lens module housing sitting on the sensor but it left no marks or smudges whatsoever. I just turned the lens module upside down and the IR filter fell out.

All this has me concluding that the "glue marks" on your sensor are from some other pre-existing cause. In fact, close scrutiny of the 6-22mm images you posted above in your first post to this thread show that those blurry smudges were already on your sensor before the IR filter fell off since the color balance on those screen shots is perfectly normal and properly IR color corrected indicating that the IR-cut filter had to have still been mounted on the back of the lens at that point in time.

_______________________________________________________________________________

You also indicate that you've asked Treeye to replace this lens for you. Why?!! There is absolutely nothing wrong with your lens! It just needs a new IR-cut filter installed and you've told me that you indeed plan to eventually install one anyway on the first lens they've shipped you using the UV cement you just received in the mail after maybe doing some IR experiments with it. As we've all been discussing at length on these pages for many weeks now, mounting an IR cut filter with UV cement is a fairly simple and straightforward procedure.

Personally, I'm not asking Treeye to send me a new lens as I see no reason to. I'm just working with them to supply a new IR filter that I know I can install myself.

As when I had an issue with my previous order from Treeye they have been extraordinarily nice to deal with and I just don't feel the need to squeeze them for a free replacement lens just because I can when the one they sent me is in perfect condition. Treeye is basically just a small business on AliExpress trying to eke out a living. It's not like we're dealing with some huge deep pocketed corporation like Amazon or even larger retailers like Gearbest or Bangood. Treeye has been earnest, sincere, helpful and friendly and I don't feel right taking advantage and making them lose money on the transaction just because the AliExpress dispute system gives me so much leverage over them. I feel better dealing with Treeye in the same spirit of good faith they've extended to me.

Treeye seems interested in understanding how I approached my IR-cut filter installation on the 2.8-12mm ƒ/1.4 lens I posted about above and I got word just this morning that they've shipped out three 9.5mm IR-cut filters for me to try. (They've generously provided a couple of extra IR filters in case I screw one up.) Perhaps they'll even adopt my IR install method after seeing how it goes on my end?
 
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TonyM

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#10
I hope you understand where I'm coming from Tony, but I've been thinking about some of what you have to say in this post some of which I find puzzling and even a bit perturbing and so after two days of kicking it around I finally decided, somewhat reluctantly mind you, to ask some questions as well as to express what is on my mind.

Firstly, I'm not at all clear how the cement from the IR-cut filter could have left such "glue marks" on your sensor. For one thing, there is such a tiny, tiny amount of cement on the filter itself I can't see how it could cause such extensive marking of the sensor. Additionally, they use UV optical cement that is completely dry, solid and inert after it cures. There is no way it could possibly cause smudges on your sensor unless it caused actual physical damage but you've told me that you intend to clean the sensor with Eclipse methyl alcohol solvent which would seem to indicate that you do have smudges on the sensor and not actual physical damage. When you told me that you fished the IR filter out with tweezers at first I thought perhaps you damaged the sensor in some way but that makes no sense really.

When my IR filter came loose, it too ended up down inside the lens module housing sitting on the sensor but it left no marks or smudges whatsoever. I just turned the lens module upside down and the IR filter fell out.

All this has me concluding that the "glue marks" on your sensor are from some other pre-existing cause. In fact, close scrutiny of the 6-22mm images you posted above in your first post to this thread show that those blurry smudges were already on your sensor before the IR filter fell off since the color balance on those screen shots is perfectly normal and properly IR color corrected indicating that the IR-cut filter had to have still been mounted on the back of the lens at that point in time.

_______________________________________________________________________________

You also indicate that you've asked Treeye to replace this lens for you. Why?!! There is absolutely nothing wrong with your lens! It just needs a new IR-cut filter installed and you've told me that you indeed plan to eventually install one anyway on the first lens they've shipped you using the UV cement you just received in the mail after maybe doing some IR experiments with it. As we've all been discussing at length on these pages for many weeks now, mounting an IR cut filter with UV cement is a fairly simple and straightforward procedure.

Personally, I'm not asking Treeye to send me a new lens as I see no reason to. I'm just working with them to supply a new IR filter that I know I can install myself.

As when I had an issue with my previous order from Treeye they have been extraordinarily nice to deal with and I just don't feel the need to squeeze them for a free replacement lens just because I can when the one they sent me is in perfect condition. Treeye is basically just a small business on AliExpress trying to eke out a living. It's not like we're dealing with some huge deep pocketed corporation like Amazon or even larger retailers like Gearbest or Bangood. Treeye has been earnest, sincere, helpful and friendly and I don't feel right taking advantage and making them lose money on the transaction just because the AliExpress dispute system gives me so much leverage over them. I feel better dealing with Treeye in the same spirit of good faith they've extended to me.

Treeye seems interested in understanding how I approached my IR-cut filter installation on the 2.8-12mm ƒ/1.4 lens I posted about above and I got word just this morning that they've shipped out three 9.5mm IR-cut filters for me to try. (They've generously provided a couple of extra IR filters in case I screw one up.) Perhaps they'll even adopt my IR install method after seeing how it goes on my end?
As someone with far less knowledge of how they apply these filters, I took the evidence in front of me and acted in what I thought was an appropriate way.

On the first day of using the lens, I noticed some strange out of focus areas on my video. I also noticed the overall focus was a bit too close, so I brought the camera inside and tried to refocus it. Being curious about the blurred areas, I removed the lens to look for dust or other marks on the sensor. That's when I found the IR filter resting on the sensor. I tipped up the camera to remove it but it became stuck in the lens holder threads, so I carefully extracted it with tweezers. Looking back inside the camera, I noticed the marks on the sensor, which appear to match those I saw on the video.

Prior to installing the 6-22mm lens, I had my fixed 24mm lens in this particular camera, and I do not recall having such blurred patches on the recent bird feeder images that I posted in my telephoto thread.

So in my mind I was disappointed that something I bought has fallen apart, and I contacted the seller to complain. I tried to be helpful by letting them know your findings about how the filter can be pushed off when zooming to the widest angle, and suggested using a smaller filter inside as you have done. They were not interested, and sent me a link to their most popular lens which has its IR filter attached in the same way as the varifocal lens. Then they offered to send a replacement lens, which I accepted.

You make the point that I could fix the lens myself. Yes, perhaps I could. Or perhaps I would mess it up. I don't have any spare IR filters to use or practice with. I happen to have some UV cement, but I've never used it before and your post about attaching the IR filter to your 2.8-12mm lens made it sound at least a bit difficult.

As to the source of the sticky glue marks on the sensor. I have swapped around lenses a number of times, sometimes from a camera like the M2 or F1 that had glued in lenses. It is possible that I have transferred some glue from one lens or lens holder to another over time, and it could be that which ended up on the IR filter, then smeared onto the sensor.

Looking closely now at the end of my 6-22mm lens where the IR filter used to be, the substance around the rim is dark and tacky, and has now marked the inside of the rear lens cap. It doesn't seem like the completely dry, solid inert UV cement you mention.
IMG_20180518_221721.jpg

At the end of the day, I bought something for £10 that is not working as intended, and has possibly put a visible mark on my more expensive camera sensor. I can spend money on UV cement, sensor cleaning supplies and a new IR filter then find the time to practice then fix the lens, but I should not have to do this. Like you, I am short on spare time and already devote more time to these little cameras than I can afford. As it is, I have already tried using a hairdryer to soften the glue and remove an IR filter from another lens, but I had no luck with that experiment. If the seller is willing to send a replacement then that is OK with me. I'm not trying to defraud them so I end up with two perfect lenses.

The sensor marking may be my fault for not keeping the lens threads and lens holders completely clean. So I will try to clean the sensor and remember to be more careful when replacing lenses.

But the rear filter should not fall off on the first day that I use the lens, and I think the seller should take some responsibility for that.
 
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Dashmellow

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#11
I do appreciate your remarks and hope to respond more fully, but as it is early Friday evening here, I'll have to follow up on this at another time.

In the meantime, allow me to reiterate my question. How can you say the lens put marks on your sensor when the blurry areas you attribute to that were clearly there in your images BEFORE the IR cut filter fell off?

As for the grime you found on your lens cap, why do you assume that is from the lens filter cement? Perhaps, they use some sort of lubricant (such as graphite) on the M12 lens threads?

Critical thinking is your friend.
 

Lola

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#12
WOW, I spent a few days trying to find some really good filters (UV/IR cut) at a decent price but gave up when the last company I talked to wanted over $400.00 for 5 10.5 mm lenses (It might have been ($700.00, have to check), now dashmellow finds out the rear mounted lenses on Varifocal, are not stable because of interaction with the FL adjustment, and Tony has smudges on his sensor (6-22 Varifocal). I received a 2.8-12 with red cut IR filter installed several weeks ago but didn't install it before my camera was stolen. I only had it going for a few weeks (camera) before some AH stole it! So now I have to test just the lens to see if it will pop off with a little pressure (very little) before putting it into a spare camera (long range hunting model) I received from a good friend.
Are we having fun yet, :rolleyes:, well I am, just have to grin and bear it :cool:, famous man once said POO happens!

I'll be looking into Sensor cleaning stuff and 9.5mm cut IR filters to fix and repair potential problems and maybe even current problems. Big thanks to dash mellow for identifying the problem/fix :cool:.

Question: Has anyone thought the filters with the blue-green color tinge are undesirable for any reason, there price is more in line with what I want to spend at this point.
 
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Dashmellow

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#13
Question: Has anyone thought the filters with the blue-green color tinge are undesirable for any reason, there price is more in line with what I want to spend at this point.
The filters with the cyan (blue-green) appearance only look like that when viewed from an oblique angle. They will look red from a different angle. That's how dichroic filters work. The filters from the 6-22mm lens in both of these photos are the same.

6-22.jpg hohaDn2l.jpg

These are basically the standard IR-cut filters that come on all dash cams actions cameras and they work fine. Those super-expensive IR-cut filters you were quoted on are used for high spec scientific, biomedical and research purposes and there would be no reason to even consider anything like that for a dash cam.
 
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Dashmellow

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#14
@Lola, I totally forgot to mention something really interesting about why IR-cut filters look RED or CYAN depending on which angle you are viewing (and especially) photographing them from.

IR-cut filters are basically a specific type of Dichroic filter designed to filter specific wavelengths of light. The simplest way to explain the phenomenon is probably to quote from the Wikipedia page on Dichroic Filters.

"Dichroic filters use the principle of thin-film interference, and produce colors in the same way as oil films on water. When light strikes an oil film at an angle, some of the light is reflected from the top surface of the oil, and some is reflected from the bottom surface where it is in contact with the water. Because the light reflecting from the bottom travels a slightly longer path, some light wavelengths are reinforced by this delay, while others tend to be canceled, producing the colors seen."

What is so interesting here is that we are literally witnessing the IR-CUT filter doing what it is designed to do.

RED and CYAN happen to be directly opposite one another on the RGB color wheel. When we observe light striking the filter from certain angles we see enhanced CYAN colored light reflecting from the bottom of the filter but the RED light (especially near IR as seen by the camera taking the photos) directly opposite on the color wheel is being cancelled out....or "CUT".

rgb.jpg
 
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Dashmellow

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#15
After providing a more detailed explanation of my approach to installing IR-cut filters on these varifocal lenses I got word from Treeye today: "We will take your advice and try to paste the IR filter in that way. Thanks again." Perhaps this will become the method they use going forward?
 

TonyM

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#16
How can you say the lens put marks on your sensor when the blurry areas you attribute to that were clearly there in your images BEFORE the IR cut filter fell off?

As for the grime you found on your lens cap, why do you assume that is from the lens filter cement? Perhaps, they use some sort of lubricant (such as graphite) on the M12 lens threads?

Critical thinking is your friend.
The marks on my rear lens cap do appear to be graphite or a similar lubricant.

When I found the varifocal lens IR cut filter loose inside the lens holder, it was still covering the entire sensor area. So it seems possible that it could have fallen off and still function OK as a filter, whilst moving around within the confines of the holder.

I have been too busy camera testing and taking time out for family fun to do anything about cleaning this particular Mobius camera.
 
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Dashmellow

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#17
The marks on my rear lens cap do appear to be graphite or a similar lubricant.

When I found the varifocal lens IR cut filter loose inside the lens holder, it was still covering the entire sensor area. So it seems possible that it could have fallen off and still function OK as a filter, whilst moving around within the confines of the holder.

I have been too busy camera testing and taking time out for family fun to do anything about cleaning this particular Mobius camera.
I dunno, the idea that the fallen IR filter could somehow have offered perfect full coverage of the sensor without a trace of what happened to the filter here sounds like quite a stretch to me. Even if it could cover enough of the sensor how could a loose, unattached filter remain in perfect vertical position up against and in the same vertical orientation as the camera's sensor in a moving car? This sounds like magical thinking, all in the service of explaining away a different implausible assertion.

I have lots to say about all this but I've been rather reticent, plus like you, I've had little time. Let's see.
 
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Lola

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#18
After providing a more detailed explanation of my approach to installing IR-cut filters on these varifocal lenses I got word from Treeye today: "We will take your advice and try to paste the IR filter in that way. Thanks again." Perhaps this will become the method they use going forward?
Congratulations, you are now an official intermediary for Treeye concerning optics:cool:. I just hope the seller passes your information along to the powers to be, so to speak.

Another question: With the inside of the lens barrel being 11mm (M12 specs) would it be of any use/help for the cut filters to be slightly larger then the 9.5 mm filters you are using, say 10mm, 10.5mm, whatever ? I'm trying to envision installing one your way in my mind before actually doing it.
 
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Dashmellow

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#19
Congratulations, you are now an official intermediary for Treeye concerning optics:cool:. I just hope the seller passes your information along to the powers to be, so to speak.

Another question: With the inside of the lens barrel being 11mm (M12 specs) would it be of any use/help for the cut filters to be slightly larger then the 9.5 mm filters you are using, say 10mm, 10.5mm, whatever ? I'm trying to envision installing one your way in my mind before actually doing it.
AFAIK, Treeye installs their own IR-cut filters on non-IR CCTV lenses that come from the factory. CCTV lenses like these varifocals generally don't come with them.

With the 2.8-12mm varifocal that I installed the IR-cut filter on, the 9.5mm IR filter was very nearly an EXACT fit. Any bigger and it would not have allowed the lens to focus easily in and out without rubbing against that inside of the lens tube. The 6-22mm varifocal appears to be about the same according to my caliper measurements but I'll know more for certain when I go to install the filter.

As to whether it would be "of any use/help for the cut filters to be slightly larger then the 9.5 mm filters", probably not. Both of these lenses have a pretty wide retaining ring around the rear element of the lens which provides a good surface for mounting the filter. The tricky part about gluing the filter is to avoid having any cement bleed out onto the glass lens surface or make contact with the inside of the lens tube when you go to press the filter on once applying the cement. Even the tiniest amount of UV glue spreads out more than expected when you press the filter into place, so having a little extra wiggle room where you can apply cement along the edge of the filter on the retaining ring is helpful.

lens3detail.jpg
 

Lola

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AFAIK, Treeye installs their own IR-cut filters on non-IR CCTV lenses that come from the factory. CCTV lenses like these varifocals generally don't come with them.

With the 2.8-12mm varifocal that I installed the IR-cut filter on, the 9.5mm IR filter was very nearly an EXACT fit. Any bigger and it would not have allowed the lens to focus easily in and out without rubbing against that inside of the lens tube. The 6-22mm varifocal appears to be about the same according to my caliper measurements but I'll know more for certain when I go to install the filter.

As to whether it would be "of any use/help for the cut filters to be slightly larger then the 9.5 mm filters", probably not. Both of these lenses have a pretty wide retaining ring around the rear element of the lens which provides a good surface for mounting the filter. The tricky part about gluing the filter is to avoid having any cement bleed out onto the glass lens surface or make contact with the inside of the lens tube when you go to press the filter on once applying the cement. Even the tiniest amount of UV glue spreads out more than expected when you press the filter into place, so having a little extra wiggle room where you can apply cement along the edge of the filter on the retaining ring is helpful.

View attachment 38378
Thanks, that was a very good explanation, when you have said before, a verty small spec of glue you were not kidding(y):cool:.
 

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