Start with Astrophotography

[FarAndBeyond]

Hi, i´m Pat from Sweden. I have always been fascinated by the universe and love those nice pictures of the objects in the universe.

So now after many hours of reading on the internet i´m ready to purchase a telescope but it all feels overwhelming, I want to buy the right equipment from the start, I can´t afford buying new telescopes every now and then. So thats why I want to start out with a  bit "better" telescope right from the start, and an equatorial mount so that I can do AP when I have learned to master the telescope.

Of course I cant afford to buy too expensive equipment, i´m thinking somewhere around 450 - 650 USD range, give or take, and i´m looking to buy second hand so that I can get a bit better gear compared to if I was to buy new gear for that same price.

I have researched not too few hours on the internet but as I said it all feels overwhelming, especially since I want to buy the right equipment from the start, that covers my needs for the foreseeable future and that I will not get disappointed with. 

I know the mount is important in AP, so what about the telescope? I understand aperture is important as well as the quality of the telescope.

I´m thinking I want to have a computerised telescope with a database of objects, that makes it easier in the beginning. I would prefer if the telescope didn't need to much calibration and adjustment, but as I have understood it is the refractor scopes that fits into that category and they are expensive in higher apertures and when they are of better quality?

Generally speaking, how big of a difference will it be between for example an ED-80 refractor telescope and a 150mm (6") Newtonian telescope in regards to how clear pictures one can get and how big magnification one can get while still getting a nice quality? Does a good quality telescope with a smaller aperture generally give better images than a medium quality telescope with a bigger aperture?

And what would you say is the minimum required aperture needed to get some decent and acceptable AP images and some decent viewing in the telescope with details?

I'm planning that in time be doing both Deep sky objects as well as planetary imaging. I was at one time looking at an Skywatcher 150PDS with an EQ3 Pro mount but I never purchased it.

I would appreciate some input and maybe even suggestions on particular scopes / mount setups that would fit my needs? Even though I have been reading a lot I still feel it´s valuable to ask some questions and to hopefully get some answers from experienced persons.

Thanks in advance / Pat.

[Steve 1962]

Hi Pat

Given that you’ve said that you’re interested in AP, I’ll give my personal opinion on a good way to start down that path on a budget.

The problem is that larger aperture scopes tend to have longer focal lengths - which put increasing demands on your mount. I would look at a shortish focal length (ie < f7 ish)  70 or 80mm refractor as your first AP scope. This will give you lovely visual views of the moon and brighter DSOs and will be relatively forgiving of your first forays into AP.

If you have a DSLR, you should be able to plug that in with T mount.

As a starter mount, the HEQ5 is a great mount and, if you can get a non go-to version (which will be cheaper) you can use the free EQMOD to control it from a laptop. Add Carte du Ciel or Stellarium and you’ve got go-to at no extra cost. Adding a finder guider at a later date will give you a cost effective ability to do longer exposures.

I would seriously consider buying second hand. People seem to look after their kit and it’ll save you 30 - 40% from the new price.

Hope this helps.

Steve

 

[carastro]

You are mostly thinking on the right tracks, but getting a high magnification scope is not only going to limit your field of view, but it will cost more and be more demanding on accuracy with guiding.

I would check out this site and compare the size FOVs you can get on targets, and see which size scope seems to be best for your needs.  However, trying to get the whole of M31 into one image is not going to be compatible with trying to image a small galaxy, so one size will not fit all.

http://www.12dstring.me.uk/fovcalc.php

I have tended to ignore small a galaxies in favour of being able to image large nebulae.  It will of course depend on what camera you plan to use.  As stated above if you already have a DSLR this will get you started, it has a large FOV.  

The size mount will also depend on the size scope you plan to use.

The general advice to beginners, seems to be a small refractor and either an HEQ5 or  EQ6 depending on what size scope you might want to buy in the future.  But an HEQ5 is fine for refractors up to ED120.

I'd suggest either an ED80 and HEQ5, or maybe even the smaller Skywatcher refractors that have recently been developed.  William Optics are good too, but I always find problems mounting them and a guider due to the small foot and lack of guide rings on some models, but these problems can be overcome.

Make sure the telescope is an Apo.

Your DSLR might need modifying for astro imaging in order to show up all the wavelengths.

HTH

Carole 

 

 

 

[vlaiv]

Hi and welcome to SGL!

I'm afraid that your budget will constrain you significantly.

If you want to go refractor route (which I support for its ease, especially on the beginning of your AP journey) - you need to think at least ED refractor, otherwise you must lower your expectations on quality of your images. Something like 70-80mm ED scope is very good for this purpose, but it alone can cost almost your entire budget (looking at prices for new equipment).

As you already know, mount is the most important part of the AP setup, and you want to start with at least EQ5 class mount (budget option) or preferably Heq5. Motorized Eq5 mount costs almost your entire budget.

I doubt you will be able to fit those two things even second hand - for a given budget.

Planetary imaging on the other hand is very different in requirements - here you can go with simple EQ3 mount + RA motor, Planetary camera and Mak or long focal length newtonian. This can fit in your budget, but it really goes against - "buy good gear now and be content with it for longer time" (it will be poor at DSO imaging).

Just to answer your question about quality of scopes for imaging. Quality of telescope for imaging is judged by wider criteria then for visual. You can have poor visual scope performing excellent on astro photography. Most of today's scopes on market (well known and respected manufacturers - not department store scopes) have enough optical quality to be suitable for astrophotography - meaning just quality of optical surfaces. What counts for AP are such things as: how flat is the field of telescope? Will image vignette? What sort of aberrations can you expect and how to deal with them (chromatic aberration, coma, astigmatism, ....). What is the overall quality of OTA and focuser - will mirror hold position, will focuser be firm enough to hold your camera, will you be able to focus easily (dual speed focuser), .... These are additional things that are important for AP.

Bottom line, your budget is very restricted and you will not be able to get very good gear from the start - so you might either consider doing incremental approach - get some gear now, and then when you save some more cash upgrade (sell current and buy better) components. This approach is good as it will not cost you much if you decide that AP is not satisfying you. Other option is to start saving for adequate budget.

 

 

[FarAndBeyond]

Thank you for your answers. So i didn’t  wanted to rush into buying a little bit better equipment but instead continue to search for the right gear.  I have gotten some ideas in what direction to look at.

But of course i wanted to get started as soon as possible....as we all do.

So in the meantime i purchased a cheaper used telescope (for viewing) since i got a good deal on it. It’s a Meade ETX-70 with the Autostar GOTO setup.

I bought it yesterday evening so haven’t really tried it yet, i only looked through the telescope briefly out of my window today in the daytime.

What i noticed though was a purple line (chromatic abberation), shouldn’t this telescope model be an apochromatic refractor scope??

Also there is a little dirt on the lens and some dust on the little mirror that is below the eyepiece inside the telescope.

so my other question is how to clean the lens and the mirror without damaging any coatings etc? 

Does the little mirror also have some coating or is the mirror not as sensitive when cleaning as the lens?

Can i clean those with household items? I don’t have any special lens cleaning solution at home, what i have is a dust blower and some camera lens cleaning cloths/microfiber cloth, i also have a lens pen.

Could one use just a drop of water on a cloth so it moistens a bit? I don’t know how sensitive these lenses and the mirror really are?

[rickwayne]

I would be extremely cautious about cleaning the optical surfaces! These will be front-surface mirrors, so you will be working on the mirror itself, not on glass, as with conventional back-silvered household mirrors. And those coatings are quite fragile. I recommend that you resist the temptation to try to clean them, especially in situ, because you are almost certainly going to make any problems worse instead of better. Can you blow anything off with a bulb? (Canned air is riskier -- sometimes shoots stuff out the nozzle.) Can you get anywhere with a soft, dirt-free, camel-hair or similar brush GENTLY applied?

This is an excellent article on the subject from Sky and Telescope magazine: https://www.skyandtelescope.com/astronomy-resources/caring-for-your-optics/

[wimvb]

On 02/11/2018 at 16:43, FarAndBeyond said:

What i noticed though was a purple line (chromatic abberation), shouldn’t this telescope model be an apochromatic refractor scope??

Hi, and welcome to sgl. The telescope you're refering to is listed as achromatic, not apochromatic. Achromatic telescopes are the more basic models with less correction.

When I read your original post, I was a bit sceptical. When I bought my first kit (sw 150pds on an eq3-PRO mount), I spent about 8000 kr new (now 9750 kr in Sweden, £ 599 from FLO). But that telescope is seriously undermounted. As others have said, you need at least an (H)EQ5 in order to be somewhat future proof. And such a mount will be hard to come by in Sweden (too small a community). But by all means, do check on astronet.se and blocket/tradera. If you need to buy from abroad, there will be the added shipping, and risk. Besides the ED80 (refractor) on an HEQ5, there's also the 130PDS (reflector), on the same mount. The latter is very popular, and has its own thread on this forum.

If you buy new, compare prices domestic and abroad. I found that EU VAT makes equipment bought abroad considerably cheaper than Swedish VAT (19-20% vs 25%). And service has been better as well.

Good luck, and have fun.

 

[Skipper Billy]

I would strongly suggest spending a few pounds on this - it will save you a lot of time, money and grief in the long run.

https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

Knowing what the Swedish postal system is like you might want to consider the 'E' version ?

Bottom line - with an ED80 on a HEQ5 you cant really go wrong.

[FarAndBeyond]

Well about the cleaning, I can see at least one dirt stain which I directly can see that its not going to come off by blowing on the lens or not even by brushing gently (or brushing at all) with a camel hair brush, that dirt stain needs proper cleaning, also the edges of the outermost lens has dirt. I would resist the temptation to clean it if it was a little bit dust only, but I have a hard time not caring about the actual dirt. Also its not only on the outermost lens, its on the little mirror below the eyepiece inside the scope as well. It even looks as there is a dust particle on a second lens behind the outermost lens (no idea how it got there?). So I really would like to do a proper cleaning this first time, and then hopefully no need to be done again, at least not in a long while? I can clearly see the dirt/dust when looking all the way through the telescope at home, when using the telescope normally outside maybe it isn't visible as much?

About the purchase of a telescope, the key thing with my purchase is to buy used gear, so for my budget I could hopefully get a telescope and a mount that would cost around 1100USD new, doesn't that get my anywhere, if not....how much would one need to spend to get decent gear? Of course my budget is not written in stone, it´s all about how good of a deal I can come by, but unfortunately used telescopes in my country seems to be more expensive compared to many other used items for example electronics etc. Also there seems to be a relatively big interest in this hobby recently since used telescopes gets sold fast.

 

Anyway, do you have any suggestions for actual telescope models that is particularly suited for AP, I saw somebody mentioned the ED80? And what is the desirable features and undesirable things in a telescope that will be used for AP? The mount I have already learnt that it is preferable with a EQ5 mount or better.

P.S. The website suggested by Red Dwarf to see how big of a object magnification one can get with a certain scope and camera was nice. When choosing a higher number on the focal length the photo gets much bigger, if longer focal length gives the ability to more magnified object photos wouldn't a longer focal length always to be strived for? And isn't there other factors at play as well when it comes to this? 

[FarAndBeyond]

1 hour ago, Skipper Billy said:

I would strongly suggest spending a few pounds on this - it will save you a lot of time, money and grief in the long run.

https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

Knowing what the Swedish postal system is like you might want to consider the 'E' version ?

Bottom line - with an ED80 on a HEQ5 you cant really go wrong.

 

Thanks maybe I check that book out. About the ED80 many have suggested it and it seems as a pretty safe bet, my only concern is ( and I know many will say bigger is not always better) the pretty small aperture. Thats why I asked in my initial post how big of a difference the 80mm aperture is compared to a say 150mm Newtonian reflector scope when it comes to magnification of the objects in the photos and quality?

But the more I read about the ED80 the more I seem to lean against trying to get my hands on one, the question is if I find it for a decent price (preferably used).

It seems good for AP together with an EQ5 / HEQ5 mount.

Are the ED80´s triplets or doublets, or are there both types? And how big of a quality difference is there between a triplet and a doublet?

[vlaiv]

ED80 is a doublet.

There are differences between doublets and triplets, but it really depends on particular model of each.

Here are some general guidelines - Triplets should be color free (by design, again subject to particular model), while ed doublets have residual chromatic aberration. This is very general statement. Simple achromatic refractor is a doublet lens - it will have loads of CA. ED doublets use special glass that reduce or almost eliminate CA (some examples exist that are virtually color free). If we are talking about scopes suitable for AP, then doublets in general will be slower scopes (higher F/ratio) if they are to be close to color free - ED80 is F/7.5 scope, while for example TS80 APO (triplet) is F/6 scope, or SW 80mm Esprit (also triplet) is F/5 scope.

Triplets will be more expensive. Due to design triplets will in general have more field curvature, and you will almost certainly need to use field flattener for large sensor (you will need to use one as well for doublets for large sensors).

Aperture is always good thing for AP, but it comes at a cost - and I'm not meaning money here (although there is that point to). Due to telescope design - larger aperture means longer focal length, it also means larger weight - all of this has impact on imaging performance. So scope should be matched to camera and also to the mount (mount is more important - if you are after very good images - mount is your number one priority).

When people recommend ED80 or 130PDS on HEQ5 mount it is for a reason - both scopes are well matched to that mount (in stock version) and to DSLR cameras people tend to use when starting in AP.

Sure you can use completely different combinations, but in that case you need to understand what you are doing and what are trade offs for your particular combination.

Nothing wrong with using for example 200mm scope with long focal length on Heq5 mount - I do it, but in order to get acceptable results, I needed to develop particular workflow and heavily tune and mod mount to cope with those requirements (find 200mm scope that is light enough, has certain properties that are needed for AP, accept that I'll need to bin my images in certain way due to smaller pixel size, perfect my guiding to required level ....).

 

[wimvb]

2 hours ago, FarAndBeyond said:

Well about the cleaning, I can see at least one dirt stain which I directly can see that its not going to come off by blowing on the lens or not even by brushing gently (or brushing at all) with a camel hair brush, that dirt stain needs proper cleaning, also the edges of the outermost lens has dirt. I would resist the temptation to clean it if it was a little bit dust only, but I have a hard time not caring about the actual dirt. Also its not only on the outermost lens, its on the little mirror below the eyepiece inside the scope as well. It even looks as there is a dust particle on a second lens behind the outermost lens (no idea how it got there?). So I really would like to do a proper cleaning this first time, and then hopefully no need to be done again, at least not in a long while? I can clearly see the dirt/dust when looking all the way through the telescope at home, when using the telescope normally outside maybe it isn't visible as much?

About the purchase of a telescope, the key thing with my purchase is to buy used gear, so for my budget I could hopefully get a telescope and a mount that would cost around 1100USD new, doesn't that get my anywhere, if not....how much would one need to spend to get decent gear? Of course my budget is not written in stone, it´s all about how good of a deal I can come by, but unfortunately used telescopes in my country seems to be more expensive compared to many other used items for example electronics etc. Also there seems to be a relatively big interest in this hobby recently since used telescopes gets sold fast.

 

Anyway, do you have any suggestions for actual telescope models that is particularly suited for AP, I saw somebody mentioned the ED80? And what is the desirable features and undesirable things in a telescope that will be used for AP? The mount I have already learnt that it is preferable with a EQ5 mount or better.

P.S. The website suggested by Red Dwarf to see how big of a object magnification one can get with a certain scope and camera was nice. When choosing a higher number on the focal length the photo gets much bigger, if longer focal length gives the ability to more magnified object photos wouldn't a longer focal length always to be strived for? And isn't there other factors at play as well when it comes to this? 

If you need to clean the front lens, I suggest you get lens cleaning fluid (eg Baader wonderfluid, you should be able to get this from a local camera dealer) and microfibre cloth (cheap at Kjell & co). The "mirror" on the eyepiece side is probably a prism. Its purpose is to get you a more comfortable viewing position. Try to clean it with a soft brush or a microfibre cloth.

My experience with buying second hand in Sweden is that the market is VEERY limited, and most of what comes out is low quality. There are several telescopes out on blocket, atm, but none of these are for AP, and most are undermounted on a manual EQ2. 

The ED80 (refractor) and 130PDS (reflector) have similar focal length, and will therefore fill your camera sensor about the same. But the 130PDS has a larger aperture, and will collect more light per second/minute. The other difference is that the 130PDS will produce star spikes, because of the way the telescope is designed (secondary mirror support). It will also need collimation (alignment of the optics) from time to time. The 80ED is pretty much point and shoot in comparison.

A longer focal length isn't always better. The andromeda galaxy is so large, that with a dslr you will need a focal length shorter than 400 mm. Otoh, M51, the Whirlpool galaxy, won't fill that sensor even at a focal length of 2000 mm. Focal length is more about what you want to image rather than bigger is better. And unfortunately, there's no one-size-fits-all.

Follow David's (@Skipper Billy) advice, and get a copy of Making every Photon Count, before you rush into buying.

Cheers,

[Joel Shepherd]

An ED80 APO will take you a long, long way (and can also be delight for visual). I've had a SkyWatcher Esprit 80ED for almost three years now and it continues to produces better and better results ... rather, my skills continue to try to catch up with its capabilities. It's true that it is not the best instrument for small galaxies and planetary nebula, but for larger nebula and medium-sized galaxies or galaxy clusters it sings.

[Knight of Clear Skies]

For AP on a tight budget, have you considered imaging with camera lenses rather than a scope? Shorter focal lengths are more forgiving on tracking, reducing the mount requirements.

[ollypenrice]

1 hour ago, Knight of Clear Skies said:

For AP on a tight budget, have you considered imaging with camera lenses rather than a scope? Shorter focal lengths are more forgiving on tracking, reducing the mount requirements.

This has to be the way.

Olly

[FarAndBeyond]

12 hours ago, Knight of Clear Skies said:

For AP on a tight budget, have you considered imaging with camera lenses rather than a scope? Shorter focal lengths are more forgiving on tracking, reducing the mount requirements.

O but that sounds so boring ( like being recommended to start out with a pair of binoculars), jokes aside, haven't really thought about it. Like I mentioned earlier my plan was to buy something "decent" (relatively speaking) so I don't outgrow it too fast. But sure if one buys a good mount and then later on adds a decent telescope, sure that could be an alternative.

The focal length....am I missing something, I thought it was the length of the tube, but I see these short telescopes having a long focal length sometimes.

 

Can chromatic aberration be corrected in software?

 

By the way, I had a chance to buy a used 150PDS with an motorised EQ3 mount with the synscan Pro about a year back, I know the mount would not been sufficient for AP, but what about the 150PDS? Maybe I should have bought it anyway?

[vlaiv]

7 minutes ago, FarAndBeyond said:

O but that sounds so boring ( like being recommended to start out with a pair of binoculars), jokes aside, haven't really thought about it. Like I mentioned earlier my plan was to buy something "decent" (relatively speaking) so I don't outgrow it too fast. But sure if one buys a good mount and then later on adds a decent telescope, sure that could be an alternative.

The focal length....am I missing something, I thought it was the length of the tube, but I see these short telescopes having a long focal length sometimes.

 

Can chromatic aberration be corrected in software? 

 

By the way, I had a chance to buy a used 150PDS with an motorised EQ3 mount with the synscan Pro about a year back, I know the mount would not been sufficient for AP, but what about the 150PDS? Maybe I should have bought it anyway?

Chromatic aberration can't be corrected fully in software I'm afraid. There are some techniques that can help you get nicer looking image - like reduction of purple halos around stars, or changing that particular color to something more pleasing, but in the end it will not correct it fully - otherwise people would not buy APO scopes

There are however tricks that you can use that will minimize CA and help you get, again, nice looking image as a trade off with some things (one being imaging time, other being color correctness) - that you can do in "hardware".

Use of appropriate filters is one way of minimizing impact of CA - there are various filters that can help, and you don't need to go for expensive stuff there - simple #8 yellow will help reduce purple halos quite a bit - but you will loose color balance, and you will need to adjust it in post processing. Another thing that you can do is to use aperture mask - slower achromat scopes have less chromatic aberration.

Couple of years ago I played around with these techniques, and I still think they are viable option for low cost AP (even slow achromats with focal reducer - planning to try out something along those lines). I conducted some tests of how different combinations of aperture mask and filters work.

Look here:

And this, as an example:

Yes, there are compound scopes that will be much shorter than their focal length, and understanding focal length and it's impact on resolution and AP is important. For beginning you want to be in 350-650mm range of focal lengths if you are set on using telescope rather than lens.

If you want to start of gradually - like get a tracking mount and do AP with simple lens first - that is fine, but do consider that mount is the most important piece of imaging kit - you want to get that one right. Scope is arguably the least important part, and certainly can be the least expensive part and still work extremely well. Just look at prices of 130PDS or 150PDS to see what I mean, but you need a good mount to carry a scope.