[cprobertson1]

[EDIT] - If I've put this in the wrong forum, eek! Sorry!

Goooood morning ladies and gentlemen!

...Even if I'm posting this afternoon and nobody says "ladies and gentlemen" anymore!

So! I want to try my hand at astrophotography - BUT - I want to buy as little as possible to do so.

I have a 70-300mm sigma lens (the star of this thread - get it?!? ...Well I found it funny... Fine, suit yourself! ) - I also have a 50/300 National Geographic telescope (that's a 300mm focal length with a 50mm aperture - which works out as... F/6)

So, in principle, I have enough to get started!

To start with I'm going to just use an Az-El mount (Azimuth/Elevation-only), I can upgrade my kit with a DIY barndoor tracker if I like it!

With that in mind, I believe I'm going to have to do focus stacking since I won't be compensating for the earth's rotation (and there is NOTHING about that sentence that I don't like!) - and for better results, I believe the shortest exposure time would be the most use!

With that in mind, does that mean that my sigma lens (capable of being stopped down to F/5.6 at 300mm) would actually be better for astrophotography than this particular telescope?

SO I have a rudimentary plan, and some questions! The below list will start with the lowest numbers and I'll slowly increment the development of each part if I see fit! This way I can spend as much or as little as I want!

• Mounting:
  1. Start with lightweight generic tripod ballasted with sandbags
  2. Construct DIY motorised barndoor tracker
  3. Build heavy-duty tripod (wide and heavy base, again ballasted with sandbags, and supports for long lenses)
  4. Build/buy proper equatorial mount for heavy duty tripod
  5. Motorisation
  6. NC control of motors > CNC control/Tracking
• Optics:
  1. Sigma lens OR 50-300mm telescope?
  2. Teleconverter?
  3. Better lens OR telescope?
• Other:
  1. Spotting tube/iron sight
  2. Holographic laser sight
  3. Digital Tracking (via CNC)

SO my questions mostly concern optics - and I'm aware you can spend a small fortune on both telescopes and lenses!

1. Is the compound Sigma lens (F.5.6 at 300mm) OR the cheap, single-element 30/300 telescope (F/6 at 300mm) likely to be better?
2. I know that a teleconverter multiplies the focal length at the expense of dropping down a few f-stops; will the corresponding increase in exposure time cause problems?

See, I wondered if the lens and teleconverter would be a better idea since A) I can stack them if I really want to (ew... yeah, I shuddered too), and B) I can use it in regular photography as well, instead of only for a niche use!

What are you folk's thoughts on this?


Note-to-self:
-ToDo: look into noise removal techniques (darkframe/flatframe) when shooting with high ISO and give it a few practice shots
-ToDo: check if in-camera high-ISO NR + long-exposure NR is preferable
-ToDo: download DeepSkyStacker for stacking + watch ScottManley ultraquick tutorial on astrophotography

---

Last edited by cprobertson1; 12-20-2018 at 07:18 AM.

[aslyfox]

have you looked at this series of articles:

Astrophotography Part 1 of 6: Planning the Shoot - Articles and Tips | PentaxForums.com

[cprobertson1]

have you looked at this series of articles:

Astrophotography Part 1 of 6: Planning the Shoot - Articles and Tips | PentaxForums.com

Ohmagod, no, I have not! That's my bedtime reading sorted!

[aslyfox]

Ohmagod, no, I have not! That's my bedtime reading sorted!

lots of info here

as well as helpful members willing to give advice

especially on how you should spend your money

[czhao1009]

Just wanted to chime in based on my somewhat limited astrophotography experience

1. What is your goal, photographing DSO or wide-field milky way?
Looks like you have lens/telescope in the range of 300mm which would rule out wide-field-milky-way-kind-of-shots.
From what I gathered, DSO photography is much much more difficult than milky way shots and, in general, need better gear and post-processing skills.

2. Az-El mount is not particularly good in terms of tracking, which you will need if you intend to take, say 100 photos and stack them later.
You will probably soon find out that at 300mm, you won't be able to make a long enough exposure before star trails become obvious, which means lots of photos need to be taken so you could stack them later to get a cleaner/better image, which means a somewhat precise tracking is a must...


3. A good GEQ mount is expensive however, I would suggest research those tracking mounts/devices designed for DSLR + lens or small/compact telescope.
The following come to mind: Pentax OGPS-1, iOptron Skytracker (or something like that, they have many models and the names get confusing very soon), etc.
Those are generally very portable, which means you could take them to a camping trip or whatever, and the setup processes are usually much simpler.

[MossyRocks]

I assume that the sigma lens you are referring to is this one or one like it. So at max aperture at 300mm focal length would be 5.6 which is faster than your 300mm telescope so that is good. However you will likely be shooting at the long end and would likely want to stop it down a bit to deal with CA and enhance the sharpness a bit so it will suffer a bit from that. That said you should still get better quality images than you would from the inexpensive telescope. So my advise here is to stick with the camera lenses until you get a nice reflector scope. Your current scope likely will have tons of CA even if it is nice to look through with your eye.

I would suggest as a progression of gear the following assuming you already have a camera with astrotracer already:
1. Get a red intensifier filter for your existing lens if you are going to be shooting in places where the milky way isn't clearly naked eye visible.
2. A sturdy tripod if you don't have one, basically you need a stable place to shoot from but when starting out you don't need one of those ultra heavy duty astro ones that can support 300lbs. A good general purpose one works just fine.
3. A release cable.
4. a Bahtinov mask for any telephoto lens you do astro with.
4. Get a handful fast primes, likely a wide or ultra wide and a telephoto in the 200mm to 400mm range that is at least an f/4. The nice thing is that these can be used for things other than astrophotography.
5. After that don't bother with other mounts and just go straight for a proper nice motorized equatorial and matching tripod. Why waste your money and time on a bunch of half efforts. If thinking of getting a telescope do some research on what you want and get the equatorial so it can handle that sized scope.
6. Then depending on what you are photographing get a big reflector (Newtonian) telescope.
When it comes to lenses you don't need to necessarily buy the greatest most modern fancy glass either. One can get very good results with old good glass. The key thing is that it be good so newer ultrawides will be better but old telephotos can be excellent lenses for astro.

I would also suggest figuring out what you want to shoot before throwing more gear at the problem, star fields, landscapes with stars/the milky way in them, planets, the moon, deep sky objects, chase tiny galaxies, etc. What you like to shoot will determine your gear selection.

I few months back I wrote up a couple of guides on starting out with astrophotography that are very much the nuts and bolts of starting shooting to get people pointed in the right direction. On one shooting the moon (always a good first target) and another one that is more general introduction to shooting other astro images. At some point I will write up a processing guide to also get people pointed in the right direction there too but I'm still working on getting better and ironing out all my regular mistakes. I don't want to point people in the wrong direction.

Now just go out and shoot even if you don't have the perfect gear yet. Then post your images over in the astrophotography group and ask some questions or for general advise on them. We are all pretty helpful over there and even the disasters I have posted there I got constructive criticism on and no one was mean about them. Trust me some of them were really bad.

I am still using astrotracer and it can provide good results provided you know the limitations of it and the conditions of where you are shooting. I am not using a red intensifying filter but it would help greatly in reducing the light pollution and would increase the contrast in the images. I live in a very light polluted area (a bright bortle 8) and these are some processed images that I took early in the evening using my 300mm f/4 lens and astrotracer on my K-3

M31 (The Andromeda Galaxy):

f/4.5, ISO 1600, 20sec per shot
The total number of shots for this totaled to about 1 hour, I want to say 187 were stacked


M51 (The Whirlpool Galaxy):

f/4.5, ISO 800, 20sec per shot
The total number of shots for this totaled to about 40 minutes, I want to say 123 were stacked

[Kevin B123]

What camera body are you using? can it use GPS for astrotracer?.

I would say read MossyRocks excellent post a few times to digest it properly.

Then think about the weather conditions where you are. I have wanted to get some Astrophotography done for a while. I plan around the new moon and for three straight months it's been cloudy, windy and generally off. Unless I want to be out a 3am, which I don't.
So I have curtailed by astro budget on the understanding that I can't achieve much time on it for my location, which is frustrating.

As you are on a budget, you are fortunate that in K mount there are plenty of old manual primes to be had for little money, for example a Pentax M 50 f1.7 can be had for £30 all day long on ebay.

Don't over stress about the tripod too much. If you are doing this in windy conditions then forget it as there will never be a long exposure without motion blur.

In non-windy conditions (you have a wind break for example) then just set the tripod as low as possible with the center column touching the ground so that it is stable. You won't want to take sandbags out in the field, way too much hassle.
That said, where will you shoot from, your backyard or a dark location?
See this site for possible locations near you:
Light pollution map

It's an absorbing subject to get into, and I think Feb-April will be better for the weather and wide Milky way shots.

[aslyfox]

What camera body are you using? . .

according to the OP's profile, he has a K 50

_____________________________________

. . . I would suggest research those tracking mounts/devices designed for DSLR + lens or small/compact telescope.
The following come to mind: Pentax OGPS-1,. . .

FYI

1 supported cameras:

- Astrotracing
KP, K-3, K-S2, K-S1, K-70, K-50, K-30, K-5 family, K-r
- Simple navigation
K-5 family, K-r, 645D
- Electronic Compass
KP, K-3, K-S2, K-S1, K-70, K-50, K-30, K-5 family, K-r, K-5 family, K-r, 645D, 645Z and K-01

2 " In Depth Review " :

Pentax O-GPS1 GPS Unit Review - Introduction | PentaxForums.com Reviews

3 comparison with built in astrotracer

https://www.pentaxforums.com/reviews/o-gps1-vs-built-in-astrotracer/introduction.html

4 User Reviews:

https://www.pentaxforums.com/accessoryreviews/pentax-o-gps1.html

[MossyRocks]

4 User Reviews:

Pentax O-GPS1 reviews - Pentax Camera Accessory Review Database

I should probably add my own review to that as I use it often.

[aslyfox]

I should probably add my own review to that as I use it often.

the last review was several years ago [ July 2015 ] so your review would be very helpful

[jack002]

I have this book, you should check it out
Getting Started: Budget Astrophotography, Allan Hall - amazon.com?tag=pentaxforums-20&

Also, come on over to our group and join us here
https://www.pentaxforums.com/forums/groups/135-astrophotography/

[MossyRocks]

The following come to mind: Pentax OGPS-1

This is really an Az-El mount but built into the camera so is ultra portable. Neither one deals with rotation and there are tracking errors that crop up. It works plenty well and would best be used as a bridge between following the rule of 200 and a proper equatorial for DSOs (deep sky objects). I've found that at 300mm I can consistently get nice shots at 20s and sometimes can get nice ones at 30s but going beyond that with DSOs I always get trails. I usually stick to running it at 1/4 or less of the time it reccomends and that dramatically improves the quality. The suggested maximum is a very optimistic number from my experience. Looking back I do sometimes wonder if I should have just made the direct jump to an equatorial. The price difference is about $500 from the OGPS-1 ($200) to the first non junk equatorials ($700).

[cprobertson1]

Wooo! Lots of good advice popped up over here overnight!

I'll start with MossyRocks post as it's a goldmine of info

I assume that the sigma lens you are referring to is this one or one like it. So at max aperture at 300mm focal length would be 5.6 which is faster than your 300mm telescope so that is good. However you will likely be shooting at the long end and would likely want to stop it down a bit to deal with CA and enhance the sharpness a bit so it will suffer a bit from that. That said you should still get better quality images than you would from the inexpensive telescope. So my advise here is to stick with the camera lenses until you get a nice reflector scope. Your current scope likely will have tons of CA even if it is nice to look through with your eye.

Aye! The telescope I have is literally 2 elements (in 2 groups) - the chromatic aberration will be terrible, and that's before we get to field curvature problems! However, I have never noticed it with my eye (the brain is literally fantastic at compensating for weird things like that... human eyes are pretty bad and need a lot of post processing!)

Begging one's pardon, it's actually a Sigma 75-300mm lens (I couldn't find it because I was typing in 70-300mm!). I actually really like it - mostly because I picked it up for £10 (~$15) and it has that vintage smell I can't get enough of!

So! Stick with the lens for now - excellent! That saves me faffing around with 3D printed adapters and miscellaneous tubes!

I would suggest as a progression of gear the following assuming you already have a camera with astrotracer already:
1. Get a red intensifier filter for your existing lens if you are going to be shooting in places where the milky way isn't clearly naked eye visible.
2. A sturdy tripod if you don't have one, basically you need a stable place to shoot from but when starting out you don't need one of those ultra heavy duty astro ones that can support 300lbs. A good general purpose one works just fine.
3. A release cable.
4. a Bahtinov mask for any telephoto lens you do astro with.
4. Get a handful fast primes, likely a wide or ultra wide and a telephoto in the 200mm to 400mm range that is at least an f/4. The nice thing is that these can be used for things other than astrophotography.
5. After that don't bother with other mounts and just go straight for a proper nice motorized equatorial and matching tripod. Why waste your money and time on a bunch of half efforts. If thinking of getting a telescope do some research on what you want and get the equatorial so it can handle that sized scope.
6. Then depending on what you are photographing get a big reflector (Newtonian) telescope.
When it comes to lenses you don't need to necessarily buy the greatest most modern fancy glass either. One can get very good results with old good glass. The key thing is that it be good so newer ultrawides will be better but old telephotos can be excellent lenses for astro.

1-good shout!

2-Currently have a half-dismantled ultra-heavy-duty tripod from an earlier project (designed to support an antenna array on a hillside during high wind for the purpose of performing moonbounce (EME) communication - and it was a heavy duty thing - made from 2x4s and welded steel - partially dismantled because I was modifying it to make each of the legs collapsable to make it easier for transport (despite it weighing a lot).

HOWEVER - that tripod is one big mutha - stable as a rock; but needs a car for transport so it's only good for back yard and car-based work (which was its original purpose). I can, however, build a much smaller variety of that which will somewhat resemble the tripods used for surveying instruments. Lightweight but with a wide splay for stability.

3-Already got one!

4-Good shout! I remember reading about those many, many years ago in relation to various telescopes; they aren't terribly expensive either! In fact...Aye! You can 3D print them! - score!

4(2)-I'll need to look into lenses at some point - I'm a bit lensed out at the moment though (my wallet certainly is!)

5-Now, interestingly, I was considering building a tracking mount for pointing an antenna array at amateur radio satellites a few months back - plug in the orbital parameters, hit "start" once the satellite passes the horizon and voila, the computer handles all tracking. The CAD work is all done (In fact, it is a remarkably simple design) - but it was never built because I wouldn't have enough space in my garden! The drive system, however, could easily be modified for polar tracking, and would be more than strong and powerful enough to support a decently sized telescope (it was, after all designed to support a 12-meter long axle with 2 4-metre-long antenna booms sticking out of it at right angles)

Definitely food for thought!

6-Some day!

So! Looks like I can get a decent chunk of that out the way myself and make a decent start!

I would also suggest figuring out what you want to shoot before throwing more gear at the problem, star fields, landscapes with stars/the milky way in them, planets, the moon, deep sky objects, chase tiny galaxies, etc. What you like to shoot will determine your gear selection.

Hrm - I don't know yet! My plan was to throw as I reasonably can at a wall and see what sticks!

It's probably easiest to go for the moon first since it's big and bright! Probably followed by a few planets, BUT at the same time I also want to try and get a shot of andromeda and the orion nebula.

So: my initial goals are for the Moon > Planets > Deep sky - by which point I should have a decent idea if I like it or not!

I few months back I wrote up a couple of guides on starting out with astrophotography that are very much the nuts and bolts of starting shooting to get people pointed in the right direction. On one shooting the moon (always a good first target) and another one that is more general introduction to shooting other astro images. At some point I will write up a processing guide to also get people pointed in the right direction there too but I'm still working on getting better and ironing out all my regular mistakes. I don't want to point people in the wrong direction.

Oooh! More bedtime reading Will have a gander shortly!

Now just go out and shoot even if you don't have the perfect gear yet. Then post your images over in the astrophotography group and ask some questions or for general advice on them. We are all pretty helpful over there and even the disasters I have posted there I got constructive criticism on and no one was mean about them. Trust me some of them were really bad.

Haha, as far as I'm concerned, nobody can ever have "perfect" gear: even if I had the most expensive and miraculously effective gear in existence, I will still take bad photos until I learn how to use it - and if I don't know the basics I'll never learn how to use it properly at all! As such I always encourage people to get their work out there (regardless of the type of work: photography, painting, music, programming, literature, dance moves - I don't care! Show people!) - sure you get a few negative people who just say "yuck that's terrible" - those are people you can safely ignore - the ones you want to listen to are the ones that tell you why it's not as good as it could be, and if you get lucky, how to improve it!

In other words, as long as you like it then it's not a bad photo (unless you like it specifically because it's bad!) and nobody can take that away from you. Unpopular does not mean bad any more than popular means good (argumentum ad populum). BUT that also doesn't mean that it can't be improved - EVERY photo can ALWAYS be improved! It's just you reach a point where the improvements get more and more subtle (diminishing return on improvements).

Lol that was a bit off topic - I was merely saying I'll get posting as soon as I get a few pictures that I actually like!

I have a bunch of other photos awaiting upload as well - just need to fire them through darktable and we'll be good to go!


Anyhoo! I'll respond to the other posts shortly - I started with this one as it was the most in-depth!

Thanks for that Much appreciated!

[MossyRocks]

I'll need to look into lenses at some point - I'm a bit lensed out at the moment though (my wallet certainly is!)

Remember that you can get very good results with old glass. I had a link to Pete_XL's capture of the objects in Orion that he captured with a SMC Pentax-A 200mm f/4 lens from 1982 or something like that. I have the S-M-C M42 mount version of that lens and I paid like $40 for it so getting glass that is good enough isn't that expensive. That and some times you can't basically steal a lens like I did with my Sigma 300mm f/4 APO macro that I got for $130 if you keep your eyes open.

Probably followed by a few planets

Unless you have a big telescope and are willing to do lots of processing this will likely be a hard one to do. By big I mean big like 2000mm (yes 2,000mm) or more. With my 300mm and K-3 when I shoot jupiter it is only about 17 pixels across. I'm not trying to discourage your, just trying to set expectations.

In other words, as long as you like it then it's not a bad photo (unless you like it specifically because it's bad!) and nobody can take that away from you. Unpopular does not mean bad any more than popular means good (argumentum ad populum). BUT that also doesn't mean that it can't be improved - EVERY photo can ALWAYS be improved! It's just you reach a point where the improvements get more and more subtle (diminishing return on improvements).

No I mean I posted some real stinkers but I was looking for help which is why I posted them and I did get that. There is a fair amount of technique required in taking the shots, but there is also even more skill required for editing them. Astro pics have so few photons you are really trying to make the most of them and things can go sideways easily. Ask questions early and often when starting so that bad habits don't develop.

sure you get a few negative people who just say "yuck that's terrible"

I've never gotten that or given that advice and I don't think anyone would here either. All of the criticism that flows over in the astro group is constructive and advice on how to correct what ever issue is being discussed is always given. Also don't be intimidated by the posts you may see from VoiceOfReason, DrawsACircle, or Pete_XL, they are all masters and are very helpful.

[Craigbob]

If you have the money, the best small (DSLR based) tracking mount you can get is the Skywatcher AZ-GT1. AZ-GTi Mount – Sky-Watcher USA

It will support a payload up to 11 lbs, has go-to capabilities so it's easy to find the faint fuzzies to photograph. can work in Alt-AZ or EQ mode (with a firmware upgrade) so you can take longer exposures.

It's light at around 8lbs so you can take it on a hike to a dark site with no light pollution.

It works with smartphones to do alignment/go-tos or you can buy an optional hand controller.

Runs about $400 including the wedge for EQ mode.