Merlin66

Joe, The "new" SM70 III scope is stopped to 60mm for solar ......

Yes, That's the stuff.

Helen, A spare lens cap as mentioned above, centre drilled to 28mm allows the SA filters to be securely "screwed" into place. the cap can then be rotated on the front of the lens to bring the spectral image horizontal to the chip. Works well.....

Valerie’s VSpec is pretty good, I grew upon it! still a little buggy, but certainly well worth trialing. As I mentioned BASS Project, also freeware, meets all my needs. https://uk.groups.yahoo.com/neo/groups/astrobodger/info?

I have three ED80 and checked and re-aligned the focuser on each. Just unscrew the three M4 screws which hold the focuser to the OTA, and gently nudge the focuser until the laser spot is central. Then re-tighten the screws while watching the laser spot. works for me!

Nigella, I use John’s BASS Project for all my Spectral processing. Easy to use, comprehensive database and good tutorial

I use AstroArt for all my image acquisition. Fabio is highly responsive to users needs - he included spectrograph slit guiding for us. Highly recommended.

There’s no further increase of the Ha sensitivity when the front filter element is removed. It does allow recording from Uv to NIR for spectroscopy. I have the full FULL Canon mod and had to add a clip in clear filter to allow focusing with camera lenses.

RSpec is just a guide. I rely on ten years experience..... using a grating is “Spectroscopy 101”

Yes, the SA 200 is designed to better fit the filter wheel. you also should look at orientating the grating to present the Spectral image horizontally across your camera chip.

As I said, one of these life compromises........ I’d still go for the 200 l/mm.

Over the past twelve years I’ve had many, many PST’s. I have modded many along the way. Finding a great PST etalon is honestly a hit and miss... I say it’s 10:80:10 10% are above spec and if found are majic and make fantastic mods. 80% are ho humm. Ok they might meet the 1A spec but nothing special... 10% should never have left the factory A great PST will make a great modded PST, a dud PST makes a dud mod.

As per the above..... I use an Ronchi grating as a final check ( on any telescope) tosee if there is any residual issues/ problems. point to a fairly bright star and replace the eyepiece with the grating, refocus to only show 5 or 6 lines and look for straight, even and un distorted lines.

Pete, 26mm is a very short spacing, I’d say the SA200 would definitely be a better bet. Could you fit a spacer between the filter and the camera to increase this spacing? This is always the compromise when trying to use gratings in filter wheels ( and other photo metric or AP applications) I have one set-up where a 207 l/ mm grating mounted in a Neumann filter drawer in front of a flip mirror ( to allow accurate setting on the target) then the camera - works out about 60mm. This gives a good Spectral image for the camera I used Atik16. (Edit) Pete, I think you have entered the wrong camera chip width in the calculator - must be more than 193 pixel???

Just check the spacing between the grating and the camera chip. The SA200 is recommended where the spacing is limited... I use the SA100 at around 60mm spacing and a 207 l/mm at around 40mm. This determines the dispersion, the length and brightness of the Spectral image. I use John’s BASS Project for all my processing. Well worth checking out. Pete, mono is best. You can always colourise the Spectral image after calibration. ken

The Newton Rings are only a problem when imaging the Sun in Ha.

I have the Meade 5000 x3 extender and the ES x3 version and they look and perform the same. I also regularly use the x2.5 PM for solar and hoped that these x3 versions would reduce the Newton Rings I experience with the ASI 174. No such luck!! Still need the T2 tilter.

James, This was discussed in a recent thread. I have never found it significant. with my spectroscope mounted behind an f10 SCT I actually end up around f11. Also, many users add a focuser to the rear cell to minimise the mirror slop, this adds at least 80 to 100 mm to the back focus, then add the OAG, the filter wheel and finally the camera. So we are well away from the design focus. I don’t hear any complaints about performance.

Robin, Most of the Spectra I obtain is though the SASER group here in the S. Hemisphere and submitted to the ProAm campaigns we contribute to.

There are more performance differences due to collimation and tuning in typical SCT’s than between brand names. I’ve seen good and bad examples of both Meade and Celestron instruments. which ever one you go for, enjoy!

Alan, Thanks. Yeah, that seems to be all it does.........

Hmmmm I have to disagree with your comment ""Meades are good but something about the optics are not as good as Celestrons"" I used Meade SCT's for many years, 8" 10 and 12" f10 and the f7 variants. They performed very well, no issues. I only changed to Celestron, a C11 when I was unable to find a suitable mount for the heavy Meade 12" SCT (bare weight 17 Kg!). Having used the C11 for some eight years now, I find it performs well and ideally suited for the spectroscopy work I do.

Alan, Thanks got that! I was more interested in the functionality of the vertical green cursor line ( right click in quality graph). All I can see is that it shows the frame and frame# at the cursor position.....to do what????

Just a comment: Although the page header says: The files below are only available for BAA members to download. Log in or join the BAA today to gain access to them. It appears possible to download the various contributions. Some good, useful material.

OT. Neil, Can you help me understand the use of the green cursor in the AS3! quality graph? Sure, you can move it across the graph but it doesn't automatically pick up that point for stacking etc? Is there something I'm missing?????