Moon - Heat waves?

Hey guys...

Finally got a decent night out with the new telescope. Now i am using a 1500mm telescope so the moon takes up the whole frame and i have finally got a shot off of it and very happy with its ability over using my DSLR lens and TC's.

So this is the best shot i could get at FULL Frame meaning stacked enough TC's to get the moon in full frame.

Very soft even after adding sharpening in PS.

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Great progress Michael.

There are a few possibilities for image distortion.

1) Atmospheric turbulence resulting from radiational cooling of the Earth, winds aloft and other weather system related factors. Decent nights of seeing aren't terribly uncommon but excellent nights are pretty rare. I might see two or three max. that I would consider truly steady. Shooting in the early morning hours(2-5 am) increases the odds of better seeing conditions due to the Earth's heat from the previous day being mainly dissipated. Poor seeing will result in poor image quality and all the best focus techniques won't help. There are times when the seeing will steady for brief intervals so it doesn't hurt to click off 20 or 30 and hope you time a few just right.

2) Internal optical tube heat currents (compounded in close tube design scopes). It takes time for the internal temps of your scope to equal that on the outside. The cooling down process causes thermal currents to swirl around inside and causes distortion. If you take your scope from very warm to very cold temps(or vice versa) this process will take longer. When possible I move the scope to at least the garage ahead of time and that helps shorten the waiting time.

3) Radiational cooling at low altitude/ground level from rooftops, chimneys, parking lots, etc. between your scope and your target.

Humm..

Well i had a straight shot from my backyard which is an open feild straight up as the moon was pretty much overhead so i am not sure about the roof top thing.

Now i don't think at this point i will be doing the 2-5am thing.. lol New baby and all we sleep when we can

Internal optics.. Humm... All i did was take everything from my nice warm room straight outside shot with in a couple of mins and then back in again.. going from 22 degrees C in the house to -20 degrees C outside So that could be very well what the issue was.

How long should i leave the scope and camrea outside before shooting to ensure everything cooled off correctly.

Also i noticed, first time using the Live View on my camera it goes in and out of focus slightly, does that effect the outcome on the sensor??? the moon was moving pretty quick through the line of sight.

I do have a AZ3 head coming as this ballhead is too hard to do any sort of minor adjustment to keep the moon in the line of sight, so i am sure i will have much better luck when it comes.

Not likely any need to keep your camera outdoors ahead of time unless temps are very radically different inside and out. The scope for sure. The time need for "cool down" varies from scope to scope. Yours not being a large tube should be fine in about 60-90 minutes. Of course longer won't hurt.

If you're seeing a sift of focus on the LCD I'm not sure. When shooting Lunar I used to rely only on the camera viewfinder to focus. I used a Canon Anglefinder C to help magnify. Then I would shoot tests and compare them on the LCD by zooming in and switching from one frame to the next(using the dial) to see how crisp they are.

A good naked eye indicator of how steady the skies are is how much twinkle you see in the stars located high in the sky or at zenith. High mag looks at Jupiter is a more critical way to determine how steady things are. The clearer the bands on the planet the better.

Now does it matter that i am shooting throught the 90 degree elbow? Like my eye peice i can remove it completely and attach the camera with the adapter directly to the telescope or i can remove the eye peice leaving the mirroed angle in and shoot that way.. I prefer this as i am not crouching down to look up at the view finder using the angle i can just stand there and look down at it.

I know what you mean about the ease of using the diagonal but I would avoid adding anything in the light path that isn't necessary. Diagonals can be knocked out of collimation just like reflector telescopes can be. Yours may not be but it takes a pretty trained eye to test one. It's possible to get one new out of the box that isn't aligned properly.

I learned the hard way with my old Schmidt-Cassegrain. I was trying to collimate the optics of the scope and couldn't get things adjusted right. I was convinced there was something wrong with the scope. Turned out the diagonal I was using was out of collimation(and it wasn't a cheap one) so I was never going to get it right by using it. That was an early lesson to never use a diagonal while aligning the mirrors of a scope. Which when I think of it now was so obviously a bad idea.

Anyway, adding one more mirror or piece of glass in the light path is just one more possible ill effect on image quality. Also I believe you'll be narrowing the light path as well. Best to use the largest diameter opening possible which is the focus draw tube. You should have seen me with my old 5" long tube refractor, I used to end up laying on the ground to check focus. That was fun

when you say telescope, do you mean you have your camera looking through a telescope one might hold up to their own eye?

winterstar wrote in post #7257472
when you say telescope, do you mean you have your camera looking through a telescope one might hold up to their own eye?

Yes,

You can see it here