jambouk

The Bayer Matrix is a physical thing; the green and blue pixels won’t significantly register photons of wavelength 656nm. This plot shows that: From: https://astronomy-imaging-camera.com/product/asi224mc

Without the IR-cut filter the red pixels will be sensitive to Ha; but you need to see where the IR-cut filter kicks in. You’ll only be using 25% of pixels with an Ha filter on though because of the Bayer matrix. The 224 is a CMOS rather than a CCD but potentially splitting hairs. You’ll have to have very long exposures with the Ha filter on compared to the images in full OSC mode.

The stars on the left look more eggy than the stars on the right. Is the imaging train square on to the light path? Is collimation perfect? Is it a quality focussed?

Yes, with this set up shoot video not stills. Work out which video mode is least compressed and use that. Also have a read around the subject: https://skyandtelescope.org/astronomy-resources/planetary-imaging-with-your-dslr-camera/

The mount is the limiting factor in that set up. I suspect you’ll be limited to 30-60 second subs depending on your polar alignment and acceptable of rejection rate of subs. I think a field flattener is good, but I would go for a better mount first.

Push the max to £900 and you’ll probably get a second hand AZEQ6. Failing that an HEQ5 or a Paramount. A solid, stable mount is key to imaging DSOs.

Interesting. But it makes no mention of the brain. Which either means the brain has no involvement, or the author is ignorant of it. Thanks. James

Is all of “dark adaptation” based inside the eye, or does the brain also contribute to the process in one way or another? James

Ah. When one comes out which plugs into my mount/handset for £10, let me know, until then I don’t see the value of spending £120 on one.

Have a read of this: https://britastro.org/node/9282 James

Can that mount take the weight of that telescope and camera etc?

Can someone share a link to one which would with a Skywatcher mount please. I can’t find one for under £120.

The clutch is unaffected by whether the mount is on or not.

Have a read of this:

The RA will take some time to “bed” in. Make sure the lever is screwed into the hilt and then you need to give it a good tighten. I plce my thumb on the mount and use my hand to pull the lever to the left side of the mount to tighten it. Over time you may need to unscrew the lever and pick a new hole in order to have enough travel in the lever to slacken and tighten it. Make sure it is deeply screwed into the clutch though, milky first one wasn’t and I snapped the lever off!

I run one of the two monthly meetings for Nottingham Astronomical Society, the one held at Plumtree which is devoted more to the amateur issues; the other monthly meeting is usually an academic talking about a topic which may have less relevance to the practical amateur astronomer, but appeals to many of us with an interest in astrophysics, space science etc. The latter meeting is held in Gotham. For the last few months both meetings have been online and accessible through the website. Observing from the city centre is possible, the moon, sun and planets can all be observed and imaged relatively easily and well if visible. Deep sky targets can also be imaged if using narrow band. If you can find a venue, I can see there may well be demand for a City Centre Astronomers group, who could meet up and chat about stuff. The issue clearly at present is COVID-19. Get in touch if you want to combine forces. James

There is a review of the EQ8-R in October’s S&T. No mention of the backlash others have complained about, and the tests of tracking were undertaken with 200mm focal length optics which doesn’t seem particularly challenging, though they managed to get good 120 second unguided subs with this.

Ok. I assumed the GPS dongles were still over £100. I hadn’t realised they are now £15, in which case, I may get one!!!!

I don’t have one, and can’t see why I’d need one, my smart phone tells me the time, date and lat/long and elevation. Unless you are parking the scope at the end of each observing session and leaving it where it is and then using the same alignment the next observing session, it isn’t even that important to get the data correct; you can be a degree or more out in lat and long, make up any elevation, and equally the date and time are only vital if using GOTO. But if you like gadgets and can’t be bothered to enter this data, get one. I’d rather buy an eyepiece.

It depends what you are trying to achieve. Vega will appears to move after about 30 seconds, but at the pixel level.

Glad it’s sorted

There may be comparisons online. It will greatly depends on the cameras in question, as DSLRs have very different quantum efficiencies from each other, and potentially from cooled CCD cameras. Also the IR cut filter used varies greatly in different DSLR cameras so some may let through next to no Ha whilst others may let through 30% of it. And then there is the Bauer matrix which varies between DSLR cameras, does Ha transmit through just the red, or through the green and blue too? And along with that you have to think about sensor size; usually the DSLR sensor is much bigger than the CCD and that not all targets emit / reflect a large amount of Ha. I think you may have to just hunt online for compatible images and exposure times. But it would be interesting to see such direct comparisons. James

It looks like it is linked with subtle diffraction spikes, but in an asymmetrical fashion. Are you 100% sure it wasn’t there before the cleaning? I don’t know how to fix it, other than to make sure that you’ve not left an obvious big smudge of something on part of the optics or displaced something, or seated the camera at an angle to the focal plane. I wouldn't have noticed it had you not said. If you don’t like it and the scope is new, I’d talk to the retailer. On the whole, optics are usually best left a bit dusty. An air puffer alone does good; cleaning them otherwise often creates many more issues than it resolves. I also wouldn’t use a micro fibre cloth as I think this could still scratch the optics. I hope you find a cure.

What camera was this?

Very nice