Optic Tracker - UFO zoom photography

conandrum · #1 19-12-2010, 09:10 PM

Hi everyone,
This is my first post here and you must know that I am very new to this.
My goal has nothing to do with astronomy or astrophotography although it has everything to do with high magnification and photography of objects far off the ground and in high orbit around the planet.
The idea came after looking at several videos on youtube taken with night vision devices.
A second idea came after discovering optic tracker which allows you to control a celestron nexstar se or meade lx200 mount to lock onto any moving target and record it.

I do not have a question as such. I need recommendations.
Facts:
1. restricted to lx200 series scopes since these scopes are not interchangeable and the mounts are not sold separately
2. restricted to celestron nexstar se series (scope & mount) or celestron nexstar se mount with maybe some other scope (here I need your help - what other scopes can I mount on these?)
3. My estimation is that a 4'' scope and up can provide enough magnification to be able to recognize the ISS for example. An 8'' to 10'' is enough to see quite a bit of detail on the ISS.
4. Choice of telescope in order to increase resolution depends on budget. The more money, the higher the resolution.

The next questions may be best for the astrophotography section, but may be relevant here also:

5. The object here is to get good quality video but since the object will resemble an airplane or jet as opposed to a galaxy, stacking stills to get an image is probably futile i guess? Will a normal HD camcorder do for the purpose?
6. I calculated that a 300x to 800x magnification is good enough for the ISS. Around 100x is good for a plane at 30000ft. Assuming a 1000mm FL, what kind of barlows/eyepieces/camera do you think would be suited for between 100x to 800x?

I hope I have provided as much information as possible to get a few good answers back in return!
If you need more details please let me know, but bear in mind that I have not done this before, and neither have the OpticTracker team who have helped me to the best of their ability.

Thanks for your time
Regards
Telis

gb_astro · #2 19-12-2010, 09:56 PM

Found this YouTube video of the ISS shot with a Nexstar 4SE at X270 and OpticTracker.

http://www.youtube.com/watch?v=zr2Zq...eature=related

You get the shape but no real detail. This would be perfect for UFO's.

Seriously though, this is impressive stuff.

gb.

conandrum · #3 20-12-2010, 03:51 AM

Thanks for the reply gb,

I have already done a lot of research on the subject.
Please visit the following thread to see where I am up to.
http://www.ufonv.com/viewtopic.php?f=19&t=916
There you can see a comprehensive comparison of ISS with various configs.

At the moment I am left with the couple of questions mentioned previously.
I would like some expert help with suggestions please based on past experience with telescopes and astrophotography.
If you know someone that could be of help, it would be great if you could please point them here.

Thanks again

Telis

NorthernLight (Max) · #4 20-12-2010, 04:30 PM

Hi Telis,

in order to get sufficient detail you need a large aperture (Ap); in order to get the required magnification (mag) you need a large focal length (fl). The relation between fl and Ap is the F-factor (fl/Ap=F). The F-factor tells you something about the brightness of your image and therefore about your required exposure time. A scope with F3 is called "fast" as it allows for short exposures (and gives bright images) a scope F15 is called slow for the opostite effect. If your target is very bright and very small, like a planet, you want a long fl scope and don`t worry about F15 or F25, because a scope F5 with 7m fl would be way to big and expensive.
Angular resolution (amount fine detail contained in image) is a function of Ap - the rule of thumb is: 2xAp=limiting magnification: 800mag/2=400mm (so you are probably looking at a 16" Cassegrain).

If you consider, just for the sake of argument and without thinking about the real math behind it, that a webcam sized CMOS/CCD sensor, with its crop factor and what have you not, behaves visually almost like a 4mm eyepiece than you come to the following equation:

Mag=fl (telescope)/fl (eyepiece)

or 800mag x 4mm fl (cam) =3200mm fl (telescope)

[the real calculation is done by incorporating the angular diameter of the object, the fl of the scope and the size of the pixels in the cam but as I said I don`t go there now.]

So a scope that does your job would be something like a Celestron CPC 11 or Meades 12" equivalent - both are F10

The biggets problem you are getting with 800xmag is the atmosphere. Bear in mind that you magnify every turbulance in the coloumn of air between you and the ISS. This infact the reason why people stack hundreds of stills out of a few thousand.

Good Luck with your project and if you succeed please post it here!!!

Cheers

Max

conandrum · #5 20-12-2010, 10:42 PM

Thanks Max,

You raised some good points there. Maybe you can help further.

Right or wrong, I thought that the best solution would be a collection of tools that are able to function extremely well within a set of pre-defined parameters for the purpose.

1. targets - helicopter to airplane size targets
2. distance - a few kilometers (say 10km), up to 1000km from the earth.
3. magnification - able to place the above target at above distances, within the eyepiece for recording, taking up 25%+ of the FOV.
4. This will not be an astronomical kit - more like a long to extremely long range spotting scope!

In my research for a solution, I thought of investigating real examples from others in order to gain an understanding of what can be achieved.

I was particularly impresed by the following examples showing he ISS at roughly 500Km from the earth:
1. Takahashi FS 128 (5'') refractor with Tele Vue 3x (focal length extended from 1040 to around 4200mm) (piggy-backed on a 12" LX200 Classic) @x (Digital Camera: Lumenera's SKYnyx2-0 VGA CCD - Lucam Recorder Software Gain 5.0 / 1/100s / 20fps) (Satellite Tracker Software)

Click here to load the video

2. Meade LX-200 10" @f20, ToUCam & Automatic tracking :
(The following clips are made by Mike Tyrrell and Phil Masding the guys from the BBC 4 special called 'The Satellite Story'. [link2]webite,http://www.astrospider.com/[/link2])

Click here to load the video

3. Celestron C8 with f.6.3 focal reducer - Manual tracking (using a 80ED Scope) (Camera: TIS DMK 31AF03.AS)

Click here to load the video

The most impressive of all is of course the Takahashi FS 128 (5'') refractor. You will notice that even though this was mounted on a 12" LX200 SCT, he instead chose to record images from the refractor (guess he used the LX200 just for the autoguiding). Does this tell us something? We can directly compare results with the second example of the LX-200 10''.The Celestron C8 is very similar to the 10'' Meade with slight loss in resolution.

I would like to hear some opinions on the type of scope suited specifically to this application (and whether it can hopefully be mounted on a mount that works with OpticTracker like Celestron SE or CPC series & Meade LX200 mounts). This is secondary though).

Cost is always an issue but I think $2000 for a scope & mount is reasonable.
Your opinions are invaluable bearing in mind that I have absolutely no prior experience in this field even though I have been reading up on it.

Thanks

Telis

NorthernLight (Max) · #6 21-12-2010, 02:09 PM

Telis,

If you ever be able to get your hands on a new Tak FS 128 and a decent mount with GOTO for less or equal 2000AUD, then please contact me immediately or better still order me one, too!!!

You are looking at some serious gear. You may get a Nexstar SE6" for $2k or a C8 on CG-5EQ mount but that s about it.

What sort of camera are going to use?

NorthernLight (Max) · #7 21-12-2010, 05:06 PM

on a second thought, the speed of GOTO mounts is limited and for your type of work only alt/az (fork) mounts come into play. For a helicopter I recon none of the existing mounts are fast enough and since you need to lock the autoguider first on your target by manually following your target, the mount hasn´t really got a chance to give you some staedy views for shooting (not to mention the time required for accurate focusing) before the target (be it plane or helicopter) has moved out of reach.
The ISS is more predictable as it follows a fixed trajectory undisturbed by atmospheric conditions (like airborne targets) and it moves rather slow between the oportunity horizons compared to an aeroplane.
I sometimes tried to follow a plane with my Dobsonian mounted (alt/az-fork) telescope and I only managed to get very brief glimpse at it (mostly not in the right focus).
I think for helicopters and planes you are far better of with a manual solution like a tripod, a DSLR and a telephoto lens.

conandrum · #8 21-12-2010, 08:23 PM

Hi Max,

I am slightly more positive than you!

Please look at a thread I started over at ufonv.com
http://www.ufonv.com/viewtopic.php?f=19&t=916

Also have a look at onkeltobi28 channel on youtube manually tracking planes (wow!):
http://www.youtube.com/watch?v=wAWY_RWELsM

Furthermore these are some of the answers to my questions from the OpticTracker team:
Q: Celestron website states:' satellites move so rapidly that a dynamic approach is needed so the scope can actually catch up and lock onto them.' Does this mean that OpticTracker makes the mount move faster than usual?

A: It depends what you mean by usual. OpticTracker cannot make telescope mounts move faster than it's designed maximum slew rate.
What OpticTracker does is it adjusts the slew speed tens of times per second to keep the target in the center of your field of view.

Q: Objects will most probably be flying at varying altitudes around the earth's atmosphere.
At max. magnification (as in this [link2]video,http://www.youtube.com/watch?v=wAWY_RWELsM[/link2]), will your software/mount be able to keep up with fast moving objects?

A: Yes, that's what it is designed to do. However, getting a lock on the target while using high magnification optical systems may post some challenges. To acquire a visual lock you need to keep the target in the field of view for about a second. It doesn't sound challenging but at high magnification the field of view is extremely small. Even with the Nexstar 4 inch telescope, without using reducer lens, the fields of view is about the same apparent size of the red dot in the view finder. So I would recommend setting up a digital finder scope with at least a couple of degrees of field of view. OpticTracker can acquire target with the finder scope and guide it into the main field of view

Q: Is the Meade LX200 series faster than the Celestron SE?
What are the maximum speeds that your software can attain on each product line (what are the limitations)?

A: The maximum slew speed on the Celestron SE is 4 degrees/second, and on the LX200 the limit is 8 degrees/second. These are the hardware limitations. That said, you don't need to slew too fast. The targets you can effectively film with a telescope is most likely going to be miles if not tens of miles away. 1 degree/second slew rate will track a target traveling at at lease 200 miles/hour 10 mile away. 4 degrees/second is enough to track a supersonic jet at that distance. In reality, the planes are most likely to be much slower and much further away.

Q: You mention ' OpticTracker can record up to 3 video streams '?
Also ' Dual Cam Tracking in Pro version'.
How many cameras can be mounted on the Celestron SE?

A: OpticTracker takes in 2 video streams and outputs 3 video streams. The stream from the main camera is digitally stabilized and zoomed on the fly to form the 3rd video stream.

Q: I do not think I will benefit from dual tracking will I? I do not know. Please comment.
A: The dual tracking is useful in acquiring the target, especially when the field of view on your primary camera is small.

Have a look at OT channel on youtube for some subpar examples of airplane tracking! I am sure these can be immensely improved upon:
http://www.youtube.com/watch?v=6v3J6MSkTgs
http://www.youtube.com/watch?v=d9oc0ytVmvQ
http://www.youtube.com/watch?v=KNY7Hbl9k78

With the right telescope & recording devices, I am 1000% sure the results will be nothing short of breathtaking. Hopefully you can now begin to see the huge potential that this method has.

Regards

Telis

Kal (Andrew) · #9 25-12-2010, 01:58 PM

This is not the easiest field to get consistant results with, and one I would strongly suggest to start off small and work your way up.

To me the starter setup would involve a short focal length scope, the shortest focal length of the nextstar series is the 5SE at 1.25 metres focal length. Even at 1.25 metres focal length I can tell you that it will be difficult to initially aquire your target. If you perfect your method then you could then step up to a longer focal length.