Merlin66

Over the years I’ve used many SCT - from all the variations and sizes of the Meade LX200 series and now the Celestron 9.25 and C11. although not perfect, they were all fit for purpose. The C11 I currently use displays good Ronchi lines and adequately meets my needs for precision spectrography.

I'd be interested in seeing the results.....

Vlaiv, Spectra are treasured resource and always treated with utmost respect. When it comes to science data there should be no adulteration or unnecessary processing. We are always looking at the integrity of the RAW data and maximum SNR. Processing is usually kept to a minimum - stacking, darks, flats, removal of cosmic ray hits and sky background removal. It's not like astrophotos where filters and blending etc etc can be applied to "improve the look" - KISS is always the rule. (Having said all that, if you're not going to use the data for anything "serious" then obviously you can play as you like - wavelet sharpening etc :-) )

Vlaiv, Thinking more.... When you use the grating as an objective grating , coma should not be an issue. The attached spreadsheet TransSpec will help you. Many observers are getting good resolution (<10A) and good results with the 100 l/mm objective grating notwithstanding the small aperture. TransSpecV3.1.zip

As you say the printer would give 6 lines/mm....this is the figure you need for dispersion calculations - much less than the 100 /lmm gratings. The aperture size gives you light grasp and some resolution.... I ended up with a 50mm sq 300 l/mm grating (thorlabs?) to use as an objective grating with a camera lens.

Hmmm, that still shows a significant LED pollution in the filter transmission bandwidths.....

Unfortunately the broad spectrum LED can't effectively be filtered out. Where you have transmission bands (Hb, OIII, Ha etc) you will also have background LED light pollution.......

A couple of comments: The link mentioned refers to IR not UV..... Shining a high intensity IR LED "searchlight" at the camera filter bears little resemblance to actual user conditions....... (In the diagram filter#2 is the one removed and Filter#1 -the anti alias/ dust shake filter is usually retained.) The attached PDF file shows real spectroscopic transmission tests done on the front filter..... The final IR transmission is not much worse than that found in the original Canon camera .................... Canon front filter test.pdf

The eyepiece box I still use was made back in the early 1970's. The foam insert has changed a little over the years and the original TV eyepieces from the 80's are still as good as ever.

OK. The UV-IR has no affect on the amount or intensity of the Ha transmitted through the Quark. It just reduces the energy loading on the Quark itself.

The “UV/IR and diagonal” reference is under the larger aperture (above 80mm) section of the document......

Pig, Sorry to correct you..... http://www.daystarfilters.com/inout_article_base/index.php?page=view/article/26/Energy-Rejection-for-QUARK---UVIR-or-Front-mount It appears NO addition energy rejection is necessary with apertures less than 80mm

Yes, but it really depends on the size of your refractor...above 110mm aperture an ERF or at least a good UV/IR filter is needed.

Thanks! Unfortunately the Spectra-L200 is no longer in production.

I designed the original OVIO multi-slit plate for the Spectra-L200. Yes, with a suitable transfer lens and the slit inclined at 15 deg you see the 6mm long slit gap and the reference number. Check out our website for more info. http://www.astronomicalspectroscopy.com/instrument.html

I use the DMK 21 618 for a while. Higher QE at Ha than the standard version, but very small webcam sized chip. There are better options availed today. (I still use my DMK 41 and DMK51)

OK, you're on the right track. I use the ASI 174MM for solar - pixel size suits my set-up and the frame rates are FAST!!! The newer ASI 178MM would be a good bet. You'll need a USB3 connection and a fast SSD drive to collect the data (2-3Gb per session) Acquisition and processing.....FireCapture or SharpCap will give you good AVI (or SER) file to allow stacking for quality. Registax 6 or Autostakker V2/V3 will do the necessary stacking and "tweaking" Any photo imaging program (PainShopPro, PS etc. etc.) can be used to apply the colourisation.... http://www.firecapture.de/ http://www.sharpcap.co.uk/sharpcap https://www.astronomie.be/registax/ http://www.astrokraai.nl/software/latest.php

You are correct. My 100mm was an approximation.

No, they are for WL enhancement...... If you eventually use a larger refractor (>100mm) , then with the Quark you may need an ERF (energy rejection filter) - a good UV-IR filter as a basic option.

I enjoy both visual and solar imaging. Yes, over a period of minutes you can see the development of the proms and movements around sun spots and active areas. Imaging a sequence with an image say every five minutes over a period of a couple of hours dramatically shows the dynamic nature of the proms and the solar surface in general.

Hmmmm That’s a little unkind for a $ 2000 investment in Ha solar filters.....

My experience with tilt tuned etalons is slightly different....takes a bit of finesse but the results are just as good as those I saw through a double stacked Lunt. (I had a "fine tuning knob" on my external double stacked SM60 filters - a Vegemite lid controlled from the eyepiece.)

I ordered a Quark when they first came out and then had to cancel the order when DayStar could not confirm that it would work in ambient temperatures above 40 deg C. The Quark only has heating to bring it on band (I believe the "nominal" operating temperature is around 28 deg ) The temperature down here in Victoria was 44 deg yesterday!

Just to illustrate the uselessness of the camera frame size.... Not a good frame of reference (excuse the pun!)

Vlaiv, Glad you found that error.... I think you need to revisit Suiter's "Star Testing Astronomical Telescopes". On p61 he models a simplistic analysis of the Airy Disk based on the Heisenberg uncertainty principle and comes up with an answer close to the 1.22lambda/D. I have yet to see an astronomical image showing the Airy Disk. (On the bench a pinhole optical system is usually used to generate the Airy disk images normal see in the text.) It needs at least a >f30 system and absolutely perfect conditions. Suiter's work is based on VISUAL and high magnifications. What we record is the PSF of the seeing disk. Re Sampling (See Suiter, p41) and the MTF Chapter 3.4. Eversberg and Vollmann in their "Spectroscopic Instrumentation" p 76 discuss at some length the issues of effective sampling - starting with the Nyquist criterion - they advocate at least a sampling rate of >3. (This again is based on the PSF rather than the "absolute" Airy Disk) I'd also refer you to Schroeder's "Astronomical Optics".