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Integration on the Mallincam means exposure not stacking time. You also have to remember that while the Mallincam integrates for X seconds, it stores that image in a buffer and outputs it as a continuous NTSC (29.97 frame/sec) video signal and not as a one shot dump.

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I've never bought into the notion that a camera equates to some particular gain in aperture. For the single reason that performance depends on subject brightness.

Take the Moon. The camera cannot reveal more than I can see directly by eye. The same goes for the planets. (Note that we're neglecting in this discussion such 'tricks' as the stacking of multiple images and other processing.)

Now consider a moderately bright object such as M42, the brighter parts of which are about 14 mag/arcsec^2. If I set my camera to an exposure about equivalent to the 'intrgration time' of my eye, which if I'm charitable about it, I might define as 1/15 second, again, my eye reveals more nebulosity.

It's only when we get down into the surface brightness regime of dimmer than about 18 mag/arcsec^2 does the camera come into its own. For then the longer integration, in conjunction with the not insignificant contrast gain due to compression of dynamic range, reveals lower surface brightness than the eye can detect.

And this is the key. If the camera can record very low surface brightness, low contrast stuff beyond visual detection in ANY telescope, one could say the camera's equivalent aperture approaches infinity. But for bright targets the camera is only as good as the scope it's attached to.

Perhaps the only target for which the concept of an aperture equivalent could reasonably apply is stars. The difference in their visibility limit both visually and in an image under given sky brightness will be pretty closely correlated. But I've never bothered to assess this, as so far my interest has mainly centered on nebulosity.

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I forgot to add that for faint objects it might appear that the camera is revealing more detail. Not so. Rather, it is the eye which is failing to reveal the detail which is there. Of course it's natural to compare the small scope image of some nebula or galaxy with the visual aspect delivered by a bigger scope, pondering upon what it would take to make an equivalent view.

If all 'faint fuzzies' had the same and nearly uniform surface brightness, this would be valid. But there is a quite large range in surface brightness from 14 to fainter than 25 mag/arcsec^2 (to which the eye is sensitive). This 11+ range in magnitudes is a brightness ratio of at least 25,000!!!

This alone points to the incredible dynamic range of our visual system.

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One persistent myth has it that for extended objects, increasing aperture means shorter exposures. Aperture by itself is not the factor. F/ratio is.

A 2"' f/5 and a 10" f/5 will yield identical image surface brightness. The same integration times work equally well for both on any given object.

A 2" f/5 will require shorter integrations than would a 10" f/7. The smaller scope's faster focal ratio delivers to the camera a brighter image.

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This really is simpler than some people make it sound. The truth is that all of these situations are simply a camera attached to a lens. Yes I said it. A telescope is just another form of the traditional lens. Our eyes are just a camera and a lens(More accurately a sensor and a lens. Our brain is the processor).

All of the same principles of non-macro terrestrial photography apply. Focal Ratio(F-number), Shutter duration, and Exposure gain are the only parameters involved in the RAW image capture whether you are using a telescope or a traditional lens, or your eye and a telescope for that matter.

Note that the absolute aperture of the telescopes front opening is not a factor in determining the final exposure of a picture or image in our brain. That is because that measurement alone does not determine the amplitude of light that reaches the sensor or our eye. The focal ratio of the entire system determines how much light reaches the sensor or our eye.

The problem with eye-piece viewing is that your eye cannot vary the shutter duration. It can only vary the aperture of your eye. This means that the only way to increase the incoming light is to decrease the F-number of the system as a whole.

There are two ways to do that. You can increase the opening of the telescopes aperture and keep the focal length fixed and it will definitely decrease the F-number. However, telescope manufactures tend to increase the focal length proportionally as they increase the front aperture in order to keep the focal ratio the same.

They do this because they know that they can just add additional optics to change the focal ratio(ie: different eye pieces, barlows, and reducers).

Therefore, adding additional optics is the second option and the most commonly used. Even for eye-piece viewing if you step up to a much bigger aperture scope you are actually increasing the incoming light to your eye by using a different eye-piece/reducer and not just by increasing the scopes aperture if the scope’s focal ratio is held constant.

If the focal ratio of the entire system(Telescope/Lens and eye-piece/reducer) is F10 then the same amount of light will hit the camera as would hit your eye. The final exposure of the picture/(image in your brain) will be determined by the shutter speed and exposure gain of the camera and the aperture of your eye.

However, there is one big difference about your eye vs. the camera sensor. Your eye has a much bigger dynamic range than any consumer camera I have come across. For high dynamic range objects that will affect the final image greatly. HDR photography can get those two pretty close though.

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my brief exposure tests on M27 and m57 thus...

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When you change the f-ratio of a telescope you are changing the effective focal length and therefore the image scale.

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Integration on the Mallincam means exposure not stacking time. You also have to remember that while the Mallincam integrates for X seconds, it stores that image in a buffer and outputs it as a continuous NTSC (29.97 frame/sec) video signal and not as a one shot dump.

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Integration on the Mallincam means exposure not stacking time. You also have to remember that while the Mallincam integrates for X seconds, it stores that image in a buffer and outputs it as a continuous NTSC (29.97 frame/sec) video signal and not as a one shot dump.

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Does the Mallincam update the screen with a buffer image every 29.97 times a second? How often does the image change when integrating with the Mallincam?

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Yes the output is 29.97 frames a second (NTSC version). The images changes at the end of each integration which can be 1/12,000 of a second to I believe 999 seconds (CCD mode on the Mallincam Xtreme). The normal or more commonly used range is 1/12,000 to a minute or two.

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