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Digitalcam through binoculars

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#1 Swedpat

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Posted 08 August 2005 - 09:38 AM

I played this morning with putting binoculars together to multiply the magnification. That often is a bad solution in comparison to a spottingscope; two optical systems with prisms and also the dust between them on the outer surfaces makes the image to be fairly bad.

At first I tried to put the Minolta 8x25 in front of the Oberwerk 11x70. That means I get a 88x70 binocular. The image was so sharpless and gray with plenty of CA so I didn't benefit anything at all in comparison to 11x.
After that I tried to do the same thing with the Bushnell 5x25, and became surpriced of the good result. 55x70 gave actually a useful image and the CA was fairly insignificant, surely better image than some lowpriced zoom-spottingscopes at the same power. This shows how much high power demands of the optical quality. The Minolta 8x25 is superior to the Bushnell 5x25 in both the sharpness and contrast, but gives despite that an unuseful image where the Bushnell works pretty well.

I attach a digitalcam picture of the views of 5x25, 11x70 and 55x70.

Patric

Attached Thumbnails

  • 550157-5x11x55x.jpg


#2 KennyJ

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Posted 08 August 2005 - 11:11 AM

Very interesting Patric -- and I see you seem to have much more success with your digicam than I ever seem to achieve using mine through my scope.

As you probably know from my posts to Cloudy Days , playing around with low power binos ( or at least one side of ) in front of larger binos / scopes is one of my pet hobbies !

Regards and keep up the good work !

Kenny

#3 Glassthrower

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Posted 08 August 2005 - 03:18 PM

Patric -

How did you couple/mate the digital camera to the binocular? Did you put the camera lens flush up against the bino eyepiece or was something else involved?

I tried putting an 8X42mm bino behind a 25x100mm bino and got a really close, but really DIM image. It was an unusuable configuration, but it was an interesting experiment that I enjoyed.

MikeG

#4 Swedpat

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Posted 08 August 2005 - 03:31 PM

MikeG,

I had the 11x70 mounted on a tripod, hold the 5x25 with the left hand and the camera with the right hand. Just that.

The reason you got a very dim image at your attempt is that you got far too high magnification; 8x25=200x! That will be even worse image than as my attempt with 88x70mm.

To get a good image with 200x power demands even with a 100mm aperture a high quality telescope with apochromatic lens or much longer focal ratio than as with a 25x100 binocular.

Regards, Patric

Patric

#5 Lew Zealand

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Posted 09 August 2005 - 02:40 PM

Coupling a digital camera to a binocular also seems to be subject to the variable designs of the optics (though I know nothing of the actual variables). This conclusion comes just from my observations and attempts to take pictures thru a few binocs.

Camera used: Kodak DC4800 3MP 28-84mm zoom

Binocs used:

Bushnell 10x50 (don't know which model right now as this was a few years ago with brother-in-law's binocs)
Minolta 10x50 WP.FP.
Oberwerk 15x70 (I no longer own these)
Celestron SkyMaster 15x70

Ranked from best to worst performance with the digicam:

Celestron 15x70
Bushnell 10x50
Oberwerk 15x70
Minolta 10x50

Notes: Attempts were done with the binocs on a tripod and digicam handheld up to the eyepiece except for the Bushnells which were handheld along with the digicam - that was a fun balancing act as many of the the subjects were also moving.

Celestrons show a well illuminated circular exit pupil (EP) at wide angle zoom on digicam and the image is quite sharp to the edge of the EP, which has a fuzzy field stop. Zoom in halfway and full frame is covered with a bit of blurriness at the edges. Zoom in all the way and image is pleasingly sharp to the edge - not as good as a regular non-binoc picture but a very satisfying picture.

Bushnells are similar at low zoom but with the edge of the FOV fuzzier. This was magnified at max. zoom with the center 50% of the FOV looking decent and the outer 50% very fuzzy.

Oberwerks and Minoltas I simply can't focus correctly to use at any zoom or binoc focus point. I don't know why. I'm assuming it has to do with the optics of the digicam and optical differences in the design of these binocs vs. the Bushnells and especially the Celestrons. These were a disappointment as I was successful with the Bushnells in my first digicam-binoc marriage and these came afterwards. I almost didn't even try the Celestrons but I'm glad I did, if only for the fun of it. :D

#6 Swedpat

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Posted 09 August 2005 - 03:22 PM

Lew Zealand,

Interesting to read your result. Maybe the optical design (and the combination of them) makes more sence than we can estimate.

At my attempt I really became surpriced why the appeareant FOV at the digital picture was so narrow through the 11x70 despite 23mm ER, and very wide through the 5x25 (stated 12mm but surely about15mm). You can see that at my photo. Even if the 5x25 has about 63º and the 11x70 has about 49º I think the ER would make most sense? At the digicam picture I can see the entire FOV of the 5x25 but not of the 11x70.

Patric

#7 Lew Zealand

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Posted 09 August 2005 - 03:58 PM

Patric,

One of my guesses used to be that long eye relief was actually working *against* taking good digicam pictures thru binocs as the Bushnells have very little ER and the Minolta and Oberwerk binocs have good ER. But the Celestron also has good ER and works the best of all of them. I don't know what to think now…


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