Spotting @ Long Range - Beating Bad Seeing

[Fred Bohl]

As an extension of the work done for the post, BEST spotting scope? started by Pat Graham,patgblue) and the fine article, Premium Spotting Scopes in Review Is Bigger Always Better? by Danny Reever, two inescapable conclusions could be drawn from all the testing. First, regardless of the optical quality or care in selection, at long range and/or high magnification the real on-range performance of spotting scopes winds up being limited by atmospheric effects. Second, there still remains a need to be able to see and analyze target bullet hole patterns at long range.

After consultation with persons more knowledgeable in applicable sciences, we are conducting experiments in two methods to overcome the “bad seeing” caused by atmospheric turbulence and poor air quality that tends to worsen as the day progresses. These methods are:

A – SOFTWARE ELEGANCE

The eyepiece of the spotting scope is replaced by a digital imaging sensor. A short video stream is taken. Using image processing software originally created for astronomic purposes, bad frames are discarded and the remaining frames are realigned to selected reference feature,s). The low quality frames are again discarded and the remaining frames are then stacked,added) to form a single frame of higher signal to noise ratio. This frame is then further filtered to increase contrast and sharpness.

PRO:
1. Produces a useful image in very bad seeing conditions.
2. Participating in the image processing enhances understanding of the interactive effects of wind and mirage,air turbulence).
3. Usable for each shooter properly equipped.

CON:
1. Image processing takes time,but not as long as a round trip to the target).
2. Lots of added equipment to haul to the shooting position.

COST:
1. All necessary equipment = $1200
2. Plus user supplied Laptop Computer

STATUS,as of 8/5/2007):

Trials continue in an effort to define a generally useful process/procedure in order to provide for more ease of use. It is also intended to provide guidance for more advanced techniques to handle the more extreme conditions.

B – BRUT FORCE HARDWARE

A package consisting of a video camera, transmitter and battery power pack is positioned at close range to the target. A receiver, LCD monitor and battery power pack is positioned at the firing position. This provides a continuous high resolution target image with almost no atmospheric effects.

PRO:
1. Produces a useful image in very bad seeing conditions.
2. Easy to use.
3. Minimal equipment at shooting position.


CON:
1. Limited to a very few simultaneous users on one firing line,limited number of non-interfering frequencies).
2. Some equipment must be taken to, set up and later retrieved from the target area.
3. The equipment down range may need some form of protection as it is in the potential field of fire. Note that the camera must have line of sight view of the target and the transmitter,near camera) and receiver,near shooting position) antennas must have line of site view of each other.

COST:
1. All necessary equipment = $1600
2. Plus user supplied Laptop Computer

STATUS,as of 8/5/2007) :

Trial completed. Borrowed equipment returned. We are researching alternate equipment to provide a cost effective multi-user solution.

 

[Fred Bohl]

Dave,

Yes the B method did use a similar system to the one in the article. Specific hardware was limited to that which I could borrow locally. I used the Laptop for a display because I had it and also had an effective hood for it to deal with bright sunlight days. A simple LCD video display with a hood would be preferable for a simple system,about $200 to $300 for the display and $50 to $90 for a good hood).

I'm sorry that you are uncomfortable with PC/Laptop use in the field. Doing the interactive image processing is teaching me a lot about the dynamic effects of air turbulence,wind, mirage, haze, pollution). It was particularly educational to do it immediately after observing the event through my rifle scope that the camera had just recorded through the spotting scope. The first benefit is enhancing my ability to discern the real images from the displaced and distorted images.

 

[Fred Bohl]

Dave,

In our initial trials we found it very difficult to distinguish between wind and target view displacement,due to turbulence) as to how the POI was affected. We borrowed some wind flags and started VERY early to avoid thermal effects for the next trial.

We did our initial reference video and firing trials with no detectable wind or mirage. As the wind picked up we ran several other video/firing sets and the correlation of wind,via flag angle to POI shift seems good. As the mirage,thermal turbulence) increased the correlation deteriorated due to mirage and wind combination distorting the true position of the wind flag in the images. Note that the firing was done with rail gun and POA was not changed between runs.

It would seem that at least for the wind flags we used, in the presence of thermal turbulence the distorted image of the flag tails may add to the confusion rather than help to determine the proper POA. Our consensus was that a wind indicator of the tilting vane with a indicator against a scale type would be more effective to judge the actual wind without added distortion from air turbulence affecting the apparent indication.

We are still working analysis of turbulence/mirage and will report on those results later.

 

[BHarvey]

The rail gun idea was something I had not thought of in terms of being able to get an idea of actual displacement of the POA in bad conditions, brilliant. I have some experience with some very good spotting scopes, but they all are of the same design.
The ones I would like to play with would be the refractor type scopes with fixed x eye pieces, like the Televue. I did some reading about what mirage actually is, refracted light, and also had read that refraction scopes have a much superior image to that of, say, a Leica APO 60 or 77 mm.
The question I had, was why would this design have superior image quality to the standard style scope?
I then started to read about polarizers and how they are suppose to work on refracted light. I picked up a cheap linear polarizer and attatched it to the objective of my NXS.
The scope was now a little pickier about how centered my eye was behind it, the image was a little darker, about 2 stops, but the contrast level was through the roof! It seemed at best, to maybe reduce mirage by 10%, but it could have been that since the contrast was so much better, that I could see detail that I never saw.
I would tend to think, if you could get the scope well above the ground, like 15', and attatch a small ccd device, or some kind of remote viewing device, that you would get a much clearer picture.
There is a BIG difference between having your spotter on the ground vs at eye level, on a bad day. An extra 10 feet might be the ticket. HHHMMMMMMMM!

 

[Fred Bohl]

BHarvey

You packed a lot of concepts into a single short post but I'll tackle a few.

This is as good a place as any to address using filters. Please see the following:Click Here

The elevated spotting scope position helps and so does an elevated target. A range setup that puts the firing line and targets on opposite slopes of valley seems to provide the best mirage conditions but very hard to read and manage wind effects. Note that elevating the spotting scope subjects it more wind and makes it hard to stabilize.

Re the type of spotting scope and lenses - if you have not yet, please read:

Premium Spotting Scopes in Review Is Bigger Always Better? by Danny Reever Click Here

BEST spotting scope? Thread by Pat Graham,patgblue)Click Here

I know they are long but there is a lot of useful information if you can wade your way through it all.

A recent turbulence,mirage) test involved setting up on a flat range very early to establish a mirage free reference POA and precise focus on the target. Later during bad afternoon mirage we ran a 300 image video string. After clearing 100 very poor frames the remaining 200 frames danced around and the initial center point never appeared closer than 4 inches to the original POA and some were as far as 7 inches out of place.