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Magnification with BYE (5x zoom)




I have the following config:

SW ED80, Canon 600D(w/BYE), 2x barlow, 9mm ep

apparent Magnifications below .....

ED80 = 12x
ED80 + 2x barlow = 24x
ED80 + 9mm ep = 66x
ED80 + 2x + 9mm = 122x or 130x
ED80 + 3.75mm ep = 160x (theoretical limit for the scope)
ED80 + 9mm + BYE(5x) = 330x ??
ED80 + 2x + 9mm + BYE(5x) = 650x ??


Could you comment on the last 2 statements above regarding BYE with 5x zoom and the calculated numbers.


(This is a magic product.  Could not do without it).  But I would like to understand the effect of the 5x zoom option/feature in the Planetary tab in terms of resulting magnification.


Thanks for your time

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The 5X Zoom feature is not really magnifying the captured stars. It is merely showing them at their true resolution.


If you compare the number of pixels in a Large image (~5184 x 3456) to the size of the LCD display (~1248 x 833) you see that the entire image cannot be displayed on the LCD without shrinking it. When you choose 5X zoom what you are seeing is the 1248x833 portion of the Large image.  It is simply a part of the Large image that has been cropped so that it can be displayed on the LCD display without having to shrink it.

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Hi Rick, Thanks for responding.


I am recording an AVI on a computer.  Got nothing to do with the camera LCD.  Without the 5x zoom, target in the AVI is small.  With 5x zoom selected the target in the AVI is larger.  To my visual senses that is "magnification" .... or APPARENT magnification.  If it is not magnification then the "zoom" suffix given to that feature is entirely misleading.


Nevertheless, what I am getting at is ..... is there a way to quantify the increase in the recorded size of a target with the 5x zoom compared to without that feature?

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Oh, based on the subject line of your post I thought that you were asking about BYE's 5X LiveView zoom feature for planetary capture. That is why I answered as I did. BYE has nothing to do with shooting of in-camera video. It does not initiate the capture of in-camera video, it does not download video files from the camera, nor does it display in-camera video.


You should consider BYE and its 5X Zoom feature for planetary capture since it records at the full resolution of the sensor.  You won't do better than that with the in-camera video options.


in order to quantify the magnification, you would need to know the details about the frame size of the AVI file as compared to the sensor size. I would expect that it would be approximately 500% of a normal video, since Canon is calling it 5X!

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Your T3i has a Sensor with 5184x3456 Pixels.  


When you record in FullHD you are storing that Full Sensor FOV at only 1920x1080 Pixels - squeezing down the actual Detail by 2.7x Horizontally and 3.2x Vertically.  Not Ideal.


When you record in 5x LiveView, you are storing a Narrower FOV but at 1:1 Pixels - every Pixel in that Narrowed FOV is recorded to the AVI as 1 Pixel.  This is Ideal for capturing Detail.  AND the Narrower FOV is Helpful for Planetary Imaging.

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Hi Rick,  I never mentioned "in-camera video" and BYE in the title does not imply "in-camera video" :-)


Hi s3igell,  Thanks for your response. I know BYE 5x zoom/liveview does is the way to go for planetary imaging


I guess I am not going to get anywhere with this.  I tried.

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Sorry, I totally misread your post. Let's start over.


The LiveView frames that BYE gets from the camera are what would have been sent to the LCD screen if it was active. That means that the images are shrunk to fit on the smaller LCD screen. When you switch to 5X zoom, the camera takes the portion of the image at the zoom box and displays that without shrinking it. So it is really a "crop" rather than a "zoom"..


I take it that you are also using eyepiece projection rather than prime focus imaging.


I will say that to display the full sensor frame in LiveView that the camera downsamples the image to fit the LCD dimensions, even if it is sending the image to the PC rather than showing it on the LCD display. The 5X is then valid when compared to the downsampled image. But it is at the same resolution (arc-seconds per pixel) as a full still image. For that reason I believe that your calculation of multiplying the magnification by 5 is incorrect, but it is too late in the day for me to try to correct the calculation. Hopefully someone who is more awake can help.


One other factor with eyepiece projection is that you have to take into account the camera lens distance from the eyepiece when trying to calculate the additional magnification.


This link may provide some answers: https://starizona.com/acb/ccd/advequipplanet.aspx. Read the sections on Eyepiece Projection and Determining Image Scale.


Again, sorry for the mis-communication.

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