Merlin66

Yes. but it sometimes needs more than one bulb to give sufficient light. I've seen set-up were a ring of four (or more?) bulbs was placed in front of the objective.

Valerio, Ran your data through BASS Project... Pretty good, the resolution is around R=971 in the red. You can see the calibration is limited to the red region - this means the calibration is not so good in the blue. More reference lamp exposure time might pull out the emission lines around 4200A The #1 exposure as you can seen doesn't appear to be over-exposed and the focus is pretty good. The response curve of your camera is obvious, the jump around 5700A is typical! This can easily be corrected by preparing an Instrument response curve and using that to "correct" your spectrum. Comparing with the solar reflected light (G2v) from Mars you've recorded a wealth of lines! Well done. You just need to open and use BASS Project to replicate these results. Onwards and Upwards

Valerio, Good to see your "first light" results! In BASS project it's easy to load all the results and compare the quality of each profile, just hide the "bad ones" and work with the "good". I'll have a look at your results and post my findings.

Many years ago I made a secondary for a Cassegrain conversion of an 12" f5 scope. I was using the Gaviola test method (very straight forward) for testing. https://www.osapublishing.org/josa/abstract.cfm?uri=josa-29-11-480 (It's also re-printed in Allan Mackintosh's "Advanced Telescope Making Techniques", Vol 1, p63)

I was lucky enough to spent a few years with Jimmy Barker while working in South Africa, he was a great guy. The scope he used was a Cassegrain with a third mirror to make a Nasmyth arrangement. He used a “hollow” Dec shaft to push the focused beam and the focuser was mounted on the end of the fork mount. I have some images... I did some observing with it, it worked very well. Not sure how it would perform for photography. Well worth considering.

Greg, I applied slant correction to you neon image, and it calibrates well. You said you were using a DSLR? Did you crop and compress the image you posted? It seems to be only 1024 pixel wide, which is much less than a DSLR. Also to match the dispersion of 1.76 A/pixel the pixel size would have to be close to 10.5 micron, based on a 600l/mm grating. The resolution is R= 1003 at 6143A The lamp spectra is similar width, but doesn't seem to match the CWL wavelength settings of the neon. I was unable to match the emission lines shown. Which lamp did you image??

Chris, On the assumption that the HEQ5 mount is working OK and the Synscan controller is doing its job, I'd accept the situation and live with it. Sounds like the "new" mother board is "different".

Greg, Thanks for the images, they show promise. Not sure I understand this comment.. Are you using the DSLR body mounted on the LowSpec, if so the design back focus should allow the DSLR to get a focused spectrum. You could double check that the collimating lens is positioned correctly and focused on the slit gap. If this is misplaced then you'd see a difference in the imaging focus position. (Your lamp images shows some tight lines which says you're not to far away)

Valerio, Thanks for the update!! I’m glad the imaging lens was 100 mm fl. It makes 100% sense and matches all the SImSpec results. You’re doing very well, I’m sure you will make great progress. We're here to help, when you need us.

Sounds promising! Re focusing: A two stage process. I use the reference lamp to illuminate the slit plate then focus the guide camera on the slit gap, to get the tightest image of the gap. This should ensure the guide camera is OK to use with a target star. Then focus the target star on the slit using the telescope focuser, it should be in pretty tight focus in the guide and present a reasonably narrow spectral band in the imaging camera. If this is not happening then the slit to collimator spacing is probably incorrect.

I was just wondering, following Valerio's journey into LowSpec spectroscopy, how the others are doing. There's obviously a few (many?) of the 3D LowSpec instruments "in progress" Any updates from the members????

Valerio, Your latest RELCO shows improved resolution R= 1219. The size of your CMOS sensor (19.1mm) is showing the field curvature of the imaging lens. It's always difficult to get a full width spectrum all in focus. (The "sweet spot" for my Littrow Spectra-L200 is only around 12.5mm.) You can cut and merge sections of the spectrum (in BASS project) with slightly different grating settings to display a larger spectral coverage in focus. Normally, in actual use, you would be focused (excuse the pun!) on a particular spectral feature/ wavelength for your target object i.e. Ha for Be stars. It's not necessary then to have large spectral coverage. The horizontal lines are "Transversalium" lines (!!) and are caused by dust/ dirt on the slit gap. You could use a blower to clean the slit plate....it's of no major consequence. Looking at the solar spectrum, obviously has the same focus issues... If I assume you took the solar spectrum at the same micrometer setting as the RELCO then there appears to be a shift of 7.2 A between the two. The close-up crop around the Na lines shows the good registration after correction. Something's moving in the assembly? It's important that the reference matches the target, this is how you will calibrate your future stellar spectra. I'm also having difficulty in reconciling your dispersion with the camera pixel size (4.63 micron), the grating (600 l/mm) and the imaging lens focal length I thought was standard in the LowSpec design (85mm fl) To get a dispersion of 0.75 A/Pixel it infers an imaging lens closer to 100mm fl. Can you confirm the imaging lens. All in all you're doing very well! It shows your LowSpec is capable of producing a quality spectrum. Just comes down to some final "tuning". I would certainly be setting it up with your scope to get a "first light" stellar spectrum. Just remember the sequence - take a reference spectrum immediately prior to the target. Good work!

Valerio, I'm a little confused.... The SimSpec spreadsheet I have for the 3D print, based on 125mm Collimator/ 80mm camera lens and a 600 l/mm grating coupled with your ASI 294 (4144 pixel x 4.63 micron pixel) should give a dispersion of 0.95 A/pixel and a resolution (30 micron slit gap) of R=983. This doesn't seem to match well with the results. The way to address the spectral blue-red direction would be to either rotate the camera by 180 deg or just flip the spectral image prior to processing. I think by flipping the grating you've ended up imaging on the -1st order rather than the +1st order. The difference being the anamorphic factor which would change from 0.91 to 1.1 this impacts on the dispersion. The dispersion would drop to 0.87 which is closer to your results. (See "Astronomical Spectroscopy for Amateurs", p150-152) I would reverse the grating to the original positioning and confirm the slit gap used. SimSpec V4.3_Paul3D.xls

Valerio, Pretty good result! Using your spectral image, correcting for slant and calibrating it against the RELCO lamp in BASS Project The dispersion is 0.76 A/pixel The resolution R= 949 @ 4764 A (5.02 A FWHM) R= 821 @ 6962 A (8.4 A FWHM) The Ne line at 5852 A is very wide (This is usually bright enough to over expose?) and the focus is better towards the blue. You're on your way! I'd certainly set it on the scope for further trials..... Onwards and Upwards.

We're having some issues getting a DMK51 to play nicely with PHD2 On the observatory Win7 32 PC I have the DMK51 installed with the IC driver: 2.9.4.1923, connected to USB2 port. It works and gives images with both FireCapture and Astroart without any special settings. With PHD and WDM webcam settings it works under UVC Video. In the camera/spanner icon the UVC video controls come up. All the options are unselected BUT the default exposure seems to be -4. The exact same camera, with the same IC driver and PHD2 connected to a USB2 port doesn't seem to run on a Win10 64 PC!!!!! The camera appears to be recognised, but the UVC "control" screen doesn't come up after selecting the WDM webcam option. Has anyone experienced similar issues/ problems? Is it a Win10 thing??

Rusty, Yes! When you want to record the Zeeman magnetic effects you need R>30000. The capabilities of the digital SHG put to shame all the “commercial “ solar filters. We can, as I said, image in any wavelength with resolutions down to <0.1A. How many expensive filters would you need to be able to do that?????

John, No impact on consistency of illumination that I know of. The Brewster angle wedge only allows the use of a polarising filter directly to reduce intensity.

What about trying Autostakkert as an alternative. It works very well on my solar SER files.

I use the Baader Hyperion x2.25 barlow regularly for solar imaging. It does a very good job. You can add a T thread to 1.25" adaptor if you want to use it with other eyepieces.

[name], I'm impressed with the performance you are achieving! What height slit (and width) do you use? It's all the more impressive as you are using a 30 x 30mm grating which I think would be vignetting the image. Ken

Pryce, Look at the image above, the telescope is well beyond the meridian and the camera has not (yet!) hit the tripod. With a "short" telescope set-up, yes you can continue observing without meridian flip for some time BUT inevitably at the object moves further and further west you'll run out of space and have to do a flip.

Joaquin, Did you have any success????

The C11 plays well with the NEQ6 mount. I have C11/ efinder/ Spectrograph/ four cameras etc. and use EQMod/ CdC/ Astroart set-up in the observatory. Not a transportable set-up!

Not a problem! You can try your setting with the telescope simulator to verify the outcome.

I’d still recommend AS3! Have you looked at PIPP? It has a strong following.