First attempts at astrophotography with Orion Solar System Imager
Hello everyone,
Having recently purchased 12'' Meade LX200 I finally had a chance to take it out for a first light imaging session with Orion SSSSI IV last weekend. Conditions were less then ideal with occassional wind gusts and less then average seeing (typical spring time weather in Canberra..). I was using Antares f6.3 reducer for lower power moon shots, did not use barlow on Jupiter due to planet's low elevation. Here are final results and yes I am still coming up to speed with Registax and Photoshop processing. I'd appreciate everyone's comments and suggestions on how I can improve my future attempts. One thing I have noticed is high noise levels on this camera, they were quite noticable on high power Moon shots. Also I could not get it to register presence of Uranus or Neptune in the field of view, even with 3x Barlow..
A good start with that camera, especially the Jupiter.
Re noise, try to reduce the gain a bit. Even if the image is a bit dim on the preview, it will be possible to brighten it post process, but at lower gain the camera should have less noise. Does your capture software show a histogram? For example, you can get a good image even when the max level is 50% during capture. Also, the longer the capture (and therefore the larger the stack size), the lower the noise in the final image.
I know your camera has small pixels, but I think even so, and even at this low elevation, Jupiter will benefit from a 2x Barlow. Worth giving it a try. However this will make the image dimmer, and might mean lowering the frame rate to 30fps or even 15fps.
For Uranus (and Neptune), you'll need maximum gain, and relatively long exposure time e.g. 0.25s or more. Start without a Barlow, then switch it in if the seeing and capture settings allow. You may need to increase the gamma to get such dim targets.
Ivan and David, thanks for your advice. Yes, I have found manual focusing quite challenging on the night - mirror shift was evident when swapping between targets and I had to deal with focusing knob backlash every time.. not used to Cassegrains and the way they operate . I hope that Peterson kit and Meade electric focuser (which I have now ordered) will make a difference.. would like to lock the primary during imaging sessions. I was also using the flip mirror from Orion for centering objects visually but could not reach parafocus with any of my Series 4000 Plossls (camera has 1.25'' adapter attached to it on SSSI end). Bintel suggested I use an eyepiece ring, has anybody else encountered this problem on LX200?
David, I am using supplied Orion AMCAP capture software which does not have the histogram, do you know of any better alternatives? I was capturing with all pixels (1280x1024) at max frame rate of 15. Camera options menu allows me to change brightness, contrast, gamma, hue, saturation, sharpness and exposure. I would appreciate some feedback from other AMCAP users as to what settings are optimal for planetary imaging (at both f10 and f20).
I had some fun recently creating a movie clip in Photoshop showing Jupiter rotation, results below. Hope to take the scope out again soon..
David, one more question - I understand benefit of longer capture times from noise reduction perspective but how long is too long for Jupiter given its fast rotation? I was geting coloured halo around the planet post stack.
Quote:
Originally Posted by lepton3
Also, the longer the capture (and therefore the larger the stack size), the lower the noise in the final image.
...but how long is too long for Jupiter given its fast rotation? I was geting coloured halo around the planet post stack.
For Jupiter at a focal length of about 7 metres I think around 2 minutes before you'd start to get smearing of detail in good seeing. In poorer seeing, or with less magnification, you can go proportionately longer. Also, the free winjupos program can be used to "derotate" longer videos.
The coloured halo sounds more like focus, or possibly IR bloom. Does the imager have, or have you added an IR block filter?
For Jupiter at a focal length of about 7 metres I think around 2 minutes before you'd start to get smearing of detail in good seeing.
Thanks Ivan - I think I was in the ball park then.. shooting at 15 fps the longest clip had about 2500 frames so under 3 minutes.
Quote:
Originally Posted by lepton3
The coloured halo sounds more like focus, or possibly IR bloom. Does the imager have, or have you added an IR block filter?
From the manufacturer's website: 'The StarShoot Solar System Color Imager IV features an integrated IR-cut filter to block both ultraviolet and infrared light' - http://www.telescope.com/Astrophotog...58/p/52175.uts
I was not using any filters with the CCD, this being my first outing I did not want to experiment too much.. I'm including an example of Registax processed image with the artefact present (I have magnified it in the second pic for clarity). This is after stack and wavelet processing. Can this be field rotation?
The colour is (lateral) chromatic aberation. It's from some optical element in the photon path. If you look at the opposite edge of Jupiter you'll see the blues partner colour: yellow. Blue-yellow and red-green fringing are the two common types, RAW converters usually have a feature in them to correct for it. There should be options or plugins to help remove it in non-RAW image formats (I've only used it when loading RAW images).
It should be very obvious on the bright edge of the moon, so might be worth doing some test shots swapping in/out anything you can that has a lens element in it to try to find which ones are causing the problem. You can also do this during the day by shooting something fine and in shadow backlit against a bright sky. Shooting bare tree branches against a bright sky is where its very noticable (or a TV antenna), where you have lots of solid "black" (underexposed) fine lines against a white "overexposed" sky. The colour fringing stands out strong and its an easy way to take shots through whatever optics you have to see which items give you the cleanest image and which are the worst offenders. Camera lenses or telescopes its all just optics and any element in the optical path to the sensor could be at fault.
Silly question, but how are you getting any usable images with this camera? Have you found Windows drivers or a registry hack that unlocks the auto exposure?
Maybe the auto exposure "stabilises" if you have a tracking mount (which I don't have) but I haven't been able to find any way to disable the auto exposure (there is always a tick in the box next to exposure that can't be unticked and the slider doesn't do anything as a result...its the only setting thats not fully manual). Even imaging the moon is useless for me currently with the drivers supplied on disc, so I've uninstalled to everything to be able to get the Toucam running again.
You got me a bit worried now since I was imaging at native f10 on the night (not using any additional lenses in the path). My LX200 is brand new and this was my only second outing / first imaging session.
On the first night out, having been late with installing Kendrick dew cap, I got some moisture forming on the corrector plate around 2am. I promptly put the main dust cap back on and brought the OTA indoors. Last Saturday night I shone a torch at the plate and discovered to my horror that it was covered by a lot of fine dust! Tried blowing some of it away with the hurricane blower without much luck.. Don't know if that first night's dew coupled with Canberra's spring pollen are the culprits.
Can condition of the corrector impact image quality in this way?
NB I have not tried taking day time photos with the SSSSI yet, will give it a try when the dusty season's over..
Quote:
Originally Posted by sil
There should be options or plugins to help remove it in non-RAW image formats
Thanks, I will try searching for these online.
Quote:
Originally Posted by sil
Have you found Windows drivers or a registry hack that unlocks the auto exposure?
I was running out of the box, unmodded version of AMCAP. All I have done is checked the Low Light option, lowered exposure setting to 4 and increased the Gamma slider to around .8. I think I will give SharpCap software the go next time as I do not like the way AMPCAP allows you to overwrite previous capture files without warning. I must have done it about three times before realising what was happening!
I've only got el cheapo newtonians so far, nothing fancy so I don't think the Orion cam will help unless they unlock the autoexposure or maybe if I get a tracking mount. From reading reviews/feedback it gets a clear mixed reaction, my guess is the negatives are from people like myself without a tracking mount who get a target lined up just out of shot, then capture video as the target moves across the screen...rinse and repeat and stack etc. With the Toucam I can lock off exposure properly whereas the Orion adjusts exposure itself which is useless. I think on a tracking mount the autoexposure keeps the image at a reasonably constant level and you can use the exposure slider to over/under expose to taste.
As for the aberations you're getting I would expect they are a refraction artifact, so the light passing through something clear (like your field flattener? or what about the clear front I see in pics of cassegrains (or is that the dust cover?). I honestly don't know about how mirrors behave, but I wouldn't expect refraction unless the mirror surface is under a clear layer. For example a bathroom mirror has the mirrored surface behind a layer of glass to protect it, telescopes to me should have the mirroring on top for maximum reflection of photons without distortion.
Dust on the mirror I wouldn't expect to cause refraction, but dew certainly could (clear water refracts light, dew drops of any size will do it). Are you shooting through an eyepiece? Does the focuser assembly have a correcting/barlow lens element in it?
The aberations are very noticable in highest contrast areas (bright edge of the moon) you can try to reduce exposure so you are not overexposing the brightest parts. After processing you should be able to bring up the brightness in the shadows without bringing up the aberations.
Something I've done in the past with photography where I'm shooting something static (not moving) with strong aberations is to take a bunch of shots but recompose each shot of the subject. So for example I'd take my camera off tripod and shoot continuous for a few seconds handheld. My slight body movements will mean the subject is in a slightly different position in each frame. The aberations change in different ways across a glass element so by shooting this way I have a bunch of shots of the subject with differing aberation amounts so I can then align and stack them to greatly reduce the effect across the whole shot. If that makes sense
First attempts at astrophotography with Orion Solar System Imager
. I hope that Peterson kit and Meade electric focuser (which I have now ordered) will make a difference.. would like to lock the primary during imaging sessions. I was also using the flip mirror from Orion for centering objects visually but could not reach parafocus with any of my Series 4000 Plossls (camera has 1.25'' adapter attached to it on SSSI end). Bintel suggested I use an eyepiece ring, has anybody else encountered this problem on LX200?
I'm including an example of Registax processed image with the artefact present (I have magnified it in the second pic for clarity). This is after stack and wavelet processing. Can this be field rotation?
Tried blowing some of it away with the hurricane blower without much luck.. Don't know if that first night's dew coupled with Canberra's spring pollen are the culprits. 
