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Merlin66

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Posts posted by Merlin66

    Keeping the Lunt warm

    in Observing - Solar

    Posted

    That's for Daystar "solid" etalons..... not for the air spaced etalons used in the Coronado and Lunt instruments.

    A claim was made that extreme low temperatures could affect the central wavelength of the blocking filter and cause to go "off band" reducing the transmission and performance of the instrument.

    Lunt now supply a heated rear plate which can be fitted to the BF diagonal to alleviate the problem.

    Here in Australia I'm more concerned about the effects of elevated temperatures.

    I looked at getting a Quark, but Daystar said I'd have to order a "special" which could come on-band at ambient temperatures above 40 deg C (The quark has no cooling capabilities and relies on heating only to come on-band). I declined the offer.

     

    EQ6-R owners club

    in Discussions - Mounts

    Posted

    The Synscan manual for V5 states the added hand controller USB port is to allow direct connection to the PC USB port. Sounds like a reasonable update from the ol' serial connection.

    (Page 20)

    https://www.telescope.com/assets/product_files/instructions/IN_620_Rev_C_SynScan_Hand_Controller.pdf

     

    (The special EQ DIr cable used by the direct mount connected EQMod gives the correct signal to the mount and won't fry the mother board)

    EQ6-R owners club

    in Discussions - Mounts

    Posted

    John,

    Welcome on board!

    Congratulations on your purchase.....

    I have and use an HEQ5 and a NEQ6 mount. Both these mounts are controlled from a local laptop. Not 100% sure about the differences with the EQ6-R Pro and Synscan V5 (I'm still using V3)

     

    If you are already comfortable using a PC and planetarium program then you could go for either ASCOM control or EQmod to control your mount.

    You can connect the Synscan controller to the PC and set the mount type to Skywatcher EQ, this will give you PC control. You still need ASCOM installed and a planetarium program.

    EQmod is an interface software, between a planetarium program and the mount. It needs the latest ASCOM drivers/ interface.

    EQmod also prefers to "talk" direct to the mount, bypassing the Synscan hand controller. To do this you need a special cable between your PC and the mount - an EQDir cable.

    I use Cartes du Ciel with my EQmod set-up. Works 100% for me.

    Read up on the EQmod capabilities and satisfy yourself that it's what you want.....

    http://eq-mod.sourceforge.net/introindex.html

    https://ascom-standards.org/

    https://sourceforge.net/projects/skychart/

    LOWSPEC - 3D Printed but Calibration Question

    in Radio Astronomy and Spectroscopy

    Posted · Edited by Merlin66

    Glad you got things sorted out....

    Time to talk serious.....

    The instrument you're building is very sophisticated, containing many optical surfaces and requires some dedication and rigour to complete, test and eventually use.

    The object of the build is to end up with a capable, usable spectrograph. To achieve success all the optics must be clean, positioned and aligned correctly.

    Re slit focus - The slit gap, a few microns when viewed through the system should be measured. The FWHM of the slit gap will confirm the focus.

    If you use the collimating lens plus a long focus lens/ scope to view the slit gap then you also need a camera. The ratio of the focal lengths of the viewing lens and collimating lens can give some magnification factor, where the slit gap appears greater/ less than it really is. The slit gap, say 20 micron when used with this system - assume the collimating and viewing lens are the same focal length with a camera which has 4 micron pixels, will appear as a 5 pixel wide image.

    I use AstroArt to do all my imaging, and it has (like many other programs) a "profile" option. You can use this to analyse your image of the slit - to measure the FWHM. The collimating lens should be adjusted to give the minimum FWHM slit image. 

    In the LowSpec design the imaging/ collimator lens have the ratio of 80/ 125, this gives a ratio of x 0.64 - this means the slit gap will appear smaller than actual (say 20 x 0.64 = 12.8 micron, or less than three pixel in the above example!)

    If the collimator is not correctly positioned, then the exit beam to the grating will not be fully collimated and parallel which can compromise the performance of the grating, and the instrument.

     

     

    • Like 1

    PST mod question

    in Observing - Solar

    Posted

    The standard PST etalon ideally needs an f10 input beam and needs to be positioned at the Majic -200mm inside the prime focus.

    you may be lucky and find by removing the focuser from the OTA that you can achieve the -200mm.

    If it works you’ll end up with a 88mm f10 system.

    • Like 1

    LOWSPEC - 3D Printed but Calibration Question

    in Radio Astronomy and Spectroscopy

    Posted

    Things will become a bit more obvious when assembled.

    I think the positioning is based on using the nominated optics, so there should be little variance.

    The collimator should focus on the rear of the slit plate.

    The grating should be vertical, and the rotation free and consistent. Rotating the grating, as you will see, brings the different target central wavelengths to the imaging port.

    Ken

     

    LOWSPEC - 3D Printed but Calibration Question

    in Radio Astronomy and Spectroscopy

    Posted

    Rockmover,

    You're doing well.

    I believe Paul's assembly instructions show how to set and align the optics (?) 

    Once installed you can do most of the preliminary testing on the bench. You can add the guide camera and get it focused on the slit plate.

    I usually check by using a laser collimator - fitted to the centre of the inlet port and a paper target centre spotted on the camera port.

    The beam should go through and by moving the micrometer, you should be able to bring the bright spot into the image port and onto the centre mark.

    Set up a fluoro lamp, and point the inlet port to the lamp. This will give you a nice spectrum which can be used to initially calibrate the instrument.

    Ken

     

    Truss mount question

    in Discussions - Scopes / Whole setups

    Posted · Edited by Merlin66

    Louis,

    I don't believe even those commercial truss designs are actually Serrurier truss designs.

    The truss sections need to vary with end load and all the joints to the central section etc. must be "pin joints" not bolted.

    (My Bsc (Hons) was "The design and construction of the Issac Newton telescope". I was lucky enough to obtain copies of Mark Serrurier's original design papers and visited Grubb Parsons to discuss the INT design and construction. )

     

    • Like 1

    Confused about white light filters

    in Getting Started Equipment Help and Advice

    Posted

    Interesting the TO site mentions the "CE & ISO Certified" which only applies to solar sun glasses - not for telescopes or other optical systems.

    They compare with "mylar" which I think is bad marketing - The Baader solar film is definitely NOT maylar based, and Baader give details of the optical properties - something I can't find on the TO site.

    For the camera lens I would make a filter from the Baader solar film to fit the lens.

     

    ASI1600mm Cool - Flats nightmare, Pt 3

    in Imaging - Discussion

    Posted

    7 minutes ago, Tommohawk said:

    There is no need to subtract bias, because both the darks and the dark flats have the bias and therefore this is subtracted from the respective lights and (light) flats. Correct?

    Yes.

    I use AstroArt and the only time bias is mentioned is when you need to compensate your darks to another temperature....

     

    • Thanks 1
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