Is this any good for astrophotography?

[varius21]

https://www.tringastro.co.uk/sky-watcher-explorer-130p-synscan-az-goto-telescope-528-p.asp

Even though I recently purchased my Dobs 8" I am snooping around quite a lot so I'm prepared in the future for beginner's astrophotography equipment. 
Would this be any good for astrophotography? The mount at least?

Thank you!

[vlaiv]

No - it is Alt-Az mount and these are no good for astrophotography.

In principle, it will track, but since it does not track in the same way earth rotates (it is not polar aligned) - it creates field rotation. This limits your exposure time considerably and stars don't look nice in the corners regardless of the type of scope you are using.

Similar scope is quite decent for astro photography:

https://www.firstlightoptics.com/reflectors/skywatcher-explorer-130p-ds-ota.html

It is version of above telescope, optimized for astro photography use. With that you'll need a tracking equatorial mount - something in EQ5 class.

 

[varius21]

Thank you very much @vlaiv! I appreciate the info and tips! 🙏

[Sunshine]

Every bit mentioned above is correct, you need an equatorial tracking mount, at least EQ5 and that scope mentioned by vlaiv would make for a good AP optical tube.

[varius21]

For a basic setup I should be expecting to spend over a grand, right?

Edited December 29, 2020 by varius21

[vlaiv]

6 minutes ago, varius21 said:

For a basic setup I should be expecting to spend over a grand, right?

There really is no way around it. AP is expensive. Much more then visual astronomy.

If you already have DSLR type camera - that is a bonus, otherwise, you'll have to budget for that as well.

Cheapest option is of course EQ5 + single tracking motor + 130PDS.

You will most likely need to crop quite a bit of frame since you won't be using coma corrector, but together that should cost you something like £520.

That is bare minimum which includes T2 adapter, EQ5 mount, single tracking motor (RA axis only) and 130PDS. That will let you make some images.

In reality, if you want to make decent images, you are looking at following list (again, include camera if you don't have one already):

EQ5 Goto mount

130PDS

Coma Corrector

T2 adapter / any extensions needed for proper distance

Finder scope + T2 adapter for it, or dedicated guide scope

Guide camera

Cables

Laptop (needed for guiding and imaging software).

So yes, only astro bits will cost you more than £1000

There are cheaper setups, but are limited to particular type of photography. You can get for example star tracker and small scope + flattener, or telephoto type lens and that will cost you less than above, but you'll be limited to mostly wide field imaging.

 

 

[varius21]

I’ll surely save the list you just posted! Thank you for taking the time! 🙏 

I’ll be using my dibs for visual pleasure for the next few months and if I feel the need to turn it into AP I’ll save up and get the best I can for my buck!

 

thanks again  you helped a lot!

[AlanP_]

48 minutes ago, vlaiv said:

There really is no way around it. AP is expensive. Much more then visual astronomy.

If you already have DSLR type camera - that is a bonus, otherwise, you'll have to budget for that as well.

Cheapest option is of course EQ5 + single tracking motor + 130PDS.

You will most likely need to crop quite a bit of frame since you won't be using coma corrector, but together that should cost you something like £520.

That is bare minimum which includes T2 adapter, EQ5 mount, single tracking motor (RA axis only) and 130PDS. That will let you make some images.

In reality, if you want to make decent images, you are looking at following list (again, include camera if you don't have one already):

EQ5 Goto mount

130PDS

Coma Corrector

T2 adapter / any extensions needed for proper distance

Finder scope + T2 adapter for it, or dedicated guide scope

Guide camera

Cables

Laptop (needed for guiding and imaging software).

So yes, only astro bits will cost you more than £1000

There are cheaper setups, but are limited to particular type of photography. You can get for example star tracker and small scope + flattener, or telephoto type lens and that will cost you less than above, but you'll be limited to mostly wide field imaging.

 

 

Was just about to post my own thread and came across this. Is this 130PDS the best telescope for a beginner when it comes to astrophotography? Most of the suggestion I came across were a Skywatcher ED 72/80mm. I just picked up a HEQ5 Pro, so now looking for a telescope for astrophotography.

[vlaiv]

1 minute ago, AlanP_ said:

Was just about to post my own thread and came across this. Is this 130PDS the best telescope for a beginner when it comes to astrophotography? Most of the suggestion I came across were a Skywatcher ED 72/80mm. I just picked up a HEQ5 Pro, so now looking for a telescope for astrophotography.

Its not the best - but it is certainly one of the best to start with.

Refractor telescopes like ED line from Skywatcher, ED80 in particular, are often recommended as the best starting scopes. This is mostly done because of newtonian collimation. This tends to be a bit scary topic for people just starting out in the hobby.

varius21 already has 8" dob so I guess collimation is not something strange / scary at this point. Also, 130p was mentioned in initial post so I just naturally proposed proper imaging version of 130 newtonian.

Besides collimation, ED80 has another strong point going for it - and that is dedicated field flattener that is pretty much "plug and play".

When starting out with new kit, it is often case of finding exact distance (not only for novice astrophotographers) between correctors and camera. Often, if usual clamping is used (screws / compression rings) there is a risk of having tilt in optical train. This is really not important for visual and that is why this type of connection is common for eyepieces, but it can cause issues for astrophotography.

It is better to have threaded connection and dedicated flattener for ED80 threads on the end of focuser tube (as far as I know) and also into camera adapter.

130PDS is very nice little scope. It is fast but not too fast at F/5. It works nicely with SkyWatcher coma corrector (it is designed for their PDS F/5 line of imaging scopes) but it also has some quirks. Collimation is certainly one. Another is that some people have issue with focuser tube protruding into optical path creating issues with stars (this depends on what camera is used with the scope).

It is of course the cheapest AP option that produces very good results and it is small and light weight (in comparison to other newtonians in the line) and not much of a sail in the wind (refractors are better in this regard). It also has perfect color correction - no chromatic aberration.

ED80, while having very good color correction is still ED doublet. If your camera is sensitive in far ends of spectrum you'll get some halos around bright stars. Here is example of M45 imaged with ED80:

When zoomed in to 100%, you can clearly see some stars having bluish (and some red) halo. This is due chromatic aberration.

It is really matter of personal preference between the two scopes - some people like spikes on stars in their images (go for 130PDS) and some don't (go for ED80)

[malc-c]

Here's my 2p worth

For imaging the mount is very important. Only EQ mounts are suitable as they track in the same axis as the Earth, thus preventing field rotation which by design is caused by the left right up down movement of an ALT AZ mount.  What you put on the mount will be a key factor in which mount you should look at.  A large long focal length refractor for planetary imaging will not bode well on an EQ5, nor will a C11 as its weight when combined with other equipment such as guide scopes and cameras will exceed the load capacity of the mount.  Personally I would go as far as suggesting an Explorer 150PDS on a EQ5 pro goto with a lightweight DSLR such as a Canon D450 would be an ideal starting point for DSO imaging.  For planetary any of the 5" Maks would be an alternative.   When it comes to DSO imaging, guiding is a must.  You can get a coupler to convert the 9 x 50 finder into a guidescope using a  ZWO 120MM mini guide camera, thus keeping the weight down but still giving you adequate tracking options. 

• So EQ5 Pro - 150PDS https://www.rothervalleyoptics.co.uk/skywatcher-explorer-150pds-eq5-pro-goto-telescope.html  £778
• Guide camera and adaptor circa £180
• EQDIR Cable to connect to laptop / computer £32 (although some new synscan units have USB connectors so this may not be required)
• APT / EOS Backyard software - £15
• EQMOD / ASCOM etc - Free
• Sharpcap - £10 (pro version has an excellent polar alignment tool)

So a modest imaging set up for DSO's can be had for £1015 give or take.  If you were looking at planetary work than you would need to purchase the EQ5 pro goto and 127 mak individually but it only increase the cost by £56. 

However if you are seriously considering imaging then ideally you should be looking at the HEQ5 pro goto mount as the defacto entry level imaging mount.  The precision and accuracy of the tracking is what you pay for, but then you're looking at £780 for the basic mount, or just shy of a gran for the belt driven version, which I would recommend.

However the biggest issue is availability..... Most of the above are impossible to get hold of due to the current shortages.

  

[vlaiv]

4 minutes ago, malc-c said:

So a modest imaging set up for DSO's can be had for £1015 give or take. 

No coma corrector?

[malc-c]

15 minutes ago, vlaiv said:

No coma corrector?

Just checking to see if you spotted that deliberate omission -

 

[AlanP_]

16 hours ago, vlaiv said:

Its not the best - but it is certainly one of the best to start with.

Refractor telescopes like ED line from Skywatcher, ED80 in particular, are often recommended as the best starting scopes. This is mostly done because of newtonian collimation. This tends to be a bit scary topic for people just starting out in the hobby.

varius21 already has 8" dob so I guess collimation is not something strange / scary at this point. Also, 130p was mentioned in initial post so I just naturally proposed proper imaging version of 130 newtonian.

Besides collimation, ED80 has another strong point going for it - and that is dedicated field flattener that is pretty much "plug and play".

When starting out with new kit, it is often case of finding exact distance (not only for novice astrophotographers) between correctors and camera. Often, if usual clamping is used (screws / compression rings) there is a risk of having tilt in optical train. This is really not important for visual and that is why this type of connection is common for eyepieces, but it can cause issues for astrophotography.

It is better to have threaded connection and dedicated flattener for ED80 threads on the end of focuser tube (as far as I know) and also into camera adapter.

130PDS is very nice little scope. It is fast but not too fast at F/5. It works nicely with SkyWatcher coma corrector (it is designed for their PDS F/5 line of imaging scopes) but it also has some quirks. Collimation is certainly one. Another is that some people have issue with focuser tube protruding into optical path creating issues with stars (this depends on what camera is used with the scope).

It is of course the cheapest AP option that produces very good results and it is small and light weight (in comparison to other newtonians in the line) and not much of a sail in the wind (refractors are better in this regard). It also has perfect color correction - no chromatic aberration.

ED80, while having very good color correction is still ED doublet. If your camera is sensitive in far ends of spectrum you'll get some halos around bright stars. Here is example of M45 imaged with ED80:

When zoomed in to 100%, you can clearly see some stars having bluish (and some red) halo. This is due chromatic aberration.

It is really matter of personal preference between the two scopes - some people like spikes on stars in their images (go for 130PDS) and some don't (go for ED80)

Cheers, appreciate the lengthy response! 

 

I''m keeping an eye out for a second hand telescope, so i'll take what I can get when a good deal pops up.  How can I avoid chromatic aberration with the ED80 if I got one of those? 

Also, what camera do you recommend? I was thinking of picking up a 600d if I found one.

[vlaiv]

2 hours ago, AlanP_ said:

How can I avoid chromatic aberration with the ED80 if I got one of those? 

It is best to ignore it. Really.

It is the feature of the scope - it is not very intrusive. There are couple of things you can do to minimize it but each of them comes at expense - either monetary expense or imaging time expense (more imaging time for same result).

1. Get mono camera + RGB filters

This comes with monetary expense as mono cameras and filters are more expensive than OSC cameras.

With One Shot Color cameras - you only focus once for all wavelength and fact that not all wavelengths of light come to same focus is most visible in this case. With mono + RGB filters - you can focus (and you often need to focus) for each filter separately. This means that you can find best focus position for blue wavelengths, best focus position for green part of the spectrum and best positions for red part of spectrum.

Any error due to chromatism will be reduced as focusing error will be smaller

2. Get special luminance type filter - this helps with both mono + filters and with OSC camera.

Astronomik recognized the fact that not all refractors are well corrected in furthest parts of spectrum and they created L1-L3 filters that progressively shorten imaging spectrum. Using L3 cuts off most offending parts of spectrum that cause the most star bloat.

This method costs both money (for this filter) and time - as it reduces amount of light that sensor captures - lowers signal in SNR equation (but for tiny amount like less than 5% - and if you want the same result, you need to image %5 longer time - that is not much).

3. Get mono camera and narrowband filters. This is not replacement technique, but I mention it as many people do it for shooting nebulae and this completely eliminates issues with chromatic aberration as it passes only one wavelength at the time (or rather very small range of close wavelengths that all focus at the same distance).

This costs the most money for camera and filters but actually speeds things up for certain targets especially in presence light pollution.

4. Get different kind of filter:

- wratten yellow #8

- baader long pass 495nm

or similar

This costs some money but costs more imaging time due to light cut off. It also skews color balance and you need to correct that in post processing.

5. Aperture mask - this costs the least in monetary terms - simple piece of cardboard will do. It costs quite a bit in terms of imaging time - but works surprisingly well.

This image was taken with ST102 - which is F/5 achromatic refractor. It has crazy amount of chromatic aberration - even for visual, let alone for imaging. Above is combination of yellow #8 filter and 66mm aperture mask. Almost no purple halos are visible in the image.

But really - out of all of these, I would just recommend mono camera + filters / nb filters or getting L3 astronomik filter. Or simply choose not to be bothered at all, as it really is modest level of chromatic aberration - that most people won't see and there are processing techniques that you can use to hide it in image.