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jonnydreads

Exposure time without eq mount

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I haven't yet got an eq mount but still want to take images tonight. Is ngc 7000 unrealistic for 20 second exposures..? 

Dslr @ 1600 iso 

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If the object is either in the East or west between 30-60 degrees that will be favourable for exposure length. Your telescope puts huge demands on the mount so you'll have to just try. However try to get well over 100 images to help.

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2 hours ago, happy-kat said:

If the object is either in the East or west between 30-60 degrees that will be favourable for exposure length. Your telescope puts huge demands on the mount so you'll have to just try. However try to get well over 100 images to help.

I have tried tonight. Nothing short of disaster again.... 

Im sure i have plenty of patience but everything in regards to imaging is working against me with this set up. To top it off I have a Macbook to process and theres hardly anything decent to process...I was kind of thinking if I could do it with this type of equipment then when I do get some equipment I'll be onto a winner ?

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It is possible but you have to work with the challenges.

Your very long focal length is one and the OTA may be wind breeze movement prone. Perhaps don't fully extend the legs. Choose target to suit best chance of exposure length.

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Yes your right. I will keep at it though. I'm determined to get something. I've got about 20 subs of m31 but they literally looks like blobs ?

I can't see orion neb from my house at the moment or I would concentrate on that for sure as I can even see that through my eyepiece quite well. 

 

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this is kind of what I'm dealing with for m31, out of focus, star trails, I think I'm just asking to much for what I have at the moment, I might get myself a bahtinov mask in the meantime too, to see if that makes a difference with the focussing, my eyesights not fantastic anyway so 2.5 million light years is pushing it a tad ?

IMG_0022.jpg

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With my AZ GTI mount I can get around 20 secs consistently. On a wind calm night I can get 25. I've taken one or two photographs at 30, but can't do so consistently.

My scope is a 127mm Maksutov with focal length of 1500.

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That looks about right for m31 single sub. The rest comes with more data and processing. You do need to get focus and try the mount legs not fully extended keep that mount still. Also what about running say Wine on the MAC then you can use DSS to stack.

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DSS can help with a little star trailing as long as DSS can recognise them it will stack. Do you own any camera lenses you could start with that it is easier to get to grips with. M31 is so big a 200mm lens is plenty.

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9 hours ago, happy-kat said:

That looks about right for m31 single sub. The rest comes with more data and processing. You do need to get focus and try the mount legs not fully extended keep that mount still. Also what about running say Wine on the MAC then you can use DSS 

I will look into that. Just didn't want to destroy the mac because I'm  not very tech. May purchase a cheap laptop just for astro

Yes good shout with the legs I never even considered that 

Edited by jonnydreads

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8 hours ago, happy-kat said:

DSS can help with a little star trailing as long as DSS can recognise them it will stack. Do you own any camera lenses you could start with that it is easier to get to grips with. M31 is so big a 200mm lens is plenty.

Yes I have a lens will try piggy back too... I wanted to anyway thanks 

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Hiya Jonny

I have a few suggestions that may be of help. Firstly NGC7000 is a large object and if you’re using your DSLR with the Nextstar 8 then you’ll only see a tiny chunk of it - even with an amazing mount you’re so “zoomed in” that you’d probably struggle to expose it. Eg in screenshot from SkySafari I’ve got the blue circle what you’d see in a 32mm plossl, and the blue rectangle showing a Canon 450d, both with Nexstar 8. Only the “Gulf of Mexico” would be framed.

If I understand your profile right you’re in the UK too, so NGC7000 is really really low in the sky at the moment.

So perhaps suggest a target higher in the sky and  smaller targets - perhaps M81 or M82 or M1.

However, I’d also agree with the suggestion to try piggybacking the DSLR instead. I’ve been doing this almost exclusively with my Nextar 4 for some time. There’s a Celestron adapter for around thirty quid, and just using a camera lens you already own (somewhere 50mm to 150mm to start with maybe) the Alt-Az tracking will be far more able to keep up (the focal length being that much shorter). At least consider it as a way to get practiced even if you want to go back to shooting through the Nextstar later.

Either way, yes, using DSS is pretty much a requirement.

 

Good luck!

9B9B5983-26D3-4B27-9D2E-EBDA1B054A93.jpeg

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Personally I wouldn't piggy back. I'd take the OTA off and have the mount carry just a camera and lens. Your image shared is not star trails I don't think but either mount stiction/jerk or a bit of breeze movement.

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This grab of a bit of your image shows close up of a couple stars that are showing either mount jerk or breeze movement, notice the break in the star. Star trails are an elongation of star shape with smooth edges. You have both really the star area covered is elongated but it is also broken by some movement or other. kappa-sigma clipping in DSS can  help make stars appear a better shape after stacking, if the stars were recognisable in registration.

 image.png.ce7ec4c254b7b1cf0478d25fa6dfc6ea.png

Edited by happy-kat
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On 21/02/2019 at 22:27, happy-kat said:

That looks about right for m31 single sub. The rest comes with more data and processing. You do need to get focus and try the mount legs not fully extended keep that mount still. Also what about running say Wine on the MAC then you can use DSS to stack.

This is the 1st sub I've ever seen and it happens to be mine so I just assumed I'd messed it up ? I expected more detail if I'm honest 

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Do take a look at the thread I had linked in an earlier reply. Detail comes with stacking. Have another go.

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5 hours ago, happy-kat said:

Do take a look at the thread I had linked in an earlier reply. Detail comes with stacking. Have another go.

Ye I will do thanks. I knew images looked different with stacking but I'm a bit blown away by how different they look....look like a different image altogether

On 21/02/2019 at 22:27, happy-kat said:

That looks about right for m31 single sub. The rest comes with more data and processing. You do need to get focus and try the mount legs not fully extended keep that mount still. Also what about running say Wine on the MAC then you can use DSS to stack.

This is the 1st sub I've ever seen and it happens to be mine so I just assumed I'd messed it up ? I expected more detail if I'm honest 

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On 21/02/2019 at 18:18, jonnydreads said:

I'm using nexstar 8se. Alt/az  and 2000mm

Operating at f/10 2000mm is asking a lot, in short exposures your really not going to get much to shout about.

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On 21/02/2019 at 22:15, George Gearless said:

With my AZ GTI mount I can get around 20 secs consistently. On a wind calm night I can get 25. I've taken one or two photographs at 30, but can't do so consistently.

My scope is a 127mm Maksutov with focal length of 1500.

I have the same mount and a 127mm Maksutov. I have just got a Canon 600D and the T-ring adapter so I am hoping to take my first step into astrophotography tonight. I will try those times and see what I get. Not hoping for much success first time around but certainly looking forward to giving it a go.

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Start off with a 50mm camera lens( or thereabouts), the telescopes with those sort of focal lenths are going to be very,very challenging to start out with.

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14 minutes ago, Ibbo! said:

Start off with a 50mm camera lens( or thereabouts), the telescopes with those sort of focal lenths are going to be very,very challenging to start out with.

You aren't kidding ???

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1 minute ago, jonnydreads said:

You aren't kidding ???

I did almost the same as you 20 odd years ago, then after some advice bought a 60mm refractor and piggybacked it on the 200mm SCT that was on a wedge.

 

Much easier, but still had a steep learning curve.

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