Canon A95 manual focus distance setting. (1 Viewer)

robert s said:

I was wondering why at 2ft the camera and the scope seem in sync with one another. I`ve been taking almost all my shots at infinaty setting and focusing with the scope. But last week I focused with the scope first on a tree then put the camera to the scope and had to adjust focus with the scope again . Then I put up the center zoom helper that zooms in closer so you can fine tune the focusing and put the manual focus on and found the are in sync at 2 ft.I was wondering would I get any advantage with depth of field by leaving it at that setting. :brains:

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robert s said:

I almost always focus my shot through the lcd screen. I have the camera on manual and set at infinaty.Works fine almost all the time. Well I thought nothing of it for awhile. Then one saterday I focused on a tree first . Then I put the camera up to the scope. I figured it should be in perfect focus but it wasn`t. So I put it on macro and adjusted the focus until it matched the scopes focus. Which was 2 ft. according to the lcd scale ( not sure how accurate the scale actually is) . I was just wondering why this was so . I got excellent results at the infinaty settings.

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john-henry said:

I have always believed digiscoping is taking a picture of what the scope is seeing but it's obviously not so clear cut as that.
I know Macro is autofocus but how can it take a sharp picture when the scope is not in focus!!!

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iporali said:

John,

There is no absolute "in focus" with the scope. It is the eye or the camera that determines whether the image is sharp or not: both the eye and the camera can compensate "misfocused" scope - the camera even more than the eye. I am not sure about the macro setting of the A95, but quite often "macro focusing range" does not reach infinity, which means that in this case "in focus" of the scope is out of camera's focusing range. The camera is practically set to be near-sighted - and it can be corrected by over-focusing the scope.

Best regards,

Ilkka

Ilkka,
Many thanks for your reply, I'm sorry to say I still can't see how it happens - but it certainly does. It seems to throw away the idea that autofocus uses contrast and edges to obtain a focus as neither of these are present. Looking through the scope it is well out of focus, not just by a "tweak". Also the A95 has an 'in-or out of' focus colour signal and a double bleep to indicate good focus, both of these show a good focus is obtained by the camera and the picture taken confirms this.

I take your point that Macro has a very limited focus range - up to 1.5ft on the A95, I suppose it's just that I cannot see what it uses to produce a sharp image from what it's seeing through the scope, especially as there is so little leeway with normal autofocus.

Regards and best wishes

John

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john-henry said:

I suppose it's just that I cannot see what it uses to produce a sharp image from what it's seeing through the scope

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iporali said:

John,

That was exactly my point.

I wish I could explain it better, but I am afraid this is about all I can do. I have an old friend, who is very far-sighted and I am very near-sighted. We often share my scope when we are birding. After looking through the scope my friend said once: "Oh yeah - I have to return this scope to unsharp for you". We both saw the same bird perfectly sharp, but the scope had to be very differently focused (about 8.0 diopters) - not just by a tweak.

You could try to test this with your digiscoping system. Focus the scope on some distinct target which is far from background or any disturbing objects. Take a digiscoped picture (like you normally do) of the target. Then try the same by slightly over- and underfocusing the scope. Now increase the misfocus. If you get sharp images from many focus positions, wouldn't it prove that the scope can be focused on "almost anything" and the camera does its best to maximize the contrast of the subject within "focus rectangle". If you only get a sharp image from "correct" focusing, I'll let someone else to try to explain this .

Best wishes,

Ilkka

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