Do I need tracking for close up lunar photography.

[PatrickO]

I've got some nice moon images using a DSLR and 500mm lens using 1-2 minute video lucky imaging. No tracking. I use PIPP to align the images.

I'd like to try some close up shots with a small long focal length telescope and a ZWO camera.

My question is do I need tracking for images of around 1/4 to 1/8 of the moon's disc?

I've no plans to do DSO photography. And I want to keep it as simple as possible.

[vlaiv]

In principle yes, but I would advise against it.

You can record a movie while letting the moon drift thru the FOV and then using surface stabilization feature to try to do "a strip" of lunar surface. You can do multiple strips and stitch them together into mosaic (many people do full disc mosaics so that is something that can be done without too much trouble).

While it can be done - I think it is too much work and requires certain skill. If you want the challenge - then sure, but if you just want to get result, tracking is much better option.

[malc-c]

IMO yes, as it's quite surprising just how fast the Moon tracks across the field of view, especially with magnification.  You could do as Vlaiv suggests, but ideally if you try and get as stable an image in the first place the better the end results, so tracking is the better option 

[900SL]

Simply, yes. At longer focal lengths you will get movement blur when shooting video unless you crank the gain right up and shoot at high frame rates. 

The moon is surprisingly fast if shooting untracked at higher focal lengths. It's also difficult to target and get in frame

[carastro]

If you take a video you can stack the frames in Registax or Autostakkert.

[Owmuchonomy]

It's not necessary but makes life a lot easier.  A tracking Alt-Az mount is fine as the stacking software (Autostakkert) will deal with field rotation.  'Long focal length'; it depends how long.  Your object will move rapidly the longer you go.

[vlaiv]

4 hours ago, 900SL said:

Simply, yes. At longer focal lengths you will get movement blur when shooting video unless you crank the gain right up and shoot at high frame rates. 

The moon is surprisingly fast if shooting untracked at higher focal lengths. It's also difficult to target and get in frame

No, not really.

Sidereal rate is about 15"/s and lunar tracking rate is very similar - just lightly off of that. For the sake of argument, we can go with this value without any issues.

Most planetary imaging is done with exposure length of about 5ms - but lunar can be done with even smaller exposures because moon is so bright - so say 2-3ms.

That is ~1/300th of a second (1/200th for 5ms exposure). 15"/s divided with 300 gives 0.05".

Moon therefore moves 0.05" in duration of single lunar exposure. Critical sampling rate for say 8" telescope is 0.41"/px - so moon moves 1/8th of a pixel during single exposure.

That is really not much motion blur to speak of.

 

[PatrickO]

Many thanks for very helpful replies. Sounds like tracking is the way to go.

I'm thinking of attaching my DSLR to a small guided telescope. Something like a Celestron Nexstar 4se.

Would that be a good, inexpensive and easy option. I don't mind doing a polar alignment.

 

[vlaiv]

2 minutes ago, PatrickO said:

I'm thinking of attaching my DSLR to a small guided telescope. Something like a Celestron Nexstar 4se.

That is very good option.

It's 4" maksutov telescope and it will have sharp optics and enough focal length. It also has tracking that is easy to use.

I've taken this lunar image with similar setup:

4" Maksutov and small alt-az mount. In this case SkyWatcher 102 Mak and AZGti.

Only difference was in camera used - I used ASI178 camera.

You can right click on the image to open it in new window so you can zoom in fully. Above image is mosaic composed out of I believe 9 individual panes.

[Sunshine]

I’ve done some nice lunar and planetary work, nothing award winning but tracking did help. It just seems easier than stripping and taking videos.

[PatrickO]

10 minutes ago, vlaiv said:

That is very good option.

It's 4" maksutov telescope and it will have sharp optics and enough focal length. It also has tracking that is easy to use.

I've taken this lunar image with similar setup:

4" Maksutov and small alt-az mount. In this case SkyWatcher 102 Mak and AZGti.

Only difference was in camera used - I used ASI178 camera.

You can right click on the image to open it in new window so you can zoom in fully. Above image is mosaic composed out of I believe 9 individual panes.

Thank you. That's a beautiful image.

[Rodd]

21 hours ago, Sunshine said:

I’ve done some nice lunar and planetary work, nothing award winning but tracking did help. It just seems easier than stripping and taking videos.

How do you track without stars?   

[AKB]

33 minutes ago, Rodd said:

How do you track without stars?   

Tracking, the thing which most motorised mounts do, is not to be confused with guiding, which, indeed, generally requires stars.

[Bugdozer]

22 hours ago, PatrickO said:

Many thanks for very helpful replies. Sounds like tracking is the way to go.

I'm thinking of attaching my DSLR to a small guided telescope. Something like a Celestron Nexstar 4se.

Would that be a good, inexpensive and easy option. I don't mind doing a polar alignment.

 

In my experience, this will work. I have the 5SE (SCT rather than Mak, but same mount) and an elderly Nikon D90 SLR. Here's an example image of the moon from a single exposure:

[Rodd]

14 minutes ago, AKB said:

Tracking, the thing which most motorised mounts do, is not to be confused with guiding, which, indeed, generally requires stars.

Ahh. I assumed all mounts track. I guess that’s not true. 

[vlaiv]

2 hours ago, Rodd said:

Ahh. I assumed all mounts track. I guess that’s not true. 

Well they sort of do - but not all have motors - there are some that only have manual tracking - which is fine for visual use - where you correct and recenter target every so often

[Rodd]

53 minutes ago, vlaiv said:

Well they sort of do - but not all have motors - there are some that only have manual tracking - which is fine for visual use - where you correct and recenter target every so often

I find I have to do that even with my mount when imaging the planets or the Moon. Kind of frustrating

[Sunshine]

5 hours ago, Rodd said:

How do you track without stars?   

Oh, I didn’t mean guiding, i meant tracking on one axis for short periods when polar aligned, switch motor on and off as needed.

[Rodd]

25 minutes ago, Sunshine said:

Oh, I didn’t mean guiding, i meant tracking on one axis for short periods when polar aligned, switch motor on and off as needed.

I wish I could polar align that well. I use a RAPA scope that claims it is pretty accurate.  But when phd2 calculates PA, I haven’t been under 5 arcsec but once, at 2.3.  Usually it warns me it could be better. 

[Sunshine]

35 minutes ago, Rodd said:

I wish I could polar align that well. I use a RAPA scope that claims it is pretty accurate.  But when phd2 calculates PA, I haven’t been under 5 arcsec but once, at 2.3.  Usually it warns me it could be better. 

Tracking for planetary imaging doesn’t have to be accurate at all, I can literally eyeball polaris through the polar scope on my Vixen polaris mount which is enough to keep a planet pretty much centered in the FOV for up to 5 min. Imaging deep sky is another story, as you know it requires much lore accurate polar alignment and guiding.

[Rodd]

3 hours ago, Sunshine said:

Tracking for planetary imaging doesn’t have to be accurate at all, I can literally eyeball polaris through the polar scope on my Vixen polaris mount which is enough to keep a planet pretty much centered in the FOV for up to 5 min. Imaging deep sky is another story, as you know it requires much lore accurate polar alignment and guiding.

Don’t the planets move differently than the stars?  Even though I get sometimes halfway decent PA, I always see the moon or planets drift so that I need to readjust gif each video I make.  And my mount has a lunar and planetary setting.   

[Sunshine]

1 hour ago, Rodd said:

Don’t the planets move differently than the stars?  Even though I get sometimes halfway decent PA, I always see the moon or planets drift so that I need to readjust gif each video I make.  And my mount has a lunar and planetary setting.   

Yes, but for planetary imaging one is not using a long exposure camera as in DSO imaging. With planetary imaging the cameras is taking a video clip consisting of hundreds of frames, software then picks out rhe best frames and stacks them. One can even track by hand with a dobsonian and achieve great images as I have seen some here do with hand tracked dobsonians. Lucky imaging is the term used, many hundreds of frames are taken, but only a few of the best, most steady frames are selected by software for stacking. In fact, one can do this without any mechanical or hand tracking at all, it just means that your bideo clip will be much shorter, and less lucky frames to choose from. With DSO’s where a single long exposure is taken, hyper accurate alignment and guiding is required to maintain a sharp image and pinpoint stars, not so with planetary imaging.

Edited January 5 by Sunshine

[Sunshine]

2 minutes ago, Sunshine said:

Yes, but for planetary imaging one is not using a long exposure camera as in DSO imaging. With planetary imaging the cameras is taking a video clip consisting of hundreds of frames, software then picks out rhe best frames and stacks them. One can even track by hand with a dobsonian and achieve great images as I have seen some here do with hand tracked dobsonians. Lucky imaging is the term used, many hundreds of frames are taken, but only a few of the best, most steady frames are selected by software for stacking. In fact, one can do this without any mechanical or hand tracking at all, it just means that your bideo clip will be much shorter, and less lucky frames to choose from. Below are examples of very short video clips taken with my manual vixen polaris mount, eyeball polaris alignment with one axis tracking.

How did i just quote my own post!?

Edited January 5 by Sunshine

[Rodd]

1 hour ago, Sunshine said:

Yes, but for planetary imaging one is not using a long exposure camera as in DSO imaging. With planetary imaging the cameras is taking a video clip consisting of hundreds of frames, software then picks out rhe best frames and stacks them. One can even track by hand with a dobsonian and achieve great images as I have seen some here do with hand tracked dobsonians. Lucky imaging is the term used, many hundreds of frames are taken, but only a few of the best, most steady frames are selected by software for stacking. In fact, one can do this without any mechanical or hand tracking at all, it just means that your bideo clip will be much shorter, and less lucky frames to choose from. With DSO’s where a single long exposure is taken, hyper accurate alignment and guiding is required to maintain a sharp image and pinpoint stars, not so with planetary imaging.

But what happens to me is the target drifts so that half way through the video, I have to move the scope. Or if I shoot 4- 5 videos, I have to reposition before each one.  The drift limits the length of my video, which gives a smaller data set from which to keep, say 10% or 20% of the frames.  Its an annoyance.  So I’ll move the scope during the video knowing that the frames taken during the movement will be discarded. That works, but always having to worry about it is a pain.