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How many MegaPixels?

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Old Saturday 13th December 2003, 23:13   #1
bryanv
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How many MegaPixels?

Hi everyone! I have just joined Bird Forum.
I am in to astronomy and love to watch birds and other wildlife through my
telescopes durring the day.
I am going to put together a digiscope setup and I am stuck on the camera.
First of all, is there a point where buying more MP is a waste of money?
I know that you can only get so much resolution out of a given appreture.
I will be shooting through at least a 78mm scope on up to a 102mm.
all my scopes have 1 1/4" and 2" eyepiece capability.
The cameras I am looking at are at 4 and 5 MP.
The Canon Powershot A80- G3-G5 or the Nikon CP4500 or 5400.

Also I would love to get as much feed back on any of the cameras mentioned
above.(or others) I am leaning towards the G3 but the A80 has a much smaller lens.
The only thing I wory about on the A80 is the smaller LCD for focusing purposes.
thanks,
Bryan
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Old Saturday 13th December 2003, 23:42   #2
KC Foggin
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Hi Bryan and on behalf of Admin and the Moderators, a warm welcome to Bird Forum.

You've come to the right place to ask your questions. We have some very talented digiscopers here. I am fairly new to digiscoping and I use the Nikon 990. I have seen some beautiful results with the 4500 which has more MPs. Sit tight, some authoritative answers should be coming shortly.
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Old Sunday 14th December 2003, 13:59   #3
Jay Turberville
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Quote:
Originally Posted by bryanv
I am going to put together a digiscope setup and I am stuck on the camera.
First of all, is there a point where buying more MP is a waste of money?
I don't know about a waste of money, but the more megapixels, the sooner you run into limits of magnification. A 5MP camera will still let you use an 80mm aperture scope at 35mm equivalent focal lengths of up to around 3000mm at moderate distances. As you know, more aperture will allow greater magnification.

Quote:
Originally Posted by bryanv
IThe cameras I am looking at are at 4 and 5 MP.
The Canon Powershot A80- G3-G5 or the Nikon CP4500 or 5400.
<snip>
I am leaning towards the G3 but the A80 has a much smaller lens.
The only thing I wory about on the A80 is the smaller LCD for focusing purposes.
thanks,
Bryan
The notion that lens "size" is a significant issue is pretty much a myth. The real issue at work that can sometimes be loosly associated to lens "size" (diameter?) is the location of the lens' entrance pupil. The CP5400 is a great case in point. Its lens is similar in "size" to the CP5000 but it does not adapt to digiscoping as well. Early indications are that it will need 30mm or more of eye relief while the CP5000 needs only the 20mm or so typical of most of the other Coolpix cameras. Lens entrance pupil information is not typically posted in camera specs so you have to rely on the experience of others or experiment yourself.

I can't speak for how well the Canon cameras will work. The best thing is to do some web research or to wait and see if people using those cameras will post replies. The CP4500 is probably your safest bet since it seems to be the camera of choice for the largest number of digiscopers. But it is getting rather difficult to locate these days.

If you want to run some numbers on theoretical resolution for different cameras and scopes, you might try the digiscoping calculator at www.jayandwanda.com. Just bear in mind that combinations seldom work at the theoretical limits It is more typical to find them working at about half the theoretical limit unless the scope to subject distance is very short.

Good luck.
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Old Sunday 14th December 2003, 14:29   #4
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I don't digiscope yest but am a keen photographer. I use a Fuji S602 (which I am told is not a good camera for digiscoping owing to its large lens).

My advice is to choose at least 3 megapixels as this will allow you to crop quite closely and still achieve a pixel-free decent sized enlargement.

You will find that you almost always have to crop and so go for the most pixels you can is the best advice. 5mp cameras are now a commonplace and quite reasonably priced. Have you looked at Warehouse Express? They offer a good digiscoping deal with the Nikon ED82 scope (superb stuff) and a Nikon digital camera. I know someone who bought this combination and is thrilled to bits.
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Old Sunday 14th December 2003, 15:01   #5
Jay Turberville
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Quote:
Originally Posted by Jay Turberville
I
The notion that lens "size" is a significant issue is pretty much a myth. The real issue at work that can sometimes be loosly associated to lens "size" (diameter?) is the location of the lens' entrance pupil. The CP5400 is a great case in point. Its lens is similar in "size" to the CP5000 but it does not adapt to digiscoping as well. Early indications are that it will need 30mm or more of eye relief while the CP5000 needs only the 20mm or so typical of most of the other Coolpix cameras. Lens entrance pupil information is not typically posted in camera specs so you have to rely on the experience of others or experiment yourself.
Good luck.
Another good source of info on the location of the entrance pupil comes from folks shooting panorama images. They often calculate the location of the "nodal point" of their camera lens. This point is the distance from the front lens element about which they must rotate their camera in oder to avoid perspective shift. The "nodal point" also happens to be the lens' entrance pupil.

http://www.nikon-euro.com/nikoneuro_...ce990_en_6.htm
http://www.360texas.com/tips/nodalpts.htm
http://tedfelix.com/CanonG1/

It is no surprise that the Coolpixes shown tend to have nodal points near or below 20mm from the front lens element. It is also interesting to note the movement of the Canon G1 nodal point as the lens is zoomed. I suspect that Coolpixes have a similar movement which probably isn't a bad thing. Having the nodal point get further away as the camera zooms can often be tolerated since at longer focal lengths, we can't see the whole AFOV from the eyepiece anyway.

I guess I got a llittle ahead of myself there and should backtrack. The principle at work in all of this is that for the camera to see the entire AFOV that the eyepiece has to offer, the eyepiece's exit pupil should be located at the camera lens' entrance pupil. If it is in front of or behind the entrance pupil, the camera's field of view will be reduced.

That is getting into more detail than I intended. You can read more at:
http://www.jayandwanda.com/digiscope...ignetting.html

Other references.
http://www.vanwalree.com/optics/misconceptions.html
http://www.swissarmyfork.com/lens_table_1.htm

I should update that page to include this info about the "nodal point" and the entrance pupil being the same thing.
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Old Sunday 14th December 2003, 15:23   #6
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Hi Bryanv

The cameras you mention with the exception of the cp5400 should be okay for digiscoping.One of our members has already had some success with a Canon G5,& uses a home made adapter.
Regards Steve.

www.freewebs.com/justdigiscoping
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Old Sunday 14th December 2003, 20:08   #7
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Welcome to Bird Forum, Bryan.

I use a Canon G3 with a home-made adapter. See my post here for details of how I connect it to my scope.

Results have been a bit mixed, but certainly better than with a Coolpix 995 that I originally had. To be fair, I think I may have had a camera with a faulty focusing mechanism, but I have heard many tales of the 995 and the 4500 being problematic with focusing.
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Old Sunday 14th December 2003, 21:17   #8
bryanv
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Thank you everyone! I really appreciate the great info. you are all providing.
There is certainly a lot to learn.
My biggest fear is the camera purchase. I really liked both the Canon A80
and G3, G5 cameras when I checked them out at the store.
I am tempted to buy a Canon and a CoolPix 4500 and try them both.
I have never seen a CP4500 in person.
Since I am using telescopes with 1 1/4" and 2" capability I am thinking
I will have quite a few eyepiece options to make the cameras work well
for digiscoping. Tele-Vue makes some nice long eye relief eyepieces with
huge FOV and large eye lenses.
thanks again.
Bryan
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Old Sunday 14th December 2003, 21:44   #9
alan_rymer
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Quote:
Originally Posted by bryanv
Thank you everyone! I really appreciate the great info. you are all providing.
There is certainly a lot to learn.
My biggest fear is the camera purchase. I really liked both the Canon A80
and G3, G5 cameras when I checked them out at the store.
Bryan
I have had the Canon A80 for about a month and like it very much, I have not posted any pictures in the gallery yet, but I posted a few hand held sample shots at different zoom setting though my 80mm scope with 20-60x zoom. See the link below.
http://www.birdforum.net/showthread.php?t=9897
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Old Monday 15th December 2003, 01:51   #10
Jay Turberville
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Quote:
Originally Posted by digi-birder
Welcome to Bird Forum, Bryan.

I use a Canon G3 with a home-made adapter. See my post here for details of how I connect it to my scope.

Results have been a bit mixed, but certainly better than with a Coolpix 995 that I originally had. To be fair, I think I may have had a camera with a faulty focusing mechanism, but I have heard many tales of the 995 and the 4500 being problematic with focusing.
I'm very curious about what point your G3 starts to vignette and what the eye relief of the Opticron 22WW is.

The I use a CP5000 which is very much like the G3 and G5 with the swing out and tilt LCD display which I like very much. It is a bit more useful than the tilting body of the CP99x/4500 cameras.
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