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Date: 8/1/2010 – San Bruno, California
Mount: Astrotrac travel system
Camera: Modified Canon XTi with Canon 200mm f/d 2.8 teleobjective (prime lens) opened at f/d 3.5 – at Iso 400. Installed on a tripod collar ring and a Manfrotto ball head.
32 exposures of 90 seconds with Astronomik CLS CCD clip filter, 12 flats frames, 10 darks, 10 biais.
For Flat fields I use an electroluminescent panel from Glowhut. This is by far the best way I found to take flats that “work” in a consistent way.
This is my second try at this with the same set up. I got much better results this time…. Even though it is taken from my backyard where usually magnitude 3 stars are barely seen. Transparency was a little bit better than usual – I would say between 3/6 and 4/6 (magnitude 3.5 stars seen at best) and M8 was quite low (below 30 deg.) so imaging was still a challenge!
The big difference with my previous posting is that my Canon XTi has been modified (Standard IR filter replaced with an astrodon IR filter by Hap Griffin) – and the response of the camera in the Red and especially HAlpha wavelength is much better…
Also this time I made sure the astrotrac polar scope had a centered reticule for better polar alignment.
I used the sane CLS CCD anti pollution filter, same digital processing, and same exposure time as in my previous try. The Astronomik CLS CCD works wonderfully with the modified Canon.
But this time I also used an “X-Tend a Sight mount” from Photosolve along with an Orion EZ Finder. It really helps to find and approximatively center the objects in the canon 200mm field of view since seeing stars through the Canon XTi is almost impossible. Then I take a short shot and re-center the object.
In addition I used a Bahtinov mask as a focus help. Focusing the Canon 200mm open at f/d 3.5 is really hard: in a fraction of a turn stars get out of focus. I found the mask to be of some help in getting more consistent results (even though you do not obtain the usual diffraction patterns you observe when focusing a telescope with the mask).
- MaximDL5: darks and flats subtraction, alignment and averaging
- Photoshop CS4: stretching, selective sharpening
- Noise Ninja: noise removal
M8 and M20 – Canon 200mm Teleobjective and Modified XTi
Details of M8/M20- Cropped image
The following objects can be seen in the field of view: M8, M20, M21, diffuse nebula Ngc6559, globular clusters Ngc 6544, Ngc 6553, open clusters Ngc 6530, Ngc 6546
Skytools 3 Atlas
Taken on 11/26/2009 between 3am and 5am at San Bruno, CA. Seeing: 6/10 (Alpo scale) – Transparency: 3/6 -Wind < 5Mpmh
Here are new pictures of Mars, shot at the end of November 2009. At this time, the disc was about 9.5″of diameter. For such a small target I had to tweak my planetary imaging set up to get better results. On the other hand, Mars is at a fairly high altitude, making it easier to deal with turbulence. There were few chromatic distortions (usually there when objects are lower on the horizon – e.g. for Jupiter in the 2009 opposition at my latitude).
Telescope: Orion Maksutov Cassegrain 7″ on Atlas Mount
Camera: DMK Imaging Source B&W with RGB Filters
Barlow: from Siebert optics – this is an excellent barlow that can be used for 1.5x, 2.5x or 3.5x power magnification. Even though the Maksutov is at f/d 15, a barlow is necessary to reach the maximum resolution. Given the space between the camera and the barlow due to the RGB filter wheel I estimate the “true” magnification I used this night to be over 2.5x, which brings the pixel resolution at less than 0.2″ by pixel with the DMK Camera.
Processing: Registax V5 (Frame combinations), Maxim DL5 (initial RBG alignment), Photoshop CS4 and Nik Sharpener Pro 3 for final image processing.
Mars – 11/26/2009 – 4.24AM – RGB composite (see green and red channel below)
Red channel : 4.24AM PST Green channel: 4.18 am PST
Two more pictures, taken respectively by 3.44AM and 3.53AM PST
Some notes about the planetary imaging set up: I used the same Planetary set up as explained in this post, but in addition, I added a Meade Microfocuser to the configuration (Meade #1209 Zero Image-shift Microfocuser for Schmidt-Cassegrain).
I removed rhe flip mirror for increased rigidity and alignment of the camera body and filter wheel.
The space gained by removing the flip mirror allows having a reasonable distance between the barlow and the camera body.
When removing the flip mirror, it becomes indispensable to use the Microfocuser because you can focus without moving the primary mirror. Which means Mars stays in the field of view instead of jumping around when you focus with the maksutov cassegrain focuser. Otherwise you need a flip mirror to re-center the planet after focus: the field of view of the DMK camera is very small and you easily move the planet “out of target” when focusing.
In addition, the electric microfocuser allows a fine grain focus very hard to achieve with the manual focuser at the back of the Maksutov Cassegrain OTA. When doing planetary imaging at high F/D it is a must-have accessory…
I would like to present the astrophotography set up I used for the recent pictures of Jupiter I took during the Jupiter Opposition of August 2009. I found this set up to work quite well, allowing me to take quickly, and in a repeatable manner high resolution pictures (when the seeing allows it!).
This set up will work on any Telescope having enough in-focus travel, which is the case for Schmidt Cassegrain and Maksutov Cassegrain Telescopes.
Telescope and accessories
First, the Telescope: Orion Maksutov Cassegrain 7″ – on an Orion Atlas Mount attached to a Pier.
I am very happy with this telescope. The scope has to be placed outside 2h before observing to cool down, but otherwise the scope is very easy to set up, keep extremely well its collimation, and has a quite a good optical quality. I noticed also that once the tube reaches thermic equilibrium, the scope is less affected by Turbulence (most of the time) than my larger aperture telescope (SCT 9.25″) when the seeing is average or below average (3-4/10 on ALPO scale) – which is unfortunately the case most of the time at my location (San Bruno, CA).
Here are the accessories / cameras I use for this set up:
- 1 – Telrad unit, with Dew heater: the Telrad is very convenient to align the Telescope and/or point to bright objects. There is no need for a conventional Finder when doing planetary observation with a go-to scope! Note the Telrad gets foggy very quickly – the Dew heater is a must as soon as the temperature drops below the dew point. The dew heater was ordered at Agena AstroProducts
- 2 – Focusing knob: It is probably not as good as an electronic focuser, but it is cheap and does reasonably well the job. The focusing knob was ordered at ScopeStuff
- 3 – Orion Filter Wheel: a must to take RGB pictures, especially with a planet like Jupiter, having a very fast rotation. RGB pictures have to be taken within 3 to 4 minutes maximum with this Telescope, otherwise the effect of rotation is noticeable when integrating RGB channels.
- 4 – Flip Mirror: with this it is extremely convenient to center planets especially with a planetary Camera having usually quite small sensor sizes. The flip mirror was ordered at Orion.
- 5 – Imaging Source Camera DKF 21AU04.AS: this is a great B&W camera with a sensitive and high resolution chip. Maximum frame capture is 60 fps! The chip sensor is very small (1/4″) but it does not matter for high resolution planetary astrophotography. However the camera cannot really be used to capture large lunar landscapes, and the Flip mirror helps saving time to center the planet in the sensor field of view.
- 6 – NetBook Asus 2G Ram/160G Disk : even though the camera capture frames at high rate, since the resolution is 640×480 on 8 bits – the size of the AVI files for a 30-40sec movie is still small (compared to my Orion Solar System Imager Camera where the Asus had trouble handling the frame download rate). The Netbook is built like a Tank which is great on the field – and has a long battery life (+6 hours).
Being new to B&W CCD astrophotography, I found the following benefits for planetary photography compared to Color CMOS sensor such as the Orion Solar system imager III:
- b&w camera are usually more sensitive, minimizing the exposition time (even with RGB filters, compared to CMOS color cameras)
- taking exposures in each channel allow an optimal focus for R/G/B – quite useful especially when captured objects are low on the horizon, with extra color dispersion caused by the athmosphere
- There is no bayer matrix in front of the sensor – for the same sensor pixel resolution, black and white sensor with RGB capture will produce more detailed images
- No bayer matrix and IR filter in front of the sensor gives complete control / more options when choosing which combination of filters to use
On the cons side, taking RGB pictures takes extra captures that have to be done in limited time (at least for Jupiter) and some extra processing time, but this is far out weighted by the benefits…
In terms of AVI/ picture processing I use the following software:
- Registax V5 for making composite images for each RGB channel.
- Max DSLR for aligning and combining RGB channels
- Occasionally, Astra Image 3.0SI for their great deconvolution utility
- PaintShop pro photo X2 for final processing: image rotation, cropping, histogram adjustment, and color adustments. PaintShop pro does the job and is less expensive than PhotoShop.
My recent scope acquisition: an Orion Maksutov Newton 190mm… I bought a “bundle” (brand new Atlas mount and showroom Mak Newt) in July 2009 .
I would recommend anybody buying a telescope to make this investment (artificial star and the book) and go through this procedure. It is worth it. A couple of month ago, I had to return a first Maksutov-Cassegrain because of some optical issues that was somewhat revealed looking a stars (but was not sure if it was due to turbulence or not) and the defect was revealed very clearly with the artificial star testing. I got a new scope because I was in the 30 days return policy – and the new scope was as good as the Mak-Cassegrain optical design permits…
Waiting for a great seeing to do a “real” star testing may not happen during the 30 days return policy. Make sure that when you do artificial star testing you have plenty of space – otherwise you introduce aberration that would not happen with “real” stars. In my case I placed the artificial star at least at 200 yards from the telescope.
To come back to my new Maksutov-Newton – I made the test and found (after thorough collimation) the optics extremely satisfactory, with nice diffraction patters in focus, and very similar (almost textbook-like) forward and inward out of focus diffraction patterns. Visual image of Jupiter was also crisp and contrasty, making it a good planetary instrument when well collimated, even though this is not the primary purpose of this scope (which is flat field astrophotography).
Look at the Perseus double cluster picture taken with the Mak Newton. Stars are pinpoint even at the edge of the picture (Canon EOS full frame). You would not have the same picture with a Newtonian (except if using a coma corrector) or even a regular Schmidt Cassegrain telescope.
This shot of M13 was taken with the Mak-Newt and my Qhy9 Black and White camera.
This shot of NGC 981 on this page was taken using the Mak Newton with my Canon XTi and an Orion Skyglow filter.
I installed (august 2009) a brand new Pier that I can use with my two mounts (new Orion Atlas and Orion Sirius).
The new Atlas Mount (bought in July 2009) is a must with heavier equipment I have now: Maksutov-Newton or Celestron 9.25″ SCT equipped with guide scope and camera. The overall assembly is far more stable than the mount and tripod and should lead to much better quality tracking and photography.
The pier was bought at Skyshed. I would recommend this company – it went pretty well and it was fairly easy to contact them to check from time to time how things were progressing.
I ordered two adapters / plate – one for each mount. A 45″ x 14″ hole was dug and filled with concrete and four 1/2″ J-Bolts are used to support the Pier.
The ordering took about 2-3 weeks. Below picture of the assembled pier with the Atlas mount plate adapter and Maksutov-Newton 190mm. I am very happy with the result!
I tried different techniques to bring in focus my Canon XTi,
Even by taken series of short exposures and using the preview / zoom functionality of the DSLR camera I found issues and results were not completely satisfactory.
I found mention of the Bahtinov mask on different blog post – and decided to give it a try.
The Bahtinov mask was built in-house for my orion 102ED using Bahtinov’s mask free templates posted on this web site
The materials used for building the mask can be found in stores such as Office depot,
I used a black plastic portfolio. Use a portfolio not too thick, that can be easily cut using a paper cutter – but rigid enough to be used as a mask. Using adhesive, the template (printed from my computer on Letter format) was glued on the portfolio plastic sheet. I used a DVD plastic box as a cover to secure the mask on the 102ED optical tube.
The way to bring the camera in focus is simple. The basic principle is the same as without the mask – doing an approximate in-focus first using the view finder – then tweak the in-focus by using short exposure and the preview mode of the camera – with the Bahtinov mask in front of the optical tube.
Below are pictures from Betelgeuse. The left picture is a 3 sec. exposure and shows Betelgeuse out of focus. The right picture is in focus. When in focus, the diffraction spikes are symmetrical with a easy to recognize pattern.
Betelgeuse – 3 sec. exposure – out of focus (left) and in focus (right)
Here are some pictures taken using the mask for focusing. The picture was shot in San Bruno, CA in a very light polluted sky – using the Orion SkyGlow anti-pollution filter and a Canon Digital Rebel XTi DSR Camera. Focus on M1 was made using approximately 6 shots on 3 sec. each on Betelgeuse. In this astrophoto session on 3/27, Focus was not changed during 2h where a total of 5 deep sky objects were shot using multiple short time exposures.
Picture of M1 – 3/27/2009