5dmkiii new focusing screen question -> now a 'did i mess up my camera' thread

[gregborkman]

I recently installed a new focusing screen from focusingscreen.com and i noticed something that i wanted to double check with you guys about.

I bought the EC-A, which is this model:

And it works great with my 35mm but what I've noticed is that on my 100-400 mkii if i go greater than 100mm it starts to not be accurate, the further i go away from 100 the less the diamond can be clean. Optically it doesnt make sense to me since the focus point will still meet at the focusing screen. Could someone maybe explain this to me? Did I installed it incorrectly (im 99% certain i did it correctly).

 

[gregborkman]

Re: 5dmkiii new focusing screen question

Update: tried it on a 24-70 and it looks fine. To me it looks like anything higher than 100 starts to make the screen unusable.

 

[midluk]

Re: 5dmkiii new focusing screen question

Does it perhaps need an aperture of at least f/4.5 to function properly? Can you try the 24-70 with the aperture closed to 5.6 (with DOF preview)?

 

[Sporgon]

Re: 5dmkiii new focusing screen question

Microprism ( and split screen) don't work at slower apertures.

This is one of the main reasons slrs used to have interchangeable screens: if you were using long teles with slower aperture you could fit a plain ground screen. If you're using the 100-400 you need to do the same, get a plain EC-s type screen.

 

[niels123]

Re: 5dmkiii new focusing screen question

Microprism ( and split screen) don't work at slower apertures.

This is one of the main reasons slrs used to have interchangeable screens: if you were using long teles with slower aperture you could fit a plain ground screen. If you're using the 100-400 you need to do the same, get a plain EC-s type screen.

So with the 200mm f/2.0 it should work fine? I guess also with the 200mm f/2.8 and the 400mm f/2.8?

 

[Mt Spokane Photography]

Re: 5dmkiii new focusing screen question

Besides issues with small apertures, focus screens need shims to be accurate. Canon sells shims in various thicknesses to adjust a focus screen to be accurate. It its not, focus will be off. The Canon service manuals give the procedure for adjustment.

Generally, with a Canon screen, just reinstall the shims from the old screen, but with a 3rd party screen, that may not work, depending on the source for the focus screen. The tolerance is very small,

 

[Sporgon]

Re: 5dmkiii new focusing screen question

Microprism ( and split screen) don't work at slower apertures.

This is one of the main reasons slrs used to have interchangeable screens: if you were using long teles with slower aperture you could fit a plain ground screen. If you're using the 100-400 you need to do the same, get a plain EC-s type screen.

So with the 200mm f/2.0 it should work fine? I guess also with the 200mm f/2.8 and the 400mm f/2.8?

Yes. It's not the magnification but the slower aperture. From memory f/4 was OK, f/5.6 one half if the prism begins to black out and at f/8 it's hopeless.

 

[gregborkman]

Re: 5dmkiii new focusing screen question

Microprism ( and split screen) don't work at slower apertures.

This is one of the main reasons slrs used to have interchangeable screens: if you were using long teles with slower aperture you could fit a plain ground screen. If you're using the 100-400 you need to do the same, get a plain EC-s type screen.

So with the 200mm f/2.0 it should work fine? I guess also with the 200mm f/2.8 and the 400mm f/2.8?

Yes. It's not the magnification but the slower aperture. From memory f/4 was OK, f/5.6 one half if the prism begins to black out and at f/8 it's hopeless.

ah! that would make sense consider 100mm is 4.5 and it starts to be incorrect any tighter than that. Thanks everyone! Luckily I also bought that s-type one as well time to swap em out.

 

[gregborkman]

Re: 5dmkiii new focusing screen question

oh boy...i think i fucked something up. After replacing the first screen the photos I've been able to take look normal on the preview lcd after i take them and when i go back and look at them in preview on the camera.
However, when i went to import them on my mac with image capture, the images were fine for a brief second before the thumbnails would go black and i wasn't able to see them any more (example 1 and 2 on link below). Then when i imported them they wouldn't preview (example 3) and ultimately when i opened them in PS I got some distorted images (example 4 and 5): http://imgur.com/a/efs5J

Did I ****** up my sensor somehow or could this be a memory card issue?

[edit 1] i tried two other memory cards and with the first card still same thing, image shows fine on the lcd but then when i import it its fucked. The previous images, in addition to the test shots i just did, that were on that memory card are now also messed up. The second card i tried seeing if the images on the card were messed up first (to check if maybe it was a transfer issue between card and mac) but they were fine, upon putting the card into the camera and taking a few photos, the photos taken now and previously on the card look fine. So now I'm completely confused. I've formated the cards and still having that issue for cards 1 and 2...both happen to be lexar i dont think that has anything to do with it but maybe. Thoughts?

 

[Maximilian]

Re: 5dmkiii new focusing screen question

...
Yes. It's not the magnification but the slower aperture. From memory f/4 was OK, f/5.6 one half if the prism begins to black out and at f/8 it's hopeless.

Oh, yes! Sporgon, you're right.
Now I can recall the old AE-1 days and what a mess it was to focus under these circumstances.
Man, sometimes it's good to be 30 years older than then

 

[Maximilian]

Re: 5dmkiii new focusing screen question

oh boy...i think i F_____ something up. After replacing the first screen the photos I've been able to take look normal on the preview lcd after i take them and when i go back and look at them in preview on the camera.
However, when i went to import them on my mac with image capture, the images were fine for a brief second before the thumbnails would go black and i wasn't able to see them any more (example 1 and 2 on link below). Then when i imported them they wouldn't preview (example 3) and ultimately when i opened them in PS I got some distorted images (example 4 and 5): http://imgur.com/a/efs5J

Did I ****** up my sensor somehow or could this be a memory card issue?

[edit 1] i tried two other memory cards and with the first card still same thing, image shows fine on the lcd but then when i import it its F_____. The previous images, in addition to the test shots i just did, that were on that memory card are now also messed up. The second card i tried seeing if the images on the card were messed up first (to check if maybe it was a transfer issue between card and mac) but they were fine, upon putting the card into the camera and taking a few photos, the photos taken now and previously on the card look fine. So now I'm completely confused. I've formated the cards and still having that issue for cards 1 and 2...both happen to be lexar i dont think that has anything to do with it but maybe. Thoughts?

Hi gregborkman!
Your link is not working right now, so all I can do is guess from what you tell us.

So when the imgae can be previewed on the camera lcd there is nothing wrong with the sensor and presumably also with the rest of the body.

Normally I would say that you have trouble after transfering the pics on your mac or using the files with the SW on your pc.

To have a better understanding please try this:
Try shooting jpeg and read out the card directly in the pc file system with a card reader (not via the camera), maybe try this with another device/pc with no MacOS installed, eg. Windows. You should be able to preview and open the jpeg files.
If this is possible I'd say everything is fine with camera, cards and OS. But the photo SW you're using might have a problem.

Let us know what you could find out. Maybe we'll get a better overview.

 

[Valvebounce]

Hi Greg.
Just looked at your shots, link working for me at least. I would say it is a card read error, the shots are very similar to a post a while back that came down to corrupt data.
If my memory serves me well I think I have read that the preview is an imbedded Jpeg which goes away as the raw is decoded.
Are you reading from the camera directly or using a card reader? Try a different card reader or swapping the way you download, try reading from the camera if you were using a card reader or vice versa.
Hope this helps.

Cheers, Graham.

 

[NWPhil]

Re: 5dmkiii new focusing screen question

Besides issues with small apertures, focus screens need shims to be accurate. Canon sells shims in various thicknesses to adjust a focus screen to be accurate. It its not, focus will be off. The Canon service manuals give the procedure for adjustment.

Generally, with a Canon screen, just reinstall the shims from the old screen, but with a 3rd party screen, that may not work, depending on the source for the focus screen. The tolerance is very small,

which camera model require those shims? I looked at Canon's webpage for the 1DsmkIII and Ec screens, and could not find a reference to the shims
Thanks ahead for a clarification

 

[gregborkman]

Hi Greg.
Just looked at your shots, link working for me at least. I would say it is a card read error, the shots are very similar to a post a while back that came down to corrupt data.
If my memory serves me well I think I have read that the preview is an imbedded Jpeg which goes away as the raw is decoded.
Are you reading from the camera directly or using a card reader? Try a different card reader or swapping the way you download, try reading from the camera if you were using a card reader or vice versa.
Hope this helps.

Cheers, Graham.

Hey Graham&Maximilian,
I was reading it from a card reader. I just read it from the camera and the images come across clean. Looks like its time to get a new card reader
Thanks for your input!

Greg

 

[Mt Spokane Photography]

Re: 5dmkiii new focusing screen question

Besides issues with small apertures, focus screens need shims to be accurate. Canon sells shims in various thicknesses to adjust a focus screen to be accurate. It its not, focus will be off. The Canon service manuals give the procedure for adjustment.

Generally, with a Canon screen, just reinstall the shims from the old screen, but with a 3rd party screen, that may not work, depending on the source for the focus screen. The tolerance is very small,

which camera model require those shims? I looked at Canon's webpage for the 1DsmkIII and Ec screens, and could not find a reference to the shims
Thanks ahead for a clarification

Read the service manuals. The shims are part of the adjustment process for matching focus in the viewfinder to what is actually in focus on the sensor.

A shim may or may not be needed, it all depends on tolerance buildup. Some third party screen sellers cut down a screen made for a different camera, and this can throw manual focus way off.

When you use manual focus thru the viewfinder, those shims are really important towards assuring that what is in focus in the viewfinder is also in focus on the sensor. Some third party screens are supplied with a shim because they have a different thickness than the stock Canon screen.

This may help.

http://www.fredmiranda.com/forum/topic/704641/0

Or just Google Canon focus screen shims

http://www.bing.com/search?q=canon+focus+screen+shims&src=IE-SearchBox&FORM=IENTSR

I can send you a copy of the 5D Classic service manual, but its locked and will not let me extract the appropriate page.

 

[Sporgon]

Re: 5dmkiii new focusing screen question

Man, sometimes it's good to be 30 years older than then

Yes indeed; we have it so good now it's quite incredible. So good in fact that all we can whinge about is 12 stops of EV range vs 13.5 !