SLS on a budget - camera and lens choice

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Tzk
Posts: 17
Joined: 17 Mar 2020, 13:28

Re: SLS on a budget - camera and lens choice

Post by Tzk » 28 Jul 2020, 07:51

Greetings,

If i fully screw the lens onto the camera body, then it's out of focus too. Try to unscrew the lens by half a turn or even a full turn. Then fix it with the small setscrew on the camera body to prevent it from becoming loose. This will change the focus range of the lens and you'll be able to focus properly.

I suspect that this lens/camera combination allows us to choose a too small flange focal distance. C-mount usually got 17.526mm and CS-mount 12.5mm if that distance becomes too small, then you're out of focus (and can't focus properly).

I've adjusted it to to focus at around 20cm distance to the object as i'm currently trying scanning rather small objects as a first test (as shown above).

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OBNRacerMan
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Location: Obninsk, Russia

Re: SLS on a budget - camera and lens choice

Post by OBNRacerMan » 28 Jul 2020, 08:38

Using common lenses from CS-Mount cameras with C-Mount cameras will make it impossible to focus at distances above 10-20 millimeters. To make full use of such lenses, they must be brought closer to the camera matrix by 5mm - but for this, a new front camera cover must be made, which would make it possible to do this.

Tzk
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Joined: 17 Mar 2020, 13:28

Re: SLS on a budget - camera and lens choice

Post by Tzk » 28 Jul 2020, 09:29

We're talking C-mount camera and C-mount lens here (at least i hope so). My YW500 (c-mount) and my ZLKC lens (also c-mount) got a bit of tolerance in the c-mount threads and thus i can reach a smaller distance than c-mount has got. That's why i needed to unscrew the lens a bit to reach the desired 17.526mm flange focal distance. I'd guess that i can reach about 17.0mm flange focal distance when the lens is fully screwed into the camera and thus i can't focus properly.

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OBNRacerMan
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Location: Obninsk, Russia

Re: SLS on a budget - camera and lens choice

Post by OBNRacerMan » 28 Jul 2020, 09:55

0.5mm is not such a strong discrepancy that it was impossible to focus at 1-2m. I have a minimum working range with this lens - about 150mm

Tzk
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Joined: 17 Mar 2020, 13:28

Re: SLS on a budget - camera and lens choice

Post by Tzk » 28 Jul 2020, 10:16

Well, a single turn of the lens made a difference of being able to focus at 1-2 meters vs. ~200mm. A quarter turn moves the focus range by a lot on my camera+lens setup. If i screw the lens in completely i can't focus closer than about 2 meters which is unusuable for small objects. C-mount got a thread pitch of 1/32" which is about 0.8mm.

I'll document the differences when i get a little time to do so.

kth307000
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Joined: 17 Jul 2020, 15:35

Re: SLS on a budget - camera and lens choice

Post by kth307000 » 28 Jul 2020, 10:26

Tzk wrote:
28 Jul 2020, 10:16
Well, a single turn of the lens made a difference of being able to focus at 1-2 meters vs. ~200mm. A quarter turn moves the focus range by a lot on my camera+lens setup. If i screw the lens in completely i can't focus closer than about 2 meters which is unusuable for small objects. C-mount got a thread pitch of 1/32" which is about 0.8mm.

I'll document the differences when i get a little time to do so.
Thank you for a good answer.

As you explained, the screen began to appear when I unscrewed the lens without completely contacting the lens and camera.
However, the image is not visible until the lens is almost loose.
The screen is visible only when the lens is turned half a turn and locked.

Therefore, the lens and camera are not properly fixed, and it is difficult to fix them.

You can fix it by loosening it slightly when it is completely locked.

I've been told that the camera and lens fit, but I don't understand why this is happening.

PS.Please understand that the sentence is not smooth because I can't speak English and write with a translator.
Attachments
549800.jpg
The screen will not appear until the lens is almost released.
Last edited by kth307000 on 28 Jul 2020, 10:39, edited 5 times in total.

kth307000
Posts: 18
Joined: 17 Jul 2020, 15:35

Re: SLS on a budget - camera and lens choice

Post by kth307000 » 28 Jul 2020, 10:28

kth307000 wrote:
28 Jul 2020, 10:26
Tzk wrote:
28 Jul 2020, 10:16
Well, a single turn of the lens made a difference of being able to focus at 1-2 meters vs. ~200mm. A quarter turn moves the focus range by a lot on my camera+lens setup. If i screw the lens in completely i can't focus closer than about 2 meters which is unusuable for small objects. C-mount got a thread pitch of 1/32" which is about 0.8mm.

I'll document the differences when i get a little time to do so.

Tzk
Posts: 17
Joined: 17 Mar 2020, 13:28

Re: SLS on a budget - camera and lens choice

Post by Tzk » 28 Jul 2020, 10:33

Whoah. That's a lot and way too much...! Are you sure this is a C-mount and not CS-mount camera? You already tried to focus with the focus ring on the lens?

As said above, i've got a gap of about a millimeter between lens and camera, not more. You got about 5mm on the picture which is the difference between C and CS mount (17.526mm vs. 12.526mm).

kth307000
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Joined: 17 Jul 2020, 15:35

Re: SLS on a budget - camera and lens choice

Post by kth307000 » 28 Jul 2020, 10:44

Tzk wrote:
28 Jul 2020, 10:33
Whoah. That's a lot and way too much...! Are you sure this is a C-mount and not CS-mount camera? You already tried to focus with the focus ring on the lens?

As said above, i've got a gap of about a millimeter between lens and camera, not more. You got about 5mm on the picture which is the difference between C and CS mount (17.526mm vs. 12.526mm).
I purchased this product.

https://aliexpress.ru/item/32864044502. ... 1595913424

https://aliexpress.ru/item/32713339739. ... 1595913424

It should be released by 5mm to show a normal screen.
5mm is the distance at which the lens should be almost released from the body.

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OBNRacerMan
Posts: 163
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Location: Obninsk, Russia

Re: SLS on a budget - camera and lens choice

Post by OBNRacerMan » 28 Jul 2020, 11:08

kth307000 wrote:
28 Jul 2020, 10:44
It should be released by 5mm to show a normal screen.
5mm is the distance at which the lens should be almost released from the body.
The reason is unknown... Maybe the manufacturer, without notice, changed the design of the mount inside the body, which made the matrix closer to the lens? Because outwardly, there are no differences in the buildings. But given the facts above, you will probably need to buy adapter rings, which are needed to attach the C-Mount lens to a CS-Mount camera.
https://aliexpress.ru/item/33024139820.html
P.S. I have already shown that my lens turned in all the way, and did not require eversion.
20190514092000s.jpg
My old YW500U3 camera with ZLKC objective
P.P.S. Если вы русскоговорящий - то думаю, вам удобнее было бы присоединиться к нашему сообществу в Telegram - на канале 3D Scanner, и более свободно общаться по данному вопросу.

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