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ETX ASTROPHOTOGRAPHY
Last updated: 7 February 2001
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ETX ASTROPHOTOGRAPHY |
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Introduction (10/31/98) Terrestrial Photographs (2/1/00) Astrophotography Web Sources (2/7/01) Digital Editing Tips (12/31/99) |
Eyepiece Projection (3/30/97) Prime Focus (11/30/96) Dual ETX Setup (1/19/00) ETX Drive Tracking (8/23/97) |
I have taken some astronomical photographs using the ETX. Eyepiece projection astrophotography has been done using a Casio QV-10 digital camera. Prime focus astrophotography has been done with a Pentax Spotmatic SLR (an OLD camera!). These photographs are Kodak PhotoCD processed. The PhotoCD processing gives excellent digital image quality compared to the Seattle Filmworks processing which has good quality. However, PhotoCD processing is more expensive than SFW processing ($8 for 24 exposures) and may take longer (2-4 weeks). It costs $20, including the $9 CD-ROM, for the first 24 exposure roll of film but you can add up to four more rolls to this same CD-ROM for $12 each roll. Seattle Filmworks processing supplies images at only 640x480. PhotoCD processing provides images in the following resolutions: 192x128, 384x256, 768x512, 1536x1024, and 3072x2048. Image quality is incredible. But please note that the astrophotos shown here are not representative of the excellent visual sharpness you see when viewing objects directly.
I recently purchased a Ricoh RDC-4200 digital camera. I won't go into a full review of this consumer camera but for a $499 camera that does 1280x960 and 640x480 at several compression modes, 
outputs in JPEG format, has a 3x optical zoom (from 35mm to 105mm), and supports Smartmedia 4, 8, and 16MB memory cards, it is a very nice camera, albeit a little slow in capturing and displaying photos and switching modes. A complete review is available at www.dcresource.com. Since this is a higher resolution camera than the Casio QV-10 described above, you will notice that photos of accessories that I review on these pages from now on will be of higher quality. However, so far my astrophotography with the Ricoh has not been as rewarding as with the Casio. In general, the techniques I have used with the Ricoh are the same as with the Casio. The only difference is that with the Ricoh I have to run the zoom to the full 3x in order to get the camera lens sufficiently close to the eyepiece to yield a near-fullframe image. Otherwise, the imaged area is only a small portion of the available frame. I have posted my initial results on the Astrophotography Gallery - The Moon page. I have attempted some shots of Jupiter but they were way overexposed even when the exposure was reduced. I have yet to try with filters on the eyepiece or reducing the ETX aperture. As I work more with the Ricoh and ETX, I'll update this information.
Eyepiece ProjectionEyepiece Projection astrophotos have been taken by manually holding the Casio over the eyepiece lens (correctly known as "Afocal technique", but I will continue to use "eyepiece projection on these pages for simplicity's sake). While difficult, the results are rather amazing. The Casio is a fully automatic exposure 
camera, which normally would not lend itself to astronomical photography. When used on the Moon it works well enough with the exposure. For other objects not as large visually as the Moon, such as Jupiter or Venus, the extensive black areas in the view will tend to overexpose the object being photographed.
I also have a Meade Basic Camera Adapter and have been using the Pentax to take some photos that are on display. See my ETX Accessories Comments for more information and some observations on using on the Meade Basic Camera Adapter. 
I now have an attachment to mount the Casio digital camera to the Meade Basic Camera Adapter. I purchased a Tiffen Casio Lens Adapter for my QV-10 (also works with the QV-10A and QV-100) for about $25. The adapter is normally used to mount 37mm lens (also from Tiffen). Unfortunately the threads do not match the Meade Basic Camera Adapter so it was 
necessary to purchase an adapter ring. After visiting two local camera shops and searching for a few hours I finally found a ring ($2) that was close to what I needed. With a slight modification (removing some extra plastic from the interior of the ring, I was able to force the Camera Adapter to thread into it. This ring then attaches to the Tiffen adapter and provides a reasonably secure mount for the Casio camera. Using normal extension rings from my Pentax system, I can lengthen or shorten the amount of projection. Unfortunately, even the shortest mounting results in a decreased field of view on the Casio viewfinder, as shown here. This can cause difficulty locating and centering objects on the Casio LCD viewfinder.
Prime Focus astrophotos are taken using the Pentax Spotmatic. See my ETX Accessories Comments for more information on the Meade T-Adapter.
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In late 1998 I attached a Pentax Spotmatic 35mm SLR with a 230mm telephoto to the ETX using the JMI Piggy-back Camera Mount and used this setup for some long duration (several minutes) astrophotography of deep sky objects. The ETX was guided using the Blessing Microstar Dual Axis Drive Corrector and monitored with the Celestron Guide Eyepiece. The results have been posted on the Astrophotography Gallery - Deep Sky page. This setup is shown below.
Well, I have just gone to the next step. If you have purchased a new ETX-90EC and are wondering what to do with your original ETX, you can try this:
I call this the "Dual ETX". I used the JMI Piggy-back Camera Mount to hold the second ETX. The top mounted ETX is the guide scope using an illuminated reticle eyepiece. The bottom ETX has the 35mm film camera at Prime Focus.
My initial trials were with the base from the original ETX (with the Microstar controller) mounted on the JMI Equatorial Wedge and Tripod, as shown above. In this configuration there were two significant problems, especially when the scopes were pointed near the vertical: (1) camera weight so far out from the rear of the bottom ETX caused the JMI Wedge latitude setting to actually slip (which I didn't notice until completing the trials), and (2) the DEC axis movement for tracking error corrections was unreliable due to the Microstar rubber O-rings slipping on the DEC rotation knob. I had to manually move the DEC axis at times to assist the Microstar. This is not the fault of the Microstar but was due to the friction of the O-rings on the knob being insufficient to overcome the excessive weight of the camera. So, counterbalancing is definitely an issue, as is stability in some orientations. But with some care it is a combination that may work.
I have also done some trials with the ETX-90EC (with the standard controller) as the base mounted on the Meade Deluxe Field Tripod, as shown below. (The ETX is actually attached to a Shutan ETX Easy-Mount adapter plate; a review will be forthcoming.) In this case I used the top ETX-90RA as the photo scope with the 35mm camera attached to its Prime Focus. I then used the bottom ETX-90EC with the illuminated reticle eyepiece in the Meade 45-Degree Erecting Prism at the rear port. This combination made guiding easy and corrected for a lot of the weight/balance problems of the previous setup. Although near vertical positions were still a problem (the DEC Lock would slip), this setup worked better as there was no slippage when making either RA or DEC tracking error corrections.
With either setup, the most difficult aspect was focusing faint objects on the camera's viewscreen. It was usually necessary to use a bright object (like Jupiter) to do the focusing and then use the photo scope's finder to align faint objects for photography. Then next most difficult aspect was finding a guide star sufficiently near the object to be photographed. This latter is a typical problem when using guide stars. But I was able to work through both of these difficulties and take some exposures. I'll report back on the results when I get the film back from PhotoCD processing and will post any worthwhile photos resulting from this new definition of the "Mighty ETX"!
[12/7/99]
The Right Tube Adapter (RTA) on the above ETX-90EC failed again. This is the same ETX-90EC on which I previously repaired the RTA using the replacement part from Meade, as described on my ETX-90EC Comments page (near the bottom). Unlike the first failure, I suspect that this failure was caused by the weight of a 35mm camera that was mounted piggyback on the Optical Tube Assembly (OTA). Normally, this weight would not cause a problem but I left the camera mounted for about three weeks with the DEC Lock engaged. Apparently the stress was too much and the RTA failed. So, a word of caution to piggyback astrophotographers: don't leave the camera (or another ETX OTA) mounted for long periods of time with the DEC Lock engaged.
[1/19/00]
I finally received my PhotoCD back with the photographs taken using this Dual ETX setup. None of the images were any good. All were trailed or had excessive vibrations in the images. So, even though the ETX drive (with a guiding eyepiece) can handle a piggybacked camera with a telephoto lens of about 230mm (which is the max I've tried), it can not handle a 1250mm lens! Oh well, it was worth the attempt.
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| I have been asked about using the ETX Astro for terrestrial photography so I thought I would put up some initial photographs done with the Casio. Using Eyepiece Projection (the only mode available with the Casio camera), you basically get a very powerful telephoto lens, probably too powerful for most things. You have limited field-of-view through an eyepiece, especially at higher powers where vignetting is really noticeable. For some reason I found focusing more challenging during the day than when photographing the moon! I did not have a good test subject today so just grabbed what was visible. | ||
 Viewfinder view |
 View with Eyepiece Projection (48x) |
 View with Eyepiece Projection (128x) |
Ivan Harris (irharris@hotmail.com) supplied the following: "We have done some squirrel pictures through the ETX. It works great although the f -stop is so high it needs to be pretty bright. Our back yard is not very bright so the squirrel moved some during the exposure (about 1 second)."  |
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Dennis Persyk (dpersyk@worldnet.att.net) supplied the following: "My astrophotos are still in a pretty crude stage of development but my terrestrial photos are better. I noted you have a section on terrestrial photography and I would be honored if you would include this. I started my ETX-90EC photography experiments with simple terrestrial shots, namely birds at our feeders. The image below is straight off the Kodak PhotoCD with no post-processing. The feeder was 50 feet from the ETX and I was shooting through two Thermopane windows at an angle of incidence of about 30 degrees. I used a Canon A1 and standard 26 mm Ploessl with eyepiece projection. The Meade variable-projection camera adapter was used with a Canon T-ring. Film was Fuji ASA 1600 and exposure was 1/360 second using the A1s internal averaging meter. The quality of the image is fair, limited mainly by film grain and very narrow depth of field probably a couple of mm. Nonetheless, the image compares well with Questar promotional brochures illustrating bird photography."  |
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There are many valuable sources of information on astrophotography on the web. I will start collecting some of them here. If you have found a useful site, send me the URL at etx@me.com.
There are some useful Adobe Photoshop tips at the following:
Several users have commented about using the Logitech QuickCam (formerly made by Connectix) with the ETX. There are some useful QuickCam tips at the following (most from the June 1998 issue of Sky & Telescope):
Subject: QuickCam Images Sent: Thursday, October 28, 1999 09:54:40 From: jim@emmgraphics.com (Jim Berry) I've gotten a few questions about the images of Jupiter and Saturn that I sent to you, so I put some information up on my web site at: www.emmgraphics.com/pilot Thanks, -jim berry
Using the ETX for long duration (greater than a few seconds) is a challenge. The following test exposures (just a bright star) were done to see just how a typical exposure would track. I should note that these tests were run before I moved and therefore the polar alignment was not perfect but should have been close enough for these short exposures. The film used was Kodak Royal Gold 1000 with the photos placed onto a PhotoCD.
| Tests using Eyepiece Projection | |||||
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| 26mm Eyepiece | 9.7mm Eyepiece | ||||
 30 seconds |
 60 seconds |
 120 seconds |
 30 seconds |
 60 seconds |
 120 seconds |
As you can see, at least with my approximate polar alignment, 30 seconds is essentially the maximum duration before tracking errors appear. As seen in some of my Deep Sky photographs, there is a tracking glitch that occurs in longer exposures that is different from how a polar alignment error would appear.
I have now tested the drive tracking with a better polar alignment from my new home (with much darker skies!). The drive continues to not track well beyond 30 seconds. I now suspect that the problem is due to the extra weight and balance change from mounting the heavy Pentax SLR camera. The reason I now believe this is because visually, even at high magnifications, I do not have any tracking errors. The ETX, while an excellent visual astronomical telescope, is obviously not designed for long duration astrophotography using heavy cameras. This doesn't mean that photography of bright objects (planets, moon, etc.) is not possible; it definitely is possible as shown in the astrophotographs in the Gallery.
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I was browsing your web site (really like it, btw) I have enjoyed reading it for the last year or 2. I saw some of the images you had taken with your ETXs and noticed some trailing on them, so I thought I'd use my newly learned image processing techniques and see if I could fix one up (I have never worked with a tri-color image). I used the next to bottom image at Astrophotography Gallery - Deep Sky (as shown below on the left) to play with. I thought you might like to see my results (shown below on the right).
Clear Skies!
Mike
PS- I used a combination of maximum-entropy deconvolution (30 iterations on each color channel) plus a low pass filter and then recombined the images.
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