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Focus on curiosity's mastcam camera

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posted on Sep, 17 2014 @ 12:22 AM
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I could be barking up the wrong tree completely but.. I thought that these cameras on the rovers did not have an automatic focus and f-stop ability. I thought they were fixed infinity focus and everything over about 1m was in focus?

Please someone correct me if I am wrong. I am sure I read that somewhere.

Anyway, my thanks to wildespace for pointing out this picture in another thread, but it suddenly hit me.

Why is the background out of focus and the foreground in focus?




posted on Sep, 17 2014 @ 12:41 AM
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off-topic post removed to prevent thread-drift


 



posted on Sep, 17 2014 @ 03:52 AM
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I hardly know anything about camera technology, but it may have something to do with Aperture settings and the depth of field?

Or they're simply manipulated photos a long with the rest of NASA's back catalog of photo deceivement

edit on 31-07-2014 by skyblueworld because: (no reason given)



posted on Sep, 17 2014 @ 05:58 AM
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I look at these pics all the time and it`s frustrating that they are able to do these things only because of our taxes funding them but they lie to us and give us blurry, purposefully obscured pics and expect us to be happy. It`s insulting and it`s another example of how our govt. sees us, nothing more than their cash cow.When a group gets upset about something the govt has done,they just lie to us.
The pics from mars were supposed to be crystal clear but they`re not even close.At least not by the time they`re done screwing with them to hide the details from us.Here`s a pic,gigapan.com... there`s some interesting stuff on here, but zoom in and try to make the details out. THEY HAVE OBSCURED THE FINE DETAILS THROUGH PHOTO MANIPULATION! AARGH!!!
Hey NASA! We`re not children and i promise we can handle it! But you`re not concerned about us are you? Knowledge is power and this is all about being 1 up on the public.



posted on Sep, 17 2014 @ 06:11 AM
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originally posted by: qmantoo
I thought that these cameras on the rovers did not have an automatic focus and f-stop ability. I thought they were fixed infinity focus and everything over about 1m was in focus?

Please someone correct me if I am wrong.



One camera, referred to as the Mastcam-34 (M-34), has a ~34 mm focal length, f/8 lens that illuminates a 15° square field-of-view (FOV), 1200 × 1200 pixels on the 1600 × 1200 pixel detector. The other camera, the Mastcam-100 (M-100), has a ~100 mm focal length, f/10 lens that illuminates a 5.1° square, 1200 × 1200 pixel FOV. Both cameras can focus between 2.1 m (nearest view to the surface) and infinity.

msl-scicorner.jpl.nasa.gov...



Why is the background out of focus and the foreground in focus?


It is called "Depth of Field"

www.cambridgeincolour.com...
edit on 17-9-2014 by hellobruce because: (no reason given)



posted on Sep, 17 2014 @ 09:12 AM
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Double post...see post below.


edit on 9/17/2014 by Soylent Green Is People because: (no reason given)



posted on Sep, 17 2014 @ 09:12 AM
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originally posted by: fartsmeller46
...Here`s a pic,gigapan.com... there`s some interesting stuff on here, but zoom in and try to make the details out. THEY HAVE OBSCURED THE FINE DETAILS THROUGH PHOTO MANIPULATION! AARGH!!!
Hey NASA! We`re not children and i promise we can handle it! But you`re not concerned about us are you? Knowledge is power and this is all about being 1 up on the public.


Then don't use the Gigapans (the Gigapans aren't from NASA, anyway).

You should go directly to the raw image and look at that. In this case, the Raw image does not provide much more resolution, but I'm not sure how you know it is due to photo manipulation. It may be just due to the limitations of the camera's resolution.

Also, while the Gigapan image you posted is of a single raw image, very often the gigapan images are spliced together from dozens of raw images. You should use the each of actual images instead; each raw image will usually be a higher resolution than the Gigapan mosaics, and in most instances you should be able to see more when you zoom in.

Here is a link to the raw images. The image in your example was taken by the Mastcam:
Raw Images - Mars Science Laboratory

Those Gigapan mosaic images are good for getting context, but the raw images should be used for any type of research.

As I said, the Gigapan example you posted is of a single raw image, and the person who made the Gigapan which raw image was used, but when the Gigapan is a mosaic of many images, you would need to know which of the small raw images to look at, and most of the time they don't really tell us which image was used where...i.e., I may see an interesting rock in a Gigapan mosaic, but it could be difficult knowing which raw image to look at for further study of that rock.


edit on 9/17/2014 by Soylent Green Is People because: (no reason given)



posted on Sep, 17 2014 @ 08:09 PM
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Hellobruce - What you have told us is good information, BUT, it does not explain what I asked. A fixed f10 lens does not have an aperture so the depth of field does not vary. As you quoted the focus is set from 2m to infinity which is what I suggested in the OP.

I suspect we dont have any learned folks coming forth to give us explanations is because there is no explanation, but I will ask again...

Why is the background out of focus in this image taken by the mastcam?



posted on Sep, 17 2014 @ 08:37 PM
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originally posted by: qmantoo
A fixed f10 lens does not have an aperture so the depth of field does not vary.


Yes it does, and the depth of field varies with the distance it is focused on.


As you quoted the focus is set from 2m to infinity


Wrong, the focus is not set, it is adjustable - as I quoted "Both cameras can focus between 2.1 m (nearest view to the surface) and infinity."


I suspect we dont have any learned folks coming forth to give us explanations is because there is no explanation,


You have been given the explanation, but for some strange reason refuse to accept the facts!


Why is the background out of focus in this image taken by the mastcam?


Again, it is called "Depth of Field"! Why do you refuse to accept that fact?
edit on 17-9-2014 by hellobruce because: (no reason given)



posted on Sep, 17 2014 @ 08:46 PM
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I have been into serious photography with DSLR's for about 12 years, and that image posted shouldn't have the background out of focus like that. It has been purposely blurred by someone. How can I say this? NONE OF THE OTHER IMAGES HAVE THIS PROBLEM, NOT EVER, Even when you can see mountains in the very, very far background.

If someone, (even the usual trolls) disagree with me, then SHOW ME other images that match this one with blurred backgrounds. This one is the first one I have ever seen in thousands of rover images.

Even if there are, It just doesn't matter any more, as it has been proven to my satisfaction that NASA hides and edits anything they don't want the public to see.
Even a big oil exec took a copy of George Leonard's book and threatened to make thousands of copies (since it was out of print and rarely found), and give them to people for free, so then NASA execs gave him access to thousands of images they do not let the public see.

I don't need any other proof than that.
edit on 17-9-2014 by NoCorruptionAllowed because: (no reason given)



posted on Sep, 18 2014 @ 12:05 PM
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I swear I saw Mastcam image or two with depth of field lke that before.

Anyhoo, I asked about this at the UMSF forum, let's see what they say.

As somewhat familiar with photography myself, I can confirm that focusing at different distances at a given aperture produces different depth of field.



posted on Sep, 18 2014 @ 12:54 PM
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Some of the new features that the Mastcam system will bring to Mars are: Active focus capability: A lens group is mechanically actuated for focus between 2 m and infinity.

From:
www.infernolab.com...

So yes, focused up close, the background will be blurred.

However, I do agree with those who believe the space agencies do not provide a lot of the data that the public has paid for. Trying to find spectral maps of planetary surfaces is difficult, and I think that is because in the future that info will be very valuable for commercial reasons. SOFIA is the other instrument that suppies very few images, and the primary contractor is under no obligation to release those images, ever. So it doesn't seem right when it is the tax payers dime that they are using to collect that data.
edit on 18-9-2014 by GaryN because: gr.



posted on Sep, 18 2014 @ 02:00 PM
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a reply to: NoCorruptionAllowed

Here you go (just a couple I was able to find quickly):





And this is exactly what you'd expect. The 100mm f/10 lens would have a depth of field ranging from about 9.5 feet to 10.5 feet when focused on an object 10 feet away. When focused on an object 25 feet away, the depth of field ranges from about 22 to 28 feet.

Feel free to plug the numbers into any depth of field calculator. The 100mm f/10 MastCam has a circle of confusion of 0.0139mm.



posted on Sep, 18 2014 @ 02:14 PM
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Yep, now I am seeing them everywhere..

Like when you buy a VW bug and start seeing them all over the place suddenly.



posted on Sep, 19 2014 @ 09:11 AM
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The article about the mastcams referred to above only says that the camera described will be replaced if the replacement is ready in time. It does not say whether it was replaced or not when the time for launch came around.

I realise the way focus depth of field etc works, but I would like to ask how the rover 'knows' to focus at a particular point, how it 'knows' what is going to be important in a particular shot.

I cannot believe that scientists would leave it up to artificial intelligence built into the rover to determine what they would be interested in. For that reason, I do not believe that the rover focuses on a point and takes the image That article said that it is ABLE to focus from 2m - infinity. My disposable camera with fixed focal length lens can do that too)

Nasa have a way of making statements (about the wind etc) which can be interpreted in various ways depending on the circumstances and for a bunch of scientists that is surprising, but for a bunch of PR and marketing men it is not at all surprising.

Bearing in mind



posted on Sep, 19 2014 @ 10:42 AM
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I would have never guessed that a camera's auto-focusing (or manual-focusing, if they use it) ability could stir so much distrust.

I'd say it's simple auto-focus, as most of the image is ocuppied by a close-by terrain, while the distant out-of-focus terrain is only in the top part of the image.
edit on 19-9-2014 by wildespace because: (no reason given)



posted on Sep, 19 2014 @ 11:53 AM
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originally posted by: qmantoo
...Nasa have a way of making statements (about the wind etc) which can be interpreted in various ways depending on the circumstances and for a bunch of scientists that is surprising, but for a bunch of PR and marketing men it is not at all surprising.


That's because most press releases/publications are written for the masses and are not written by scientists.

If we look at more technical papers (written by NASA scientists/NASA-related scientists, and not by NASA public relations writers), we can find more technical information.

The MastCAMS do have an active focus, not a fixed-focus. The camera has an autofocus feature, and this link below makes mention of the speed of that autofocus:

Mast Camera (Mastcam); PI: Michael C. Malin, Malin Space Science Systems


The full range of focus requires between 45 and 60 seconds, but autofocus around a predicted focus point can be accomplished much faster.

The cameras include auto- and commanded-focus capability and auto- and commanded-exposure control. Radiometric accuracy is < 10-15%, and precision 5-8%. Exposure times are expected to vary from a few tens of msec to a couple of hundred msec, depending on the band-pass filter and the desired signal-to-noise ratio.



Digging a little deeper (and more technical), I found an paper about the zoom feature that was originally proposed for the MastCAMs, but a feature that was ultimately abandoned as a cost-saving measure. Even though this paper is about the zoom feature, it makes mention of the active focus (along with a mention of the abandoned zoom feature):

A Zoom Lens for the MSL Mast Cameras: Mechanical Design and Development


Some of the new features that the Mastcam system will bring to,Mars are:

- Active focus capability: A lens group is mechanically actuated for focus between 2 m and infinity...

...Variable focal length, though originally planned, will not be part of Mastcam's capabilities.


Page 7 of that paper goes into more detail about the motor drive for the autofocus mechanism:

Focus Drive System
The focus mechanism, shown in Figure 9, moves the focus lens group with the following drive system:

1) the stepper motor rotates a pinion gear through the Oldham coupler; 2) the pinion gear drives a smaller 8 spur gear, increasing speed to meet focus speed requirements, supported by a duplex pair of angular contact ball bearings; 3) the spur gear rotates a 2-start lead screw through a custom 2-start helical flexible coupling; and 4 )the lead screw drives the focus group axially along a linear bearing via a lead screw nut captured within the focus lens cell subassembly. The lead screw is made from stainless steel; the lead screw nut is brass, which prevents lead screw wear. Wear debris from the brass nut, potentially detrimental to optical performance, was shown in tests to be adequately contained within the lubricant grease mixture. The focus group motion is limited by hardstops that contact the linear bearing slide at both ends of the travel range.

A snubber restraint pin limits launch and rover driving loads on the single linear bearing that supports the focus group. The pin, located on the focus lens cell opposite from the linear bearing, travels along an axial slot in the lens structure. The pin makes contact with the slot during high lateral loads, limiting the strain in the linear bearing. The helical coupler is protected from overstraining by stops that limit the axial displacement of the lead screw which would otherwise tend to over-extend or over-compress the coupler.


Here is an article about the delivery of the MastCams to NASA from the manufacturer of the cameras -- Malin Space Science Systems. In this article, mention is made about the motors for the active autofocus (as well as NASA's decision to eliminate the zoom feature from the mission-ready cameras):

MSSS delivers Mast Cameras for MSL, restarts work on zoom version of Mastcams

The Mastcam focus and filter wheels are driven by precision mechanisms developed by Alliance Spacesystems (www.alliancespacesystems.com). The focus mechanism uses a stepper motor to position an internal focus group by means of a cam. The filter wheel mechanisms use stepper motors to drive 8-filter wheels to position the desired color filters in front of each camera's CCD detector.



Here is a PDF detailing he engineering cameras (the Hazcams and the Navcams). The Engineering cameras have only a fixed focus, and not an active focus/autofocus:

The Mars Science Laboratory Engineering Cameras


edit on 9/19/2014 by Soylent Green Is People because: (no reason given)



posted on Sep, 19 2014 @ 11:55 AM
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Everything you probably want to know about the MastCams lens' mechanical design: A Zoom Lens for the MSL Mast Cameras: Mechanical Design and Development

It includes information on the focus mechanism:

The focus mechanism actuates the Focus Group axially over a ~9 mm range of travel to provide focus at distances from 2 meters to infinity.



posted on Sep, 19 2014 @ 12:02 PM
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The autofocus in the MastCam are similar to the MAHLI autofocus. You can read about that here: Curiosi ty's Mars Hand Lens Imager (MAHLI) Investigation


Autofocus is anticipated to be the primary method by which MAHLI is focused on Mars.
The autofocus command instructs the camera to move to a specified starting motor count
position and collect an image, move a specified number of steps and collect another image,
and keep doing so until reaching a commanded total number of images, each separated
by a specified motor count increment. Each of these images is JPEG compressed (Joint
Photographic Experts Group; see CCITT (1993)) with the same compression quality factor
applied. The file size of each compressed image is a measure of scene detail, which is in turn
a function of focus (an in-focus image shows more detail than a blurry, out of focus view of
the same scene). As illustrated in Fig. 23, the camera determines the relationship between
JPEG file size and motor count and fits a parabola to the three neighboring maximum file
sizes. The vertex of the parabola provides an estimate of the best focus motor count position.
Having made this determination, MAHLI moves the lens focus group to the best motor
position and acquires an image; this image is stored, the earlier images used to determine
the autofocus position are not saved.

Autofocus can be performed over the entire MAHLI field of view, or it can be performed
on a sub-frame that corresponds to the portion of the scene that includes the object(s) to be
studied. Depending on the nature of the subject and knowledge of the uncertainties in robotic
arm positioning of MAHLI, users might elect to acquire a centered autofocus sub-frame or
they might select an off-center autofocus sub-frame if positioning knowledge is sufficient to
determine where the sub-frame should be located. Use of sub-frames to perform autofocus
is highly recommended because this usually results in the subject being in better focus than
is the case when autofocus is applied to the full CCD; further, the resulting motor count
position from autofocus using a sub-frame usually results in a more accurate determination
of working distance from pixel scale.



posted on Sep, 19 2014 @ 07:15 PM
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Ok, thanks all for the detailed responses. I accept that the mastcam has an autofocus feature and mechanism.

This leaves me with a couple of questions some of which I posed previously.

1) why would scientists want the AI to decide what is the item of interest in a scene?

I can understand why a camera used for close-up work needs to have such an arrangement because they make 3D anagraphs(?) of the pictures and this gives depth and scale. There is a pair of mastcams which can achieve the same thing allowing the same depth and scale to be brought out in those images.

2) What does point focus and depth of field bring to the table of scientific investigation? Why is it necessary?

To me, having one part of your image in focus and another part out of focus is an aesthetic thing and we use it to make the picture look better or more dramatic. If you can have all (or mostly all) of the image in focus at the same time, this MUST surely be better for scientific study of the picture? Hence question number 2 above.

Apart from the above, there is the cost aspect of a photo taken on Mars. Each image must cost at least hundreds of dollars and so each must be used for the maximum cost benefit. You do not throw away half of your product (because it is out of focus) which is costing you (or the taxpayer) a lot of money per item. I just do not understand it so maybe someone else has some insights into the NASA mindset?
edit on 19 Sep 2014 by qmantoo because: cost aspect



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