Digiscopes
- Thread starter KeithH
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In your example the scope is 20x.
As a rough comparison divide the focal length of the lens by 40. So it is about 10x. Maybe a bit more.
http://www.ehow.com/how_5916091_calculate-magnification-250mm-lens-camera.html
As a rough comparison divide the focal length of the lens by 40. So it is about 10x. Maybe a bit more.
http://www.ehow.com/how_5916091_calculate-magnification-250mm-lens-camera.html
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Reading that link, it's dividing the effective focal length by 50 which makes it 400 x 1.6/50 = 640/50 which is approx 13. I think it's more a field of view calculation as it then depends on the sensor you have behind it (in megapixel count) which determines the angular resolution of each pixel. Think of it this way - if I had 2 DSLRs one full frame, one crop, with the same size pixels on the sensor, then the calculation of "magnification" would yield 8 and 13 on the method in the link. However, as the pixels are the same size in the two different sensors, they would each sample the same small angle of the scene but the full frame would cover a wider angle.
It's really not a good idea to think in terms of "magnification" as it depends on the size of the pixels on the sensor as to how big the image turns out...
It's really not a good idea to think in terms of "magnification" as it depends on the size of the pixels on the sensor as to how big the image turns out...
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Thanks for the info. I'd welcome your opinion on the following :-
I have a Canon 70-200 f2.8 IS lens. This is a great lens, I also have a Canon 2 X Extender.
I can either take the Digiscope route, or buy another 2 x extender to 'stack' them.
I quite fancy the latter, as it reduces the amount of equipment required.
Any thoughts, thanks Keith.
I have a Canon 70-200 f2.8 IS lens. This is a great lens, I also have a Canon 2 X Extender.
I can either take the Digiscope route, or buy another 2 x extender to 'stack' them.
I quite fancy the latter, as it reduces the amount of equipment required.
Any thoughts, thanks Keith.
If you were to scope you would need as large an ED scope as you can manage. That would cost and yes more equipment.
With stacked TCs you will get f11 at best and, what, a 1/1000sec. That is going to be tough isn't it ?
I don't know how they would compare IQ wise.
With stacked TCs you will get f11 at best and, what, a 1/1000sec. That is going to be tough isn't it ?
I don't know how they would compare IQ wise.
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Wildlife, mainly birds.
I'm wondering if it's worth Digiscoping when I'm not too far from achieving a similar result with the equipment I've already got. I'm aware of the limitations of stacking TC's, but I'm not too sure whether a Digiscope would be much of an improvement.
Thanks Keith.
In your OP is it 20 x 50 or is 20-50 x something.
20 x isn't much for a scope. If its 20-50 then obviously the max is 50 x magnification.
Digiscoping will allow you to take shots that are just not feasible with a conventional camera and lens though don't expect the same IQ. This is an interesting forum
http://www.birdforum.net/forumdisplay.php?f=243
20 x isn't much for a scope. If its 20-50 then obviously the max is 50 x magnification.
Digiscoping will allow you to take shots that are just not feasible with a conventional camera and lens though don't expect the same IQ. This is an interesting forum
http://www.birdforum.net/forumdisplay.php?f=243
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Kenko Pro Field Deluxe 70 A was the scope I was looking at, it is 20x to 50x so the max would be x50.
Thanks for the link, there's loads of info there!