First Time. Lots to do but lots of learning already :)

[BenOak]

I have finally managed to cobble together enough to start on my astrophotgraphy journey. Below is my first attempt which is horrendous when comparing to what is possible, but for a first go, not all that bad.

I have the Star Adventurer GTi mount, with a Nikon D5300 DSLR and the stock 18-135mm lens. I took 35 x 60sec images at F5.6 at 90mm at ISO 1600. I stacked and processed with SIril but didn't take any bias frames so this is just the lights.

My main issues in my mind are problems with alignment because its hard to get the aligning stars in the middle of the view finder consistently. I need to take the bias shots. I think my focus is off. I didn't check the frames for any problems prior to stacking so this is all 35 frames. I think the exposure time is too long. My post processing isn't that great.

What would your recommendations be, any suggestion, gear tips if anyone has the same stuff etc that I should consider and try next time?

My other lenses are a Nikkor prime 50mm and a Sigma 70-300.

Next steps once these issues are sorted out will be for a small scope to go on the mount with the camera directly on that. I have a 305mm Dob so unfortunately thats far too heavy for any mount.

Edited January 31 by BenOak
Typo

[Elp]

If your polar alignment is good you shouldn't really have to keep recentering the camera if the mount is sidereal tracking. The benefit of moving the camera however is you are manually dithering which helps with removing fixed pattern noise when stacking.

60s at F5.6 is okay for deep sky, I usually do 60s most of the time but sometimes dial it back if imaging in colour due to light pollution, in the case of M42 Orion it does overexpose the core of the nebula but it is a unique target in that if you want to see the inner stars in the centre you have to do a composite image, one with very short exposures (like less than 5s or so) and one with your usual deep sky exposure time. Blending them together requires post processing in Photoshop/Gimp/Affinity/Equivalent.

For a better image you need to take flats and dark flats and dark frames and calibrate your light frames when stacking. You'll be able to push the stretching of the levels more to reveal more faint details as a result.

Focusing with a camera body can be challenging. If you don't have focus assist what I tend to do is take a short exposure, then check the image and zoom right in, rinse and repeat on both sides of focus. Takes less than 5 minutes. You could use a bahtinov mask but it'll be hard to judge the diffraction pattern in widefield, the preview method works just as well and you don't need anything other than what you already have. Focusing camera lenses manually takes a deft touch, almost to the point where you're not turning the focus barrel at all as the tiniest touch can mean the difference between slightly bloated stars and being in focus.

As a first go I'd be happy what what you've got in the image.

[carastro]

Pretty good for a first attempt. 
 

Suggestions.  I would consider using a Samyang 135mm lens rather than a small scope as l am not sure your mount is up to a telescope.  The Samyang lens is vastly superior to the stock lens and will give a smaller FOV.  
 

Flats are imo the most important calibration frames to take so do try to learn to do these.  
 

Well done.  
 

Carole

[Coco]

Slippy slope... get your wallet ready..

[BenOak]

1 hour ago, Elp said:

If your polar alignment is good you shouldn't really have to keep recentering the camera if the mount is sidereal tracking...

...60s at F5.6 is okay for deep sky...

...For a better image you need to take flats and dark flats and dark frames and calibrate your light frames when stacking. You'll be able to push the stretching of the levels more to reveal more faint details as a result...

...Focusing with a camera body can be challenging. If you don't have focus assist what I tend to do is take a short exposure, then check the image and zoom right in, rinse and repeat on both sides of focus. Takes less than 5 minutes...

I felt that the stars don't look round which I thought was an alignment issue. You use 3 star alignment on the Adventurer GTi and so I try to get the star exactly in the centre of the viewfinder but I figured if it's not perfect each time then there will be a slight drift. I do have a spare spotter scope that I am going to fix to the dovetail bar next to my camera which I am hoping will give me a more accurate alignment.

As for the exposure and f number, would there be a better option with the lenses I have? Would the 50mm f1.8 give too wide a view?

I need to sort out the bias shots.

When I was focussing I tried using the live view on the camera and it seemed ok but images themselves didn't so I just eyeballed it with Betelgeuse. Is it possible to tell if the blurriness of the image is due to focus or a slight drift?

1 hour ago, carastro said:

....I would consider using a Samyang 135mm lens rather than a small scope as l am not sure your mount is up to a telescope.  The Samyang lens is vastly superior to the stock lens and will give a smaller FOV.  

...Flats are imo the most important calibration frames to take so do try to learn to do these...

I will look into that lens as for a scope, the mount takes up to 11lb so I figured a lightweight small scope would be better than a camera lens. I take it that may not be the case?

Thats two for two advising on the bias shots. I will look into that next time.

1 hour ago, Coco said:

Slippy slope... get your wallet ready..

Yeah I know. I had that with my original scope, now its with this. A small lottery win will solve all those issues good enough. Just need to find out where you get one of those!

[Elp]

1 hour ago, BenOak said:

more accurate alignment

Learn to drift align using the darv method. It's the most accurate way of PA and ideal if using camera bodies.

[carastro]

It was flats l mentioned as being important.   
 

To be honest there will always be problems using this type of mount but if that’s what you have and don’t plan to upgrade you will have to learn to do the best you can with it.   
 

With a Samyang lens l managed to acquire a very nice Bahtinov mask  that works well with it.  It wasn’t cheap about £40 if l recall with the postage and laser cut from a guy in America again  if l recall.  Just trying to remember his name.   Will amend this post if l can find him. 

Found it: 

https://www.lonelyspeck.com/sharpstar-2-precision-bahtinov-focusing-mask-filter-for-astrophotography-by-lonely-speck/

There could of course now be someone in the uk making them that small as it was a few years ago. 
 

carole

Edited January 31 by carastro

[ollypenrice]

This thread covers the issue of small scopes on Star Adventurers. It will address most of your questions. 

When focusing a camera lens on stars, try concentrating on stars at the intersection of the 1/3 lines, imaginary lines parallel with the chip sides but a third of the way over to the other side. These 4 points will give you the best compromise for the chip as a whole.

If you zoom in at this point, critical focus can often be found by looking at the faintest stars which only appear when focus is right.

Starnett++ and StarXterminator: these modern star removal/replacement software tools work well on all kinds of astrophoto but are particularly effective on camera lens images because smaller apertures always produce larger stars. Some might say, 'Learn about this later,' but I'm not so sure. Being able to stretch the nebulae and the stars differently makes processing so much easier.

The Samyang 135 is a stunning astro lens, as Carole says.

Olly

[BenOak]

Thanks everyone. The lens is outside of my budget for now so I'll work with the lenses I have but I'm not a big believer in just buying more expensive equipment as a beginner. I need to know how to do it before I spend more money. I know the mount is up to the job and the tracking is fine when aligned properly, there are plenty of shots out there using it that prove that, including with little scopes that I would think are less forgiving than a camera lens. The same for the camera body too.

I will work on getting sharper stars and then go from there as I feel that the stars are too large and too numerous in the shots I took. I was just surprised at seeing both the horsehead and flame nebula, without which, I probably wouldn't have kept the image. Although my lenses aren;t expensive ones, they range from 18-300mm so I should have enough to work with, and learn what works and what doesn't.

 

 

[Elp]

You've already tried stopping down to f5.6 which for me would be the limit for imaging astro, stopping down is usually the thing to do to reduce star bloat. From my experience, most lenses aren't suited to astro, fixed primes are best and even then they need to be made right for the job (glass type/materials etc), but try with what you have at hand.

[Budgie1]

Overall, for a first image, I'd be happy with what you've achieved.

Apart from what the others have said, my advice would be: Concentrate on the basics, read lots, watch loads of videos and get out there and practice.

There's a difference between Star Alignment and Polar Alignment. Star Alignment makes it easier for the mount to find a target for you. Polar Alignment make sure the mount will track with the rotation of the Earth, so your target won't drift out of the frame, your stars will be rounder, meaning you can take longer exposures.

Do you're Polar Alignment first, then your Star Alignment. You can download free apps which help you with the Polar Alignment and there's also instructional YouTube videos.  

Calibration Frames: There are four basic types of calibration frames:

• Lights
• Darks
• Flats
• Bias

I'm sure there are others, but I found this link handy when I started using calibration frames: http://deepskystacker.free.fr/english/faq.htm

I know the Samyang 135mm F2 lens is out of range at the moment but, it's a really good lens, both for astro and terrestrial photography. It gives a good field of view and the ED lenses don't bloat the stars or leave a magenta halo around them, like cheaper lenses will. Keep an eye out on the second hand market as they do come up from time to time.

[h107]

That is a good first image! 

Everyone has added some really good things to think about so I'll add something a bit different. I think before you start AP you kinda think "ah, I can take images with my camera so I can do space right?" but there are so many factors to take into account that will only come with just practice and a hell of a lot of patience. Try not to compare images too much with other peoples are every one has a different idea on what and why they like to capture images/how long they have been taking astro images and what their equipment is. 

Get used to checking the weather all the time, haha.