Ultra Distance Focusing: Several weeks ago a posted reply to what I think I recall being a message about focusing on the moon. The answer mentioned some method or protocol for getting...

JCam Loc: MD Eastern Shore

Several weeks ago a posted reply to what I think I recall being a message about focusing on the moon.

The answer mentioned some method or protocol for getting more a precise focus. I thought I had copied down the name of the method, but now can't find it.

Will someone out there re-post the name of the method?

I'm using a Canon 60D with the 18 - 135 mm lens.

Thanks!

dlmorris Loc: Loma Linda, Ca

On the Canon 60d, go into live view (the button with the picture of a camera on it) then press the "+" button twice (giving you a 10x view) and focus on that.

David LM

busted_shutter

dlmorris wrote:

On the Canon 60d, go into live view (the button with the picture of a camera on it) then press the "+" button twice (giving you a 10x view) and focus on that.

David LM

Hmmm? Anything similar in the Nikon D5100?

Danilo Loc: Las Vegas

The focusing adjustment of most lenses stops at a certain distance, beyond which everything is "in focus". That point is designated as "infinity", symbolized with a sideways 8.

Wide-angle lenses will usually max-out around 25-35 feet, after which it's all in sharp focus. Long focal length lenses (200-500mm) will max out somewhere around 200ft to 200yds. Clearly the moon is beyond all these limits, so you should be able to just bang your lens to "infinity" and shoot the moon.

But Wait!! Just so you know, some lenses have a nasty habit of allowing it to focus "beyond infinity" to allow for different lens mount specifications. You'll want to ensure your lens does not focus beyond infinity. Most OEM lenses do not.

dlmorris Loc: Loma Linda, Ca

To get a really good image of the moon you need at least 500mm or more focal length (1000 is pretty good---a telescope...) but anything is worth a try! Let us know how it turns out!

SX2002 Loc: Adelaide, South Australia

Don't know if Canon have it but my D7100 has a 1:3 crop setting that doubles your focal length...turns my 150 -500 @ 500mm into 1,000mm...
Haven't tried it on a moonshot yet though. I did some a few years ago at 500mm so it will be interesting to see what the difference is...

Nikonian72 Loc: Chico CA

SX2002 wrote:

Don't know if Canon have it but my D7100 has a 1:3 crop setting that doubles your focal length...turns my 150 -500 @ 500mm into 1,000mm...
Haven't tried it on a moonshot yet though. I did some a few years ago at 500mm so it will be interesting to see what the difference is...

Cropping in camera is the same as cropping in PP, which means a tremendous loss of pixel count = loss of resolution.

SX2002 Loc: Adelaide, South Australia

Nikonian72 wrote:

Cropping in camera is the same as cropping in PP, which means a tremendous loss of pixel count = loss of resolution.

Yep, but still a 16mp shot...

amehta Loc: Boston

SX2002 wrote:

Yep, but still a 16mp shot...

The point is that the crop setting doesn't do anything compared to cropping later except make the files smaller. The real win with that mode is being able to shoot continuous longer, since the buffer won't fill as fast. Not a big issue for moon shots. :-)

selmslie Loc: Fernandina Beach, FL, USA

SX2002 wrote:

Don't know if Canon have it but my D7100 has a 1:3 crop setting that doubles your focal length...turns my 150 -500 @ 500mm into 1,000mm...
Haven't tried it on a moonshot yet though. I did some a few years ago at 500mm so it will be interesting to see what the difference is...

Your D7100 is already a crop sensor so your 150-500 is cropped to work like a 225-750mm lens. When you change from a 1.5 crop to a 3, you the FF equivalent becomes 450-1500.

The problem with cropping is that when you cut a linear dimension in half you end up with 1/4th of the area, so 24MP becomes 6MP. As Nikonian pointed out, this is a massive loss of pixels and resolution.

SX2002 Loc: Adelaide, South Australia

selmslie wrote:

Your D7100 is already a crop sensor so your 150-500 is cropped to work like a 225-750mm lens. When you change from a 1.5 crop to a 3, you the FF equivalent becomes 300-1500.

The problem with cropping is that when you cut a linear dimension in half you end up with 1/4th of the area, so 24MP becomes 6MP. As Nikonian pointed out, this is a massive loss of pixels and resolution.

According to the Exif data, the 35mm equivalent is 1,000mm, on my 150-500 @ 500mm..?
It seems to double the focal length for all my lenses..?
You may be right though as in full sensor mode the Exif shows that there is no difference in the focal length...I think there is a Nikon upgrade to fix this issue...as it doesn't worry me, I won't bother getting it...
My D90 always shows the correct equivalent...

amehta Loc: Boston

selmslie wrote:

quote=SX2002 Don't know if Canon have it but my D... (show quote)

The D7100 crop mode was written wrong, it's a 1.3x crop, so combined with the 1.5x DX crop gives about a 2x crop compared to FX, and he's left with 14mp (24mp / (1.3 * 1.3)).

selmslie Loc: Fernandina Beach, FL, USA

SX2002 wrote:

According to the Exif data, the 35mm equivalent is 1,000mm, on my 150-500 @ 500mm..?
It seems to double the focal length for all my lenses..?
...

In that case you only changed from a 1.5 crop to a 2.0 crop. The change in area takes your 24MP down to 13.5 MP, still a significant drop in pixels but only about a 25% drop in resolution.

What confuses many is that resolution and pixel count are not directly proportional. Resolution is a linear measurement but pixel count is an area measurement. When you crop an image by 50% in each direction and then print it to your standard 8x10, you cut the resolution in half but you cut the total number of pixels by 75% (1/2 x 1/2).

selmslie Loc: Fernandina Beach, FL, USA

amehta wrote:

The D7100 crop mode was written wrong, it's a 1.3x crop, so combined with the 1.5x DX crop gives about a 2x crop compared to FX, and he's left with 14mp (24mp / (1.3 * 1.3)).

The D7100 is a DX crop sensor, about 16x24mm. Like all other Nikon DX sensors the crop factor is 1.5.

Nikonian72 Loc: Chico CA

According to Nikon, the D7100 sensor is 23.5-mm x 15.6-mm, which is a normal APS-C sensor size: http://imaging.nikon.com/lineup/dslr/d7100/spec.htm .

Compared to a full frame sensor of 36-mm x 24-mm, a crop factor of 1.5x is used to calculate "35-mm film" equivalency.