So the alternative - just scrunching up as close as possible and seeing only the center of the field, missing the field stop edge, seems preferable! "Fool me once, shame on you" comes into play here; and I've had my share of "fixes" that failed utterly.

FOV to focal length calculator

I then turned to Jupiter. The detail was very well contrasted in the equatorial belts with excellent visual acuity. I occasionally witnessed some small amount of chromatic aberration around the planetary limb but it wasn’t particularly bad. I could sometimes detect an amount of scatter near the field stop and even some sporadic ghosting, although again, it wasn’t really a problem. Europa was right next to the limb and about to transit. I observed it once it was past the limb itself and could still see the moon above the surface of the gas giant for several minutes .

And one of the most popular among those solutions is e-CAM130A_CUXVR_3H02R1 180° FOV camera – a synchronized multi-camera solution that can be directly interfaced with the NVIDIA® Jetson AGX Xavier™ development kit. This camera solution comprises of three 13 MP camera modules that are based on the 1/3.2″ AR1335 CMOS image sensor from onsemi®. These 4K camera modules are positioned inwards to create a 180° FOV as shown in the image below:

I very much like orthos but at present only have two: Baader 6 and 10.  I am of an age where the Ploessl was considered "very wide field" and the Erfle "so wide you fall into the eyepiece, not a pleasant experience." The ortho was 'standard' and everybody had aspirations to step UP to them from their Ramsdens...

You also have an option to capture the same field of view with sensors of different size. This can be done using a lens with the appropriate focal length. As a result, the same FOV can be achieved using a small sensor with a short focal length lens and a large sensor with a long focal length lens.

FOV is one of the most critical parameters considered while integrating a camera into an embedded vision system. Whether it’s an intelligent transportation system, autonomous mobile robot, remote patient monitoring system, or automated sports broadcasting device, FOV plays a major role in ensuring the necessary details of the scene are captured. The FOV of the lens can be set as wide or narrow based on the end application requirements.

The build quality seems perfectly adequate even though it’s obviously a relatively inexpensive Abbe eyepiece. Especially compared to Takahashi and Ohi built orthoscopics which can cost up to three times as much as the forty quid (£39.60) I paid for this particular eyepiece. The AFOV is a claimed 48° which is a good 6° wider than most Abbe orthoscopics and I suspect the extra field is created by the deployment of a larger field stop than usual for its focal length. As it is purportedly a true Abbe the extra field is probably to aid target acquisition and would be expected to exhibit an amount of lateral edge astigmatism. There is a claimed eye relief of 4.2mm which is 0.15mm longer than a 5mm Ohi Abbe orthoscopic.

The eyepiece has no dust caps but it is supplied in its own plastic bolt case. The housing is almost exactly 50mm tall and appears to include the tapered barrel as an integral part of its aluminium housing. The barrel itself has a 28.5mm filter thread and is competently baffled. I discovered that my Baader, GSO and Lumicon filters all threaded fairly smoothly into the barrel. However, Meade and Barsta 2x Barlow elements were not easily threaded in all of the way. A GSO 2x short Barlow element threaded perfectly. The eyepiece features a flip-up rubber eye guard which is a rarity on most orthoscopics. I couldn’t separate the barrel by unthreading it and I assume it is essentially a monocoque design, which is also unusual in my experience. The housing is very light as a whole and feels a fair bit lighter in the hand when compared to both a 5mm Kokusai Kohki orthoscopic and a 6mm Vixen NPL Plossl.

Let’s look at Autonomous Mobile Robots (AMR) as a reference. These autonomous systems perform obstacle detection and obstacle avoidance (ODOA) to seamlessly navigate their environment. Many of them require FOVs in excess of 180 degrees. This ultra-wide FOV is achieved by using multi-camera systems.

fov和焦距的关系

"Snap - ZING" went something; and he discovered that the shaft going into the knob had a mysterious inner shaft that seemed as though it had been spring-loaded.

Ergo, when - last year - I accidentally started loosening the wrong peripheral screw around the back of my C-11, to add a small bracket, and realized almost immediately that it was one of those that had a lockwasher and nut rather than being fitted into a threaded hole, I instantly STOPPED.  The other side of the bolt was totally invisible behind the primary but it was obvious by the "feel" that it was one I should not have touched (Celestron is completely at fault here, for they have NEVER, to my knowledge, documented WHICH screws are captive, and which are intended for accessories; and all of them have the identical bolt-head.  I have actually complained to them, and got no meaningful response.)

FOV to focal length

Prabu is the Chief Technology Officer and Head of Camera Products at e-con Systems, and comes with a rich experience of more than 15 years in the embedded vision space. He brings to the table a deep knowledge in USB cameras, embedded vision cameras, vision algorithms and FPGAs. He has built 50+ camera solutions spanning various domains such as medical, industrial, agriculture, retail, biometrics, and more. He also comes with expertise in device driver development and BSP development. Currently, Prabu’s focus is to build smart camera solutions that power new age AI based applications.

Most embedded camera applications require the FOV to be wider enough to cover a large viewing area. For instance, a fish-eye lens is characterized by a wider FOV and larger depth of field (DOF) and is hence suitable for surveillance applications. On the other hand, for a zoom/telescopic application, you might require a normal/narrow FOV.

Many modern-day embedded vision systems utilize multiple types of lenses and sensors with different feature sets and varying costs. The design of the camera systems integrated with these components plays a huge role in achieving the required image quality.

Again: discretion is called for and now I AM PARANOID about this stuff; and unlike you, I do not particularly like to dismantle things and poke around to figure out the mysteries inside them!

Focal length is the defining property of a lens. Simply put, it is the distance between the lens and the plane of the sensor, and is determined when the lens focuses the object at infinity. It is represented in mm. Focal length depends on the curvature of the lens and its material. The shorter the focal length, the wider the AFOV and vice versa. Please have a look at the below image to understand this better:

Industrial automation systems for functions like quality inspection rely on cameras with accurate FOV settings to scrutinize products on assembly lines. They capture imaging data required for thorough product inspection by detecting defects instantly. Moreover, manufacturers can optimize their inspection processes, reduce errors, and maintain consistent product standards.

I once wrote to Mike Swanson, the creator of the infinitely useful site "NexStarSite.com" and asked if he might put in a page about the removable, versus non-removal, 'accessory' screws on the backs of SCTs and Maks.  He did not feel it was necessary because he felt the info WAS available from Celestron; suggested I go to their help pages online and type in simply the word "screws".  I did so--and at the time (maybe it's changed by now) got an article that warned about undoing the wrong ones and merely said "peer into the scope from the front and see which ones are held by nuts".

fov是什么

I got first light with the 4.8mm using my 72ED DS Pro. The seeing was a good Antoniadi II~I but the transparency was distinctly below average. The orthoscopic gave a convincing sharp and well contrasted view of Saturn at 87.5x. Saturn was fast approaching transit and I could see a fair bit of detail on the planetary surface and the rings, including the Cassini Division. In fact, I thought the contrast was better than the 6mm Vixen NPL that I directly compared with the 4.8mm ortho’.

Similarly, for the calculation of VFOV and DFOV, instead of width (or horizontal F0V), corresponding height and diagonal dimensions of the object are substituted in the above formula respectively.

Most of the embedded camera applications require the FOV to be wider enough to cover a large viewing area. For instance, a fish-eye lens is characterized by wider FOV and larger depth of field (DOF) and hence is suitable for surveillance applications. On the other hand, for a zoom/telescopic application, you might require a normal/narrow FOV.

Automated sports broadcasting systems use cameras with a wide FOV to cover entire fields or courts. Hence, all the movements within the sporting area are captured, which means viewers can experience the game in an immersive way. A wide FOV is also important for capturing aspects such as player movements and strategic plays, which enhances the overall broadcasting quality. Furthermore, wider FOV cameras streamline production by potentially replacing multiple conventional cameras, reducing setup complexity and personnel needs.

He told me this in deepest despair but I never heard about his eventual efforts to try to resurrect the thing from the dead; we never mentioned this again, and finally lost track of each other.  I do not know if he tried to have a factory repair or just gave up.  (This was some years before the inner workings of the C8 focuser assembly were documented on the web with x-ray drawings, so who knew?)

Smart traffic systems utilize cameras with a wide FOV to seamlessly monitor and manage road traffic. Such cameras capture comprehensive views of large areas for performing real-time traffic flow analysis and incident detection. Covering wide road sections also means they can promptly identify traffic violations, accidents, and congestion. Additionally, the broader view empowers advanced features like vehicle counting, object classification and lane discipline monitoring. This provides crucial real-time data that helps optimize traffic flow and improve overall safety.

Viewangle

field ofview中文

To open the C-11 OTA and tighten it again, requiring removal of the corrector plate and then replacement of the tiny wood shims and re-alignment, would cause possibly as much as two days of adjustments, based on previous experience.  I shall wait until one fine day, long into the future, when the corrector plate NEEDS cleaning on the interior side, and not take further chances.  Then, I shall re-tighten this screw, the further collimation chores being a given and necessity anyway.

Remote patient monitoring systems rely on cameras with an optimal FOV to provide accurate and complete observations of patients. These cameras ensure that all relevant movements and conditions are captured so that healthcare providers can monitor the health of patients. It leads to timely medical interventions and improved remote patient safety.

Field of view

I have one of these.  It came with a used telescope that I purchased.  I know absolutely nothing about it until I googled it and found your post.  Thanks for sharing.

This unusual ‘alleged’ Abbe fully multi-coated orthoscopic has a focal length of 4.8mm. I say ‘alleged’ as I don’t actually know if this is indeed a genuine Abbe design. From what I can gather it has two lens groups consisting of a triplet and a single lens. So, the odds are it is an Abbe eyepiece and very probably manufactured in China. Mine has no brand name but these eyepieces have also been sold as Kson, Ascension, Apogee and University Optics orthoscopics.

For example, imagine that the camera and the object are fixed at a working distance of 30cm. In this case, the HFOV and VFOV are measured manually using a scale (in mm) as shown below:

Your review piqued my curiosity.  For some years I used a 5 mm Ramsden even in my C-11 - pause now for gagging and retching - for ONE purpose: it had SUCH a bright view that I used it when looking for incredibly faint photographic 16th mag PGC's or 1 arcsecond diameter planetaries.  It blew away the comfortable 5 mm Hyperion...but was absolutely *painful* to employ.  Later, after my fill of this masochism, I came to my senses and obtained a TMB in that focal length (but that Ramsden was NOT thrown away!)

Broad perspectives generally equip Autonomous Mobile Robots to navigate complex environments and avoid obstacles. A wide FOV also ensures that robots can detect and analyze their surroundings in real time, boosting their ability to move safely and operate in dynamic environments, such as warehouses, manufacturing floors, and public spaces. A large vertical FOV ensures that obstacles at any height are detected, allowing robots to navigate under hanging obstacles such as shelves or overhead conveyor. For warehouse AMRs, two cameras placed on opposing corners, each providing a 270° FOV, can offer complete situational awareness. This setup enables the AMR to navigate freely in all directions—left, right, forward, and backward—while also turning efficiently without worrying about blind spots or objects coming from behind.

What helps e-con stand out when it comes to this solution is our proprietary 180-degree stitching algorithm that can process images from multiple cameras to create a 180 degree image. To learn more about this solution, please visit the product page.

Generally for a sensor, FOV refers to the diagonal measurement – which is called DFOV or Diagonal FOV. Horizontal FOV (HFOV) and Vertical FOV (VFOV) will vary based on the aspect ratio of the image sensor used.

Each embedded vision application has different sensor size requirements to get the best output. A small sensor will have a narrow field of view while a large sensor can provide a wide field of view.

At least this one does NOT have that kind of top; but it still looks difficult for somebody like me to use.  I observe small exit pupils with no spectacles, at least; but the idea of trying to spend a lot of time enjoying, say, Saturn or Jupiter with an eyepiece like this is no longer viable.  However, *maybe* it's the sort of gadget that might assist, if one has a motorized tracking scope; has the object already nicely centered; and then wishes to amp-up the view for a couple of minutes, perhaps to verify a faint phenomenon not clear in a lower power, "comfortable", ocular.

However, selecting and evaluating sensors and lenses can be challenging. The right combination can help build a highly optimized embedded vision system that meets all your standards. Of course, when selecting a lens for an embedded camera, numerous factors, such as Field Of View (FOV), must be considered.

e-con Systems has 20+ years of experience designing, developing, and manufacturing OEM cameras. That’s why we understand the nuances involved in selecting lenses with the right FOV for your application. We can expertly guide you through the entire process of selecting the lens rather than merely acting as a camera supplier.

Apparently orthroscopic eyepieces are expensive because it is costly to properly and accurately cement the triplet part of the element. The use of an inexpensive housing may be a way to keep the overall unit cost down.

Field of view (FOV) is the maximum area of a scene that a camera can focus on/capture. It is represented in degrees. There are three ways to measure the field of view of a camera – horizontally, vertically, or diagonally as shown below.

Now, the C8 would NO LONGER FOCUS, as the complicated assembly was totally wrecked.  HE SOLVED THE PROBLEM: no more focusing shakes! (Also, no focusing...at all.)

I do have a huge 2 HP cutoff saw (below) which I use for grinding or cutting heavy metal pieces, which would make very quick work of the raised ring about the top periphery.  But it is anything but *delicate* in its operation and would likely make a huge mess with a resulting rough and uneven surface: for to do it RIGHT, the object to be cut has to be held very solidly by clamping; and to hold this small cylindrical eyepiece with required force would then also mess it up beyond repair.  The end result of an ATTEMPT to fix this design error would be a completely ruined eyepiece: no doubt metallic particles would get all over everything and if there was any oily substance around the edge of the eye lens, would become attached.  Cleaning with solvents would possibly result in a seepage, with tiny metal flecks all over one or two lenses, perhaps even between elements.  I can predict a cascade of issues that will result in ONE EYEPIECE BEING THROWN IN THE GARBAGE, not being usable at all.

Please write to us at camerasolutions@e-consystems.com if you need expert help integrating cameras with different FOVs into your applications.

Now let us discuss FOV calculation. In many applications, the required distance from an object and the desired field of view (which determine the size of the object seen in the frame) are known quantities. This information can be used to directly determine the required angular field of view (AFOV) as shown below.

Meanwhile the already poor transparency was getting worse. I decided to split some doubles while I could still locate any before the steadily encroaching cloud enshrouded them. The extra 6° of field helped me find Iota Cassiopeiae more easily, but it took a 2x Barlow to properly reveal all three stars of the system at 175x. The stars were all well defined and their individual colours were easily perceived. The expected lateral astigmatism was basically undetectable when using the Barlow. But even without the Barlow it didn’t seem particularly problematic and was far closer to the field stop than I expected. I split a few more doubles at 87.5x including the Double Double, Struve 2470/74, Albireo and Almach. I could also quite distinctly see the Ring Nebula, albeit often using averted vision. Eventually I turned back towards Jupiter and could make out the GRS pretty easily at 87.5x.

Conversely, if you know the FOV and the working distance, then you can calculate the dimension of the object using the below formula.

Meanwhile, you could check out the article What are the crucial factors to consider while integrating multi-camera solutions? if you are interested in learning more about multi-camera integration.

This same friend, BTW, had a Synta-made Orion-US 127 mm Mak.  It came with a tripod foot that he wanted to remove; he assumed that its bolts were into threaded holes and so simply unscrewed them -- and "BING, tinkle" -- the washers and nuts were now rolling around inside the OTA.  (They were absolutely invisible to him when he peered through the corrector from the outside before trying this.) Again--NO info about this in the PDF manual or any printed sheet with the scope.

Having 2 or more cameras enables a higher resolution, prevents lens distortion, and offers a wider FOV. To achieve high imaging quality in multi-camera systems, a lens having an FOV of around 60-70 degrees is usually chosen. But it is important to note that this is determined by a multitude of factors. There is no ‘one-size fits all’ approach to this. It is recommended to take the help from an imaging expert like e-con Systems as you go about picking the right field of view and lens for your application. Please feel free to write to us at camerasolutions@e-consystems.com if you need a helping hand.

Well, I did not go further.  Bolt would not tighten down again; and continuing to unscrew would send a lockwasher and nut into the interior; who knows WHAT damage this might do?

Having two or more cameras enables a higher resolution, prevents lens distortion, and offers a wider FOV. To achieve high imaging quality in multi-camera systems, a lens having an FOV of around 60-70 degrees is usually chosen.

From the previous section, we understood the definition of FOV and its relation with several other lens parameters. Let us now discuss how to choose the right FOV for an embedded vision application.

e-con Systems has led from the front when it comes to innovation in embedded vision. And one of our key strengths is the platform side expertise especially on the NVIDIA Jetson series. Leveraging this, e-con has designed many multi-camera solutions that offer an FOV of up to 360 degrees.

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Problem is: in a number of scopes I have had, usually these things are NOT directly visible from peering into the corrector from the outside, even using a VERY powerful illuminating torch.  I of course did this on the C-11 in the incident above: NONE of the screws on the back (or, rather the nuts mating them) were visible.

But it shook a bit on the original tripod mount and wedge which were frankly under-designed.  The common suggestion was an electric focuser; so he ordered one.  When it came, it was immediately obvious that this new c.1990 gadget was not intended for the OLD, original C8 focuser knob.  Said knob had at least one grub screw; when that was removed it still would not come off the shaft.  My friend had a "bright idea"! He clamped the knob right at the gray metal surface of the back of the OTA and rigged up something to hold the tube, and the clamp, perfectly steady; got out a hacksaw, and started chomping away.

In this article, let’s explore the importance of FOV in embedded vision, the factors that determine FOV, as well as which applications rely on this the most.

fov参数

Bolt was still obviously attached to the lockwasher/nut, so I merely wrapped a small length of wire around the exposed threads it to stabilize it.

These devices are in effect FRAUGHT WITH PERIL.  Do-it-yourselfers are often let down, because they actually would have designed them BETTER than the factory did, with more proper opportunity for modifications.  If the maker has put some removable screws (into threaded holes) on the back, for attaching finders, and there are ALSO two to four IDENTICAL looking screws (or rather, bolts) near them, WHO is to know which are attached with nuts, and which are removable--if the documentation does NOT mention it, and if the sales person and even phone customer support from the company has no idea how to give proper instructions.

I had purchased a Vixen 4 mm PL for highest power in one of my scopes...but discovered that there is a raised ring, part of the design of the molded top, that is nearly 2 mm in height, all around the top periphery of the unit.  I cannot get my eyeball close enough to see the *claimed* 50d AFOV.  Maybe 30d is visible at a glance straight-on.  One has to crane one's head and 'look at the edge' and move all around the circle to get a *glimpse* of the edge of field.  Ridiculous!  The alleged 'solution' as it were, is to use a grinder and remove the elevated ring!  (Then maybe one could see 40d of the actual 50d available.) I wish they had made it like the volcano-top Japanese orthos I used to have, oh sometime back in the 19th century as I dimly recall.

Also, let us consider a popular embedded vision application like autonomous mobile robots (AMR). These autonomous systems perform obstacle detection and obstacle avoidance (ODOA) to seamlessly navigate their environment. And many of these robots require FOVs in excess of 180 degrees. This ultra-wide FOV is achieved by using multi-camera systems.

However, it is extremely important to understand that many factors determine this. There is no ‘one-size fits all’ approach to this. It is recommended that you seek help from an imaging expert like e-con Systems as you pick the right field of view and lens for your application.

FOV also depends on the distance between the camera and the object. As discussed earlier, if the objects are closer to the camera, the FOV becomes wider. This is because shorter focal lengths require shorter working distances for proper focusing. Thus, the lens to sensor distance has to be designed based on the working distance.

I have one of these.  It came with a used telescope that I purchased.  I know absolutely nothing about it until I googled it and found your post.  Thanks for sharing.

The worst one was NOT committed by me personally.  A good friend owned a classic C8 that had, IMO, the BEST optics of any one of that venerable line of instruments I've ever peered into.  I saw Mars, at an opposition, at more than 400x: and it looked more detailed and fantastic than in ANY scope I've used in the past half-century.  It was truly a C8 in a million.

I'm lucky in the fact that my eyesight allows me to use very small EP's, although I usually use the shortest focal lengths for lunar/planetary observing. The simplicity and precision of the build and design can't really be beaten IMO. That being said, the TMB clones come very close, and the TV DeLites are even closer.