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Leaks from IR modules in some lenses

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15 replies to this topic

#1 sharkmelley

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Posted 04 July 2020 - 03:03 AM

Some lenses contain an IR LED (infra-red) module which can leak IR light affecting long exposures - it's very obvious with modified cameras.

 

I don't think it's a well-known problem in the astro-community, which is why I'm starting this thread to gather further information and to make the issue more widely known.

 

It recently came up here in this thread, in which there are numerous examples:

What is going on with my sensor?

 

KolariVision has also noticed the problem:

Canon RF lens internal IR LED: Fact or Fiction? 

 

So far, we have clear examples from both Nikon and Canon lenses.

 

If you notice this leak in a long exposure dark frame then one possible way to confirm it is a lens problem is to tape over the electrical contacts before attaching the lens to prevent power reaching the lens.  Then re-take the dark and see the the problem goes away.  I'm not suggesting this is a sensible solution - it's simply a method of diagnosis.  Since the lens cannot be detected by the camera, you may also need to go into the camera's menu to allow it to shoot without lens.

 

If you have any examples or solutions then please post them here.  It will be interesting to find out how widespread this problem is and what, if anything, can be done about it.

 

Mark


Edited by sharkmelley, 04 July 2020 - 03:42 AM.

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#2 DanielJStein

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Posted 04 July 2020 - 10:45 AM

Thanks for posting this Mark. Thanks to your helpful steps in diagnosing the issue, I was able to confirm there is an IR module located within the following 2 lenses:

 

  • Nikon NIKKOR 35 f/1.8 S for Nikon Z mount bodies
  • Canon EF 24-70 f/2.8L II for Canon EF mount bodies

 

Another non-permanent solution for this is to slightly unmount the lens so there is no electronic communication between the lens and body. I am not sure if this may introduce more light leaks, however. 



#3 sharkmelley

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Posted 04 July 2020 - 10:55 AM

It seems it's not only a recent problem. I found a 12 year thread on DPReview which mentions the same issue on a Nikkor18-200 VR and a Nikkor 70-200 VR:

https://www.dpreview...s/post/26831066

 

Back then the solution was to switch off AF and VR on the side of the lens but this didn't help with Daniel's lenses.

 

Mark


Edited by sharkmelley, 04 July 2020 - 10:57 AM.


#4 the Elf

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Posted 04 July 2020 - 11:28 AM

I found this now and then on the web. The simple solution suggested was not to turn the lens to the final position when attached to the body so that the electric contacts don't match. If the aperture is fully open and focus can be moved manually this will probably work well.


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#5 DanielJStein

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Posted 04 July 2020 - 12:29 PM

I found this now and then on the web. The simple solution suggested was not to turn the lens to the final position when attached to the body so that the electric contacts don't match. If the aperture is fully open and focus can be moved manually this will probably work well.

That what I am going to implement. I may also put some electrical tape around where the lens meets the body to ensure there are not light leaks from not fully mounting the lens. 



#6 erictheastrojunkie

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Posted 04 July 2020 - 01:51 PM

That what I am going to implement. I may also put some electrical tape around where the lens meets the body to ensure there are not light leaks from not fully mounting the lens.

My concern is focusing the lens, if the lens has no electrical contact with the camera some lenses may not be able to focus at all. This was a problem with the 24mm GM from Sony and I would bet it will be a problem with the Z mount lenses, I'll try with my Z6 this afternoon.

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#7 sharkmelley

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Posted 04 July 2020 - 05:09 PM

We obviously don't yet have a full picture of what's going on.

 

For instance KolariVision shows very obvious IR leakage from the following lenses (amongst others) on the full spectrum modified Canon EOS R:

  • RF24-70mm F2.8 L IS USM
  • RF24-105mm F4 L IS USM
  • RF24-240mm F4-6.3 IS USM
  • RF70-200mm F2.8 L IS USM

These lenses are designed for the new RF lens mount of the Canon EOS R.  One very obvious question is what happens if these lenses are used on the astro version of the camera i.e. the Canon EOS Ra?  Does it create the same artefacts or maybe the IR wavelength is filtered out by the EOS Ra?

 

Mark


Edited by sharkmelley, 05 July 2020 - 05:21 AM.


#8 the Elf

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Posted 05 July 2020 - 04:12 AM

All lenses you list are zoom lenses. Not exactly first choice for AP. I don't know what Canon is assuming when selling astro cameras. Do they expect we use them with a telescope or do they sell lenses suitable for AP as well? If so, these should be primes. I guess the Ra is like the standard version but with the cut off wavelength behind the Ha line. I don't think it is full spectrum (all UV and IR) and I do not even expect it sees a lot of IR either. Simple test: put a daylight blocker like the Hoya R72 in front and take a few shots in your garden. Should look like this:

 

IR.jpg

 


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#9 DanielJStein

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Posted 05 July 2020 - 01:54 PM

My concern is focusing the lens, if the lens has no electrical contact with the camera some lenses may not be able to focus at all. This was a problem with the 24mm GM from Sony and I would bet it will be a problem with the Z mount lenses, I'll try with my Z6 this afternoon.

Sent from my Pixel 2 XL using Tapatalk

Since the Z lenses use a focus by wire system, you could in theory focus with the lens fully mounted, then slightly unmount by pressing the release button while grabbing the lens barrel where there is no focusing ring. The focus should be maintained. The focus system is focus by wire but the act of focusing itself is still a mechanical function which should not change when the lens loses power. 



#10 Julien_Astrolab

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Posted 23 October 2020 - 07:14 AM

Hello everyone,

I have been a silent reader of CN for years and today is my first reply to a thread.

Just to introduce briefly myself: my name is Julien, french guy living & working in Germany and doing DSLR modifications.

I was actually wondering if I should open a new thread but finally decided to reply to this old one.

This topic is beeing discussed on german forum as well, but the chance to get feedback remains somehow limited since it deals with the official Canon Ra and RF Lenses, which together are not yet so popular on the scene.

I have lately modified for some customers a couple of Canon R & Rp. Doing a standard Mod (i.e LPF2 / OWB being removed, the LPF1 / UV-IR Cut Filter remains installed).

With those Mod Ra/RPa, pictures have been totally fine with the old EF Lenses & Adapter. However, as soon as RF Lenses are in use, then you get IR Flares.

 

Beispiel_Ra.jpg

 

As mentioned earlier in this thread, Kolarivision has reported this RF Lens issue already with their Full Mod / Infrared Mod. Here is the link.

Beispiel_Kolari.jpg

 

Something in the RF lens leaks infrared which can reach the sensor.

 

I was realy surprised to see that the remaining LPF1 / UV-IR Cut filter from the Mod Cam doesn't manage to filter this out. This "feature" of the lens is really annoying.

 

So now the 1.000.000 $ (or €) question: how does the official Canon Ra perform with those evil RF Lenses? Has anyone already done the test? Kolarivision has tested many RF Lense with their Fullmod and not all seem to show the issue.

If the official Canon Ra doens' show it, it would mean that the Mod of R & Rp cameras will restrict their usage to old Lenses. If the issue remains whatever the cam, then it would be a shame.

Has anyone any experience with the official Canon Ra & RF Lenses?

 

Best regards,

 

Julien


Edited by Julien_Astrolab, 23 October 2020 - 11:22 AM.

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#11 Jawknee

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Posted 21 November 2020 - 02:35 PM

Hi, I have this issue with my Nikkor 70-300 f/4.5-5.6g and my stock d5600. I have a red gradient and a red ''flare'' in my darks. Weirdly enough, the darks correct the lights half of the time...

 

A fellow astrophotographer point me this thread and told me that the sixth pin on nikkor lenses supply the power to the lens. I did a masterdark with a piece of tape on that pin and problem solved! The lens still communicate with the camera so I can control apperture and my photos show the complete exif. The autofocus stopped working but that's not an issue for AP.

 

Here's my masters without and with the tape, an image that shows the the ''flare'' and my little piece of tape.

 

In lens IR led solved

 


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#12 DanielJStein

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Posted 15 January 2021 - 09:16 AM

Update: The Canon 70-200 f/2.8L II USM should also be added to the list. I was shooting darks at 70mm when I unfortunately discovered a small blotch. Interestingly enough the zoom effects where the blotch shows up on the sensor.


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#13 theskro

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Posted 10 June 2021 - 09:56 AM

Is this issue only encountered when using camera lenses?  If using a telescope mounted with a T-ring has anyone encountered this issue?



#14 piaras

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Posted 10 June 2021 - 02:14 PM

Interesting that the IR LED that monitors the shutter must be different in the Ra verses the R and RP bodies.

I will keep this mind but with all my EF and FD lenses I likely will not be purchasing more.

Pierre



#15 asanmax

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Posted 10 June 2021 - 10:55 PM

With tons of cameras modified and a huge amount of lenses tested I can confirm that some lenses DO cause internal leaks, specifically zoom lenses.

But thankfully, most of us don't use zoom lenses for astrophotography. 

 

Cutting out power to the lens with a piece of electrical tape over contacts is a good solution for Canon lenses. Unfortunately, some Nikon lenses keep the aperture closed all the way when disconnected.

Not sure what would be a solution for those lenses.



#16 the Elf

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Posted 11 June 2021 - 11:10 AM

Is this issue only encountered when using camera lenses?  If using a telescope mounted with a T-ring has anyone encountered this issue?

Telescopes do not have any electronics inside. Still any LED in the Camera can cause the same trouble. The fat shiny red LED that many Canon models have does cast light on the sensor. Putting some black silicone on it is the safe way to get rid of the problem.




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