SCT and DSLR

[adavis (Andrew)]

Originally Posted by Outcast

If you shoot in live view mode, the mirror is already out of the way & will reduce shake to some extent.

If you do not have a remote control for your camera, use the self timer set on 10 second delay, this will allow the camera & mount to settle after you press the shutter... not sure if timer function is available on video setting..

If you use video & timer function is not available in this setting then just delete the first 5 - 10 seconds of video to remove any vibration artefacts... otherwise, let Autostakkert do it's thing & select only the best 10 - 20% of frames for stacking...

To be honest, you are on a hiding to nothing trying to achieve sharp images with only single shots... video & processing as described is really the only reliable way.

Next time you have a visual observing session, look at the moon at high magnification... you will see that it does not remain in sharp focus all of the time... this is due to atmospherics (and can be other things such as tube currents, thermals off rooftops, etc...)... now imagine trying to time your single snapshot with when it is perfectly sharp... pretty much impossible...

Video on the other hand captures all of it, in focus, out of focus & everything in between. When you stack only the top 10 - 20% (less percentage if you have a large quantity of frames) you get nothing but, the sharpest images.. then in Registax wavelets.. you sharpen what you have even further & then, and only then will you have sharp planetary or lunar images...

Edit: You have to trust the Bhatinov mask focusing.. if you get that right, your images will be in focus at the point that atmospherics allows... what you will be seeing in the back of the camera will be exactly the same (minus colour) that you get at the eyepiece.. that is the focus flutters in & out due to atmospheric conditions, commonly referred to as seeing conditions...

Thanks for the explanation, it does make sense.

Just to be clear, I am not expecting a single shot to be sharp or the only process, I do know about stacking and using video, and expect to do this.
What I am doing primarily so far is basically using the DSLR with OLED screen to be a viewfinder.

I'll give all the suggestions a good go this weekend if the seeing is good.

cheers
Andrew

[Outcast (Carlton)]

Originally Posted by adavis

Thanks for the explanation, it does make sense.

Just to be clear, I am not expecting a single shot to be sharp or the only process, I do know about stacking and using video, and expect to do this.
What I am doing primarily so far is basically using the DSLR with OLED screen to be a viewfinder.

I'll give all the suggestions a good go this weekend if the seeing is good.

cheers
Andrew

Likewise Andrew, what you see on the OLED screen will represent viewing conditions, that is why what you see won't look very 'in focus' although, it may 'flutter' into focus for brief moments. The other way to see this is to look at the moon at high magnification.. the worse the seeing conditions the worse the flutter (infocus to out of focus) will be. Seeing conditions will allow brief (read very brief) moments of in focus...

In short, you may see literally micro seconds of infocus image through your display but, that will largely depend on your sampling rate & refresh rate, your eyes (via the brain) will produce sharper 'moments' than your video screen as your brain operates at a far faster refresh rate & also interpolates data in a manner your sensor & video screen cannot..

Trust your bhatinov mask focus, it is spot on, assuming you have the central spike directly intersecting the centre of the crossed spikes. Essentially, you have to ignore what you are seeing on your screen/monitor, capture the video, process it & then, and only then will you achieve your sharp planetary images..

Please trust me on this one... I have learnt it the hard way... I know what you want to achieve & as I & others have stated, there is only one way... video capture/stacking/wavelet sharpening...

[adavis (Andrew)]

Originally Posted by Outcast

Please trust me on this one... I have learnt it the hard way... I know what you want to achieve & as I & others have stated, there is only one way... video capture/stacking/wavelet sharpening...

Yep, no problems, I do 100% trust what everyone is telling me.
What is confusing me is that on the same night, in the same minutes, I can see beautifully sharp images through the eyepiece, but swap to the DSLR and refocus with Bahtinov, for a soft image.

Give me the weekend to follow everyones suggestions and I'll report back.

[Outcast (Carlton)]

Originally Posted by adavis

Yep, no problems, I do 100% trust what everyone is telling me.
What is confusing me is that on the same night, in the same minutes, I can see beautifully sharp images through the eyepiece, but swap to the DSLR and refocus with Bahtinov, for a soft image.

Give me the weekend to follow everyones suggestions and I'll report back.

Yep, that is indeed quite normal... our brain's ability to capture that sharpness as we view is far superior to what a video screen can replicate...

[bojan]

Originally Posted by Outcast

... our brain's ability to capture that sharpness as we view is far superior to what a video screen can replicate...

Exactly.

We have built-in image enhancement software in our brains.. which is still better than anything available so far...