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| Like eliminating vignetting, trying to get a bird properly focussed
is another major endeavour in videoscoing. Superficially, it seems getting
the camcorder properly focussed onto the bird seems a simple and straight
forward procedure. In actual fact, it can be difficult depending on the
situation. In this section, I would attempt to describe the various methods
of focussing and discuss the pros and cons, based on my observations and
experience. I must say I do not have scientific proof or theoretical basis
for some of the things I write but it does seem to work, at least for me
using a Swarovski scope coupled to a SONY camcorder. In addition, I am
not too sure whether what I write is applicable to digiscoping (i.e. with
a digicam instead of with a camcorder). Most digicams have spot focus which
is a really handy feature when it comes to focussing. I welcome any comments
or corrections so that I can post them here.
Before trying to attempt the various focussing methods discussed below, it is important to be thoroughly familiar with all the controls on the camcorder related to focussing, including the focussing ring, how to switch from auto to manual/macro/infinity focus and the menu structures etc. Preferably, you should be so familiar that you can select the focussing modes and perform focussing on the camcorder and scope without taking your eyes off the camcorder LCD. If you often videoscope under bright sunlight, an appropriate LCD shade would also be need. Some of my observations with regards to videoscoping:
Method A: Camcorder focussing mode set to auto. This is perhaps the simplest and fastest way of focussing but definitely not the sharpest. You just spot the bird into the LCD, frame/compose the video and turn the scope focussing ring until you get a sharp video of the bird. As long as the scope's focus is set close enough to the actual distance, the camcorder's autofocussing mechanism will do the rest to get a sharp bird. However, remember that camcorder's focussing algorithm makes use of the contrast offered by the bird and all surrounding as well as background objects. Most camcorders do not have spot focus algorithm i.e. they evaluate the contrast offered by ALL pixels in the CCD and decide on the 'correct' focus, possibly based on the position of the pixels closest to the average contrast. This usually means that the focus is not set precisely on any part of the CCD! It is also possible that there may be some bias towards parts with better contrast, and I suspect also brighter areas. Depending on the auto programe selected (portrait, landscape, low light etc), there may also be bias towards a closer or further objects. Obviously, the situation is very complex and the camcorder has to do a lot of thinking and calculations! No wonder it is difficult to get a perfectly focussed bird with this method. However, there are situations where this method can work or it would be preferred. These are:
Obviously, this method takes a little longer to execute than Method A but the extra effort is well worth it. It can be used in situations where the camcorder auto focus does not work or does not hold. Method C: Camcorder focussing mode set to macro. I find that this method gives me the sharpest focus ever but it is very difficult to execute. With this method, I fix the camcorder focus to macro, then try to spot the bird in the LCD and fine tune with the scope focussing ring. Sounds simple but it is very difficult! The reason for this is that I notice when the camcorder is set to macro, the whole setup seems to have a shallow depth of view. The scope focus have to be very close to the actual distance in order to see the bird in the LCD, which is not always the case. It is sometimes so shallow that I do not even realize that I have already scoped in the bird but could not see it because it is so out of focus! Very major effort is required in frantically spinning the scope focussing ring to get the bird into focus. In fact when a bird is too far away, correct focus on the scope can never be found with the scope focussing ring. Another major problem is that the focus is quickly lost if I change the camcorder zoom, however small that change may be. All these means that it takes a much longer time to start recording. Hence, this method is used mainly for birds that will wait for me and birds that are very close. In the second situation, the much increased depth of view from the close distance compensates for the difficulty in finding the perfect focus with the scope focussing ring. Method D: Camcorder focussing mode set to infinity. With this method, it is easy to scope in the bird because even if the scope is grossly out of focus, you can still see it in the LCD. It is also easy to get apparently 'sharp' bird because the depth of view seems longer and precise adjustment of the scope focussing ring is not necessary. This method is used for birds that are very far away, birds in flight (just to enable me to scope the bird into the LCD easily) or in 'precious' species where I need to take some 'insurance' before trying to record better focussed videos. However, this is the method I avoid because I am usually trying to record very well focussed video. Sometimes, I may also use a combination of the above methods, as mentioned in the table below. Suggested methods for various situations: |
| Situations | Method | Rationale/Comments |
| Stationary bird with no obstruction, dark background | A or C | Easiest situation. Use method A to quickly get some reasonably sharp video. If the bird stays long enough, use method C to get a perfect focus. |
| Partly covered bird or bright background | B | Use this method to avoid camcorder auto-focussing onto branches etc in front of bird or onto the background. |
| Low light situations or using slow shutter | B or C | Use method B if bird is too far for camcorder macro mode. Otherwise, method C is preferred. If the shutter speed is so slow that you always get a blurred video once your hand touches the scope, use method A. |
| Birds in flight | D&A | Preset the scope focus at an appropriate distance and wait for bird to fly into view with method D. Using method D initially will ensure you find the bird more easily although focus is soft. After the bird is scope into the LCD, switch to method A to let camcorder take over for fine focussing. Use the slowest shutter speed possible to avoid motion blurring (usually about 1/300 or 1/425 on SONY models). Do not add any filter or switch in the ND filter so that you can use a smaller aperture for better depth of view. |
| Birds in motion varying distance | A or B | Select A or B depending on whether range of bird motion exceed auto focussing range of the camcorder. |
| Very active birds at close distance | C or A | Possible to use method C due to long depth of view. Otherwise, revert to method A. |
| A very far bird | D | Either use method D or give up! |
| It is important to remember that sharp bird videos are also dependant
on a variety of other factors. These include bird movements relative to
the shutter speed, depth of view (related to distance from bird), light
and atmospheric conditions, quality of lens etc. You need to run through
your mind whether any one of these factors had been operating unfavourably
before concluding that poor focussing is the cause of a blur bird.
Comments sent in by readers:
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