The moon with a P&S ???

Raz · October 16, 2005

Hi!

Nik’s recent moon shots inspired me to have a go at it, even though I doubted my P&S results.

I used the Shaytech Moon Exposure Calculator.

I took it at (4 megapixel) 420mm, ISO 50 (since my camera is very noisy), 1/160, f/8, and it was on a tripod.

The autofocus didn’t manage to do its work, and in manual focus, I saw the picture getting better as I approached the infinity marker, but even when I got there it wasn’t quite in focus.

What you see is a full size crop.

So, can someone please explain what differences from an SLR make the differences in the result? Is it optics? Electronics?

Thanks

Raz

pathfinder · October 16, 2005

P&S cameras are quite capable of very good astrophotographs. They have been used for years by linking them to the eyepiece of telelscopes - google for digiscoping and you will find a ton of links.

Generally they are inferior to DSLRs because their sensors are much smaller and the individual pixel wells also tend to be much smaller which makes them inherently noisier, especially with longer time exposures where noise becomes more of an issue. A lot of us are eagerly waiting for a good APS or full frame sensor to be installed in a range finder style camera. Epson has done this with an APS sized sensor but it is still a work in porgress.

Here is an image captured with a CoolPix 995, shot through one eyepiece of a Canon binocular - the binocular was tripod mounted - the CoolPix was HANDHELD, hence the blurry image. Takes a few tries, but if you're patient, you'll catch a few frames. I just need to buy the adapter I guess

Raz · October 16, 2005

Thanks Path, you sure had me googling for a while.

But putting the noise issue aside, why can't I get those lovely craters?

I can see them in Nik's shot, even though it's 20mm shorter than mine

So, if it's not the focal length, what other factors play a role? Is it also to blame with the small sensor?

Thanks
Raz

Jekyll & Hyde · October 16, 2005

Raz wrote:

But putting the noise issue aside, why can't I get those lovely craters?

I can see them in Nik's shot, even though it's 20mm shorter than mine

J: You need only sleep on it (for a couple of nights). :snore

H: Your answer will appear before your eyes.

J&H

Nikolai · October 16, 2005

Raz,

Raz wrote:

Thanks Path, you sure had me googling for a while.

But putting the noise issue aside, why can't I get those lovely craters?

I can see them in Nik's shot, even though it's 20mm shorter than mine

So, if it's not the focal length, what other factors play a role? Is it also to blame with the small sensor?

Thanks
Raz

As PF alsready mentioned, P&S can be and actually are used for astro- and seleno-photography quite successfully. You just need some teleconverter -Hubble prolly would be the best, but Palomar would do just fine, too:-)

When I posted my shots at the canon 20D forum at dpreview, one of the response I got was a mind-blowing moonshot taken with (P&S) FZ30 and teleconverter Raynox2020pro:
http://forums.dpreview.com/forums/read.asp?forum=1019&message=15437252

Of course, if you follow the thread you will see it's quite a TC:-). The whole assembly gave him effective focal distance of 1457 mm, while for for my 20D (1.6 FOV crop factor) and (borrowed) EF 100-400L at 400mm the effective focal distance was "only" 640mm, i.e. 2.2 times shorter than FZ30 + Raynox.

As to the "lovely craters":-) - the are best seen next to the terminator line, i.e. NOT when the moon is full. Other than that - my last shot was taken at ISO 200, 1/650sec and f/5.6 - cellphone cameras can do that nowadays.. So all you need is a "reach"...

The rest is purely in God's hands... I mean: altitude (get to the mountains), air clarity (get to the mountains!), clear cloudless sky (move to SoCal:-), light pollution (get to the desert/mountains) are things that could affect your shot most severely.

After that - it's only about how "long" your lens is...

Good luck with the moon shot! I'll surely try another one tonight:-) Wish I had TC 1.4x, so I could jump from 640mm to 896mm:-)

Nikolai · October 16, 2005

Fogot one thing

Raz wrote:

Thanks Path, you sure had me googling for a while.

But putting the noise issue aside, why can't I get those lovely craters?

I can see them in Nik's shot, even though it's 20mm shorter than mine

So, if it's not the focal length, what other factors play a role? Is it also to blame with the small sensor?

Thanks
Raz

I said yours is 4mp. Mine's 8.2mp. Hence with all other things being equal my 100% crop must be 2+ time larger than yours.

Besides, 20D' sensor is known for its good response to sharpening. Two different cameras of the same resolution can respond differently to sharpening process: one can be sharpened a lot w/o bringing in a lot of noise (thus revealing those "lovely craters"), the other one plain can't - it's a "sensor thing"...

HTH

pathfinder · October 16, 2005

Jekyll & Hyde wrote:

J: You need only sleep on it (for a couple of nights). :snore

H: Your answer will appear before your eyes.
J&H

Nice to see you back Jeckyll&Hyde

:

Raz · October 16, 2005

AH HUH! So effective focal length is what I should now google about, and try to figure out what's mine.

So, size does matter after all...

Thanks all for the info. I bet Mr. Hyde showed himself only because of the (almost) full moon...

Raz

Raz · October 16, 2005

just to make sure
So, when you said you used a 400mm lens, this number is for 35mm film, but since the sensor is smaller, you get a larger effective focal length.

When I said 420mm, it's already "35mm equiv" so that's it for me (w/o a TC).

Am I right?

Raz

For all the n00bs like me, I read it here.

Nikolai · October 16, 2005

In most cases yes

Raz wrote:

So, when you said you used a 400mm lens, this number is for 35mm film, but since the sensor is smaller, you get a larger effective focal length.

When I said 420mm, it's already "35mm equiv" so that's it for me (w/o a TC).

Am I right?

Raz

For all the n00bs like me, I read it here.

The actual focal length does not depend on the sensor size, it's simply lens assembly property. However the effective focal length does depend on so called FOV crop (or sensor size). For 20D it's 1.6x... For fixed lens cameras they usually specify the effective one, since it looks more advantageous marketing wise (most consumers only worry about how much "tele" their camera is)...

The moon with a P&S ???

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