Stephen
Lifetime Member
Still collecting.......
Posts: 2,718
|
Post by Stephen on May 12, 2014 9:35:21 GMT -5
Earlier reply mentioned distortion, and despite being able to remove both barrel and pincushion, all the digital methods do leave some other distortion, stretched edges and non linear effects across the image, small figures at the end of a row taken with a wide angle lens will be nearer correct height, but may be wider than they should be!
Buildings proportions may alter after "correction", but look OK due to losing the distortion from the lens.
One type of extreme fish eye you cannot correct is a sky upwards shot. Most level mild fish eye landscapes that are not too extreme are correctable, but will still have proportional problems, not too mention soft edges due to stretching.
Stephen
|
|
|
Post by philbirch on May 12, 2014 9:40:39 GMT -5
wow, this needs a good looking at. Thanks for this info.
|
|
daveh
Lifetime Member
Posts: 4,696
|
Post by daveh on May 12, 2014 11:12:03 GMT -5
Our eyes distort objects but our brain is very clever at seeing scenes as normal. If you hang upside down long enough your brain will turn the scene so it's the right way round (although it's not quite "as easy as that"). The camera isn't so clever and it records things by much more straightforward principles of physics. If you pan your head the brain stitches the scene as it goes. Mind you cameras are starting to be able to do that. In a sense everything is correctable in the software, but the result often becomes so distorted in itself that it becomes even less acceptable than the original distortion. It seems to me that the whole point of a fish-eye lens is to give a fish-eye view. Perhaps you recall this photo, which was adjusted to take out the distortion of the buildings. At the same time, as a simple manipulation, it elongated the bus. However much of that elongation can be eliminated. It just takes time to find the best way, or ways, of doing everything to end up with the desired result. Uncorrected original:
|
|
Stephen
Lifetime Member
Still collecting.......
Posts: 2,718
|
Post by Stephen on May 12, 2014 17:02:27 GMT -5
Most of the interest in these corrections for fish eye through barrel distortion, is from the 4/3 micro digital formats and larger, like Sony, where CCTV short focal length C mount lens are used, via mount convertors.
Most of the cheaper ones barely cover the micro 4/3 sensor, let alone give a "true" image, and corrections via the Gimp or Photoshop are needed to un-scramble the barrel distortion, and in the Gimp, smooth out the exposure differences between the centre and the edge with the same add-on.
The attraction of these CCTV lenses is the cheap price, the sharpness is usually good, but they distort, especially on 17mm equivalents or wider.
Stephen.
|
|
Stephen
Lifetime Member
Still collecting.......
Posts: 2,718
|
Post by Stephen on May 14, 2014 15:41:18 GMT -5
Not quite so unexpected, the three NP-80 batteries that came with the bargain Fuji Finepix 4900z are date expired, one works, but the other two are 12+ years old now, pre-dating the Fuji camera, when they were fitted to Leica cameras.
One battery has no response from the mains charger, the other takes a small charge and might recover a bit with use. The original Fuji version works, but about half charge by estimate, but might improve with a bit of "working".
I have ordered one new battery from Ebay, I will get more after proving out the camera is fully working. No point in wasting money if the camera proves dud in any way.
I might try controlled pulse charging of the batteries, it works with Ni-cads, etc., it has to be carefully done with Lithium batteries. They are charged with 50 hz DC pulses at the RMS value of the normal charge, or a little more, keeping under the max current usually used, with a meter in line to check. Then discharged with a resistive load, and charged again for several cycles.
The Smartmedia memory cards all works fine, two 128meg, and one 16meg, miss labeled, so even better value, 128meg smartmedia second hand are now expensive, and new even more! I tried Recova on the cards, but they had been wiped beyond formatting standard, so no old images on the cards! They had some recovered frame numbers, but in a format that the Fuji does not use, perhaps the cards were used in another camera. I then used a total wipe program myself and formatted them, 100% clean operation.
Looking forward to a full try out over the weekend, as long as the battery holds up!
Stephen
|
|