Robin and Martin - the images I posted all have no LPS filter in the imaging train - took it out of the equation to simplify things.
I think the most telling fact is that Image No.3 with no reducer and no LPS filter in place has a reflection.
So if I do the 'look up the tube' test and see some form of reflection within the optical tube - where does that leave me exactly? What do I do - flock the baffle? Doesn't seem like there's much else I can do!
Bugger, I thought the clip filter was in place.
How about avoid M42 I wouldn't advise pulling the scope apart.
I had a look and can't see any example images of M42 from my rc8.
But I'm not using a canon either. The canon still has one filter over the sensor.
Bugger, I thought the clip filter was in place.
How about avoid M42 I wouldn't advise pulling the scope apart.
I had a look and can't see any example images of M42 from my rc8.
But I'm not using a canon either. The canon still has one filter over the sensor.
Robin - The only reason I bought this scope was to do an in-depth study of M42
I had similar problems, but they were due to shiney black parts in the focuser and camera adaptors. Just because these are black don't exclude them from your review. In my case it was these shiney black adaptors that were the issue. I simply spray painted them with flat black epoxy.
I had similar problems, but they were due to shiney black parts in the focuser and camera adaptors. Just because these are black don't exclude them from your review. In my case it was these shiney black adaptors that were the issue. I simply spray painted them with flat black epoxy.
Good luck,
Steve
Thanks Steve - I'll have a critical look at all the elements in the imaging train for telltale shiny bits. Planned to head out to Bunnings today so I'll add flat black paint to my shopping list.
Back from Bunnings with Flat Black paint. Found 6 exposed silver screw holes at the front of the OTA which I painted straight away. Also few shiny bits in the imaging train accessories dealt with too. Baffle looks completely matt black and shine-free!
Hope I can test it out soon.
Doug
ps...one last thought! Would performing these tests under a bright moon be a problem with regard to creating reflections?
I knew you didn't have a filter in the imaging train that is why i didn't react to the post after mine
I am going to take my RC8 apart tomorrow to spray every shiny part i can find (just to be sure) even though i don't have any reflections.
PS: I am imaging with a QHY9 Mono so that might make a difference.
I hope your reflections will be gone after spraying.
If the moon doesn't make a reflection in the image then just about nothing can
You could even point close to a street light and see if you get a reflection.
Martin.
Quote:
Originally Posted by dugnsuz
Robin and Martin - the images I posted all have no LPS filter in the imaging train - took it out of the equation to simplify things.
I think the most telling fact is that Image No.3 with no reducer and no LPS filter in place has a reflection.
So if I do the 'look up the tube' test and see some form of reflection within the optical tube - where does that leave me exactly? What do I do - flock the baffle? Doesn't seem like there's much else I can do!
Last edited by mill; 10-12-2011 at 02:05 PM.
Reason: addendum.
Hmmm, yes the point about the reflection being present in all three images is rather pertinent now that I think about things.
So it cannot be the reducer. That is ruled out.
All the images were taken without the LP filter in place. So that is ruled out.
Are you imaging with the mirror up prior to release?
Eliminating the shiny parts is a good idea anyway.
Adapters was raised and that is a good idea too. Something in the later part of the imaging train is causing this issue.
Don't worry about the baffle now Doug. Now that I have thought more on this it seems very unlikely this is a problem. I will ring and have a chat. See if we can nut this out.
Hmmm, yes the point about the reflection being present in all three images is rather pertinent now that I think about things.
So it cannot be the reducer. That is ruled out.
All the images were taken without the LP filter in place. So that is ruled out.
Are you imaging with the mirror up prior to release?
Eliminating the shiny parts is a good idea anyway.
Adapters was raised and that is a good idea too. Something in the later part of the imaging train is causing this issue.
Don't worry about the baffle now Doug. Now that I have thought more on this it seems very unlikely this is a problem. I will ring and have a chat. See if we can nut this out.
Thanks Paul - appreciate it.
No mirror lock up used - will check it out.
Another thing I realised while painting the shiny parts(!) was that when I removed the Losmandy D plate in order to save weight, I returned the allen bolts into the OTA. It looks like they protrude into the OTA but not below the first scope baffle blade - I removed them too and covered the holes in the tube.
Try flocking the inside of the secondary shroud. That fixed a similar thing on the CDK. The big curve reflection is similar to what I saw on mine at times.
If the secondary shroud is a bit too wide then you can get extraneous light going up between the secondary and a slight gap if you follow me. The secondary needs to be masked off a tad but the flocking will take up a few mm and block any reflections coming off the shroud itself as well as block any slight mismatch on the sides of the secondary with the primary.
Haven't got a clue how to to do that Greg -- sounds very complicated?
That's the little container your secondary sits in. Just flock it a little. Another thing to look for is sharp (shinny) edges on adpaters. They create those bright rings.
That's the little container your secondary sits in. Just flock it a little. Another thing to look for is sharp (shinny) edges on adpaters. They create those bright rings.
OK understood - but , I would have to unscrew and remove the whole secondary unit to do that, correct?
Doug i found that the part that reflects the most light is the 50 and 25mm extensions you get with the scope.
I have just painted these with flat black on the inside.
Before anyone starts, i did this because i want to use a reducer sometimes.
My cheap Bintel flattener doesn't introduce any reflections.
What you are getting is light is coming down the path in your telescope and a small fraction of that light is bouncing back to the secondary from a filter/corrector or the chip itself and then, from that, back to your sensor. Hope that makes sense and helps you.
What you are getting is light is coming down the path in your telescope and a small fraction of that light is bouncing back to the secondary from a filter/corrector or the chip itself and then, from that, back to your sensor. Hope that makes sense and helps you.
Cheers,
Nathan
Thanks Nathan - this thread has been quite illuminating (pun-sorry).
Painted any shiny surface I could see (including the extension tubes) with flat black paint. Pointed the RC8 to Orion on Tues night and got no reflections - haven't posted the image due to tracking errors, but I will upload it tonight for the forum's critical inspection.
I hope I've found the cure and I can focus on imaging instead of technical fiddling!
Cheers for all the help so far.
Doug
Here's the latest effort (latest being from last Wednesday).
Being a dozy so & so, I loosened the counterweight shaft instead of the RA lock by mistake and roughly returned the weights to an approximate position without doing a critical re-balance - so I think balance is way off thus affecting tracking.
Stars are uniformly 'eggy' accross the whole field (D'Oh!) but more importantly, after flat blacking all the shiny bits and insides of the extension tubes, it looks like there aren't any large annoying reflections on this one.
And, my new (2nd hand!) Astrotech Flattener was used on this image with no optical surface reflections noted too.
I wouldn't advise pulling the scope apart.
it's the imaging I like
