I have a D3100 and am getting into astrophotography. I have a tracker that I mount my telescope on and connect my camera to the telescope. My pictures always come out blurry. I might have an issue with the collumination in the telescope, but I'm also wondering if my D3100 can cause a slight vibration when the shutter is released when taking a picture. I focus my shots in Live View mode, and they look clean, but when I take the picture it comes out soft and blurry. Any help is appreciated. Thanks!!
D3100 vibration
- Thread starter JimK
- Start date
BF Hammer
Senior Member
Multiple things to watch for here. Keep in mind I only know what you reveal in the original post about what you do.
Tripod under the telescope could be inadequate. Star tracker might be overloaded or must be balanced better with the counterweight kit. Polar alignment not quite right. You could be choosing an unrealistically long exposure time for the star tracker's ability. You are touching the camera with your hand as you take the photos (using a remote shutter or self timer mode required), mirror slap during shutter release.
The last point has to be addressed with the camera settings with any DSLR. Mirrorless bodies have an advantage here. I have only used D7000 or better DSLR bodies so I cannot advise on if a D3100 even has a Mirror-up mode (press shutter once to raise mirror, press a second time to release shutter). A way around that is to use LiveView so the mirror is locked in the up position the whole time.
Then there could be the surface you are set up on. Wooden deck could be trouble. Should be firm ground or pavement.
Tripod under the telescope could be inadequate. Star tracker might be overloaded or must be balanced better with the counterweight kit. Polar alignment not quite right. You could be choosing an unrealistically long exposure time for the star tracker's ability. You are touching the camera with your hand as you take the photos (using a remote shutter or self timer mode required), mirror slap during shutter release.
The last point has to be addressed with the camera settings with any DSLR. Mirrorless bodies have an advantage here. I have only used D7000 or better DSLR bodies so I cannot advise on if a D3100 even has a Mirror-up mode (press shutter once to raise mirror, press a second time to release shutter). A way around that is to use LiveView so the mirror is locked in the up position the whole time.
Then there could be the surface you are set up on. Wooden deck could be trouble. Should be firm ground or pavement.
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Thanks so much for your reply!
The counter weight was set properly, but the polar alignment was not totally accurate; I was taking pictures in front of my house instead of in my backyard so I pointed the tracker in the general direction for the north star. The tracker did track the moon fine, never drifting out of the frame.
I did have a cable release hooked up to my camera on a 2-second delay, but also noticed that the strap at times was causing some motion from swaying. Exposure times varied between 1/15th to 1/125th with exposure compensation on some shots.
I did finally try the mirror lock-up function, but tried to refocus the shot in Live View mode which made it worse. Couldn't get the focus back to where it was and then just gave up for the night.
I also was using a T-adapter on my camera to connect to the telescope; don't know if that had any affect on the focus. Will try not using the T-adapter next time to see if that helps.
Thank you for your suggestions!!
BF Hammer
Senior Member
Isn't the T-adapter required to mount on a telescope?
So you list a combination of things that are going to each introduce motion blurs. I did not even mention possibility of the lenses in the telescope fogging either.
I would have a hard time advising past that without observing what you're doing and how. Generally, you could try putting stick-on Velcro to your cable release and fixing to a tripod leg. The 2 second delay actually sounds OK for the task.
When I photograph night sky objects, I like to pick a bright star to focus on, then move to the real subject. If you use LiveView and zoom in the display as far as it goes, then just turn the focus untill the star is as small as it will go. It will always grow larger and more fuzzy on either side of correct focus. That should be infinity.
So you list a combination of things that are going to each introduce motion blurs. I did not even mention possibility of the lenses in the telescope fogging either.
I would have a hard time advising past that without observing what you're doing and how. Generally, you could try putting stick-on Velcro to your cable release and fixing to a tripod leg. The 2 second delay actually sounds OK for the task.
When I photograph night sky objects, I like to pick a bright star to focus on, then move to the real subject. If you use LiveView and zoom in the display as far as it goes, then just turn the focus untill the star is as small as it will go. It will always grow larger and more fuzzy on either side of correct focus. That should be infinity.
Here's my T-adapter (1st 2 pictures.)
I think I'll try just using the ring to mount the camera to the telescope (3rd pic)...I don't know if the length of the T-adapter affects the focus at all.
I have taken off the camera strap. I'll also try 2 and 10 second timers.
I think I'll try just using the ring to mount the camera to the telescope (3rd pic)...I don't know if the length of the T-adapter affects the focus at all.
I have taken off the camera strap. I'll also try 2 and 10 second timers.
