The Lazy Astronomer

To my knowledge, you can't change the fan speed. You could turn the cooler off, although that would obviously negate one of the main benefits of an astro camera over a DSLR.

When just tracking a mount should be basically silent, no? Slewing is another story, but then if you're imaging surely you're not constantly slewing around anyway. Can't speak for other manufacturers, but the fans on the ZWO cameras suitably quiet - I can't really hear mine from more than a couple of metres away. In fact, my whole setup is far quieter than the hedgehogs rustling around in the bushes!

If you can't see anything in a 10s exposure then it was probably a focus issue. If you didn't manage to get it resolved last night, try focusing on a distant object in the day.

I stand corrected!

Absolutely no reason the 1600 couldn't be a 'lifetime' camera. It's a solid performer, and its only real issue is the microlensing artifacts on brighter stars. The suggestion of 294MM is also a good one. I was in a similar position last year and opted for the 294MM as my paper assessment concluded it was better in pretty much every aspect when compared to the 1600, but it is more expensive, partly because they don't seem to be interested in selling it bundled with filters and wheel like the 1600. If you're struggling to justify cost, then the 1600 is probably the better option for you.

Hope you it find it to your liking 👍 Plenty of tutorials on youtube to help you out learning it. Be sure to check out the unofficial manual too, loads of tips and tricks in there (pdf download available on Startools website).

Or Startools 😉

No, I must admit I've not actually seen any reasoning behind it, other than the point that he says the technical documents for the sensor (which I've not seen either) apparently advise against using the affected gain range (but again, there doesn't seem to be an explanation of any potential impact to images taken within that range). Unfortunately, my understanding of the technicalities of the subject is rather limited, so I'm just left stuck thinking "does it really matter?" The persistent cloud and rain here over the last 3 or 4 weeks has meant I've not even been able to test it!

It's not that it's unusable, far from it - I've been using it at unity gain for the last 6 months and have taken some pleasing images, and I've seen plenty of others using 120 gain with good results as well. This is why I'm not sure if it's a non-issue in the 'real world'. The weird narrowband flats I think are a feature of the sensor itself, rather than anything to do with gain settings. From what I've been reading, this camera seems to be very picky about calibration frames (lots of people having issues with flats). In my last image, I had to reshoot temperature matched flats and flat darks (-10C) in order to get the flats to properly calibrate the lights. For 2 previous images though, I had used room temperature flats and flat darks and these had worked. Still no idea why suddenly the room temp flats didn't work, but I'm wondering whether it was somehow related to sensor non-linearity and maybe somehow that's affected by sensor temperature? (I don't know what I'm talking about 🙃) This is exactly what I'm thinking at the moment. I've read conflicting things - someone pointed out that if a non linearity was repeatable then it shouldn't be an issue, but Mr Glover seems to be of the opinion that the 120 - 190 gain range should be avoided entirely. I suppose the only way to know would be to do some real world side-by-side tests at gain 0 and gain 120 to see if there's any effect on the image. If only the clouds would clear... 🤔

Now that's a serious purchase! You will not be disappointed, l took delivery of the 100 a couple of months ago and it is fantastic - I firmly believe the Esprits really punch above their weight. 👍 A note on the weight though: I was really surprised how hefty the tube was for mine - I know all the weights and dimensions are available online, but still it was a bit of a shock just how big it actually was - I can only imagine how much of a beast the 150 must be!! P.s. the stock focuser is more than capable too.

So, I have the ZWO294MM camera, and whilst searching around the internet trying to resolve some troubles with flats on my most recent image, l stumbled upon this post on the Sharpcap forum from Robin Glover. I tried this out for myself, scope pointed at a wall in the middle of the day, and sure enough, at 120 gain and no filter, it was not possible to saturate all of the pixels, no matter the exposure time. The minimum value as reported by N.I.N.A. was around 58000 - this was the same for a 2 second exposure and a 2 minute exposure. When l tried 119 gain (LCG mode), it was possible to saturate all pixels, and at gains of around 140+ it was also possible to fully saturate the sensor. My questions, then, for the far more learned than I, are: should l not be using this camera in the gain range where it doesn't seem to work properly? Would it be better to stick to the LCG mode and treat it more like a traditional CCD (high read noise, so longer subs needed, but huge full well depth)? Or would it be better to use higher gains (no real change in read noise from 120 gain, so no change in sub length, but lower well depth and reduction in dynamic range). Or, is it a non-issue and should I just continue imaging at 120 gain? Thanks in advance!

I know ZWO cooled cameras draw a max of 3A, I would imagine the draw of other manufacturers to be broadly similar. Cabling is able to carry a surprisingly high current - decent 0.5mm2 cable is able to carry over 10A

With a cooled cam, use darks. I believe the general consensus is bias frames are of no benefit with a cooled cam. Also, use flat darks.

I've just added an eaf and a dew heater to my setup, so am currently going through the same cable mess. Fortunately my main imaging camera has its own usb hub which powers and controls the eaf and a filter wheel, but I've had to order a seperate usb hub as well. Hoping I'll be able to get away with a bus powered one, but I will find out when it arrives tomorrow. I think the best way to deal with it is to try and strap as much of the cabling as possible onto the scope so there is the minimum possible loose cabling connecting to power/pc (and make sure there's plenty of slack!)

I am very much looking forward to v1.8!

Knowing @alacant, this will all have been done in Startools.

This is plate solving like they used to do 😁

During stacking, your stacking software should be able to align images to a reference frame without including the reference frame in the stack. I do LRGB imaging with a mono cam, so do all the time in DSS.

The purpose of flats is to correct uneven field illumination in the light frames. If you have vignetting in your lights (which you do), then you should see the same vignetting in the flats (which there is). The calibration process should use the flats to, er, flatten, the image. However, your stacked image still shows vignetting, which shows your flats have not flattened the image. So something is not right. That's why l was asking about your settings, to get a bit more information as to why they're not working. While I think of it, how did you take the flats? I think with DSLRs you put them in AV mode and let the camera figure out the exposure time*. Is that what you did? *I have no experience using DSLRs for astrophotography, but I think that is right.

It looks like you've found a solution now, but just FYI, N.I.N.A. does have a module for manual focus targets. Saves having to import the coordinates each time. 👍

The same vignetting is clearly visible in both the flat and in your earlier image, so the flats are significantly under correcting - it's almost like they weren't applied at all. What settings did you use for shooting the flats? What were your DSS settings? Have you tried stacking without darks? (darks not usually recommended for DSLRs anyway)

Looks suspiciously like vignetting to me. Could you post up a copy of your master flat?

Answers in order: yes, yes, no, yes, yes, yes. With a bit more detail: you'll need a laptop or a mini PC with appropriate drivers and software to control the camera. Plenty of freely available software for this - my choice is N.I.N.A. Getting the software and the drivers initially set up can be a little faffy, but once all installed and configured there's no need to do it again. If you run into issues there, the people on this forum will be able to provide solutions. Exposure lengths can be set to basically whatever you want (from memory, ZWO cameras can be set anywhere from 32 microseconds up to 2000 seconds). ISO is replaced with 'gain', but it's basically the same thing. The camera manufacturer should provide details on various aspects of the performance at different gain values; you can use that to help you decide what gain to use (you can also run your own sensor analysis in Sharpcap, should you so desire). The standard file format for astro cams is FITS, all the stacking software will handle FITS files, you may need to download a FITS viewer program to look at the individual images outside of the capture or stacking software (again, loads freely available on the web - I use ZWO's one). All the usual calibration frames will still be required: at a minimum, darks and flats, ideally flat darks as well. The advantage of set point cooling on an astro cam means you can build a darks library to reuse many times, negating the need to take darks every session, provided you stick to the same camera settings. Advice here would be pick a temperature, pick a gain, take a load of darks for the various exposure times you normally use, and then stick to those settings for all of your imaging. Obviously you can just shoot some more darks whenever if you wanted to use different exposure lengths to what you already had darks for. Wow, that became a looong post!!

Really good review, felt honest and unbiased, and nice little bits of humour injected in too. Would be interested in seeing more - perhaps @FLO could sponsor you to live in the Atacama so you have enough clear sky time! 😅

Nice image, great improvement on the first one 👍 I think your short focal length will probably limit you on this target. M13 is around 16 - 17 arc minutes diameter, so with your setup you're it'll cover just a little below 500 pixels on the sensor (or, to put it another way, about 1% of available sensor area).