Which of these looks sharper/better to you?

Started 2 months ago | Polls thread
LoneTree1 Contributing Member • Posts: 922
Re: Which of these looks sharper/better to you?

StefanD wrote:

TheSonyEnthusiast wrote:

kiwi2 wrote:

TheSonyEnthusiast wrote:

The first shot is mine and I think the reason the first photo has the moon periphery out of focus is because teleconverter shrinks the already narrow depth of field of the 70-400.

I don't think you'd be having a DoF issue with something 400,000 kilometres away. It looks more like motion blur. Don't forget the moon is constantly moving across the frame unless you are tracking it on a EQ mount.

With the TC the f-ratio become slower and it exaggerates lens softness. What was the ISO and shutter speed?

While I will admit the shot was at 1/20 of a second, if it were motion blur it would affect the sharpness across the entire image. The reason I think it may be depth of field is due to the preciseness necessary in manually focusing; I took a series of shots barely nudging the focus each time toward infinity, and a fraction of a millimeter either way resulted in less resolved craters.

According to this DoF calculator, the DoF of a 600mm lens at f/8 focussed at the moon (384402000m) ranges from 1500m to infinity. That should be enough to have the whole moon in focus.

Not so much with long camera lenses, but with uncorrected telescopes, lack of a field-flattener can mean slightly defocused edges of images but anything with a field-flattener should show clear focus across the frame.

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