Endolf

4 minutes ago, newbie alert said:

You can't just say that and then leave it...at least show us the reason why it's  peeing down

Here it is, I've attached my existing ASI1600MM Pro Cool and guidescope. It's at an odd angle so the guidescope looks slightly larger than it should, but as the guidescope is 50mm and the new scope is 61, there isn't a huge amount of difference

On 19/08/2020 at 06:31, newbie alert said:

Maybe a sharpstar, think they're now doing the 60mm as a triplet

https://www.365astronomy.com/sharpstar-61edph-ed-triplet-apochromatic-refractor-telescope.html

It's arrived this morning :), I got the reducer too for 275mm focal length, now for some more cloud......

I'm not sure I'd ever want starless as a final image, I think it makes for an interesting exercise, and I think that removing the stars, processing the nebula (or other target) and then adding the stars back in later is not really much different to creating a star mask and processing the image around the stars. Another tool in the box rather than a magic bullet.

As for my images, I've only been doing this since February this year and I'm still on a trial for PixInsight, so I know full well that I've a lot to learn on processing

The F ratio is useful for gauging how long it will take to gather enough photons for the frame being shot. The key is that the f ratio doesn't tell you which part of the ratio has changed. If the target you are shooting fills the field of view of the camera combination with say a 1000mm focal length and say 200mm aperture, then shooting the same target at 200mm aperture at f4 will mean the target is smaller on the sensor, if you then crop and upscale to produce the same final image, then you've just lost all the extra photons. If on the other hand, you go to 1000mm but with an f4 (increasing the aperture rather than reducing the focal length) then you will be gathering more photons on the same target.

I thought I'd have a quick play with the latest pixinsight with starnet plugin to see what would happen. These are all just taking my final jpg images and applying the processes. I *think* the better approach will be to remove the stars after the early stretching is done, then do the rest of the processing and then add the stars back in right at the end.

Ekos on StellarmateOS on a pi 4gb. I use it because I wanted something I could leave out with the rig that wasn't my laptop. I also liked the idea of being able to use the rig away from home without requiring a large power supply, the pi + mount etc use enough without adding a laptop, so being able to control the rig from my phone seemed like a nice feature.

I'm also an advocate for open source, so other than the mobile app part being proprietary, the rest being open source appealed to me.

6 hours ago, newbie alert said:

Maybe a sharpstar, think they're now doing the 60mm as a triplet

https://www.365astronomy.com/sharpstar-61edph-ed-triplet-apochromatic-refractor-telescope.html

Ooh, that's interesting, not seen them before. They do some nice fast newts too :).

Seems to get some good reviews if used with their own reducer/flattener.

Thanks

Hi

So having got the 200/1000 newt up and running earlier this year I've been happily imaging at 1000mm. I'm looking at adding a second scope to the mix and a wider field. I started looking at the WO Zenithstar 61 with the 0.8x reducer/flattener. This would give me 288mm at f4.5. This seems to frame up some of the larger targets quite nicely (M45, M42, M31, Heart and soul etc) and at f4.5 it's also a bit faster than my newt. My plan is just for an additional scope at this point, so still mounting it on my EQ6-R pro with the ZWO ASI1600 + filter wheel and also reuse my guide scope/cam.

It turns out the 0.8x reducer is no longer available, seems some people have found issues (I don't know what) and WO are looking at it, so I was wondering what alternatives are available.  The ZWO redcat 51 is an obvious example, it's even wider but slightly slower, are there any similar quality, similarly priced scopes that people can recommend?

Thanks

Thanks @AstroRuz, I found this really useful. I've developed a different way to do the star selection, but having the information to start with was invaluable.

I had exactly the same issue, I found a "solution"....

I spent a few hours on each of the last 2 nights doing my first narrow band project, I decided on NGC 6888 as it was well placed and seemed like a good size for my setup.

Just over 4 hours of data over the 2 nights, using a custom RGB combine in Astro Pixel Processor to get the colour image from the narrow band data.

I'm pretty pleased for a first attempt

Nautical dark for narrowband, astro dark for broadband, clearoutside.com lists the times.

And then there is the guide scope, and the 2 cameras, and possibly a filter wheel and filters, something to control it all, auto focuser, then the second rig....

Unfortunately astro photography does seem to be a bit pricey. If you already have an astro modified camera, I have seen some budget builds, people getting lucky with second hand items.

3rd vote for the HEQ5 if you want to mount a 130 or maybe a 150. If you are starting with the 130, but plan on going up to something like a 200 in a year or two, you'll need to consider something like the eq6-r pro.

My mistake, I just stretched one of the original darks and it has a very similar pattern of hot pixels, so it seems they have been there from the start.

Hi

I started taking some darks this evening having not used my gear for a month only to find I now have a huge number of hot pixels in my darks, has anyone else experienced anything like this?, is it terminal?, I've only had the ASI1600MM Pro camera since the beginning of May and only got in a few sessions before losing astro darkness. The darks I got back then appeared ok, so it wasn't defective on arrival. I've attached a sample from the middle of one of the darks and attached the fits files if anyone can shed any light on it.

Thanks

Dark_300_secs_005.fits Dark_300_secs_004.fits

Accurate PA is about refining the accuracy of the tracking. The 2 or 3 star alignment will have a similar effect, but isn't as good as getting good PA to start with. Just like guiding can compensate for some poor PA, so can the star alignment routine, ultimately, the better the PA, the better the tracking will be. If your tracking turns out to be "good enough" for what you are trying to achieve, then spend the money else where, if it's not, getting a PA scope and routine might be worth the investment.

2 minutes ago, FMA said:

I tell to go to vega and the scope goes in the direction but is not in the eyepiece and I have to loose the clutches and find it( manual says that should be done with the arrow keys for more accuracy) is that correct?

Yes, the mount "learns" how far out it is during the alignment, if you use the clutches to do this it doesn't know it's been moved, so you have to use the arrow keys.

I might have to turn a cupboard in to a dark room....

Thanks.

Good thought, I checked by doing a test dark at 300s, similar results, this was with the camera removed from everything and a cap screwed over the sensor, so it's coming in through the camera somewhere.

1 hour ago, Adreneline said:

I've never tried to image the ISS let alone during a lunar transit.

In some ways I think it's easier, I knew exactly where it was going to be, all I had to do was track the moon, the timing was the only issue, without the moon I think it would be harder to get on target and you'd still have the timing issue. It's the only time I've ever attempted it

Hi

I tried to get some flats and darks during the day time with my 8" newt and my ASI1600MM Pro cooled camera. I had assumed that being cooled, I could bring the temperature down to the same as when I'm shooting and be able to take calibration frames during the day. My first attempt was awful, the darks just were not. I remove the camera, filter wheel adapters and coma corrector assembly from the scope to try again and found them better, but still not looking like I expected a dark to look (I had glow in the corners for example). I waited till dark and tried again and got something that looked like I was expecting, stretched, it's a uniform noise/grey across the whole image.

As I wanted to take flats this way too, I decided I needed to sort out the light leaks. I realised that the gap round the primary mirror was one big source, so I've made a cap for the rear of the scope for when I'm shooting indoors. It should help reduce dust getting in to the scope when stored too. By wrapping an old pillow case around the focuser (covering from the scope body right up to the filter wheel) I've managed to get the light levels closer to that good dark image. But I've noticed another location where it leaks. I *think* it's in the camera body itself. Being a cooled camera it has cooling grills in the body, and I *think* light is getting in to the body this way, the bright spots are the 4 corners of the image. Covering these to get better darks would be a bad idea, as the cooling would stop working.

Has anyone else experienced this with cooled CMOS cameras?, is there a way to reduce this?, am I analysing my darks and flats too closely?, or am I really going to have to go back to shooting flats (with an ELP) and darks in darkness (given we have no astro dark at the moment).

I've attached a 300s dark.

Thanks.

Dark_300_secs_002.fits

I got inspired by Dylan O'Donnell and his guide to shooting lunar transits of the ISS, so I subscribed to calsky and waiting. On the 25th I got the notification that I was due a transit on the 28th. It was only due to skim the edge of the lunar disc, but I thought it was worth a try. I went back and watched his guide again and planned my evening. 

First was camera choice, the ASI1600 just doesn't give a reasonable frame rate, and it's mono, so I went back to my Canon 600D. Dylan's guide suggests an shutter speed of 1/1600th or faster to get blur free images, which ruled out video on the Canon, so I tested the number of shots and the speed of them shooting in continuous mode. 6 shots in ~1.5 seconds and then the buffer is full. I played with the idea of shooting in a lower res jpeg format to see if I could get more images in the buffer, trying to get the timings perfect was going to be a challenge otherwise. In the end I went with raw and the assumption that I'd probably not succeed on my first attempt, so I'd learn something if nothing else. 

The night before I went out with and set up including my laptop, normally I use Stellarmate on a raspberry pi, but this time I also needed the canon software running on windows to trigger the continuous mode shooting.

I found that in auto mode the camera was shooting ISO 6400 at 1/1600th of a frame to get the moon right, so I knew I was on the limits of the setup.

The night of the event I set alarms to get the setup done, "you should be done by now", final checks and a 1 minute alarm. I got the focus done as well I could see on the live preview of the camera and waiting. I wasn't able to PA as it wasn't dark enough, so I knew tracking would have to be tuned a couple of times in the run up.

As the 1 minute alarm sounded I had my finger on the trigger and stared intently at the seconds on the clock. At 22:11:14.5(ish) I pushed and held the button. 1.5s later I looked up at the moon and watched the station go by. Then I went back to see what I'd managed to capture.

I saw that there were some white pixels in the image, so I captured another 60 images of the moon to stack.

And here it is, the ISS right over the terminator. The ISS is totally over exposed, so there is something to improve for next time, but I'm quite happy for a first attempt, I was expecting to miss it completely.

And because it appeared in all 6 shots, I put an animated gif together

Thank you for the replies, the ASI1600 (cooled) is looking likely then.... I guess the next question then is which filter wheel to go for, they do 3 bundles with 1.25", 31mm and 36mm filters....
I understand the zwo filters have improved, so I'm tempted with a bundle with 7 filters, LRGB + Ha/SII/OIII....