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Old Jun 26, 2003, 5:55 PM   #1
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Default Minolta 7Hi and Digiscoping

Hello Lin Evans:

I have just discovered this section on Steve's website. Would it be possible to Digiscope using a Minolta 7Hi(49mm threaded lens) and a Meade ETX-90? Not knowing anything about optics or telescopes it is not obvious what must be done to accomplish the task at hand.

Thanks,
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Old Aug 25, 2003, 5:26 PM   #2
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I hope someone gives an answer. I have the same question. Only mine it the 7i which is not a great deal of difference.
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Old Aug 26, 2003, 6:31 AM   #3
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Hi David,

Though it is "possible," it's really not going to be a very satisfactory solution. Two things make using the longer zoom Minolta cameras a less than optimal solution for digiscoping:

1. Zoom range
2. Objective lens configuration

To digiscope with any camera which has a great deal of focal length, one needs a very low power eyepiece on the scope to control the "power" factor and keep it within a usable range so that there is sufficient light to avoid using the higher ISO ranges on the camera with all the noise and issues which this brings.

ScopeTronix and Eagle Eye (http://www.eagleeyeuk.com) make low power eyepieces which will let you connect your camera to a telescope, but then the second of the two issues becomes a factor. That is because of the relatively large objective and typical optical configuration, the Minolta will not allow much of a range beyond full focal length without serious vignetting.

For a camera to be truly useful for digiscoping, it's very helpful to have a "range" of vignette free zoom. Cameras with larger objective lenses in general don't make good digiscoping candidates because vignetting (shaded or black corners) begins very quickly as one decreases focal length from full telephoto.

If your purpose is to shoot fairly close celestial objects (planets, moon, etc.) then you might be happy with the results. On the other hand, if you want to use the combination for birding or wildlife, you would do much better to spend your money for even a used digicam which has a configuration amenable to digiscoping.

By far the most popular digicams for digiscoping are the CP series Nikons with their tiny objective swivel lens. You can often find a good used CP950, CP990 or even a CP4600 (all excellent digiscoping tools) for less than you will end up spending trying to adapt your Minolta for a task it's not well suited for.

Best regards,

Lin



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