Imaging with Canon EOS 700D

[Matt S]

Hi all - I recently decided that I’d start to try a bit of photography using my 700D. It didn’t go very well, and I’m pretty sure why (me), but wanted to get some thoughts on what I should be doing here. 
I’m not expecting great things from my setup but figure I should be able to capture something reasonable. 
 

Equipment: Skymax 127, EQ3-2/pro, Canon EOS 700D

I’ve only been capturing images of the moon so far for a little practice, but after spotting the super faint smudge of M51 the other night in my eyepiece I thought I’d try and see if I could capture anything on camera.

Perhaps my first error was that I’d aligned/focused using the eyepiece not the live view on the camera, so taking a few long exposure shots after attaching it probably isn’t going to show me much (it didn’t).

I guess  my question is, should I be setting my scope/tracking up with the camera attached first, finding a bright star and getting focus on that before slewing off to something like M51?

I’d been struggling a bit using the live view - I had it on the Moon, but then found I had to turn the shutter etc right down so it was hard to see when I actually wanted to take photos as it would be too bright otherwise (but then dark/hard to see on the screen).

Given how faint M51 was in my eyepiece I’m a little unsure what sort of settings I should be using to first locate it properly, but then what sort of settings I should try to shoot with.

 

Last question: I don’t have a shutter release st the moment - longest setting is 30” without using bulb mode. What do people generally use for longer timed shots? Holding a shutter release cable for 5 mins for however many shots I need seems a bit impractical…

[Elp]

Hi, it's good that you've decided to try something with what you already have, imaging is difficult at the best of times.

How have you attached the camera to the telescope?

Apologies if you already know this - You can capture through an eyepiece but the best way is to screw it directly to the focus tube with a t ring adaptor which provides a typical dslr backfocus of 55mm from front of ring to the camera imaging sensor (this dimension can vary between camera models and adaptor thicknesses as well as scope setup). The backfocus is the required distance for a camera to be able to achieve correct focus, once set focus is achieved once the focus tube has been racked to get the focus point onto the camera sensor.

You have to focus via the camera/live view or what I normally do, take an image and adjust focus and reiterate a few times until I'm at the desired focus whereby stars are their smallest. A better way is to use an inexpensive bahtinov focus mask on the front of your scope which produces a diffraction spike on bright stars which you have to get dead centre, once this is focussed you can remove the mask and continue.

I assume your Ra axis of the mount is correctly polar aligned to Polaris first in equatorial mode as without this you will get star trails, once it's set and your sidereal guiding rate is set that's a good start. If your mount is not motorised you will start to get star trails the longer you expose. This can also happen if the setup isn't balanced in both Ra and Dec axis'.

The moon is quite bright and requires a fairly quick shutter speed. For deep space you need the opposite, long slow shutter speeds. As galaxies are typically quite bright compared to nebulae anywhere between 30s-60s would show a galaxy centre as a concentrated ball of light typically (depends on the galaxy, some you'll start to see the faint form of the shape). Exposures up to 2-3 minutes even better but this generally benefits from autoguiding which is another ball game entirely, some setups can guide quite well without autoguiding. Then you need to take many photos to get a lot of cumulative signal and stack them afterwards in computer software with calibration frames. Pretty much all the nice astro images you see are post processed afterward to get the details out of them.

Typically with dslr I use iso range of 800-1600, you don't want it too high or too low.

Regarding locating I assume the 3-2 pro has goto functionality, if so the controller should say once it's slewed to a target. If you don't have goto the best method is identifying local stars and zero-ing to your target and taking a few preview images on the way.

Your best friend when using a DSLR as a basic setup is an affordable digital intervalometer, you can set delay, seconds to keep the shutter open, number of images to take etc and set the dslr into bulb mode. It's imperative the setup isn't touched when taking a long exposure photo so another reason to use one, once you set and press the "go" button it will continue to take images until you stop it or its completed the set amount of images you've input.

I'm sure you'll have more questions which people will be able to help with so feel free to ask away. You've taken a first step which is progress.

 

[Nik271]

Dear Matt,

First: you should always refocus after attaching the camera, don't assume that the eyepiece and the camera attachment are parfocal, 99.9% of the time they won't be. In fact with a Maksutov you shoud check the focus now and then during shooting because the mirror moves slightly in a different position.

I have the Skymax 127 and its focal length 1500mm is very demanding on the mount. So with EQ3-2 you are severely handicapped. I doubt it will track well even for a 30 second exposure.

The other issue is that with focal ratio F/12 the Skymax is a very slow scope which is OK for bright objects like the Moon and planets but pretty poor choice for DSO.  M51 will barely register after a 30 second exposure. It can be done: take many 30 second exposures and stack them but even then it will take an awful lot of time. For DSO you are better off with a fast Newtonian or a refractor.

Edited April 28, 2022 by Nik271

[Stefan73]

I'm using an Eq3 pro and Canon 550D and I'd definitely echo getting a Bahtinov Mask, eg https://www.firstlightoptics.com/bahtinov-focus-masks/starsharp-bahtinov-focus-masks.html is the one I use.  Then get the telescope pointing at a bright star, zoom in on live view and use the mask to focus.

Finding galaxies can be a challenge as you won't see  much or maybe anything in the view finder or live view.  I tended to use the GOTO functionality to find the nearest bright star in the catalogue, and I could identify,  to what I wanted to photograph, and then do a Pointing Accuracy Enhancement on that unless it's spot on.  Then goto the object of interest.  It's worth having an illuminated reticle eyepiece to help with all the aligning.

You can use an intervalometer as suggested or it looks like magic lantern supports your camera and that has a built in intervalometer and very long exposures for bulb mode. See https://magiclantern.fm/.  I certainly had success with that. I don't think I've reliably managed longer than 1 minute exposure with the Eq3 Pro  and even then some frames end up with star trails due to periodic error (but that's with an F5 scope so easier than yours).   Just take lots and lots of photos without touching anything and delete then ones with star trails.  An hour or twos worth of total exposure should show something nice after a bit of post processing.  You'll have to experiment to see what exposure length you can get away with.

These days I've discovered the wonders of astroberry which is a whole bundle of useful astrophotography software.  It can handle the goto via plate solving and has camera control to deal with the intervalometer side of things (and much, much more). 

 

[alacant]

20 hours ago, Matt S said:

using my 700D

IMHO, that's the strongest item in your setup. We use them all the time with beginners and not so beginners alike.

Rather than start with the telescope (that's gonna be difficult), why not have a go with just the camera and a lens? Try e.g. a whole constellation with the lens at around 50mm to get started. Optimum ISO:800.

You can control exposures from a laptop with the software that came with the camera, or from your 'phone (there are loads of apps) using an OTG cable.

Cheers good luck and HTH.

Edited April 28, 2022 by alacant

[Matt S]

Thanks for the feedback all, I appreciate the thoughts.

@Elp

Quote

How have you attached the camera to the telescope?

I’ve attached via a T-ring / nosepiece (mostly as it made it easier to pop an eyepiece back on if i decided to, I’ve not tried it yet directly screwed onto the scope). I’ve added a polarscope and the Synscan controller/motors to the mount - I’m then using PS Align to try and get my alignment as good as possible.

On 28/04/2022 at 02:05, Elp said:

A better way is to use an inexpensive bahtinov focus mask on the front of your scope which produces a diffraction spike on bright stars which you have to get dead centre, once this is focussed you can remove the mask and continue.

Thanks - I like that idea, I’ll try things out and look at a mask once I’ve got the basics down (and I’m not spending 1/2 an hour setting it up!

On 28/04/2022 at 02:05, Elp said:

Your best friend when using a DSLR as a basic setup is an affordable digital intervalometer, y

Perfect, thanks - I had no idea what one of those was called, cheap one on it’s way! 

 

On 28/04/2022 at 08:47, Nik271 said:

So with EQ3-2 you are severely handicapped. I doubt it will track well even for a 30 second exposure.

Thanks @Nik271, you’re likely right - I hadn’t really planned on using the scope for these purposes, but with the planets being out of sight for me (for a while at least) I thought I’d see what else I could see/do with it. I’m trying everything I can to minimise backlash etc on the mount - alas I’m not sure I’ll be allowed another mount right now….

On 28/04/2022 at 08:47, Nik271 said:

It can be done: take many 30 second exposures and stack them but even then it will take an awful lot of time. For DSO you are better off with a fast Newtonian or a refractor.

I’ve not been able to get out under clear skies to try again since posting this so I have no idea if 30s (or even less will be my limit, I’m really curious how far I can push it really.

I had been wondering about whether I should look at a different scope at some point - I really do need to spend more time with this one first though.

On 28/04/2022 at 08:56, Stefan73 said:

and then do a Pointing Accuracy Enhancement on that unless it's spot on.

@Stefan73, Interesting - I’m currently doing a 3 star align, then going to objects and simply using the keys to find/centre an object if it didn’t end up in view after the go-to ran. Is a PAE different from doing that (i.e. one of the utility functions in the Synscan controller)?

On 28/04/2022 at 08:56, Stefan73 said:

These days I've discovered the wonders of astroberry

My plan at some point is to run that from a Pi (3 or 4) attached to the scope, mostly so I wanted to run Firecapture. I don’t have a guide scope or guide cam so I think that side may have to wait (although I love the idea).

 

On 28/04/2022 at 09:41, alacant said:

why not have a go with just the camera and a lens? Try e.g. a whole constellation with the lens at around 50mm to get started. Optimum ISO:800.

@alacant - good idea, I’ll try that too! I guess my focus has been on what I can push the scope to see/do. 

I didn’t actually realise there were apps that would let me control some of this - it’s be a lot easier using the Canon app on my phone than trying to look at a screen on the camera that’s potentially pointed awkwardly. My camera doesn’t have WiFi/BT - so I assumed those apps wouldn’t work - but if I can plug a cable into my iPhone that would be handy. No Idea what cable/adapter’s I’d need!

 

 

[Stefan73]

8 hours ago, Matt S said:

I’m currently doing a 3 star align, then going to objects and simply using the keys to find/centre an object if it didn’t end up in view after the go-to ran. Is a PAE different from doing that (i.e. one of the utility functions in the Synscan controller)?

It's pretty hard to do that for something you can't easily see in a view finder / live view, like most galaxies.  You might be able to find it with an eye piece and centre it but then you have to refocus for the DSLR which is hard without a bright star and a mask to help.   Or you end up taking endless trial photos to try and frame whatever you're interested in.

I 'm guessing the PAE uses the delta from the chosen object to GOTO nearby objects rather from your initial alignment star.

My workflow pre-astroberry was to do the usual alignment to get started and make sure polar alignment was ok.  GOTO a nearby star to what I wanted to photograph, get the focus right on that and PAE if necessary,  then GOTO to the object I wanted.  If your 3-star alignment is getting you where you want then obviously don't worry about PAE.

These days I just wait until it gets dark enough for plate solving to work.

8 hours ago, Matt S said:

My plan at some point is to run that from a Pi (3 or 4) attached to the scope, mostly so I wanted to run Firecapture. I don’t have a guide scope or guide cam so I think that side may have to wait (although I love the idea).

You don't need a guide scope at all to get value out of astroberry and the like.  For the price of two USB leads and a PI (I'd definitely go at least 2GB pi-4) you can get plate solving to work which takes the guess work and much of the frustration out of framing pictures, and it will function as an intervalometer too.  Having spent an evening photographing completely the wrong area of the sky it was a welcome enhancement for me! 

I think a lot of its value depends on how much of a computer person you are though.  If you aren't then it's probably easy to end up replacing one source of frustration with another...  Also I'm not sure plate solving would work just with camera lenses, but probably exact positioning is less important then. 

[happy-kat]

With the 1100d I use DSLR Controller on Android with the camera USB cable and an OTG cable to control and focus the camera using a mobile or tablet. If also using an intervalometer plug the connector in but don't connect the intervalometer until you're done using DSLR Controller which does actually have it's own time lapse tool.

[alacant]

9 hours ago, Matt S said:

No Idea what cable/adapter’s I’d need!

This into the 'phone (or whatever connection apple use these days). Then this to the camera.

Cheers

Edited May 3, 2022 by alacant