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Questions Regarding Equipment and Wide-Angle Astrophotography

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#1 astro378

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Posted 15 August 2019 - 10:52 PM

Greetings.  I am interested in getting into astrophotography and I was looking to start with some wide-angle nightscapes.  I have a rebel T3 with the 18-55mm kit lens and a sturdy mount (Manfrotto 055), and access to Photoshop and Lightroom.  I found this article and, while it was a helpful primer, it is a bit old and I wanted to get some feedback on what I should consider upgrading (camera, lens, buying tracking equipment, etc.).  So I had a few questions:

  • The article states that star trailing can be minimized just by taking shorter exposures (10-30 seconds)?  The photos seem to speak for themselves.  Will tracking equipment make a meaningful difference (at least for a beginner)?
  • The article recommends Rokinon lenses, but again it's an older article.  Are Rokinon still considered good lenses?  Any insight on other good brands and recommended focal length is welcomed.
  • Would upgrading my camera be a better bang for my buck versus buying a better lens?  I presume that even a more current model Rebel would be a significant improvement.

I don't want to do this half-cocked, but does it makes more sense to just go out and shoot with the equipment I have and process some photos (and push upgrading down the road)?  

 

If anyone can give some insight or point out potential pitfalls (e.g., unnecessary purchases or necessary purchases you would have made in retrospect), it would be appreciated.  If anyone needs to know my budget, I have about $1000 to spend (if more is needed that would be good to know and would help temper my expectations).  Again, I appreciate any thoughts and comments.  Thanks in advance.

 

EDIT: Thank you to the kind moderator who moved my post to the correct subforum.  Apologies for not reading carefully enough.


Edited by astro378, 15 August 2019 - 11:29 PM.


#2 ShaulaB

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Posted 15 August 2019 - 11:16 PM

As Geordi Laforge would say, "Reading is fundamental."

Beginners Forum (No astrophotography here - please read the forum description)



#3 Jond105

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Posted 15 August 2019 - 11:22 PM

Moved to B&II for better fit. Remember to read forum guidelines. 



#4 james7ca

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Posted 16 August 2019 - 12:34 AM

One issue that's going to have a major impact on your wide-field imaging is the amount of light pollution you have at your site. It's not only the brighter skies but the gradients you will get when trying to image over a large area. So, if you have dark skies with little to no light domes from surrounding cities then it's possible to do some really amazing work with just a wide-field, normal, or short telephoto lens. With light pollution you probably want to keep your targets pretty high in the sky, maybe within 30 degrees of the zenith (for really good results).

 

As for exposure times, 10 to 30 seconds is a little optimistic unless you are using a very wide angle lens. But, it depends upon how sharp and round you want your stars to appear (and how closely you look and how large you want to display or print the results). I use a "rule" of 100 divided by the focal length of the lens and that gives you a good starting point for a maximum exposure in seconds. I think the traditional (and often repeated) 500 "rule" is outdated and really more appropriate for film-based cameras, not digital imaging with today's small-pixels (but, YMMV).

 

You can expose longer when imaging closer to one of the celestial poles, but if you want really pin-point stars and if you are imaging near to the zenith then the "rule" should probably be something like 50 divided by your focal length (that means a maximum of 1 second for a 50mm lens). That said, with a wide-angle lens and when imaging the Milky Way you can still try exposures in the 10 to 30 second range, but don't expect them to look sharp in anything other than a 4x6 inch print or on you phone's small display.

 

I'd say start with what you have before spending any more money. Also, don't overlook the possibilities of buying a used, manual focus lens from a place like ebay. Some of these older lenses can be purchased in good condition for around $100 (U.S.) and they can produce good results as long as you close them down by a few f-stops.

 

As for using a tracking mount, yes, that can help greatly but in my experience the performance/quality of the low-end camera trackers varies a LOT from sample to sample, so you never really know what you are going to get (some samples are pretty good, some are very bad and it probably makes little difference in the make or brand).

 

In any case, as I suggested earlier I'd just start with the equipment that you currently have, which means just about any camera body, a lens that has a manual focus ability, and a tripod. You may also need some type of remote camera release or intervalometer, since you don't want to be touching the camera when you start your exposure. I don't know whether your Rebel T3 has a built-in intervalometer, but many cameras can be used with an accessory intervalometer, or with software like BackyardEOS or BackyardNikon, etc.

 

For image samples and other tips on technique, you can do a search here on CN. Here are just a few samples from my own work:

 

(fixed tripod)

https://www.cloudyni...d/#entry8888970

 

https://www.cloudyni...d/#entry8881987

 

(tracking mount with camera lenses)

https://www.cloudyni...a/#entry8752209

 

https://www.cloudyni...r/#entry8509606

 

https://www.cloudyni...s/#entry9549322

 

And below is an image of the constellation Lyra that I took with a Nikon D5100 DSLR and a Nikkor 50mm f/1.8 Ai-S pancake lens set to f/4 (ISO 400, a stack of 32 images, each exposed for one second, producing a total integrated exposure time of 32 seconds). No guiding or tracking was use, just the still camera on a fixed photo tripod. You can even see the Ring Nebula in this image, if you know where to look, it appears as a very faint star. This was done under red/orange zone light pollution, but when Lyra was near to directly overhead.

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  • 8910264763_2afce9e464_h.jpg

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#5 sg6

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Posted 16 August 2019 - 02:25 AM

I would have said some form of tracking would be the main initial requirement. Short exposures may mean minimal trailing but there is also general movement across the sky and to an extent we seem to rely too much on some software solving a problem we create ourselves.

 

The sort of basic requirement for AP is an equitorial mount, driven at least, goto better it seems. Then a short fast scope of in this case lens (scope acts like a camera lens in any case so the same). Then you need to collect multiple images - simple Intervalometer will do that. Everything is MANUAL. Say this as many DSLR users seem to rely on the auto processes of the camera.

 

Now a basic mount is a home made "Barn door". However will say they fit the requirement and are inexpensive but you need to know what to do to build one. So not exactly easy. Never seen one and so never seen one in use.

 

There are AP ones from Skywatcher and iOptron like the Star Adventurer, of these I am unsure. Cost as much as a small Eq and I have the idea that you may as well just buy the small EQ. Difficult choice. Think both Skywatcher and iOptron items say or mention the ST4 port for guiding. Catch is just one motor so cannot really be guided. Interesting point.



#6 james7ca

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Posted 16 August 2019 - 02:59 AM

Barn door mounts that are manually driven (by hand) aren't that difficult to make. You just need (at minimum) a hand saw, a drill, and a screw driver. The cost is limited to some short pieces of wood, one door or piano-type hinge, some screws, a long 1/4" x 20 (threads per inch) bolt and some 1/4" nuts. The most expensive component (which is kind of optional) is a ball-head camera mount which might run you from $15 to $30.

 

Instructions for building one of these can be found on the internet (also called a Scotch Mount or Haig Mount).

 

I built and used one of these for my first "long" exposure images of the night sky. Not something you'd want to use on a cold winter night, but otherwise quite capable and kind of fun.



#7 Hesiod

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Posted 16 August 2019 - 10:43 AM

As always, the plan to start with the equipment you already have is good, since by doing so will learn by yourself the limits and disadvantages.

At 18mm 10-20" are doable, especially if are not too fussy and aim near the pole; however, in my opinion a simple tracking device is the easiest and most cost-effective upgrade you can do.

With your budget can get a capable commercial device such as those sold by iOptron, Skywatcher or Vixen (I have this one), which is more than adequate for the present task and grant a decent space to grow, being able to manage even short teles (I use* 200 and 300mm focals).

Also, the tracker can offset the lack of speed of cheaper/older lenses, and allows you to use always the camera's optimal shooting parameters.

 

The 055 is a very nice tripod for trackers (I use one myself) due to its light weight and good payload; a good ballhead is a strong asset (I use the MonoBall P0, which is very small and light but incredibly strong; a lighter and cheaper option could be the 496, which I use for daytime or constellation shots: the head can manage lenses such as the ef200, but the RC2 quick release mechanism has a significant amount of play so I would suggest at least to upgrade this to an ARCA-type system).

Skywatcher and iOptron trackers are bundled with a "polar wedge" and a polarscope, while with the Vixen you have to purchase them separately. With a 18-55 can do without them (you would need a second photographic head nonetheless), but are mandatory if want to squeeze the most from your device. Some uses photographic geared heads instead of astronomical wedges: the latter are cheaper and lighter, the former sturdier and more accurate (for the most).

 

Here's how could look such setups (in the first picture you can see the optional kit for the Polarie: it was not required to handle the depicted payload, but I left the rig assembled from the previous session. In the second picture may see how it should look with a light and short lens)

gallery_215679_8115_2625275.jpg

 

gallery_215679_8115_6057724.jpg

 

 

 

 

 

 

*to do so  with my Vixen Polarie I have to use a set of optional accessories not included with the tracker, unlike with iOptron and Skywatcher models



#8 ericthemantis

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Posted 16 August 2019 - 11:39 AM

Don't upgrade your camera yet. It is probably still way more capable than you are (my T5i is definitely still more capable than me).

 

Rokinon and Samyang (same company) are both really good lenses. But they are not as cheap as the old article says anymore. When I start investing in "nicer" lenses, it will probably be a Sigma or Rokinon/Samyang.

 

I have had great success with my kit 18-55mm lens on my T5i. I did OK without a tracker, and still do untracked when I don't want to spend the time setting up the tracking mount and polar aligning. But a tracker has helped me do some really cool shots with the 18-55mm lens, and more particularly my 70-300mm Sigma F/4-5.6 that came with the camera when I bought it (craigslist).

 

The even better improvement for me, though, as far as overall quality of my images, was learning to properly use calibration frames, especially flats. You can get some awesome looking pictures with your T3+18-55mm on a tripod with enough sub exposures and proper calibration frames. All images below were with my Canon T5i (700d) on just a tripod.

 

(kit lens)18mm f/4.0, 30 seconds, ISO 800, 10 frames stacked

House and Pleiades 5x4 edit.jpg

 

(kit lens) 18mm f/3.5, 20 seconds, ISO 1600, 9 frames stacked

Courthouse Milkyway_brightened.jpg

 

(kit lens) 18mm f/3.5, 13 seconds, ISO 1600, 60 frames stacked (soft-glow on the stars due to thin high clouds, gave it an Akira Fujii look)

Hazy Sedona Milkyway.jpg

 

24mm f/2.8 pancake lens, 15 seconds, ISO 400, 10 frames stacked

Meteor 4 cropped.jpg


Edited by ericthemantis, 16 August 2019 - 11:51 AM.


#9 ericthemantis

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Posted 16 August 2019 - 11:47 AM

And don't forget about star trails. Keep reading. Keep researching, and start trying. Use the kit lens and figure out if you like the short focal lengths or maybe slightly longer ones. I don't think you need a new lens yet. If you do decide to splurge on a new lens, Rokinon is fine. Look at the f/1.4 wide-angle lenses, like their 14mm, and even their f/1.4 or f/2.4 24mm. You'll spend $300-$500 vs the $1000+ for an equivalent Canon lens.

 

24mm f/2.8, 13 seconds, ISO 400, 600ish frames stacked for trails.
Trails No Planes.jpg



#10 miwitte

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Posted 16 August 2019 - 12:35 PM

Also learn about processing as you can take hundred of short exposures and stack them into one master which can add up to hundreds or thousands of seconds of a single exposure. That's the trick. More exposure equal more signal which increases the signal to noise ratio. Then with processing techniques you can stretch and get more signal out of the background. There is data in the sticky on top of this forum use it with some of the trials of processing software.
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