Merlin66

Yeah, I was thinking of the discussions on dithering..... I’d like to think that the stacking software is capable of re-aligning the individual images.....but not sure. (I haven’t seen examples to quantify)

I don't use drizzle, but I'm interested in the possible imapct on resolution. Moving your image +/- a few pixels infers to me that you're spreading the star FWHM and reducing the possible resolution. Is this correct?

You are achieving some excellent results. Well done. The curved spectral lines "smile" is not uncommon, and is aggravated by the use of long slits (as used in the SHG) The rays passing from the extreme ends of the slit reach the grating at different angles from the central rays and consequently have different refractive angles. The curvature varies with wavelength. In a SHG which uses a CCD/ CMOD detector this smile (and any residual tilt/ slant) can be corrected in the software before processing to an image. With the linear array it may a case of compromise between the resolution and the impact of the smile. Variation of the line position - this is usually associated with the grating positioning and the accuracy of the grating holder. Any differences between the axis of the grating grooves and the axis of rotation can cause some movement. There may be the added complexity of thermal/ structural deflection etc. etc. (Again, these issues are not as critical in the digital CCD/CMOS arrangement.) Your eyesight must be better than mine I don't see any significant Newton Rings, but if they are there, they are caused by interference within the cover plate of the sensor. In narrowband solar imaging they are worse with reduced bandwidth and increased focal ratios. The usual solution is to apply a slight tilt to the sensor. Onwards and Upwards.

Yes. This is also the centre of the visible chart.

With your solid adaptor can you use the screwdriver, or a steel rule between the adaptor and the edge of the base to "jam" against the base section while turning the adaptor? Or access the base through the slot in the adaptor??

Next to the magnifying glass Icon (top middle) "Position " icon click and then enter the RA/ Dec you want. Click apply. Then right click on the chart centre, telescope/ slew to cursor position. Works for me.

OK, looking at John’s image it would be appear that the mounting socket is threaded into the base casting. It looks like the clutch assembly is not holding the base securely enough for the adaptor to be unscrewed... Is it possible to confirm this by looking into the “gap” between the mount and the adaptor while trying to unscrew the adaptor to see if the “base” is turning with it. If so, then the design seems to rely on the clutch assembly to hold the base solidly enough to release the adaptor screw. Bumma!

An interesting problem. Just to be sure....the adaptor you show is screwed into the base of the mount. Does the base of the mount rotate during normal usage on this screw/ adaptor or is it fixed. Assuming it is fixed, you say rotating the adaptor, holding the base of the mount secure that the adaptor still stays attached to the base but can rotate. This infers to me: The socket in the base of the mount which screws onto the screw, is loose relative to the mount base. This socket should obviously not allow the adaptor to rotate without the screw tightening or loosening. I don’t know how this socket fits within the base, other examples I’ve seen have the threaded socket machined into the sold base of the mount. I your case it could be a threaded insert in the base which has come loose. You’d need to be able to access this socket from inside the base and at least hold it firmly enough to release the screw, then look at ways and means of re-securing it solidly to the base. This sounds like a manufacturing/ design fault. Have you contacted the supplier?

James, I think it will depend on the effective open aperture close to the image plane. Baffles, focuser size, filter size can all cause vignetting and reduce the fully illuminated circle.

I’ve been using an ADM dual saddle on the HEQ5 for the best part of ten years, no issues. I ended up fitting a GEOPTIC equivalent on the NEQ6PRO, no issues. when I upgraded my older TV Systems mount, I went for an ADM dual saddle. They are very well designed and well built. I would recommend either.

Just a side comment....... The Baader Hyperion x2.25 barlow is a very useful piece of kit. The T thread connections allow it to be used with almost any camera. I use it for solar imaging (I also have and use the TV x2.5 PM ) I'd be interested to hear how it performs against the other Baader x2.25 barlow https://www.baader-planetarium.com/en/baader-q-barlow-2.25x--1.3x.html or the VIP barlow https://www.baader-planetarium.com/en/accessories/optical-accessories/barlow-lenses-coma-and-glaspathcorrectors/vip-2x-modular-barlow-lens-visual-and-photographic.html

Valerio, The spectrograph is designed to use the blazed 1st order spectrum. (The angle of rotation for the 2nd order is twice as great....just use the bright 1st order.) If you want a higher resolution use a grating with more l/mm.

Yeah, not all filters fit everything! As mentioned there's no real standard.......

Valerio, I wouldn't worry too much about the "halo" - I have seen similar when high gain and very bright light sources are used. Will not impact on the usual target objects. (You should also flip your spectrum to bring the blue edge over to the left hand side. This is how all spectra are subsequently measured and calibrated. I've slant corrected and calibrated your spectrum using BASS Project. resolution, R=319)

You could always plate solve your image to confirm......

Valerio, On first glance that's how it appears, but it is only chrome coated on one surface. This surface is where the slit gaps are etched through the coating. This should face as Paul says towards the inside of the spectroscope. If you look carefully you'll see the difference. Ken

The EQMod control screen shows how...just click unpark and click the star icon to get sidereal tracking.

Peter, I use the SW/ Orion electronic motor on all my solar imaging ED80's. I drive the 10:1 focuser knob with a XML timing belt - gives very fine control.

You may be interested to know that back in 1992 the very first digital spectroheliograph was conceived and built by Philippe Rousselle using a single line scanner (2048 x 1 array, 14 micron pixels) - almost identical to yours. He used an ATARI 1040 computer to interface and control the array.

Interesting. I have a spreadsheet which may be of interest to others considering a SHG. SimSpec SHG.xls

H-K, Thanks for the correction! I found FireCapture V2.6 has a setting for x2, x3, x4 binning. I just tried the Time lapse with both the ASI 1600 and the ASI 174 - worked for me.

Barv, Which version of FireCapture? V2.7? I'd post your problem on the FireCapture group, Torsten is very supportive and I'm sure can help. https://groups.io/g/firecapture/topics I did see a message that some Mac users are having issues with the ASI 462..... (I use FC with the ASI 174 and ASI 1600 - no issues)

Michael, That's what they were like in the early 1900s. With the introduction of the webcam in the 1990s we were able to simplify the design and using digital scanning to assemble the solar image. The current digital spectroheliograph (SHG) is very capable, and the grating in the spectrograph section can be tuned to any central wavelength allow us to image in CaK, Mg, He, Na, H beta, H alpha etc etc. The software used to "reconstitute" the solar image has also improved over the years. Wah-Heung Yuen's "Spectra Line Merge" and John's "BASS Project" are among the freeware favourites. My recent book "Imaging Sunlight - Using a digital Spectroheliograph" covers the subject, and describes many current SHG's and how to make and use them.

Well done! More info please..... (your focus looks good!)

Dexter, Sorry mate, I disagree. There are many products today which are much better than those produced in the past. We have good quality product available today which we could only dream of when I started back in the 1960’s