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Frenemy90210
Will a telescope work if its front lens (Objective lens) is replaced with a pinhole ? What if both lenses ( Objective and eyepiece) are replaced with pin holes ?
Frenemy90210 said:Will a telescope work if its front lens (Objective lens) is replaced with a pinhole ? What if both lenses ( Objective and eyepiece) are replaced with pin holes ?
I had tried it a few years ago without much success. Frankly nothing was visible. May be somebody else knows/experienced otherwise.davenn said:since you labelled you thread with an "I" tag, you should be used to doing research as a undergrad student
so what do you think?
how about trying it out and telling us what happens
Dave
Frenemy90210 said:I had tried it a few years ago without much success. Frankly nothing was visible. May be somebody else knows/experienced otherwise.
So, @Frenemy90210, can you tell us what is different between observing the sun and, say, a galaxy, that could make it work for one and not the other...?sophiecentaur said:A pinhole is good for looking at sun spots safely. (Projection method)
. . . . and why the best and most expensive camera lenses have so much glass on the front?russ_watters said:So, @Frenemy90210, can you tell us what is different between observing the sun and, say, a galaxy, that could make it work for one and not the other...?
I only want to mention that the emphasis here lies on projection. Just in case: Do not look directly into the sun, pinhole or not!sophiecentaur said:A pinhole is good for looking at sun spots safely. (Projection method)
I can see what you are getting at. Sun emits lot of light and in the other case its not. The reason I asked the question was to know if there is a workaround to that problem. I guess not.russ_watters said:So, @Frenemy90210, can you tell us what is different between observing the sun and, say, a galaxy, that could make it work for one and not the other...?
The workaround is to use many many pinholes over a large area and arrange the phase delay through each hole to be the same so that a coherent image is formed from all of the holes . That's what a lens achieves for you.Frenemy90210 said:know if there is a workaround to that problem.
And a pinhole is so small that diffraction will noticeably affect resolution.Khashishi said:The bigger the aperture and the wider the field of view, the more light you will collect. Typically, if you are measuring something dim like a galaxy you will be photon limited. A pinhole doesn't collect much light.
That still wouldn't take care of diffraction. Also the actual increase would involve extremely long exposure times (days) for any but the very brightest astronomical objects.Khashishi said:Another workaround is to use a very long exposure time, though you are going to run into issues with background noise and the rotation of the Earth.
sophiecentaur said:A pinhole is good for looking at sun spots safely. (Projection method)
I agree:Frenemy90210 said:I think it will be great if this statement is re-written/re worded completely from safety point of view. There might be children who are reading this page. Children might be stare at the sun directly through a pin-hole.
trainman2001 said:Therefore, going the other direction with a pinhole, while it does focus light rays, serves little or no purpose in astronomy simply because it can't capture enough light to make a useful image.
A telescope with a pinhole objective is a simple type of telescope that uses a pinhole to collect and focus light, instead of a traditional lens or mirror. The pinhole acts as the objective, creating an image by allowing light to pass through and converge onto a viewing screen or eyepiece.
The pinhole in the telescope's objective acts as a small aperture, allowing a limited amount of light to pass through. This light then travels through the telescope's eyepiece, where it is magnified and focused, creating a viewable image. The size and placement of the pinhole determines the telescope's magnifying power and image quality.
A pinhole objective is relatively simple and inexpensive to construct, making it an accessible option for amateur astronomers. It also has a large depth of field, meaning it can focus on objects at varying distances. Additionally, the lack of traditional lenses or mirrors can reduce chromatic aberration, resulting in clearer images.
One major limitation of a pinhole objective telescope is its limited light-gathering ability. The small size of the pinhole means that only a small amount of light is able to enter the telescope, resulting in dimmer images. Additionally, the size and placement of the pinhole can affect the quality of the image, and it may be difficult to achieve high magnifications.
While not as commonly used as traditional telescopes, a pinhole objective telescope has some practical applications. It is often used in camera obscuras, which are used for artistic and educational purposes. It can also be helpful in certain scientific experiments, such as studying the properties of light and optics.