[SOLVED] Image quality on Git2P after 90 FOV lens swap

user777

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Hi all

Up until recently I've been very happy with my Git2P camera. The videos are razor sharp, the images likewise... The only thing somewhat bothering me was the 170 degree FOV with its very significant fisheye distortion.

So after seeing that GitUp started offering 90 degree FOV lenses without distortion I was very happy about it. I read up on the topic, I saw the relevant lens swap video on Youtube and after reading several threads on recommendations I decided to go with the f2.8 4.1mm lens which I purchased directly from the official GitUp webstore.
I had seen several such 90 deg lenses on other sites (ebay, Amazon etc) but I decided to play it safe and get the authentic lens straight from GitUp.

The lens came very quickly and just some days ago I finally found the time to do the swap.
I followed all the instructions carefully, disassembled the camera, removed the base with the 170 deg lens from the sensor and went ahead to install the 90 deg lens.
Much to my surprise, the new lens' base just wouldn't fit!

The distance between the two mounting holes is a couple of mm less than the original base! No matter how I tried, it would just not fit properly!
After comparing the two bases, I discovered that the tabs on either side of the 90 degree base are slightly shorter than the 170 version.

So after some thinking I put back the original base and decided to just unscrew the 170 degree lens and put the 90 degree one in its place. This worked perfectly, so I reassembled everything and started focusing the camera. After careful calibration with a chart I thought I was ready. Or so I thought...

I took some test videos and pics and when I pulled them up on my PC I was shocked to see how bad the image quality was! While the center of the lens was tack sharp both the left side as well as the right side were a total mess! Completely smudged and blurred. It is so bad that it almost looks like those diorama effects on some cameras where the sides of the photos are smudged to simulate a very shallow DOF.

Here is an example:
90 deg lens image sample

The same story continued with the video modes. Regardless of resolution the sides of the picture remained very badly blurred. Interestingly, if you examine the sample pics you can see some blurring on the top side of the center of the lens.

I thought that maybe the base was not seated properly after removing it. So before taking apart the camera again I decided to try the 170 degree lens to see what happens. If the base was to blame then it should have the same badly smudged areas. However, after focusing the lens and taking a few sample pics/videos everything seemed to be very sharp. (Please note that I had put both contrast and sharpness to maximum in order to help with the focusing)

170 deg lens image sample

So my question to you is, now what?
Did I get a badly decentered lens? Is the 4.1 lens incompatible with the Panasonic sensor of the Git2P? There is no such indication on the GitUp website.
How can I contact the company and return the lens? I know that they reply on the threads here occasionally so it would be very nice to hear from them how we could proceed. In the meantime, and ideas and/or suggestions would be most helpful!

Thanks a lot and apologies for the long message!
Cheers
Nick
 

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That's a pretty pricey lens and since it is sold by Gitup specifically as a replacement for the Git2 it shouldn't do that. Sometimes an out of focus problem on one side or the other can be caused by other problems such as a warped sensor plate, a bad lens mount or an out of alignment lens (for example, if you stripped the threads screwing the lens in). Here, with the problem on both sides of the image it suggests that you got a defective lens. I would suggest tagging @gitup here on DCT and see what they have to say about the problem after viewing your images.
 
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user777

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That's a pretty pricey lens and since it is sold by Gitup specifically as a replacement for the Git2 it shouldn't do that. Sometimes an out of focus problem on one side or the other can be caused by other problems such as a warped sensor plate, a bad lens mount or an out of alignment lens (for example, if you stripped the threads screwing the lens in). Here, with the problem on both sides of the image it suggests that you got a defective lens. I would suggest tagging @gitup here on DCT and see what they have to say about the problem after viewing your images.
My thoughts exactly. After reading the reviews on this lens and seeing how it was the most expensive of the lot, I thought it would provide at least a very good IQ level.

BTW how can I tag gitup so that they come in and see the topic? (I opened up a ticket on their website for good measure, so I'm sure we'll get to the bottom of this.) :)
 

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I believe, you have not adjusted focus properly. You need to turn it a bit to infinity - check your chart from at least 3-4 meters not only in the center of FOV, but closer to left or right edge too and find optimal position, where edge is acceptable and center is still sharp. The same lenses are installed on git2p and git3 90 deg and quite ok even in full resolution.
 

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I think it is possible you haven't got the lens mount sitting square to the PCB, possibly you have some dirt under the left side, or maybe you have tightened the screws unequally or too much. I suggest you take the mount off again and check the contact surfaces with a magnifying glass, if there is anything uneven you can use some very fine sandpaper on a flat surface to clean the surface up. Rotate it 180 degrees from it's current position before putting it back. When you tighten the screws, tighten them only enough to prevent the mount moving/rattling, any more and you risk distorting the mount plastic which can put the lens out of alignment.
 

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My thoughts exactly. After reading the reviews on this lens and seeing how it was the most expensive of the lot, I thought it would provide at least a very good IQ level.

BTW how can I tag gitup so that they come in and see the topic? (I opened up a ticket on their website for good measure, so I'm sure we'll get to the bottom of this.) :)
Firstly, to "tag" another member so they will be notified that you mentioned them in a post just put the @ sign in front of their name. (As you can see, I've already done that with @gitup back in my other post.)

When I mentioned, "a bad lens mount or an out of alignment lens" in my previous post I was referring to the same thing @Nigel is talking about. I was working on the assumption that you installed a new lens by screwing it into the existing threaded mount on your camera. If the new lens ships already mounted in a threaded lens module mount which is then screwed to the sensor plate you could have indeed over-tightened one or both of the mounting screws or encounted some other issue seating the mount to the plate. The rear element of the lens needs to be perfectly aligned parallel with the sensor plate.
 
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user777

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I believe, you have not adjusted focus properly. You need to turn it a bit to infinity - check your chart from at least 3-4 meters not only in the center of FOV, but closer to left or right edge too and find optimal position, where edge is acceptable and center is still sharp. The same lenses are installed on git2p and git3 90 deg and quite ok even in full resolution.
Fair enough and I will try to give this a go but if I turn the lens even slightly it loses the very sharp center focus. So does that mean that I can either have a very sharp center FOV with blurred edges or acceptable/ok center with equally ok edges?
 
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user777

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I think it is possible you haven't got the lens mount sitting square to the PCB, possibly you have some dirt under the left side, or maybe you have tightened the screws unequally or too much. I suggest you take the mount off again and check the contact surfaces with a magnifying glass, if there is anything uneven you can use some very fine sandpaper on a flat surface to clean the surface up. Rotate it 180 degrees from it's current position before putting it back. When you tighten the screws, tighten them only enough to prevent the mount moving/rattling, any more and you risk distorting the mount plastic which can put the lens out of alignment.
When I mentioned, "a bad lens mount or an out of alignment lens" in my previous post I was referring to the same thing @Nigel is talking about. I was working on the assumption that you installed a new lens by screwing it into the existing threaded mount on your camera. If the new lens ships already mounted in a threaded lens module mount which is then screwed to the sensor plate you could have indeed over-tightened one or both of the mounting screws or encounted some other issue seating the mount to the plate. The rear element of the lens needs to be perfectly aligned parallel with the sensor plate.
Guys, in my first post I mentioned that I firstly tried to install the NEW mount with the 90 FOV lens before resorting to screwing the new lens on the existing threaded mount. The new mount just wouldn't fit on the sensor board. The holes on the new mount are spaced a few mm too short. So, when I was lining up one hole the other was slightly off preventing the screw from fitting properly.
So I put back the original threaded mount and then screw the new lens on.

Coming back to the suggestion that the mount is not seated properly, if that were the case wouldn't the 170 FOV lens also be out of focus?
As you can see from the samples, when I mount the 170 FOV lens everything is nice and sharp.
That would exclude the possibility of the badly seated mount right? Or am I missing something?
 

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Yeah, the next thing I was going to suggest is swapping the 170º lens for the 90º lens to compare the edge to edge sharpness but apparently you've already done that. It wasn't clear if your original 170º lens screen shot was from before you altered the camera. It's sounding more and more like there is an issue with the mount and not the lens optic itself.

It's very puzzling that Gitup would sell a dedicated custom lens (& mount) for their own camera that has different screw spacing than the original mount from the same camera.
It would be useful to measure the distance apart of the screw holes on the mount you received vs the ones on the original mount. Typically, the screw spacing on M12 threaded lens mount housings are 18mm, 20mm and occasionally 22mm. The scew spacing measurements of the two mounts will be useful when you get to talk to Gitup about the problem.
 

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So does that mean that I can either have a very sharp center FOV with blurred edges or acceptable/ok center with equally ok edges?
It is inevitable due to field curvature. I have adjusted focus several times on Git2P, and was very surprised at first, but it is possible to achieve good focus across all frame, just make sure, your focusing target is far enough during adjustments and check edges.
In case you have lens/holder misalignment, it would be out of focus on one side, not equally on both.
 

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Did you installed the firmware for the 90 degrees lens?
 

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In case you have lens/holder misalignment, it would be out of focus on one side, not equally on both.
If both screws were over-tightened so much that it warped the sides of the plastic lens mount it could conceivably cause a focus issue on both sides of the image. In this case it seems worse on one side than the other.
 

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Coming back to the suggestion that the mount is not seated properly, if that were the case wouldn't the 170 FOV lens also be out of focus?
As you can see from the samples, when I mount the 170 FOV lens everything is nice and sharp.
That would exclude the possibility of the badly seated mount right? Or am I missing something?
The focus for the 90 degree lens needs to be more accurate since it will have less depth of field, also you need to focus it further away due to it having less depth of field. You may find that with care you can get both centre and sides in focus for things at some distance.

When the centre is sharp, are the two sides both focused too close/too far, or is one side too close and one too far? In the latter case the lens is probably at an angle due to the mount not being seated flat, in the former case it is likely to be an issue with the lens since the mount can't cause that...
 
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user777

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Some random thoughts here...

I really liked the camera's sharpness as it came from the factory. This summer I rode on my motorcycle through basically all of Europe and I got some amazing videos. The only issue I've had is with the very significant fisheye distortion of the 170 FOV lens.

I do prefer the 90 degree FOV but after mounting it on the camera and seeing how much it sticks out from the front plastic case I did not like it at all.
To be honest, I like my equipment to look stock and with the 90 FOV lens the plastic lens barrel leaves a very significant gap. On top of the cosmetic issue I am concerned about water getting into the electronics.

If the lens would have worked nicely then I'd either put up with the gap or try and find a front panel from a 90 FOV Git.

But this whole thing seems to be getting more and more complicated.
I am definitely not going to start shimming or modding the lens base. Should I just put up the camera for sale instead and get a 90 FOV model from the factory?
 
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user777

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When the centre is sharp, are the two sides both focused too close/too far, or is one side too close and one too far? In the latter case the lens is probably at an angle due to the mount not being seated flat, in the former case it is likely to be an issue with the lens since the mount can't cause that...
Regarding the focusing possibility, did you notice how in my sample the top center also seems not to be in focus? How can the dead center be in focus while the top center be out together with the sides?

PS. Here is another sample of the 90 FOV.
 

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Nigel

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Regarding the focusing possibility, did you notice how in my sample the top center also seems not to be in focus? How can the dead center be in focus while the top center be out together with the sides?

PS. Here is another sample of the 90 FOV.
I suspect the lens is tilted slightly to the top left, plus I suspect you could focus it slightly further away and get more in focus.
I think it is worth taking the mount off again and running it across a sheet of flat sandpaper on a hard flat surface such as glass a couple of times to clean the base, plus you might have mounted it the other way around from original resulting in combined errors adding up instead of cancelling - it is worth another go, and when focusing note if both sides are too close or too far.

If you can find a tube of the right diameter and put it over the lens barrel, maybe with a layer of tape to tighten the fit then it will look original again, and make sure you fit 90 degree firmware so that the stabilisation works correctly.

You could always upgrade to a Git3 90, a very nice upgrade, but it shouldn't be necessary, the lens you have bought is a very good one and should work, but it doesn't take much to knock a lens out of focus and focus across the image isn't always at exactly the same point, just hopefully close enough to be able to get everything within the depth of field, and it is always more difficult to focus with longer focal lengths.
 
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user777

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Nigel thanks so much for taking the time and all these suggestions mate. I really do appreciate all the help here.

So I took apart the camera again to check the lens mount; (having done that a couple of times now it's a very quick thing to do!)

It looked fine but just in case I took it out, cleaned it and remounted it making sure it's lined up properly and that the screws are tight but not overtightened. I checked the mount under a very bright light and there is no light leaking through where the mount meets the board; I think it is mounted properly?

Also, before mounting the base I took a few pics comparing it to the base that came with the 4.1mm lens.
As you can see in the following pics, there is a significant difference to the mounting points. (The top lens is the 90 FOV and the bottom one is the original 170 FOV)







BTW, I don't know if this is of any significance, but the 90 FOV mount has the number 2 stamped on the top right corner, while the 170 FOV mount has the number 9 (or 6 if you flip it)...
 
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Nigel

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Also, before mounting the base I took a few pics comparing it to the base that came with the 4.1mm lens.
As you can see in the following pics, there is a significant difference to the mounting points. (The top lens is the 90 FOV and the bottom one is the original 170 FOV)
I have no idea why they don't match, must be an explanation but unfortunately China is on holiday so it may be a while before you get an answer from Gitup. I can't see how using the wrong base will affect your image other than it may result in it going out of focus in very hot/cold weather, but unless you use it as a dashcam in parking mode then it probably wont make a noticeable difference.

Question is, is there any improvement having reseated it? But I guess we need to wait for daylight so you can focus it at a decent distance, no point trying to focus the 90 degree accurately indoors.
 

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Too many ¯\_(ツ)_/¯
going by the part numbers (and your findings) you have the Panasonic version camera but you've purchased a lens to suit a different size sensor (Sony), expect that is part of the problem
 
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user777

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going by the part numbers (and your findings) you have the Panasonic version camera but you've purchased a lens to suit a different size sensor (Sony), expect that is part of the problem
Well yes, I've mentioned even in the thread's title that I have the Git2P -which obviously stands for Panasonic.
However, this exact model comes with a 90 degree 4.1mm lens which should be the one that the company sells on their website.
In addition to that, I didn't just go blindly into buying the thing; I followed the guides of some other people who have the same Git2P and installed the 4.1mm lens with supposedly good results.
Anyhoo we'll see if I can get a better focus tomorrow. (I'm not holding my breath about it but you never know...)
 
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