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Frequently Asked Questions - MaxIm DL
No, we do something much better. The camera control allows you to take image sequences and save them to disk. You then use the Combine feature to add the images together, with alignment.
While this might sound like a little bit more work, it has many advantages:
You can inspect each image and reject any that are trailed due to periodic error in the drive, wind gusts, etc. The alignment tool allows you to leaf through the images and discard bad frames.
Sub-pixel image registration is supported, and several different alignment methods are available, ranging from automatic star matching to manual overlay.
You can apply a full calibration, including bias, dark and flat, prior to summing the image. If there are any hot pixels you can also clean these up before they propagate through the combined image.
You can do a median combine instead of sum combine, which can eliminate cosmic ray hits, hot pixels, etc.
You have the original "raw data" and can reprocess the image if desired.
Yes! MaxIm DL is the first image acquisition software to offer uninterrupted autoguiding during image sequencing when using dual-chip CCD cameras. Other applications require you to restart the autoguiding for each exposure; MaxIm DL will automatically reopen the shutter and reacquire the guide star after the image download completes.
You can even take image sequences when using a color filter wheel - the filter wheel will be automatically advanced between exposures.
Yes, you can use RGB or CMY filters. You can also combine a luminance image in either case.
Yes! Unlike many astronomical image processing packages, virtually all of MaxIm DL's processing functions work equally well on monochrome and color images.
Yes! While most programs turn your computer into an expensive clock during exposures, MaxIm DL allows you to view and process images while an exposure is in progress.
Yes! While most programs turn your computer into an expensive clock during exposures, MaxIm DL allows you to view and process images while an exposure is in progress.
No. When you calibrate the autoguider, MaxIm DL notes the angle of motion of the star, and automatically compensates for it. This means you can attach your autoguider camera in any orientation, without any impact on guiding.
Yes. All cameras will work as autoguiders. Some cameras include built in relays for commanding the mount; if not, many mounts can be controlled via the Telescope Control, through the Starlight Xpress relay box, USB autoguider output devices, etc. Please note that connecting two cameras usually requires separate ports. You should be aware that excessive shutter wear may occur with some cameras, and that a few camera models are too slow for effective autoguiding.
Yes. Changes to the settings do not get used until you restart the autoguider, but you can just hit the "Stop" button and then the "Start" button again. Guiding will continue as if there was no interruption. This is possible because the autoguider controls are completely independent of the camera controls. Note that for situations where the main camera and autoguider share a shutter, you may have to turn off auto dark frame subtraction.
The autoguider is not calibrated properly. Go to the Guide tab Settings and set the X and Y backlash to zero. Set the X and Y Cal. Times to 20 seconds, or the highest you can use without the star going off the chip during calibration. If selectable, set your mount to 0.5X guide rate. Find a bright star and run the calibration procedure. Now try guiding on that star. If it still oscillates, try reducing the Agressiveness setting.
Remember, if you change Declination, you must either use the declination compensation feature or recalibrate. If you are not using the declination compensation feature, just leave the setting at 0.
It reduces the amount of correction applied. When the setting is 10, 100% of the error is tracked out. When it is 8, 80% of the error is tracked out.
Why would you want to reduce the aggressiveness? If the agressiveness could be set over 100%, the software would overcorrect and the tracking would go unstable; the star would bounce back and forth until it left the guide box. Calibration accuracy is never perfect because of backlash in the mount; decreasing the aggressiveness ensures stable guiding. A lower aggressiveness will also prevent the mount from following small random motions caused by scintillation and wind loads.
Generally speaking, reducing the aggressiveness improves the stability of tracking at the expense of response time. Usually a value between 5 and 8 provides the best tracking; you should experiment to see what works best in your setup.
Almost all telescope mounts have some degree of mechanical backlash in their gear systems. If you reverse the direction of motion, there will be a slight delay until the gears re-engage. On some mounts, the telescope will even go in the wrong direction briefly!
The backlash is measured in seconds; i.e. when you change directions, it is the duration in time while pressing the button before the telescope mount starts moving.
he term "stiction" comes from "static friction." Static friction occurs when two objects in contact are at rest or moving very slowly relative to each other. Dynamic friction occurs when the two objects are in motion. Static friction is always larger than dynamic friction, so when an object starts moving, the amount of friction present can change very rapidly. An example of this happens when you brake your car. Just before the car stops, you have to let up on the brake pedal; otherwise the car jolts to a stop (if you've been driving for years, you may not even be aware you are doing it).
Stiction occurs between the teeth in a gear system. Of particular interest here is the effect on worm drives, which are typically used in astronomical telescopes. When the drive is stationary, the gears "stick together." When the worm starts rotating, it pulls on the teeth of the worm wheel. In this situation, the wheel can bend, or the mounting or bearings can flex, at right angles to the normal rotation. The resulting motion is usually backwards - you try to move the mount North, and it goes South! This only happens for a brief period of time after reversing directions; eventually the worm turns enough that the gear is forced to move in the correct direction.
Stiction problems can be complex mechanically; it can often be hard to determine what the root cause is. Many telescope mounts - even high-end models - suffer from this problem, and it may vary between different samples of the same model. The problem has a terrible effect on guiding because it forces overcorrection, and it cannot be effectively solved in software.
If you experience bad guiding in declination and cannot resolve it through adjusting the calibration or aggressiveness, you may have a stiction problem. One solution that works is to note the average drift in declination, and disable corrections in that direction. The guider should only be able to push against the average drift, not with it. This works surprisingly well. Some users deliberately adjust their polar alignment slightly off to ensure that the drift is in a consistent direction. You should avoid large offsets that may cause field rotation.
You can disable one guide direction by clearing the appropriate Output checkbox in the Guider Settings section of the Guide tab Settings dialog. These check boxes only affect tracking corrections, not calibration, so you do not have to re-enable the direction in order to calibrate the guider.
Yes! If you do not at least take a single dark frame you are giving up a lot of your camera's performance. If your camera has a shutter, at the very least turn on the "Simple Auto-Dark" feature. However, we strongly recommend using at least some of the more advanced calibration techniques for best results.
It is not absolutely essential, but you will get up to 41% more noise if you don't average dark frames. It's easy to do. Just set up the camera to take a sequence of dark frames (if your camera does not have a shutter, just cover the telescope) at the same temperature and duration as your intended light exposure. Then open the Set Calibrate dialog, click the Select Files... button under Dark Frame, and choose all the frames you just took using the mouse and shift or CTRL key. Click OK, and you're ready to calibrate.
That depends. If you are just doing dark frame calibration without scaling, then you don't really need them. The bias is included in each dark frame.
If you are taking flat field frames or using dark frame exposure scaling, then you must use bias frames. Flat-field frames need to be bias corrected (and dark corrected using Auto-Scale/Apply to Flats if you are taking long flat-field exposures) otherwise they will not scale the image properly. If you are scaling dark frames, the bias part of the dark frame should not be scaled, and therefore must be subtracted first.
That is the simplest and often best way to go, but there are other ways to do it. You can use the Auto Scale or Auto Optimize features to compensate for different exposure lengths. This works better on some cameras than others (In particular, the hot pixels in Kodak KAF series CCD sensors tend not to scale properly).
This can be a major problem since the ambient temperature usually drops during the night. As the dark current drops, the calibration frames "over-do it." The answer is to use the Auto-Optimize feature. It automatically scales the dark frames to minimize the RMS noise in the image.
That depends. Flat-field frames are the hardest calibration to do correctly; in some cases, you can get by without doing them, but at some loss of performance.
If you are doing photometry, you absolutely need flat-field frames. If you are doing "pretty pictures," then it depends on what you are doing. If you have bright skies due to light pollution, you'll probably want to flat-field. If you have vignetting, then you'll want to do it. If you have dust spots, a can of compressed air is actually more effective!
If you are going for the faintest possible limiting magnitude with a long exposure, then the limiting factor is caused by the fact that your target is fainter than the sky background (even at a dark site). In that case, the flat fielding error will set the ultimate sensitivity limit.
Take at least 25 bias, dark, and flat-field exposures. Use the same temperature as the light frame for all, and use the same exposure for the dark frame as the light frames. Turn on the Auto Scale feature, and use the "Apply to Flats" option for dark frame scaling. Use median combine if you have any hot pixels or cosmic ray hits. If you are doing median combine, it's a good idea to increase the number of calibration frames somewhat.
The spectral response of the CCD camera varies slightly from pixel to pixel, so the flat-field only works perfectly if the spectrum of the flat-fielding light matches that of the target. When shooting for very faint objects, the sky background dominates, so the color of the sky background is what you need to match. This is best done with sky flats.
The usual way to take sky flats is to turn of the clock drive and let the stars trail. Take a LOT of exposures; 50 is a good number. Use the median combine option, which will drop out the stars since they will not match locations between images. The calibration command automatically "normalizes" the flat-field frames to the same intensity, so if there is a slight shift in light levels it won't hurt anything.
Since sky flat exposures tend to be long, be sure to turn on the Auto Scale feature and activate Apply to Flats. This will apply both bias and dark-frame subtraction to the flat fields.
MaxIm DL is designed to do all the calibrations in one step; there are a number of subtleties to calibration and the software knows how to handle them, but only if it knows all the calibration steps you are planning to do. It is strongly recommended to do all calibrations in one step, and do NOT perform any modifications on the raw calibration frames beforehand.
Take your dark frames with the STAR2000 guider running, and with the image type set to Light, not Dark. Also, some tweaking may be necessary to get the best possible amplifier glow suppression. To do this, open the Pixel Math command (Process menu). Enter the light frame for Image A. Enter the dark frame for Image B. Select Subtract. Set Add Constant to 100. Set Image A Scale Factor to 100%. Zoom out and pan the image preview window until you can see the amp glow area. Now adjust the Image B Scale Factor to minimize the glow. Click OK.
Yes, the Homeyer driver works via the serial port. Note, however, that not all such filter wheels are compatible with the higher voltages on the RS-232 port. Damage to the filter wheel might result if the maximum input voltage is exceeded. We have only verified at this time that Homeyer wheels are compatible with this interface.
The following circuit will convert the voltages on a serial port output to work with a CFW8-style filter wheel. Note: use this circuit at your own risk; incorrect wiring could damage the filter wheel.
White is Pin 2, Black is Pin 5, and Red is Pin 9.
The USB protocol is designed to provide completely error-free communications bewteen the computer and the peripheral (camera). Unfortunately this does not account for peripherals that do not respond correctly, whether due to bad drivers sending the wrong message, or incorrect firmware in the peripheral itself. Normally such problems would be detected by an "I/O timeout", where the operating system gives up after trying for a time; unfortunately this basic precaution was not included in Windows. As a result, if this type of error occurs the application will lock up. If this happens, briefly unplug the USB cable to unlock the application. You should also contact the camera vendor for assistance in resolving the problem.
MaxIm DL will operate under Windows XP, Vista, 7, and 8.
If you upgrade operating systems, MaxIm DL must be reinstalled.
MaxIm DL is designed for Microsoft Windows. You can use Boot Camp to run Windows and MaxIm DL. Some customers have reported success using the latest version of VMWare Fusion, but we do not officially support this configuration and cannot provide technical support in that environment.
If you use Boot Camp to run Windows then all functions are available including camera control. Some customers have reported success using the latest version of VMWare Fusion, but we do not officially support this configuration and cannot provide technical support in that environment. Parallels is known not to work.
We only accept VISA and MasterCard. Please note that only your bank can explain the reason for declining a transaction; for privacy reasons we do not receive that information. Some banks have unusual restrictions on internet purchases - especially international sales - but will process the payment if you call them to pre-authorize the transaction. Also if you submit three unapproved transactions on the same day, our payment server will automatically lock out that credit card for 24 hours.
You receive free upgrades via download for one year from the date of purchase. You are entitled to any upgrade that comes out during that time. After your upgrades expire, you can purchase an upgrade subscription.
First, check the Troubleshooting section of the built-in help; the answer to your question might be there.
The easiest way to get support is to run MaxIm DL and use Help menu Technical Support. You can also go directly to our Technical Support page. Remember to include your serial number and a detailed description of your problem. If you did not purchase your software directly from Diffraction Limited you will need to register your copy first.
If you purchased from us directly, you are already registered.
If you purchased from a dealer, select Help menu Register Online. Fill out the form and click Submit. For MaxIm DL and MicroCCD you will automatically be sent your permanent license when you register.
Yes, Version 4 and 5 licenses can be upgraded; however there will be a fee for transferring the registration. If you purchase a second-hand copy, please have the original owner write to us stating that he/she has transferred the license to you, and that he/she has deleted all copies of the software and transferred all disks and manuals to you. We will also need a copy of your bill of sale.
Once we have received this, we will record you as the current owner of that particular license. However, if you wish to have the license reissued under your name, you will have to pay a re-registration fee of $100. A new license with your name, but with the SAME Expiry Date as the original license will be sent to you. If you would like a new expiry date, then you will have to purchase a one-year or two-year subscription at the current posted subscription prices, in addition to the re-registration fee.
Version 1, 2, and 3 are no longer upgradable. The original owner can apply for a $50 discount voucher against the purchase of a new license.
No. That is a violation of our software license agreement and is strictly prohibited. You were sold one license which permits you to use a single copy of the software on a single personal computer. That includes any and all updates, no matter whether the update was minor (e.g. 5.00 to 5.01) or major (e.g. 4.62 to 5.00).
Contact us via Technical Support. We'll need some basic information to confirm your identity, such as your name, telephone, and address. If that checks out we'll send you your license, plus a link to download the software. Please note that we do not have downloads available for Version 3 and earlier.
Upgrade and subscription terms are subject to change without notice.