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Astrophotography and Sketching >> DSLR & Digital Camera Astro Imaging & Processing

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pfile
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Reged: 06/14/09

removing the mirror in a canon DSLR
      #5725147 - 03/11/13 02:56 AM

from time to time i've noticed DSLR images here and there that seem to have a strong horizontal gradient only near the bottom (or top) of the long edge of the frame. i've often wondered what causes this.

it seems perhaps that with certain fast optics, due to the steepness of the light cone, the mirror is casting a shadow on the sensor.

check out this link - this guy has removed the mirror from his DSLR. the first flat shown on the page shows the gradient i'm talking about. certainly not for the faint of heart but pretty interesting.

http://www.markshelley.co.uk/Astronomy/Projects/Mirrorless/canon550mirrorless...


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mmalik
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Re: removing the mirror in a canon DSLR new [Re: pfile]
      #5725223 - 03/11/13 04:34 AM

I wonder if any of the modifiers (Brent/Hap/Gary, etc.) would do this or have done this?


I presume there would be better/simpler way to accomplish this with open camera during typical sensor mod? Thx


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bilgebay
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Re: removing the mirror in a canon DSLR new [Re: mmalik]
      #5725250 - 03/11/13 05:22 AM

This was one of my dreams for a long time. I was worried that there would be some sort of sensor to check if the mirror was in place before letting the shutter go off. It appears there is not.

Rob, thank you for sharing this link.

Clear skies.


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JPGriffin
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Re: removing the mirror in a canon DSLR new [Re: bilgebay]
      #5725408 - 03/11/13 09:10 AM

Thanks for posting this information. I was wondering why I kept getting such obvious vignetting on the bottom of my pictures using relatively fast optics (f/2.8 300mm lens and f/3 OS Veloce RH200 astrograph).

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fishonkevinModerator
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Re: removing the mirror in a canon DSLR new [Re: JPGriffin]
      #5725428 - 03/11/13 09:21 AM

I'm excited about this.

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Rankinstudio
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Reged: 04/05/08

Loc: Southern UT
Re: removing the mirror in a canon DSLR new [Re: fishonkevin]
      #5725544 - 03/11/13 10:35 AM

That makes perfect sense. I think I am going to try this.

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pfile
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Reged: 06/14/09

Re: removing the mirror in a canon DSLR new [Re: mmalik]
      #5725611 - 03/11/13 11:15 AM

Quote:

I wonder if any of the modifiers (Brent/Hap/Gary, etc.) would do this or have done this?


I presume there would be better/simpler way to accomplish this with open camera during typical sensor mod? Thx




well, the link was originally posted on DSLRModifications after gary gave some advice to the guy who removed the mirror, so at least gary H. knows about this. most likely the other modifiers are on that list.


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Rankinstudio
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Re: removing the mirror in a canon DSLR new [Re: pfile]
      #5725632 - 03/11/13 11:30 AM

I would like to hear if the camera works right with BackyardEOS before I do this.

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Rankinstudio
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Reged: 04/05/08

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Re: removing the mirror in a canon DSLR new [Re: pfile]
      #5726659 - 03/11/13 07:23 PM Attachment (15 downloads)

Easy mod. I'll post before and after flats when I shoot some tonight. That hot screwdriver went through those hinges like they were not even there. Took 5 mins.

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piaras
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Reged: 01/26/09

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Re: removing the mirror in a canon DSLR new [Re: Rankinstudio]
      #5726670 - 03/11/13 07:31 PM

I have always seen this on my 350D. This mod is only viable with a body that has Liveview, just remember thats 450 and newer.
Pierre


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guyroch
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Reged: 01/22/08

Loc: Under the clouds!
Re: removing the mirror in a canon DSLR new [Re: Rankinstudio]
      #5726672 - 03/11/13 07:32 PM

Genius idea, permanent mirror lock!

I have a few spare DSLRs... that usually means I'll try it on one of them

Guylain


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zerro1
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Re: removing the mirror in a canon DSLR new [Re: guyroch]
      #5726688 - 03/11/13 07:41 PM

Quote:

Genius idea, permanent mirror lock!

I have a few spare DSLRs... that usually means I'll try it on one of them

Guylain




I think this is what I was seeing that I emailed you about. It's a pretty profound shading in some instances. Don't have anything on hand to show but if I locate an image I'll post it.


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nofxrx
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Re: removing the mirror in a canon DSLR new [Re: mmalik]
      #5726899 - 03/11/13 09:26 PM

Quote:

I wonder if any of the modifiers (Brent/Hap/Gary, etc.) would do this or have done this?


I presume there would be better/simpler way to accomplish this with open camera during typical sensor mod? Thx




Yes, I for one would definitely offer this on "AP dedicated" DSLRs!
And re: being easier/simple while performing the filter mod...the filter mod only really requires removal of the rear parts of the camera..we do not touch the front(on most DSLRs) for filter mods.
But, it could be done at the same time.
And could be cheap.


And no, there are ZERO sensors on/in the camera that have anything to do with the position of the mirror...so should be simple and cheap to add this to the mod services. (now, I say this, but I have not tested to see if any errors would come up on the AF system, metering system, etc, which is all used by the mirror...in theory, I see no side effects of the mirror being removed, OTHER THAN losing the features of the camera that come with the mirror..)


What I find weird however, is that this issue is not common on ALL cameras, or even a set model. it seems to really vary between camera model, scope, FF/FR(if applicable), filters, etc, etc..
So, I would STRONGLY advise people to test their cameras for this issue BEFORE sending out for a mod to see if you even need it.
Since this mod would be 'sorta' permanent, I would not recommend it IF you ever plan to use the camera for daytime, or even sell it in the future.
People may not want a camera that has no: viewfinder, AF system, metering, etc...which are the reasons we buy DSLRs in the first place(besides for AP use lol)

Cheers!


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Rankinstudio
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Re: removing the mirror in a canon DSLR new [Re: pfile]
      #5727129 - 03/11/13 11:34 PM Attachment (28 downloads)

I have noticed the light meter doesn't work now. I can live without it. Everything else works fine.

Before (Definitely had the problem)

Both Shot on my 8" F3.9 with the Paracorr II


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Rankinstudio
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Re: removing the mirror in a canon DSLR new [Re: pfile]
      #5727133 - 03/11/13 11:35 PM Attachment (24 downloads)

After:

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pfile
Post Laureate


Reged: 06/14/09

Re: removing the mirror in a canon DSLR new [Re: Rankinstudio]
      #5727200 - 03/12/13 12:08 AM

amazing. that really confirms it. except for camera lenses i don't have any optics that fast so i'll probably leave my 50D alone. i figure that canon bodies probably already work properly with canon lenses.

congrats on the mod!


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Rankinstudio
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Re: removing the mirror in a canon DSLR new [Re: pfile]
      #5727234 - 03/12/13 12:25 AM

Quote:

amazing. that really confirms it. except for camera lenses i don't have any optics that fast so i'll probably leave my 50D alone. i figure that canon bodies probably already work properly with canon lenses.

congrats on the mod!




I actually noticed this over a week ago when I had first light with my new scope, the F3.9. I figured it had to be the mirror blocking the light path but wasn't sure what to do about it. This thread* came just in time! I'm set now.



Edited by Rankinstudio (03/12/13 12:46 AM)


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guyroch
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Reged: 01/22/08

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Re: removing the mirror in a canon DSLR new [Re: Rankinstudio]
      #5727262 - 03/12/13 12:43 AM

Quote:

Quote:

amazing. that really confirms it. except for camera lenses i don't have any optics that fast so i'll probably leave my 50D alone. i figure that canon bodies probably already work properly with canon lenses.

congrats on the mod!




I actually noticed this over a week ago when I had first light with my new scope, the F3.9. I figured it had to be the mirror blocking the light path but wasn't sure what to do about it. This threat came just in time! I'm set now.






WooHoo


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LeCarl
super member


Reged: 03/16/11

Re: removing the mirror in a canon DSLR new [Re: guyroch]
      #5728988 - 03/12/13 09:03 PM

100% agree, I done this to my 2 T3i since last year, really better, and dedicated astro cam is a dedicated astrocam...

I used force instead of heathen screwdriver, but this is a good idea

(I removed all pentaprism part too, this add weight and not needed at all now...)


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Daniel Oliva
newbie


Reged: 11/21/13

Re: removing the mirror in a canon DSLR new [Re: pfile]
      #6452002 - 04/07/14 01:38 AM

I earned an EOS 20D from a friend and decided to remove the IR filter. I have no Canon lenses, so could not test the camera before the mod. I only checked the sensor and mechanism taking some pictures without a lens.
After the procedure, I attached it to my Orion 6" f/5 for test and noticed a dark shade on the bottom of the pictures.
The first thing I tought was I had made any mistake during the mod, but later I detected the mirror was not completely lifted. As this is an old and very used camera, possibly the mechanism was already faulty.
Reading this post, something came to my mind: why not only stick the mirror lifted with a black tape? Isn't it enough? In my case it solved the issue.


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