Improve your imaging....maybe

[Keithp]

Hello everyone,

It's 00:25 and I'm determined to go for an all nighter, tonight. Along the way, with my limited imaging capabilities, only the recording though, I found something out that might be useful to anyone starting out in trying to capture something. It may already be well known by those more experienced but I thought I'd share it anyway.

All the gear was set up before it went dark, roughly polar aligned by compass, sun was just going down, moon just under half crescent following it over by about a third of the sky as you look up. Started here and got some nice shots, few avi-s. Being a novice at this... no problems getting a nice focus on the moon!

As we've finally had some nice clear nights and warm days the atmosphere was churning a bit when I went for 15mm ep plus the X2 barlow plus the camera zooming to max(fuji claim 10x:p) and it showed in the avi-s of the moon. Next swung it over to the left a bit and picked up Saturn, no camera just lenses and eye, no problems.

Thought ah, lets get some shots again of Saturn...camera hooked up and nothing... couldn't get a focus in or out just black..

Took the camera off the lense and viewed again with the eye and Saturn was there but out of focus, focused up but while doing it took it back and forwards out of focus and noticed something. Taking it well out of focus the image shifted over to one side and grew dim, that's the image you would see in the pictures about collimation. But the image was hitting what I would call the edge of the field of view of the eyepeice, turned the ep around...no difference. Locked it in the barlow and turned the barlow around...again no difference.. finally loosend the 2 inch to 1.25 inch adapter (2 screws) spun that around and saw the imaged move. Centred the image, still well out of focus and it improved a bit, but I couldn't centre it fully. While it was like this I then decided to adjust the primary mirror screws, already having apparently collimated the scope just before it went dark. And that did it!

Put the camera back on and could see the out of focus image, focused that first then zoomed the camera half way, focused that, then zoomed to max and focused again, hey presto!

I think this just shows how important collimation is on a Newt. Going back out shortly to continue, batteries all re-charging at the mo.

Jupiter and Neptune should be up in a couple of hours....the next targets...

Hope this helps

Regards

All

Keithp

PS, just thought ... maybe this should have gone under tips, tricks etc...doh!

[Keithp]

Dam! just missing it, Jupiter that is. I can see it but where the scope is can't....that is so frustrating!

I have a small fir tree in the line of sight, bit too early for the chain saw!

Maybe later in the month

[BlueAstra]

Chainsaws are always an important addition to the astronomer's tool kit

[Kokatha man]

Hi Keith, hmmmm.....without suggesting your account and remedy isn't correct (collimation can "slip" even though you attended to it beforehand).....but is it possible that collimation was "thrown out" down the imaging train by the attaching of the camera and fiddling with adaptor screws....?

Can't quite interpret exactly what you're saying re chain-of-events but collimation is also effectively altered if anything in the optical train isn't in kilter with the rest - eg, if when you rack the focusser out it sags/flexes to one side or another (doesn't stay perpendicular to the optical alignment) then mis-collimation results.....

This is quite common with cheaper focussers and/or heavier cameras and effects refractors as well as reflectors.....not necessarily as pronounced as your experience reflected but certainly plenty enough to take the "edge" of any details in planetary imaging AND move the image around wildly.....in camera electronic "zoom" mode, or more obviously on a pc screen with planets and longer f/l's (ie, with barlows) many focussers cause the planet image to literally disappear as you attempt to adjust focus (and the optical alignment spoken of above alters!)

Having said all that this cause of the phenomenum usually self-rights itself once the focussing mechanism is returned to a more stable position (or the additional weight causing it is removed - ie, for you it would have been interesting once you'd re-collimated to put the ep back in and check again.....)

Anyways, you may well be correct in your assumptions as I've said.....and I'm sure you've discovered that targetting a small light-source like a planet when using barlows is a more difficult venture....!