**How is FOV calculated in astrophotography?** **FOV = ((57.3 / 1040) * 22.3)**

The long side of the frame has a field of view of 1.23 degrees.

**How is FOV telescope calculated?**

**Determine Your True Field of View**

- Divide the focal length of the scope, 1,200mm, by the focal length of the eyepiece, 25mm, to determine that that combination provides 48X magnification.
- Divide the AFoV, 50°, by the magnification, 48X, to yield a TFoV of 50/48, or about 1.0417°.

**How is field of view calculated in CCD?** Take the two and use this formula: **(135.3x D) / L**. This will give you the field of view (in arcminutes) for your telescope and imaging device.

**How is apparent field of view calculated?** With the conventional method used previously, the apparent field of view was calculated by **multiplying the real field of view by the binocular magnification**. (With this formula, apparent field of view wider than 65˚ is called wide field of view.)

## How is FOV calculated in astrophotography? – Additional Questions

### What is a good field of view for a telescope eyepiece?

The apparent FOV for each eyepiece ranges from **45o to 68o** and is a result of how the eyepiece is designed. When used in this example with an 8-inch telescope with a focal length of 2032 millimeters, the magnifications range from 41x to 75x.

### What is field of view example?

It’s **the distance from the lens to the sensor**. So if you’re shooting with an 8 mm lens, that means your sensor is 8 mm away from your lens. A short focal length like this, means a wider field of view.

### How do you calculate the area of the field of view?

If the angle of the field of view is a degrees than you can see a/360 of the circle so the area of the sector you can view is **(a/360) × (π r**^{2}) square units.

### How do you calculate the field diameter of a microscope?

To calculate field of view, you need to know the magnification and field number of the microscope’s lens currently in use. **Divide the field number by the magnification number** to determine the diameter of your microscope’s field of view.

### How do you calculate exit pupil?

To calculate the exit pupil of a binocular, **divide the objective size by the magnification**. For example, a 7X50 binocular delivers an exit pupil of 50/7=7.1mm, while a 10X50 binocular delivers an exit pupil of 50/10=5mm.

### What is a good exit pupil?

The ancient dogma on this topic, printed in countless books, says “The human pupil dilates to a maximum diameter of 7 millimeters.” Therefore **7 mm** is supposed to be the ideal maximum size for the exit pupil of binoculars or a telescope. This is the reasoning behind the popular 7×50 “night glass” binocular.

### What exit pupil is too small?

The 25x/inch (1mm exit pupil) and **50x/inch (0.5mm exit pupil)** “limits” are attempts to provide guidelines on just how close you have to be before you can resolve the Airy disk and thus reach the limiting resolution of the telescope.

### How important is exit pupil?

Why is the Exit Pupil Important? It is important because **the only light rays which pass through this virtual aperture can exit the system and enter your eyes**. Therefore with all else being equal, the larger the exit pupil diameter, the more amount of light will be delivered to your eye.

### Is exit pupil the same as eye relief?

**Eye relief is the distance from the outer surface of the eyepiece lens to the position where the exit pupil is formed** (eyepoint). Looking through binoculars from the eyepoint, you can obtain the whole field of view without vignetting.

### How can I measure my pupil at home?

MEASURING YOUR OWN PD

**With your face straight, hold the ruler against your brow.** Close your right eye and align the ruler’s zero to the center of your left pupil. While looking straight, close your left eye and open your right eye. Read the mm line that lines up with the center of your right pupil.

### Does Barlow affect exit pupil?

**The diverging rays leaving the Barlow result in moving the exit pupil further out**, thereby extending the eye relief. In short to medium focal length eyepieces the change is not noticeable. However, in the case of long focal length eyepieces, the increase can be significant and not without performance consequences.

### Does a Barlow increase back focus?

**A side effect of Barlow lenses is the increase in back focus** (the distance between the telescope to the end of the optical setup). Due to their design, some telescopes like Newtonians/reflectors, have very little back focus. Barlow lenses can help you increase it.

### What is the difference between a Powermate and a Barlow?

In a Powermate the light rays have the same angle coming out as they did going in, so it’s just pure magnification with no external knock-on effects. A Barlow will increase the eye relief, which can be either good or bad depending on the original eye relief of the eyepiece and your personal preference.

### Does a Barlow lens decrease quality?

Actually, it doesn’t depend much on the Barlow. **All Barlows dim the image in line with the increase in magnification**. Back in the 70s and 80s Televue produced a 1.8x Barlow that did dim the image compared to the same magnification produced without the Barlow.

### Is a 3x Barlow better than 2x?

All other things equal, **there is no deficit or degradation with a 3X Barlow as compared to a 2X Barlow**. In fact, the TeleVue 3X Barlow is one of the very best Barlows available.

### Should you use a Barlow lens for astrophotography?

For visual use, Barlow lenses from 1.5X to 3X are common. Generally, **Barlow lenses of greater than 3X are considered applicable to astrophotography** though there is nothing to prevent you from using one with your eyepiece.

### Can I use 2 Barlow lenses together?

Good news, **you can stack two 2x Barlow lenses and get the same 4x power**! Stacking Barlows doesn’t add the factors, it multiples them – thus stacking a 2x with a 3x gets you 6x.