Merlin66

Louise, Don't know how ShapCap handles darks, alignment and stacking. I use an ATik 314L with the Spectra-L200. Buil's ISIS, Valerie's VSpec and John's BASS Project are all suitable for the spectral processing - taking the raw spectral image to a 1D profile. Edit: Misread... you mention IRIS not ISIS. Yes, this can work, but it's now getting a bit dated.....

Louise, Yes, you've got the main points.... the telescope focuses the star image onto the front of the slit plate (and seen by the guide camera), the light goes through the slit and is made parallel by the collimator... the beam hits the grating, the light is dispersed into a spectral image which is then focused by the imaging lens onto the CCD chip. At this stage bench testing is the way to go...a bright desk lamp (or fluoro) shining into a paper diffuser on the entrance should give enough light to work with at the slit. The "test" imaging system should be focused on infinity and not re-adjusted during the test. If the collimator is correctly positioned, the slit gap will be in focus. You may be able to use your dummy grating (mirror on 3D block) to align and focus the collimator and confirm the final imaging arrangement. Which program will you use to obtain your spectral image? It should be able to analyse the image (using the measurement/ profile tools) and give you a FWHM result - mine (AstroArt) shows the result down to 0.01 pixel. Ken

Still clouded in..... Nothing showing in GONG today.... http://halpha.nso.edu/

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.

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)

Yeah, some interesting proms.... Pity we have heavy cloud down here in Victoria, Australia, tried to image them earlier this morning but beaten by cloud.

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/

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.

Yeah, that looks like the one I had machined.....

Unity gain for the ASI 1600 is 139. I also set the Gamma to 50 when using FireCapture.

The standard SCT thread is a 2" x 24 tpi. I had the same issue mounting a Meade flip mirror on my ED80..... Ended up getting a special threaded adaptor machined.

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.

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

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

I use an 80 L grey tub, with lid hinged with fence wire, for the best part of ten years. worked very well.

I see the GSO Ad says: The trusses are also designed to flex equally, keeping the optics in collimation regardless of the position of the telescope. I'd like to see the technical data to back that up......

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. )

Not exactly the same problem, but similar Re. plastic life expectancy...... Many of my SkyWatcher plastic fittings have turned "Gold" !!! I do solar observing, and can only assume it's due to the UV exposure down here in Australia.

In my fifty years of astronomical experience I have never seen a proper amateur Serrurier Truss telescope. Never. Truss designs are just that truss designs.

Louise, Andrew beat me to it!

Louise, A telescope is not necessary....basically what you’re doing is good to check the guiding on the slit... The next stage is to get the collimator focused on the rear of the slit plate. softly softly......

Louise, Another step along the way......

The cooler/ cold regions as recorded in an IR image of the Nebulae clearly shows the new star formation areas...... https://apod.nasa.gov/apod/ap160718.html

Sounds like a plan.....

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.