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Fail - yet again...

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#1 Andy Taylor

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Posted 06 February 2013 - 08:13 AM

It's been a rotten Jupiter season for me. Equipment problems and horrible weather has seen me outside imaging just twice.

This was from Saturday night. Seeing looked fine... :smirk:

Just for fun, see if you can diagnose the problem shown in the image. :question:

Shot with:

8" Dynamax SCT (No - that's too obvious :smirk: and I've had great images from this scope before now)

SPC900NC in optimised color mode.

3x Barlow.

IR block filter.

Captured in Sharpcap. 2 mins @ 10fps.

Rough process in Registax 5.

I know what the problem is... :tonofbricks:

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#2 ToxMan

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Posted 06 February 2013 - 09:43 AM

Hi Andy,

Well, you didn't leave the dust cap on. That's obvious, too. I would have used a 2x barlow. The 3x probably gave you an image much too large for seeing. But, from your previous posts and knowing your sense of humor, I have a feeling it is something entirely out of my mind...

Failure? Naw. You got a recognizable image on the chip. Just not the results you were hoping for. A month or so ago, I spent about 2 hours setting up and got nothing. Zip. Nada. No image.

Paul

#3 valy

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Posted 06 February 2013 - 10:25 AM

Just for fun, see if you can diagnose the problem shown in the image.

My 2c:
- no mount mentioned so you forgot turning ON the shake reduction while holding the OTA
- internal currents
- to many frames while stacking
- thru window

#4 Chris_H

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Posted 06 February 2013 - 10:56 AM

Well your stacking is messed up but I'm sure that's not it! :grin:

#5 Andy Taylor

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Posted 06 February 2013 - 11:24 AM

Nope.

#6 sfugardi

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Posted 06 February 2013 - 12:14 PM

Andy, when the edges on the stacked show a shadow, it is usually from poor unstable seeing. If you drop to the smaller barlow and increase the frame rate to 15 or 20, you should be able to freeze the seeing better. Not sure about your setup, but I would recommend at least 2hrs of scope cooling with fans directly blowing before imaging.

Regards,
Steve

#7 Andy Taylor

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Posted 06 February 2013 - 01:01 PM

Andy, when the edges on the stacked show a shadow, it is usually from poor unstable seeing. If you drop to the smaller barlow and increase the frame rate to 15 or 20, you should be able to freeze the seeing better. Not sure about your setup, but I would recommend at least 2hrs of scope cooling with fans directly blowing before imaging.

Regards,
Steve


The first four runs were at a lower mag and at 10 & 15fps. Same issue.

I believe the SPC900NC compresses data over 10 fps...

Seeing looked pretty stable for a change.

Fans were running for approx that time. Temp was stable too (around zero).

Tracking was spot on also... :smirk:

Hint: look at image from slightly above.

#8 ToxMan

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Posted 06 February 2013 - 01:09 PM

Overhead wire or tree branch passed thru FOV?

#9 Mike Phillips

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Posted 06 February 2013 - 01:19 PM

It's always something in this sport, if it's not weather it's equipment. This AM I got setup on Saturn and everything from and equipment standpoint went well. The seeing was horrible! I sat waiting until dawn, nothing but a spinning top of a ringed-planet!

I give up, what's up with your image? Glad at least you know!

Mike

#10 Andy Taylor

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Posted 06 February 2013 - 01:25 PM

I give up, what's up with your image? Glad at least you know!

Mike


I'll let you all hang for a while longer. :grin:

This is something else to put on your lists of things that can't possibly happen...

But do... :smirk:

#11 ToxMan

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Posted 06 February 2013 - 01:39 PM

Come on guys! The list is still too short...

Cable caught on something and stopped mount. (Too simple?)
An earthquake occurred in your neighborhood.
A night bird landed on your telescope to perch.
A critter took up residence inside your optical tube.

#12 Tassydevil

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Posted 06 February 2013 - 02:10 PM

Its meant to be the moon :)

#13 Chris_H

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Posted 06 February 2013 - 02:13 PM

Things that can't possibly happen...but do...

:shocked: She told you she finally understands why you spend so much time and money on this awesome hobby! :grin:

#14 Greg K.

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Posted 06 February 2013 - 03:28 PM

Hmm did you forget to remove your Hartmann or Bahtinov mask after focusing? BT,DT.

#15 DesertRat

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Posted 06 February 2013 - 03:40 PM

Secondary slipped wrecking collimation?

Dispersion corrector sideways?

Processed while in a sleep state - or too much of that UK ale?

Can't wait!

Glenn

#16 Andy Taylor

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Posted 06 February 2013 - 04:25 PM

Secondary slipped wrecking collimation?

Dispersion corrector sideways?

Processed while in a sleep state - or too much of that UK ale?

Can't wait!

Glenn


I must admit that some beer had been imbibed but did not cause this particular problem.

Talking of sleep - I'm off to bed - have to be up at 5.00 as usual.. :(

All will be revealed.

More tomorrow.

#17 azure1961p

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Posted 06 February 2013 - 10:11 PM

Poor stacking is all I can pull up - due to bumpy seeing.

G,nite.

Pete

#18 ToxMan

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Posted 06 February 2013 - 11:45 PM

Alright, you said it was a problem that is thought impossible, but needs to be on the list of possibles...I'll go with my wife's suggestion...double exposure. Hey, I'm a believer in Occam's Razor.

#19 Andy Taylor

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Posted 07 February 2013 - 04:35 AM

Alright, you said it was a problem that is thought impossible, but needs to be on the list of possibles...I'll go with my wife's suggestion...double exposure. Hey, I'm a believer in Occam's Razor.


Yay!!! We have a winner. :grin:

Tell Mrs ToxMan that she wins a cigar. :bow::lol:



I don't usually use the IR filter with the SCT but it was already screwed on after use on my Carton refractor.

I did a dust check and all was fine so I left it in place.

Possibility No 1:

What I didn't realise was that the filter had become loose on the thread and may have tilted just enough to cause a ghost image from the two faces of the filter.

Possibility No 2:

A "narcissus" effect caused by reflected light from the CCD returned by the filter.

Possibility No 3:

If (2) Then this could also be caused by a slightly tilted ccd.



This also begs the question - does the use of any filter cause a similar effect when imaging bright objects?
Even with a perfectly square filter there must be some overlay of a ghost image. :question:


In my work (motion picture lenses) when front filtering this effect happens when using multiple filters. Our filter stages can tilt to remove this problem...

No wonder the stacking went bonkers.

Oh well.

#20 ToxMan

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Posted 07 February 2013 - 10:31 AM

Very interesting, Andy. I have often wondered if filters get slightly tilted. Or, the possible effects if filters are stacked in the optical train. I've considered light reflecting off filter and CCD for bright objects, like the moon or sun.

Since you work with video and the optics, I wonder if you would know why I got these patterns in my images taken with an older planetary camera, DMK31. It seemed to occur when pushing the image size with C8 + 2x barlow + FW + camera, adding extension tubes to get to f23. As I increased image size and gain to make up for dimming, the pattern appeared. TIS reps said it is Moire. But, I don't know how I can get Moire.

Here is an example:

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#21 Andy Taylor

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Posted 07 February 2013 - 11:18 AM

Very interesting, Andy. I have often wondered if filters get slightly tilted. Or, the possible effects if filters are stacked in the optical train. I've considered light reflecting off filter and CCD for bright objects, like the moon or sun.

Since you work with video and the optics, I wonder if you would know why I got these patterns in my images taken with an older planetary camera, DMK31. It seemed to occur when pushing the image size with C8 + 2x barlow + FW + camera, adding extension tubes to get to f23. As I increased image size and gain to make up for dimming, the pattern appeared. TIS reps said it is Moire. But, I don't know how I can get Moire.

Here is an example:


Heck - my camera experience is more with good 'ol 35mm movie cameras, although I am being dragged kicking and screaming into the digital world.

The new cameras use a low pass filter which causes it's own optical can 'o worms.

I have no knowledge of the DMK31 but I would imagine that the fringing could be a camera artifact or even maybe an interference pattern from the CCD and the reflection from a slightly skewed filter. :question:

#22 ToxMan

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Posted 07 February 2013 - 12:11 PM

Thanks, Andy. Honestly, it has been a dilemma. Bottom line, I don't try to image that way. Every setup has a sweet spot and when conditions are right, the real fun begins. Enjoyed your thread. My wife told me I'm not as smart as I think...she got a kick out of your thread, too.






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