DSLR camera lens for full moon?

[Ozone]

With the lunar eclipse coming, I would like to get an idea of what type of lens I would need. I have six inch scopes, but even without EP's it doesnt fit the whole disk in the FOV. Just want to go bear camera mounted on my atlas mount. I have a Canon T3i, Thanks.

[Thalestris24]

Hi

You can check how the moon will appear in a fov  calculator Just enter lens/telescope data manually.

Louise

[Scooot]

This was at 355mm with my canon 450 to give you an idea.

[petevasey]

What are the focal lengths of your scopes?  I imaged the September 2015 Eclipse with my Canon 700D (same size sensor as your T3i/600D) on my Meade 127 refractor which has a focal length of 950 mm.  And the Moon nicely fit onto the chip - image below.  So if one of your telescopes has a focal length around 1000 mm or less you should be ok.  Of course you will need a suitable 't' adapter and sleeve to fit your focuser.  I use a 400 mm camera lens for Solar Eclipses - the larger field of view is required to pick up all the corona.  For fields of view etc. you might find my free 'Astrophoto' program useful.  On my software page around half way down.

Best of luck,

Peter

[Ozone]

I have a 750 by 150 f5? Newt, but I dont think I was able to get it in the FOV. It will fit as far as imaging, but I want to use video and record some of it. I dont think it fit in movie mode even at 1080, I may be wrong, but this scope is badly out of collimation, and I cant find my laser! The other two are an RC at f/9 and 1200mm? And a mak cas at 150 by 1800mm f/12.

[Ozone]

It will fit in both in imaging mode according to a fov calculator, but not movie. Guess I may just have to image. Any recomendations on exposure length, iso speed? Thanks.

[David Smith]

Try and keep he ISO as low as possible. Exposure will need to vary through the duration of the eclipse, anything from about 1/250th down to 1/4th at mid eclipse but these are rough guides only.

[petevasey]

Here is a screenshot from Skymap Pro showing framing for three different focal lengths at maximum eclipse.  So the Moon will just fit in with the RC.  What I don't understand is why you believe video won't work - the camera sensor size is unchanged, just the format is different.  I suggest you experiment if we have a clear night before the actual eclipse night.  Or if you have a white light Solar filter for your scope, have a try on the Sun -its apparent diameter on 20th January is around 1 arc-minute less than the Moon at totality.

Best of luck,

Peter.

[JamesF]

I use my 450D quite a bit for lunar imaging, on the back of a 127 Mak.  In that configuration the focal length is probably around 1400mm and the image absolutely fills the frame, so anything from there down ought to work for stills.

Not sure about video mode though as my camera isn't new enough to have it.  Does it crop the frame for that?  If so I'd personally prefer the higher resolution of the still frames anyhow.

James

[Thalestris24]

Edit: removed incorrect post

 

[david_taurus83]

The one time I photographed the moon. Canon 600D at prime focus in my 200p reflector. 1000mm focal length. Fits nicely.

 

Edit: Sorry, I just seen your post regarding the video mode. It would likely take some time from start to finish. You could take a series of stills over the period of the eclipse and stitch together to make a movie time lapse.

[petevasey]

OK, I've done a quick experiment with my 700D, and sure enough there is a loss of height in video mode.  Not a problem in width - plenty room there, but the height reduction is approximately 15%  At the 1200 mm focal length the frame height for a still photo is 42' 41".  So with a 15% reduction it will be 36' 17".  Still just enough height to encompass the Moon which at totality will be 33' 40".  Go for it!  (all figures courtesy of Skymap Pro).  But I still suggest an experiment prior to the actual eclipse ?

Cheers,

Peter.

[JamesF]

7 minutes ago, petevasey said:

But I still suggest an experiment prior to the actual eclipse ?

100% agree with this.  A couple of "dry runs" makes everything more likely to go smoothly on the one occasion that you absolutely have to get it right.  Make notes if you need to.

James

[Thalestris24]

Edit: removed my inaccurate post

Louise

 

 

 

[Scooot]

46 minutes ago, Thalestris24 said:

Here's 12dstring fov for movie mode:

At 750mm:

At 400mm:

There you go - a 400mm lens would do fine but quite expensive to buy. A cheap 500mm mirror lens would do but would slightly crop the top and bottom and be a pain to focus. A 400mm Celestron Travel Scope 70 would do the job nicely. It's cheap and light but would need an (30-40mm) t2 extension tube

Louise

Hmm I don’t think the sensor size is correct in that last image? 

Edit

My apologies, I haven’t changed the image size, ignore this  

[philj]

I use a micro four thirds for most of my lunar images these days. The small sensor size coupled to my 127 EDT refractor at native f7.5 means the disc just fits on the sensor. Despite the small sensor size it gives excellent quality. Couple that with a few hundred subs stacked and it works even better. I use Olympus Om D em 10 and 1. Both work well.

[petevasey]

Getting a bit confusing here.  The sensor in the 600D is an APS-C size, 22.3 x 14.9 mm,  5184 x 3456 pixels maximum coverage, at a ratio of 3:2.  As you know the resolution can be reduced for still photos, for example to 1920 x 1280, but still uses all the chip in the 3:2 format.  But for video the (16:9) format is 1920 x 1080, and that is not 3:2.  So some cropping must occur, in this case in the vertical height, from 1280 to 1080, i.e. a loss of approximately 15% as I mentioned earlier.  So if putting a chip size into a framing calculator for video, in this case it needs to be 22.3 x 12.57 mm

Here is the framing as shown in Skymap Pro for the two cases.  The Moon should just fit in on the 1200mm focal length telescope.  But it will be a lot easier on the 750mm Newt if you can collimate it ?  Here is a link to full specs for the camera.

Peter

[Stub Mandrel]

1200mm (150PL) works well with my Canon 450D (APS-C sensor)

 

[Thalestris24]

Edit: Hmm on the other hand it looks like it's only the 3x zoom (actually x2.7) digital zoom that only uses 1920 x 1080 pixels so I stand corrected.

It must do some clever software/firmware pixel selection to use almost the whole chip in normal video mode.

Louise

[Thalestris24]

Removed

[petevasey]

9 minutes ago, Thalestris24 said:

I believe the use of 1920x1080 for video is like a region of interest crop with 16:9 aspect ratio. In other words it's as if the sensor is smaller but, obviously, with the same size pixels. Anyone with a 600d/t3i can check this by taking a short video and inspecting a single frame.

Louise

Yes, that is the case, Louise.  Sort of.  But with reduced resolution using intermediate pixels, so the width of the scene being photographed is still the same as a 3:2 still image using all the available pixels - only the height is cropped.  There are different video resolutions available, for example  1280 x 720  still keeping the 16:9 ratio as 1920 x 1080, and the same image frame just a coarser resolution.  The gain is in frame speed.  There is an even lower video resolution of 640 x 480 (4:3).  That crops the width and uses all the vertical height of the sensor.

It's easy to see the results by switching from still frame live view to video.  At the two 16:9 ratios the width photographed remains the same as a still frame but the height is cropped.  Vice versa for the 4:3 ratio.  My Skymap image above is correct.

Peter.

[Thalestris24]

5 minutes ago, petevasey said:

Yes, that is the case, Louise.  Sort of.  But with reduced resolution using intermediate pixels, so the width of the scene being photographed is still the same as a 3:2 still image using all the available pixels - only the height is cropped.  There are different video resolutions available, for example  1280 x 720  still keeping the 16:9 ratio as 1920 x 1080, and the same image frame just a coarser resolution.  The gain is in frame speed.  There is an even lower video resolution of 640 x 480 (4:3).  That crops the width and uses all the vertical height of the sensor.

It's easy to see the results by switching from still frame live view to video.  At the two 16:9 ratios the width photographed remains the same as a still frame but the height is cropped.  Vice versa for the 4:3 ratio.  My Skymap image above is correct.

Peter.

Yeah, I did edit that post... I'd misunderstood how the Canon video actually works - d'oh. I've probably succeeded in completely confusing the op due to jumping to the wrong conclusion. Stupid of me as I've made videos with my 550d so should have known better. I'll crawl into a corner and hide now.

Louise

[petevasey]

51 minutes ago, Thalestris24 said:

Yeah, I did edit that post... I'd misunderstood how the Canon video actually works - d'oh. I've probably succeeded in completely confusing the op due to jumping to the wrong conclusion. Stupid of me as I've made videos with my 550d so should have known better. I'll crawl into a corner and hide now.

Louise

Och, dinna fash yersel, hen.  Naebody's perfect!  ?

Have a great New Year, isn't Hogmanay the time for drowning sorrows?

Cheers, (hic)

Peter.

[Thalestris24]

1 minute ago, petevasey said:

Have a great New Year, isn't Hogmanay the time for drowning sorrows?

It might be but I'm teetotal and not Scottish!

[petevasey]

Ah, well, as you live in Glasgow I assumed.....

As I said, nobody's perfect ?

Peter