23.05.2020 Second digiscoping expedition. First video: A Shelduck family.

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Captured at 300 yards on the opposite bank of a small lake: Conditions overcast and windy. I was quite shocked at the considerable distances involved when I checked later using Google Earth.

I cycled the seven miles to the lake and was delighted with the comfort of the Viking Optical tripod S'port carrier/bag system. It was quite effortless and felt weightless on my back as I leaned naturally forwards onto the handlebars. The S'port tripod carrier system is a well thought out product with which I have yet to find any obvious fault. It easily manages to house my 85mm spotting telescope, zoom eyepiece, camera adapter, Lumix still camera in its case and my 8x42 Nikon binoculars.

The digiscoping [afocal] system includes a Vortex Razor 85mm, Canon IXUS117HS, Vortex PS-100, camera adapter, Manfrotto 055 tripod with Manfrotto 500 "fluid" video  head.  

https://youtu.be/8a5zKkE7j4s





I was very pleased with the steadiness of the Manfrotto tripod and head. It really is a class product!

I am really rather disappointed with the optical quality of my stills and videos. Perhaps it would be have been different on a sunny day with much shorter exposures or "slower" focal ratios? I used the 2 second, self timer for both stills and videos. I didn't record which still images I "snapped" without the timer.

I'm still struggling with framing, focusing and monitoring on the small camera screen even with my strongest reading glasses. [+1.5 to my normal +1] I really do need a magnifying glass to use this small screen to best effect.

The looseness of the Vortex Razor, rubber eyepiece ring [spectacle] is a real pain! I was having to constantly monitor the uprightness of the image on the small camera screen and mostly failing to do it correctly. The human eye does not expect to see sloping water in images!

I have to admit to being disappointed with the optical quality of the Vortex Razor. Violet, chromatic aberration showing strongly around white objects like swans and Shelducks in both stills and video! Look at the violet overlay on the backs of the Shelducks! Is this real?

Still image [right] captured at 17/20mm zoom. 1/80 sec at f5.6. 17/20 is close to maximum zoom on the little Canon compact. This was needed to completely remove the black corners due to vignetting.

Unfortunately I have no record of the degree of zoom used on the 'scope itself. I was experimenting quite a lot with zoom to see if it made much difference to the optical colour correction and sharpness of the image. Rather pointlessly since I could not separate the final zoomed images.

After considerable searching online, I finally found an answer to the amplification factor of the camera. Thanks must go to a helpful and knowledgeable person on a forum:

Camera amplification of the telescope's own magnification:

The focal length of the camera lens / the sensor diagonal [both in mm.]

My little Canon Ixus 117HS has a maximum focal length of 20mm at full zoom. Its sensor diagonal is 11mm. 20/11 = 1.8. So the telescope's minimum 27x 1.8 becomes 48.6x system magnification at maximum camera zoom. And so on, up through the telescope's own zoom range of 27-60x.

But, then I saw a focal length of 17mm registered against most of today's still image specs: This is independent of the telescope zoom which cannot be recorded by today's clever, digital technology.

17/11[mm] = 1.5.  So 27x 1.5 = 40x. 30x 1.5 = 45. 40x 1,5 = 60x. 50 x 1.5 = 75. 60 x 1.5 = 90x!

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