Last updated: 22 June 2007

This page documents astrophotography comments, tips, and photos. Contributions welcome. Be certain to see the other articles on the main Astrophotography page.

Subject:	Off-Axis guider + CCD
Sent:	Friday, June 22, 2007 08:29:19
From: (
Is it possible to attach a CCD camera to the Meade off-axis guider? My
DSI won't attach because the camera end doesn't seem to be for CCD - it
is only threaded for normal cameras.

Know of any adapters? Ideas?

Noah Blaser
Mike here: The OAG uses a T-Ring style adapter to attach the camera. You would need a T-Ring type with a 1.25" eyepiece tube. I haven't looked for such an adapter but I would think they exist.
Subject:	Focusing with DG-2
Sent:	Tuesday, June 19, 2007 14:12:47
From:	Tom Collins (
I have had similar difficulties getting sharp focus while doing prime
photography with my DSLR camera.  Have you tried focusing with a
Hartmann mask?  Do you know if a Hartmann mask aids in fine focusing or
only gets you close?  I was hoping to make a mask and give it a try.
Mike here: I didn't think to try it with my Hartmann Mask but I have found the Mask only moderately useful in the past.
Subject:	Help With Astrophotography using ETX 125Pe And Philips toUCam Pro II
Sent:	Friday, May 18, 2007 06:16:27
From:	Simon Cowley (
First of all I have found your website very useful. I am trying to take
pictures of Jupiter and Saturn using the Philips toUcam Pro II.
Unfortunately with little success. With jupiter it was just a big blurry
disc with a yellow haze. Now could this be a focal length problem..
Using a 2x Barlow lens which only gives me a focal length of 3800mm. I'm
assuming I need between 4000 and 6000? Is this correct and is this where
i'm going wrong. I'll buy a 5x Barlow if need be..
Any help will be much appreciated Mike.
Kind Regards
Mike here: It almost sounds like you are overexposing the image. Set the software for shorter exposures. Before going with the Barlow Lens I suggest just imaging without it. Adding the extra magnification, while reducing the exposure and enlarging the image, adds focus and tracking complications.
Subject:	Meade ETX 125 Load Bearing Capability
Sent:	Wednesday, May 2, 2007 05:16:28
From: (
Recently purchased a ETX 125.  Love it!  I also bought a piggyback
adapter from JMI.  In the instructions from JMI, they cautioned against
using lens longer than 80mm because of weight.  However in your book I
see several pictures that obviously have much more weight than SLR with
80mm.  How much weight can I put on the scope without damaging the
drives and gears?  I would like to use my Canon 5D with 100-400L zoom. 
Together they weigh about 8 pounds.
Mike here: Wow that is a heavy camera/lens combination. I have used my Pentax Spotmatic plus telephoto lens and Nikon D70 with the 18-70mm and the 50-200mm lenses piggybacked (separately) on my ETX-90RA without any problems. If you find that the weight is too much, adding a counterweight system could help; lots of tips on the Helpful Information: Astrophotography page.


Thanks for the response.  I had just bought the book and had only
scanned the pictures.  Now that I have read it I understand there is a
limit.  However your experience has helped me a lot.  Yes the 100-400L
zoom is a very heavy lens.  I think I might be able to use it only in
alt-az mount.

Do you anticipate an updated version of the book?  There seems to be a
lot of newer info that I would like to see included.

Thanks again
Mike here: Yes, there are new models and new techniques and new accessories and so little time...
Subject:	Off Axis Guider for the ETX
Sent:	Monday, April 30, 2007 16:19:24
From:	Tom Collins (
Is there an off axis guider suitable for use with an ETX-125?  If so,
how difficult is it to make corrections to the tracking using the hand
controller?  Will this require an adapter to go from the thread size on
the back of the ETX to the SCT threads?  And finally, does it make sense
to use this setup on an ETX-125 or is this for larger aperture scopes?
Mike here: There is no Off-Axis Guider designed for the ETX. However, you could use the Meade #777 Off-Axis Guider ( but then you would also need a SCT Accessory Adapter (such as discussed on the Accessory Reviews: Miscellaneous page). I haven't been able to test my OAG on the ETX as I have not been able to locate my SCT Accessory Adapter! However, as I mentioned on the 21 April update to the Helpful Information: Astrophotography: Astrophotography Tips page, you would likely need to add a counterweight system to balance all that weight at the rear. You can make corrections using the hand controller.
Subject:	ccd cameras
Sent:	Tuesday, April 24, 2007 18:03:14
Could you recomend a ccd system or a dslr camera for astro photos with a
etx 125 

Thanks For Your Input Gary Wade
Mike here: You can spend <$100 or >$4000 or anyplace inbetween. I suggest looking through the items on the Helpful Information: Astrophotography page to see where your interests are. Digital cameras can work wonders as can webcams. And there are the SAC and Meade (and Celestron) imagers. Then there are the high end imagers as well. The LPI and DSI imagers from Meade include some pretty impressive image processing software.
Subject:	ETX125PE and Off-axis guider
Sent:	Thursday, April 19, 2007 09:29:12
From: (
I am looking at an off-axis guider (the Meade #777). I searched on your
sight and found reviews using the Meade LX series..I did find something
about the Meade #777 and the ETX, but if I read it correctly, it sounded
like the ETX125PE could not handle the weight.

I am wondering if the 125PE  can handle the weight of the off axis
guider and the nikon D70.
Mike here: I haven't tried mine on the ETX. First you would need an SCT Accessory adapter and then likely a counterweight system to balance all that weight at the rear.
Subject:	USB Active Extension Cable by Aucoin, Richard ((G.)) (
Sent:	Tuesday, March 13, 2007 07:03:18
From:	Kim Miau Lee (
The other one is this, 

The content is exactly the same.


-Robin Lee 
My Astronomy Blog-

Subject:	USB active extension cables
Sent:	Tuesday, March 6, 2007 05:58:04
From:	Aucoin, Richard ((G.)) (
Not sure if anyone seen this yet. Seems like the solution of getting a
decent run of USB cable to the imagers without signal degradation. Check
out the link and see what you think of article.   Rick

Subject:	Lunar eclipse 3-4/03/2007 with Meade DSI + ETX125PE
Sent:	Monday, February 12, 2007 03:19:08
From: (
Lunar eclipse 3-4/03/2007 with Meade DSI + ETX125PE

Thanks for let me know your point of view and advice about my actual
challenge, I finally think impossible; even with the Mogg Reductor,  I
have problems with the field of vision to track the WHOLE Moon with my
Meade ETX125PE  + DSI or WebCam TouCam Pro  + Mogg reductor.

Thanks for your help
Jeanine, 73 this month, 3825'N, 024' W  
Mike here: I don't have a DSI but I suspect that the long focal length of the ETX-125 would prevent you from getting a full moon image at the focal plane with the DSI (or even the webcam). Depending on the amount of reduction with the focal reducer, you may still not be able to do it. Sometimes a shorter focal length telescope comes in handy!
Subject:	Unsteady photos
Sent:	Sunday, February 11, 2007 12:11:52
From:	Jerry (
Can you help again, I have a DS 2102AT-TC refractor scope with autostar
#497 which I have coupled together with my Canon 30d DSLR camera. I can
manage to get superb lunar shots, but when trying for things like
saturn, Pleadies or the great Orion nebular I try to shutter expose for
15-30 secs, but I am getting star streaks even when tracking with
autostar. Is there any way of overcoming this? Hoping you can help.
PS Saving for the LXD75-8"SC as recommended by yourself.
Mike here: The AutoStar doesn't track that accurately for unguided exposures. Also, in Alt/Az mode you will get "field rotation" for longer exposures. But what I suspect you are seeing in your current exposures is image vibration from movement of the mirror as it moves. This movement will cause the telescope to vibrate. You can avoid that motion by using the "hat trick" method; hold something (like a hat or other light obstructing device) in front of the telescope aperture, release the camera's shutter (requires a Bulb setting mode), wait a few seconds for vibrations to dampen out, flip the cover out of the way, and then bring it back over the aperture to end the exposure, and release the shutter. With practice you can get consistent exposures under a second. Of course, this method is better suited for longer exposures. Note: you will need a manual release method for the shutter (my Nikon DSLR has a wireless remote). Touching the telescope is OK but only if you press the shutter to open it in Bulb mode and then press it again to close it.
Subject:	Lunar imager or dsi for etx90
Sent:	Saturday, February 3, 2007 18:22:35
From:	WAFFL (
Hi Mike, love the site!  I own an etx90 ec and would like to get some
photos of the upcoming lunar eclipse in March. I wanted to know if I
should spend the extra money for the Deep Space Imager or just get the
Lunar imager. Is the ETX90 capable of taking advantage of the DSI? ...or
am I wasting my money.
Thanks for your input
Mike Wagner
Mike here: The DSI can image successfully with the ETX-90. Just keep in mind that you will need to gain some experience with it to get the most out of it. Also, you will need a #497 AutoStar for either the LPI or the DSI. For the DSI you really need a Windows computer with USB 2.0. If you have only USB 1.1 then the LPI may be the better choice unless you plan to upgrade the computer.
Subject:	Astrophotography image processing
Sent:	Monday, January 29, 2007 23:03:41
From:	Steven Abba (
This may sound like a stupid question, but I have to ask. If I take 10 -
15 sec. exposures and stack them, wouldn't it be the same as taking 1 -
15 sec. exposure and making 10 copies? It would be easier to stack.

Thanks again,
Steven Abba 
Mike here: Yes and no. You add up the "signal" but you also add up the "noise". With different images you add up the signal and tend to cancel out the noise.
Subject:	ete 125 and a small refractor piggybacked?
Sent:	Sunday, January 28, 2007 08:19:35
From:	Stephen Olson (
I really love your site. I am on it daily! I currently have a meade
etx125PE. I love it, but would really like to get into taking pics. I
got the DSI2 color, and I dont think the 125 really works well with it.
I was hoping to piggyback another telescope with the 125. I really dont
want to buy another scope and mount. Is it possible to piggyback a small
refractor? If so what would be the limits? Any ideas? Hope your having a
great weekend!
thanks again,
Mike here: I have piggybacked my PST on my ETX-90RA ( That works great. I piggybacked an ETX-90 on an ETX-90 ( and that didn't work out so great. But a small refractor on the ETX-125 could work out better. You could use Losmandy tubes or for a simpler but effective solution, use a piggyback camera adapter on the ETX-125. The only issues you will have either way are weight and balance. You could make a counterweight system (see the Helpful Information: Astrophotography page for lots of tips on them).
what are Losmandy tubes?

this is what one of the guys in the meade dsi yahoo group reccommended

think its safe? Also what else would I need to get it setup? Sorry for
all the questions.
Mike here: Losmandy: The weight isn't bad. But you will need a way to mount it on the ETX, hence some rings, both on the ETX and on the refractor. You do realize that the costs are going way up to reach your goal... For two other sources of rings, see the Astronomy Links page.
Subject:	Horsehead nebula with ETX-125
Sent:	Wednesday, January 17, 2007 09:36:38
From:	Harri Hytnen (
I have been wondering, could it be possible to picture Horsehead nebula
with ETX-125 in prime focus.

Last night I tried this experiment and it really seems possible. At lest
from the technical point of view.
Mike here: From a dark site and with sufficient exposure time (or number of exposures if stacking images) there is no reason that the ETX can not capture the Horsehead nebula. If doing a single long exposure the difficulty will be tracking accuracy and field rotation (unless you mount in polar mode).
Subject:	Re: ETX 70 AT
Sent:	Sunday, January 7, 2007 03:24:53
From:	jkdfjsks sfsfsdds (
Dear Mr. Weasner.
I have a ETX 70 AT.
I all so have a DSI and a LPI.
I want to take photos with DSI and use LPI as a guider via autostar
Which is the instrument that i need for that job ?
An off axis guider ?
I need the exact model.

Many many thanks
Stelios Ambazidis
Mike here: You need another telescope. The ETX-70 won't handle the weight of an off-axis guider with both the LPI and DSI attached. Plus, if you want to use the AutoStar Suite you will need a #497 AutoStar, not the #494 that is standard with the ETX-70. I've not heard of anyone using the LPI/DSI combination with an off-axis guider but it sounds like an interesting idea.
Subject:	Soory
Sent:	Friday, January 5, 2007 16:56:14
From:	rbwhite (
I'm sorry to ask what is probably a dumb question. If one can't be sure
that a camera attached by adaptor to the port at the bottom of the tube
is in focus, then what is the point of having that feature, and the
ability to switch the mirror out of the way?
Mike here: SLR cameras CAN be sure (or reasonably sure) that the image is in focus. Also, the port has other uses as well. Keep in mind that before there were digital cameras and digital imagers, there was film. And not all film imagers had viewfinders. So, tests (or mounted, then unmounted viewfinders) had to be used. We got it easy now days!
Subject:	RE: Is Compressed RAW (new Nikon D40 NEF format) OK for astrophotography
Sent:	Friday, January 5, 2007 01:29:48
From:	Tom Hanson (
thanks for your reply. I'm not daunted by the extra processing needed
for raw, I just wondered if the compressed NEF format on the D40 gave as
good results as the uncompressed NEF on the D70 and D50. Do you know of
anyone who's tried the D40?

many thanks, and a great site by the way! 

regards Tom 
Mike here: Don't know of any D40 users but there is a review at the Digital Camera resource page ( A great site.
Subject:	Is Compressed RAW (new Nikon D40 NEF format) OK for astrophotography
Sent:	Thursday, January 4, 2007 07:22:16
From:	Tom Hanson (
I own an ETX125 and am contemplating buying and piggybacking the new
mikon D40. Can you answer whether the NEF format is ok. Compressed Raw
almost seems a contraction in words, and a friend of mine said I must
stick to RAW format to avoid detail loss when compression occurs (for
Jpeg etc).


regards Tom
Mike here: People have been using JPEG for years for astrophotography so the loss of data has been tolerated by most people. I've been using Raw with my D70 for over a year. Your choice whether you want to deal with the requirements of using Raw or start with the easier to use JPEG format.
Subject:	Re: Using DSX90 on a mountaintop?Thanks Mike!
Sent:	Tuesday, January 2, 2007 09:43:23
From:	Andy Horanic (
Thank you for you speedy reply- I will go read in your webpage as you

Hope to leave in about 2 months or less.

Have you ever photographed Aurora yourself?

I notice Optics Planet has sale on Meade video cameras for 100 dollars-
wonder if these will work?

Have you ever made spectrum displays? Is it possible to measure Doppler
shifts from these?

Do you have a Mac laptop? What's your advice on the type of Mac
computer(laptop) to do the editing?

The sky above is often referred to has the Heavens, our eyes are NEVER
good enough when looking up...perhaps this is telling us something...
Have you had a chance to see the DK book called 'The Universe'?- Got it
as a present last Christmas- a wonderful book!!

I better go for now...Florida is 80 Again today!!!! Not good viewing least I can see the Moon.

All the best
And a Happy and Prosperous New Year,
Andy Horanic
Mike here: Yep, photographed aurora; don't need a telescope for that. The video cameras are nice to display an image on a TV screen. Beyond that they are not too useful (in my opinion). I haven't done any spectroscopy in decades but as you can tell from the Guest Astrophotography pages, several people have done this with the ETX. As to whether you can measure "red shift" will depend on the accuracy of your spectroscopy equipment and techniques, including how you generate lines for comparison purposes. Yep, use a PowerBook G4 17". Which model works best will depend on what you want to do, including more than just astrophotography. My next laptop will be a MacBook Pro 17". But then I do a lot with my computer, including video editing and making DVDs, Raw image processing, and some scripting. Don't recall that book; but there are many excellent resources available.
Subject:	Astrophotography questions
Sent:	Monday, January 1, 2007 20:31:56
From:	Steve (
I have two questions relegated to astrophotography.

1.  What is the best tracking accuracy that can reasonably be expected
with the LXD55 mount expressed in terms of arcseconds per minute drift

2.  Is there a way to set up binning with the DSI II?
Mike here: I have never measured it but you can correct for it using the AutoStar PEC setting. However, I have left an object centered in a medium power eyepiece and come back a couple of hours later and the object was still basically centered. And that was without any PEC adjustment. As to binning, don't know since I don't have a DSI II.


Thanks for the prompt response.  As to binning, I had to ask since the
instructions don't go into it, but I guess, since they don't go in to
it, you cant do it.

As to the drift question,  check me on this.  If a medium power eye
piece had a field of view of  half a degree that would be 30 x 60 or
1800 acs.  So if the target was still centered within about 10% or 180
acs in two hours or 120 minutes then the drift would be 1.5 acs per
minute.  Does that sound reasonable?  I asked because I wanted to
establish the longest exposure that was practical without drifting out
of the fov of about half a pixel on the DSI. At f3.3 the fov for one
pixel is supposed to be about 2.6 acs so after about a minute photons
are going to be slopping over on to a different pixel from where they
started.  I doubt I can get the mount to track as well as you can so a
30 second exposure without noticeable drift should be doable for me and
should be ok.  A lot of the images I see in magazines have 10 or 20
minute exposures, so I could easily stack enough sub images to get that
exposure time.  Thanks.
Mike here: Sounds OK but there is no reason you can't get the mount to track as well as many other people have.


Thanks for your confidence.  As I work (play?) with it I will try to get
some accurate numbers for drift.

Subject:	ETX 125
Sent:	Monday, January 1, 2007 12:14:49
From:	rbwhite (
I have an ETX 125. I have a converter so that I can mount my Ebel XT at
the bottom port, and the mounting words well. What I don not understand
is what I can do to make sure that the picture, while in focus at the
eye piece, can be in focus at the camera. Please help me.
Mike here: I'm not familiar with "Ebel" cameras but if it is a SLR you can focus using the viewfinder. If not a SLR then you will have to determine where the focal plane for the camera is in relation to the back of the ETX and focus the image on a piece of tracing paper at that distance. You could then possibly make an eyepiece focus at that same position by adjusting it in the eyepiece hole (this may or may not work depending on the camera).


Should I understand that when an slr camera is mounted on the rear port
using an adapter, that if the eye piece at the side of the tube is in
focus, the camera will also be in focus?
Mike here: The image at the camera's focal plane will probably NOT be in focus when the eyepiece image is in focus to your eye. Depending on the eyepiece and camera and its adapter, you may be able to create a condition (by trial and error) where you can insert an eyepiece, focus it, and have the image in focus at the camera.

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Copyright ©2007 Michael L. Weasner /
Submittal Copyright © 2007 by the Submitter