[This is a repost of a question from Mike.
Hi Mike, I hope you don't mind, I moved your question to its own thread -- Paul]

Hi Paul,
I am somewhat of a beginner at astrophotogphy. I am using my 20 year old Meade LX3 SCT with a Losnmandy G11, a SV NH2 and and a ZS66 ED refractor for guiding. I use AA 4 and my camera is an SXV-H9C and a Lodestar for guiding. I am working through some elongated star issues with the SCT but have some decent pictures when I use the refractors to image and the SCT to guide. I recently took apart the SCT and re-greased the baffle and have made some mount changes to minimize flexure. I guess my quetion is that I am committed to using my SCT but I am not sure this program will be a huge help. I'm looking for an opinion. Should I invest in this program or should I start saving to replace the SCT with an LX200 ACF with mirror lock? I like the real time collimation but is it that much better than by eye? Also - will this program work with AstroArt? Lot's of questions - look forward to hearing your (and other users) opinions. Thanks - sorry for the long post.

Mike Savo

Hi Mike,

If you have an SCT, CCDInspector can certainly help. It can help in a number of ways:

1. Collimation: while you can collimate with just an eyepiece, CCDInspector makes it much more convenient and precise, since you can do your collimation without running between the front and back of the OTA, and without removing the camera off the telescope.

2. Image grading and measurement. CCDI helps you determine if there is a collimation problem, or a sag or a tilt in the imaging train (happens a lot with SCTs). It can also help you detect and measure mirror flop.

3. While taking images, you can use CCDInspector monitor the result to tell you how good the images are, if the focus needs to be readjusted, or guiding tweaked.

4. After taking many frames you can easily sort through them using CCDInspector to find the best ones to combine into a master.

5. CCDInspector also helps with the analysis of flat frames -- these are often tricky with SCT's.

6. If you decide to move up to a larger CCD, CCDInspector can predict whether your SCT will produce usable images with the larger chip, and how bad the vignetting will be.

CCDInspector can answer your question about whether you need a mirror lock or not. If you take a bunch of shots at different sky positions, you can measure the amount of tilt and collimation error that's introduced into the image: that will tell you whether you really need a mirror lock or not.

Remember that CCDInspector is available for a 30 day free trial with all the functions and features enabled. You can decide whether it helps you or not.

CCDInspector works with AstroArt and pretty much with any other software through the Generic Camera driver. The Generic Camera driver allows CCDI to automatically examine any new images written to a specific folder (of your choice). AstroArt will save each captured image, and CCDInspector will automatically pick it up, analyze it, and delete it (if you'd like).

Regards,

-Paul

Hi Paul,
Thanks for the reply. I was thinking the same thing - use the trial version and see how it does for my pictures. I downloaded the manual and I need to read it further but I do have a question. I understand about analyzing a picture that AA places ina specified folder - that's easy but how does CCDI work real time? What about binning 2x2 for focus since I use a color camera? Thanks - hope I'm not bugging you too much. Just want to make sure I get the most out of it when I try the trial version.

Mike

Hi Mike,

CCDI can handle color images (Bayer matrix) automatically -- you just need to tell it that the image will be a color image in the settings.

If you bin your camera 2x2, then the images AA will save will be binned as well. In this case, you simply need to tell CCDI that the images are no longer color (Monochrome).

CCDI works with your camera control software, AA in your case. You use your software the way you normally would to capture focus images. You'll just need to tell AA to save each focus image into a folder.

Each time a new image is captured by AA, it will be saved to the specified folder. CCDI monitors this folder, and as soon as a new image is saved there, it'll pick it up (in real time) and analyze and display the results.

Don't worry about asking questions: this is what this forum is for!

Regards,

-Paul

Hi Paul,
I thought of one more thing - are there any tutorials I could look at in addition to the manual? Thanks.

Mike

Hi Mike,

Sorry, no tutorial yet... I'll look into what it takes to make one.

Regards,

-Paul

quote:

Originally posted by Mike Savo:
Hi Paul,
I thought of one more thing - are there any tutorials I could look at in addition to the manual? Thanks.

Mike

Hi Paul,
It's been a while. I had convinced myself that I did need CCDI but have been reconsidering that decision. Of all the capabilities I see in the program I am most intereseted in the real time collimation and the real time tilt indicator. Being able to sort the individual files for star quality Aspect and FWHM is pretty cool too but... I do have additional questions. Seems the display for the tilt indicator and the collimation are very similar despite accessing them through different menu key strokes. How are they different? If the collimation is off, I know what to adjust on the SCT. I am assuming that if tilt is off, the program is thinks that collimation is good - although I see a collimation number is listed. What am I asking... If tilt is off, what should I adjust to fix it? Hope this makes sense - if not we can trade sme messages. Thanks!!

Mike Savo

Hi Paul,
I just reread my post. The second sentence should say I had convinced myself that I did not need CCDI but have been reconsidering my decision. Makes a bit of a difference. Sorry...

Mike

quote:

Originally posted by Mike Savo:
Hi Paul,
It's been a while. I had convinced myself that I did need CCDI but have been reconsidering that decision. Of all the capabilities I see in the program I am most intereseted in the real time collimation and the real time tilt indicator. Being able to sort the individual files for star quality Aspect and FWHM is pretty cool too but... I do have additional questions. Seems the display for the tilt indicator and the collimation are very similar despite accessing them through different menu key strokes. How are they different? If the collimation is off, I know what to adjust on the SCT. I am assuming that if tilt is off, the program is thinks that collimation is good - although I see a collimation number is listed. What am I asking... If tilt is off, what should I adjust to fix it? Hope this makes sense - if not we can trade sme messages. Thanks!!

Mike Savo

Hi Mike,

Tilt is really a form of miscollimation at the chip of the camera. CCDI has some intelligence to try to distinguish this from the more complicated collimation issues where, for example, the primary is not aligned to the secondary in an SCT (or an ACF, or an RC). While tilt is a linear phenomenon, misalignment of two non-flat mirrors produces a much more non-linear effect. Mathematics of trying to separate the two is not fool-proof, so parts of one error can, and sometimes do, affect the other.

It's easy enough to tell if tilt is occurring by collimating the scope using CCDI. Once the collimation error is reduced to the lowest possible value, any reported tilt is due to a tilt at the imaging plane.

Regards,

-Paul

Hi Paul,
I had a question about the collimation viewer for the SCT. It shows the three knobs for collimation. The manual says that these correspond to the bottom of the tube. So this is just an arbitrary condition that I would assign an A, B and C to the knobs and just rearrange the positions on the viewer to where my arbitrary assignment is when the scope is pointing at the star field being used to collimate. Is that correct? Im was a;sp wondering if an open cluster like M35 or either half of the double cluster would be suitable for collimation. Thanks - I am about ready to purchase the software!! Thanks.

Mike Savo

Hi Mike,

The knobs on the display are there to help you visualize your OTA and collimation knobs. You can adjust their display position to match the orientation of the knobs on your OTA. You'll have to keep track of which one is A, B, and C on your telescope -- or you can simply mark them on the OTA itself. I've placed sticky labels with the letter next to each of the knobs on my SCT. This way, when a certain direction of collimation error is reported, I can quickly tell which knob to turn.

M35 or half of the Double cluster would work well for collimation. How well depends on your field of view: you'll want to get at least 150 stars in the FOV for best coverage. If there are too few stars, you can simply increase exposure or average a few images together.

I don't recall if I had mentioned this before, but there is now also a single defocused star collimator available in CCDInspector. This provides the same numerical and direction display as the multi-star collimator, but uses just a single bright defocused star. On those occasions that you can't find a suitable star cluster near your pointing position, you can always use the single defocused star collimator:

http://pk.darkhorizons.org/CCDI/1StarCollimation.htm

Regards,

-Paul

Hi Paul,
I didn't know there was a single star option. That is exactly like the visual procedure but with the software telling you when you have it right and the camera in place. Very nice!! So then once this is completed and the collimation is good on a single star in the center of the field what results would be expected by looking at multiple stars? Is the multiple star collimation prefered? I'm thinking that once the single star alignment is optimized, that any adjustment with multile stars would not be the right thing to do. I would want to look for any sag and then the curvature map would simply show the scope capability. Is that correct?

Thanks.

Mike

Hi Mike,

Either collimation method will let you collimate your scope to a level better than is possible with a purely visual collimation. The major difference between the two are:

1. The single star collimator requires defocus of a star to about 50 pixel diameter on your chip. For SCTs and other movable primary systems, this may be difficult (for example if the primary is locked down in a remote observatory). Also, moving the primary may actually change collimation when refocusing in mass-produced SCTs, so a multi-star method may work better in this case, since it's performed while perfectly focused.

2. Multi-star method may not be the best method for small FOV systems, especially with long focal lengths, as it may be hard to locate suitable star clusters with enough stars to cover the FOV. Also, certain times of year when the Milky Way arms are low in the sky or below the horizon will make locating a suitable star cluster more challenging. This was the main reason I developed the single-star collimator this winter

3. Multi-star method can easily be used to double-check collimation without touching focus, for example at the start of an imaging run.

Either method will help collimate your scope. Which method you use comes down to convenience and what works best with your type of scope.

Regards,

-Paul

quote:

Originally posted by Mike Savo:
Hi Paul,
I didn't know there was a single star option. That is exactly like the visual procedure but with the software telling you when you have it right and the camera in place. Very nice!! So then once this is completed and the collimation is good on a single star in the center of the field what results would be expected by looking at multiple stars? Is the multiple star collimation prefered? I'm thinking that once the single star alignment is optimized, that any adjustment with multile stars would not be the right thing to do. I would want to look for any sag and then the curvature map would simply show the scope capability. Is that correct?

Thanks.

Mike

Hi Paul,
I realize that if I don't buy the software after all this you are going to kill me!! Don't worry I am buying the software but I do have another question!! My camera control software (AA) is not directly supported by this program so my focus window will not be visible to the single star collimation method since those images are not saved. In my case I need to do a sequence of short images with a possible delay between each image and save those to designated file that I have CCDI pointed to - is that correct and will that work? Thanks again.

Mike

Mike,

We have a policy against killing potential customers

With AstroArt, you'll want to use the Generic camera driver in CCDInspector. This is where you'll point CCDI to a specific folder, and then ask AA to save all the captured images to that same folder. Name of the saved file(s) doesn't matter, as CCDI will detect any new file written to that folder.

Start AA capturing a long sequence of images (can also be sub-frames, just select the center of the chip leaving some blank space around the defocused star).

Start CCDI Defocused Star Collimation viewer, and optionally, the Image Viewer to see the star itself.

CCDI will ask you if you want to automatically delete images after processing: answer Yes.

As soon as the next image in sequence is saved to the specified folder by AA, CCDI will it pick up and show collimation results. You may need to add a delay between images to make sure the frames are not captured faster than they are being processed. When capturing a full frame CCD image, this is unlikely to be a problem, but a couple of seconds delay between captures may be advisable.

This will definitely work, and has been tested like this even with webcams capturing defocused star images.

Regards,

-Paul