Rolleiflex sl35 mirror stuck in the open position and shutter won't release to send the mirror back down.

I just checked my SF-1, and the mirror will go through four cycles while trying to load the film. You should be able to hear the mirror go up and down when you open the back and close it, then turn the camera on. I cannot get my SF-1 to keep the mirror up. Check to see if you have the mode set to bulb, and that the shutter release isn't stuck down - that will keep the mirror up until you release the shutter button or turn the camera off.

Also look carefully inside the lens mount on the side nearest the red dot. at the horizontal spot there is an internal button. It should be at the bottom of the track it runs in, about 1/3 of the way from the screw below the red dot to the lens release button. That moves up when the mirror goes up, and down when it comes down. If it is in the up position, you could perhaps try to gently move it downwards. It definitely moves up and down with the mirror on my SF-1.

Try this before spending money on anything:
Open the camera front and back: ie, take off the lens, open the back door.
With clean hands, put fingers in from both front and back.
VERY GENTLY slide the shutter curtain to the side, as it would do if the shutter release was working.

In my case, when I let go of the curtain, the whole situation resolved itself, the mirror went back up into position and the winder and release both started working again.
Thanks to DF on photonet for this tip: http://photo.net/sony-minolta-slr-system-forum/00X5Nn

Your second curtain is not releasing the mirror to come down.
This happens with weak 2nd shutter curtain tension.
If the wind lever is stuck and the mirror does not come down then the mirror tension spring came off.

If the batteries are flat or missing you wont get LED's to light up and it will set itself to 125 naturally. I know as I have tried it. It could be that the shutter has got stuck on its way down and it is preventing the mirror from coming down as a result this is a mechanical issue, not battery related. The best way I found to release the mirror was to gently, really gently stroke the shutter nearest to the film down towards the groove it goes home in. Recommend a cotton budd so you don't damage the shutter leaves or get grease from your fingers on the movement. This should release the mirror. The next thing to do is try preventing the shutter getting stuck again by removing the bottom plate which will allow you access to the cogs for the shutter. it is tight in there and it is recommended by some that you remove some of the movement to see and clean them up. I did this but it is tricky and it involves winding on the camera and rocking parts out with itself. Not easy to do. The shutter cogs are brass (or look like it) and they may have old oil stuck inbetween the teeth which needs cleaning out with a tooth pick and then lubricate but not with WD40 which gets sticky with age. Use a cotton budd again with the lubricant on so you don't affect other sensitive parts around this section. Alternatively send the camera for a good service. I just had mine done, got it sorted with a warranty for 12 months to and cost me just £45. They cleaned everything up, new light seals and sorted issues common to this model of camera. The photos are instantly back to their best. Compare a good service to a series of wasted film with an inconsistent camera. Peace of mind too, it is worth it and so is the camera!

merry christmas! :) Your shutter is broken.

If its black when you look thru the viewfinder its likely because the mirror is stuck in the up position. It will often do that if the batteries are exhausted. Try replacing the batteries.

The mirror might release back down if you turn the shutter speed dial to M90. This is a manual release of 1/90 second for when you need the shot but don't have any power.

When you look in the lens opening and adjust the aperture dial, you are seeing the aperture open and close. Not the shutter. You need to open the back of the camera (without film) and take a photo to see the shutter curtains open and close.

You should have a read thru the manual to become familiar with the camera and its operation:

http://www.cameramanuals.org/nikon_pdf/nikon_fg.pdf

By "stayed up", do you mean that the mirror remained in the up position so that you could not see anything in the viewfinder or do you mean that the shutter actually remained open? I do not remember the exact features on your camera, but in general, this is what I would do.

1) Remove the film from the camera and take a picture. Note if you see anything in the viewfinder. If you see nothing, the mirror is in the up position. Verify this by removing the lens and opening the door on the camera back. Look through the lens hole. If you can see through the rectangular hole at the film plane, the shutter is open. If instead you something is obstructing the hole, the shutter is closed. In any case DO NOT TOUCH THE SHUTTER! The shutter is what is covering the hole.

2) If the mirror is in the up position, check to see if your camera has a feature that allows locking the mirror in the up position. Some cameras have this feature to allow use of lenses with very short focal lengths. If this is the case, simply unlock the mirror.

3) If the shutter is the problem, your shutter speed may be set to "T", which stands for time. In the time exposure mode, you press the shutter release once to open the shutter and a second time to close the shutter. Cameras with a "T" setting also have a "B" setting, which stands for bulb. This is a throwback to the old days when it was common to use air-powered shutter releases rather then cable releases. The bulb was a rubber bulb that you squeezed to force air through a tube and push a pin to activate the shutter. The "B" setting keeps the shutter open as long as you hold the shutter release in, but as soon as you take your finger off the shutter release, the shutter closes. Both of these settings are used to make timed exposures. If you find that the problem was that the shutter was set to "T", set the shutter speed to 1/25th second or so and try again. The following sequence should occur; the mirror will flip up and the viewfinder image will disappear, the shutter will open for the prescribed time and close, the mirror will return to the down position and you will again see through the viewfinder.

If this does not work, you may need to take it in for repair.

Caused by build up of dirt inside shutter release button :drip small amount of cleaning solvent like methilated spirits , isopropanol or benzine between the button and external wall using tweezers and then lift the button up and down by inserting tweezers into the inner cable release  thread .
If this does not work you will need to remove the front cover and clean more fully the release mechanism on the inside of the fron cover. 4 retaining screws are under the leather covering in the front ( 2 on top and two on the bottom )

This happened to me to both the Canon's I had. I found out it was a dead battery. Once I replaced those it worked fine. The battery is hidden under the hand grip which can be taken off using a coin in the screw slot.

Sincerely,
Karin

Could be 1 of two things: 1. Mirror linkage failed. 2. Something is holding the mirror; sticky foam or the lubrication has dried out. Remove the lens, use slow shutter speed to release the shutter. While mirror is stuck in the up position, very gently pull down on the front edge of the mirror. If it frees up immediately it was stuck on the foam. Might be able to see a mark on edge of mirror from the foam. Hope this helps.