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Extreme Digiscoping (1 Viewer)

Celestron Regal 100 F-ED and Nikon V1

Here's one taken this morning at 100m (as measured by Google Earth) with the Celestron Regal 100 F-ED, Baader 17mm Hyperion Eyepiece, Nikon V1 with Nikon 28mm f/3.5 lens. That's around 2400mm eq. focal length. Not bad for a $700 scope.
 

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Just for the heck of it and to get double duty out of my Nikon V1 I use for digiscoping, I decided to test out the V1 with an old Nikkor 400mm f/3.5 manual focus lens with a matched Nikon TC-301 2X teleconverter. This put me out to around 2160 mm FOV with this rig. It turns out to work pretty well. Here's an example of a Belted Kingfisher I took with this combo. I still digiscope, but good results at this focal length and the light-gathering capacity and resolution of this rig is impressive.

Rick

That's a very fine shot of a Belted Kingfisher (tough subjects!). I'm very impressed with the resolution of the shot, it speaks well to both the 2x TC as well as the 400mm lens. 800mm is some reach, but you still had to be hiding somewhere closeby to pick up that Kingfisher!

Just so you know, technically speaking, you're only reaching 800mm f.l. with the 2x TC. I know, you did qualify it with "FOV," but the gain suggested by the "crop multiple" is a somewhat spurious -- not b/c you don't gain something by using a full format lens on a crop sensor, but b/c the technology is doing something that's not immediately apparent.

The reason crop bodies are affording some extra "resolution reach" is twofold: Photosite density & lens sweet spot.

The Nikon V's Cx sensor (a 2.4 crop Aptina) has 3.4 micron photosites (same as the 24MP Sony sensor in the D3200 & D5200). Having photosites that finely packed enables the sensor to resolve some very fine details from top-notch lenses. And it just so happens that your Nikkor 400 is an excellent lens & is sufficiently sharp to serve the sensor's 3.4u pixel pitch resolution. Even with a 2x TC, which understandably is going to soften the image by the same factor, that lens is still rendering fine on the 2.4x Cx crop sensor.

Here's something else surprising about using larger-format lenses on a crop medium: By only using the sharpest, brightest & contrast-iest part of the lens' image, you may even be gaining a half stop (or more) of brightness over the rated aperture of the 400mm. Since the 400mm Nikkor is very sharp in the center, and you are cropping at 2.4x, you are taking the absolute sharpest center of the image circle & projecting it on that Cx sensor's closely packed photosites.

The crop sensor is effectively *upscaling* the highly resolving center of the lens' image circle by token of its finer pixel pitch (about 1.4x finer than a full frame sensor's 4.9u pixel pitch).

I'm seeing a similar level of gain in relative brightness using medium-format long lenses on a D3200 ... the crop factor from 645-format film to a Dx sensor is 2.5x (close to your Cx sensor's 2.4x).

OK, so, since the Cx sensor's crop is 2.4x, 800 x 2.4 ='s 1920mm FOV. But at what point will the absolute resolution fall below this very simple metric: Lenses resolving to 55 lines/mm qualify as sharp (l/mm is the old school metric, new being line pairs/mm or 27.5 lp/mm). It would appear that your 400mm resolves a very sharp image in the dead center, somewhere in the neighborhood of 83 lines/mm (if you can crop to 150% & still look sharp), or perhaps 110 lines/mm (if you can pull off 200% crops).

The point being that a lesser lens will not lend as well to the resolving power of the crop sensor's 3.4u (micron) pixel pitch, and so the functional *gain* will be lowered. A superb lens might allow for deeper crop in post-processing (say, 200% crop), while a decent lens might only afford 150% crop. A 3rd-rate lens will drive you nuts if viewing 24MP images on Flikr, but it'll be OK if printed on 3x5 glossy, but at a 50% crop (or -66% crop ) ;).

So if 150% crops are coming out OK from the 800mm effective focal length, then your effective reach is 1200mm. If 200% crops, then 1600mm (tack sharp). If a mediocre lens were used (say a Samyang 100-500/5.6 zoom full of fungus like the mushroom bazooka I got for $20 at a yard sale) then the effective crop is going to be 50% (it won't look sharp unless I shrink the image .. in other words, the effective reach reduced by a soft lens (well, we knew this...)
 
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Neil

Well-known member
Here's one taken this morning at 100m (as measured by Google Earth) with the Celestron Regal 100 F-ED, Baader 17mm Hyperion Eyepiece, Nikon V1 with Nikon 28mm f/3.5 lens. That's around 2400mm eq. focal length. Not bad for a $700 scope.

Not bad at all.
Neil
 

janvangastel

Well-known member
Buzzard at 174 meters

A couple of days ago, I digiscoped this Buzzard. Distance measured with Google maps. Not very detailed at this distance, but I am still happy with it. Taken with Panasonic DMC G3 camera with 30 mm Sigma lens, Swarovski ATM 80HD and DCB adapter. Total magnification 60 x.
 

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Neil

Well-known member
A couple of days ago, I digiscoped this Buzzard. Distance measured with Google maps. Not very detailed at this distance, but I am still happy with it. Taken with Panasonic DMC G3 camera with 30 mm Sigma lens, Swarovski ATM 80HD and DCB adapter. Total magnification 60 x.

Looks ok at that distance. Did you use AF or manually focus?
Neil.
 

Neil

Well-known member
I cranked the eyepiece up to 70x for this closeup from about 50 meters
Neil

Sony RX 100 M2 and STX 95 mm Scope and DCB 11 Adapter
Mai Po Nature Reserve,
Hong Kong,China
January 2014
 

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Common Loon
Celestron Regal 100 F-ED, Baader Hyperion 17mm eyepiece, Nikon D40 with Nikon 28mm f/3.5 lens. Not really extreme in focal length, just in distance.
Google earth measures at 170 meters
 

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Neil

Well-known member
Common Loon
Celestron Regal 100 F-ED, Baader Hyperion 17mm eyepiece, Nikon D40 with Nikon 28mm f/3.5 lens. Not really extreme in focal length, just in distance.
Google earth measures at 170 meters

Not bad at that distance.
Neil.
 

Neil

Well-known member
Not a great deal of action out in the wetlands on Friday so I was pleased when this osprey dropped in to have a drink and a splash. Distance was about 280 meters so I cranked up the eyepiece to 70x. I had taken my big Benro tripod so more stable than my usual light weight setup. Magnification about 4,000 mm
https://vimeo.com/86239028
Neil
Sony RX 100 M2 and Swarovski STX 95 (70x) and DCB 11 Adapter
 

Neil

Well-known member
Not at extreme distance but in extreme weather. Thunderstorms all day kept all the birds hunkered down. This was about 140 meters and about 60x on the zoom.
https://vimeo.com/91143113

Neil

Sony RX100 M2 and Swarovski STX 95 mm Scope and DCB 11 adapter
Mai Po Nature Reserve,
Hong Kong,China
2nd April 2014
 

rrepp

Member
Combination

I've got a Nikon 82ed fieldscope, and the FSA 1 adapter. I'm wondering if this would work with a Nikon 1 camera with FT-1 adapter, and what would the magnification be? Thanks for your time.

Bob
 

rrepp

Member
Marco
Correct. I have the FSA-L1 adapter. And 82mm fieldscope. I also have Nikon V1 camera. I thought with FT-1 adapter on V1 it would connect to FSA-L1 and wondered what I'd have for power through 82mm scope. If Im correct in my thinking that it would all connect
 

Marcobf

Well-known member
OK, well with the ED82 and FSA-L1 you get 1000mm x sensor multiplier so with a DX camera it's 1500mm and with a Nikon 1 it's 2700mm

Have fun :D
 

Tord

Well-known member
OK, well with the ED82 and FSA-L1 you get 1000mm x sensor multiplier so with a DX camera it's 1500mm and with a Nikon 1 it's 2700mm

Have fun :D
No it's not. The focal length is not changing. The angle of view is.
 

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