D700 Light Leaks? Something is wrong with my sensor...

Here is a screen shot of several shots from View NX... shot a few star shots tonight - from 3200 upward I am getting a strange blooming of light on one area of my sensor... it is in all these shots as you can see... 3200 - Hi 2 ISO I am seeing this strange light leak... any ideas? They are different focal lengths... so it's not a light source on the ground or anything like that...



--
'Procrastinate now, don't put it off.'

'Vista is the ME of our generation.' - John C. Dvorak

Looks like light coming in through the viewfinder to me, did you close the viewfinder shutter?

Cap your view finder

I think this is noise. Did you use long time noise reduction?

Read your manual. Don't open the lens chamber while your are running your household vacuum cleaner

Ok, yea I thought of the viewfinder after I posted... how is the light streak in the same spot even though I have moved location and focal length... I understand the viewfinder glass stays the same... so that would make sense...

--
'Procrastinate now, don't put it off.'

'Vista is the ME of our generation.' - John C. Dvorak

How long were the exposures and what lens where you using?

Steve

Exposures were anywhere from 1 second to 8 seconds... ISOs were between 3200 to 25,600 ...

Lenses were Nikon 105 VR, and Nikon 80-400 VR...

SteveL54 said:

How long were the exposures and what lens where you using?

Steve

Click to expand...

--
'Procrastinate now, don't put it off.'

'Vista is the ME of our generation.' - John C. Dvorak

Those are relatively short exposures but it just might be the VR mechanism. Even if the VR switch is set to off it still emits near IR that polluts long exposures.

You must have the VR off and the lens AF switch set to M. Setting the camera body AF switch to M has no effect.

Here's a long thread discovering the problem

http://forums.dpreview.com/forums/read.asp?forum=1039&message=26783756

I'll save you some time. The correct solution is detailed in the very last (150th) post

Follow-up confirmation was done in these continuation posts:

http://forums.dpreview.com/forums/read.asp?forum=1030&message=26820887

http://forums.dpreview.com/forums/read.asp?forum=1039&message=26830245

Steve

PhotoTraveler said:

Cap your view finder

Click to expand...

The mirror should seal the chamber from light entering through the VF during the exposure.

Steve

Have you managed to close Viewfinder ?
whats the result

Closing the viewfinder will do nothing as others have explained when the mirror is raised, it does that!

However one possible idea is that I had this same thing happen to me with my D100 years ago.

In this case it was caused by a defective shutter blade hinge that let light through the hinge pivot point as it travelled vertically past the sensor.

When the shutter was replaced, problem solved and it never happened again. I hope this might help.

--
John,
Land Down Under

http://www.pbase.com/got_that_shot_images/aviation

On long exposures (say over 5 seconds), my D2x would occasionally leak light via the viewfinder if the environment behind me was lit. Closing the viewfinder on multi-second exposures resolved the problem.

While I understand that the mirror 'should' eliminate stray viewfinder light, it still can't hurt to try with the viewfinder closed.

It's easy and it's free, try to close the viewfinder on the D700 to see if the image results change.

--
John Miranda
http://www.johnmiranda.com

John Miranda said:

On long exposures (say over 5 seconds), my D2x would occasionally
leak light via the viewfinder if the environment behind me was lit.
Closing the viewfinder on multi-second exposures resolved the problem.

Click to expand...

That would make me wonder if the mirrors are not properly aligned since they aren't sealing the chamber.

Neither my D70 nor D300 VF's leak light during exposures. I can point the back of the D300 VF toward a light and take a 30 sec exposure at ISO 3200 with lens cap on and the frame is black except for the usual noise and hot pixels.

John Miranda said:

While I understand that the mirror 'should' eliminate stray
viewfinder light, it still can't hurt to try with the viewfinder
closed.

Click to expand...

Agree.

John Miranda said:

It's easy and it's free, try to close the viewfinder on the D700 to
see if the image results change.

Click to expand...

It's also easy to check to see if the VR units are causing the fogging. Just put on the lens cap, close or cover VF, and take a 30 second exposure at high ISO. This source of IR fogging is not a malfunction. It's a "feature" of some VR lenses and it shows up in 30 second exposures at ISO 3200.

Steve

In most cases the light entering this pathway would be insignificant, but it happens. The primary mirror is partially transparent. After all auto focusing takes place on an image cast through this mirror then reflecting off of the secondary mirror. If light/images can pass through this mirror to focus, then it can certainly leak light into long exposures. That's why there is a viewfinder door on high end models and a cap included with cheaper models.

mfletch said:

In most cases the light entering this pathway would be insignificant,
but it happens. The primary mirror is partially transparent.

Click to expand...

The D700 mirror could be different, but looking at the D70 mirror, only the central portion of the mirror looks semi-transparent.

mfletch said:

After
all auto focusing takes place on an image cast through this mirror
then reflecting off of the secondary mirror.

Click to expand...

The secondary mirror folds up directly under the primary mirror during the exposure. I believe that should seal the semi-transparent section.

I set the D300 into sensor cleaning mode and looked at the top of the chamber were the mirror is during exposure. It looks pretty tight to me. The bottom of both mirrors are backed by opaque material. I put a flashlight up to the VF. I didn't see any obvious light leakage.

mfletch said:

If light/images can
pass through this mirror to focus, then it can certainly leak light
into long exposures.

Click to expand...

As mentioned in a previous post, I've taken several 30 sec exposures at ISO 3200 with the D300 without covering the VF in a reasonably lit room with no obvious light leakage. In one I intentionally directed light into the viewfinder. I did the same with my D70 at ISO 1600. (The D70 exhibits pronounced amp glow under these conditions.) There was no difference between shots taken with the VF covered and uncovered as viewed on the camera's LCD.

mfletch said:

That's why there is a viewfinder door on high
end models and a cap included with cheaper models.

Click to expand...

It's definitely needed during exposure metering when the VF is not covered by the photog. That's reason enough to have the eyepiece shutter or cap.

The D700 manual does mention closing the eyepiece shutter to avoid "interfering with exposure". But I suspect this may just mean exposure metering.

I don't believe it's needed during the actual exposure. But I could be mistaken.

I don't know if Nikon specifies the extent of permissible light leakage around the mirror assembly. So I could just be lucky with my two cheaper bodies.

With wear and age I suppose the seal can become less effective.

Steve

This problem is well explained on the Nikon website under the heading, astronomical photography with DSLR, especially with their second example which looks like your sample picture they have provided. You are suffering from color bloom which is generated by excessive heat generated by pushing your sensor gain so much to capture a night event.

Rick.

looks like sensor heat noise (amp noise) - and looks like you're also revealing some of the stitching patterns of how the sensor was made.
--
A poor photographer blames his tools.

SteveL54 said:

The secondary mirror folds up directly under the primary mirror
during the exposure. I believe that should seal the semi-transparent
section.

Click to expand...

Yes it does fold up directly under. I agree that this blocks most of the light that could come in through the viewfinder. I just don't agree that it "seals" out all possible light. It's in the path of light, but it has never been the job of the mirror an an SLR to seal the viewfinder from incoming light. If that were the case, there would be no need for the viewfinder door. This isn't a new issue. Long ago, I would just stick a piece of gaffers tape over the viewfinder when doing a longish exposure without my eye to the viewfinder. It's rarely an issue and in fact, might not be the culprit for the OP's issue. But light through the viewfinder WILL give similar problems, so why not flip the viewfinder door shut(since it's easy enough and it's there in the first place), and try again. It might not be the problem. It would be silly to send a camera to service and wait 2 months to find out nothing is wrong.

SteveL54 said:

I set the D300 into sensor cleaning mode and looked at the top of the
chamber were the mirror is during exposure. It looks pretty tight to
me. The bottom of both mirrors are backed by opaque material. I put a
flashlight up to the VF. I didn't see any obvious light leakage.

Click to expand...

I'm not sure why, but I tested this also. I put the D700 and D300 each in cleaning mode, with lens off. I looked through the viewfinder while shining a penlight around in the mirror chamber. I wasn't suprised to see a dim light coming through.

No, the mirror does not seal it off, that's why view finder shutters exist on some cameras, and other cameras come with a plastic thing on the camera strap that covers the view finder.

When your eye is to the camera, it is blocking most light from coming in that way. When your eye is not there, light can get in.

The mirror just moves up out of the way, it doesn't trying to seal anything off. For it to do that, it would have to made a face seal with the stuff above, that kind of hit would be bad.