C&P from another post in 'Beginners' about UWA that detracted into fish, that may be worth noting here:-
I love my fish.. bit of an acquired taste, and needs very careful cooking; but still; can be a lot of fun.
I have two; first I've had for many years, a 12mm Panomar branded Sigma; the 'affordable hobby' fish of the '70's. It's fixed focus, relying on that short focal length and conservative, I think its, fastest aperture is f8, to give huge DoF to save complexity of a fine-focus helix; does make me wonder why any-one wold be too concerned about having 'focus' let alone auto-focus on a fish. Originally on an OM mount; later re-mounted to M42 for 35mm film cameras; it kept me from making the leap to digital for a very long time; Meanwhile Small-Sensor digital seems to have made horter focal lengths and UWA lenses more commonly available and more popular; anything much under 28mm for film was rare and usually damned expensive, and fish were even rarer. Anyway; making the leap to electric picture maker couple of years back with a D3200, which I chose over the D3100, with a mind towards fish.. I treated myself earlier this year to the
Sigma 4.5mm 'Full-Round' for DX. Maily because twenty odd years with the 12mm I felt I was never getting the 'real-deal', with a mere 170 degree diagonal angle of view and cropped circle images.
Not unfamiliar with most fishy quirks.. its still taking QUITE a lot of getting used to... A few intial observations:-
1/ you get a circular image in the middle of the frame (obviously!) But, means you are only 'using' about a third the frame, of both view-finder AND the sensor. 6,000 x 4,000 pixie image crops to about 3,200 x 3,200 pixie 'square' around the image circle; the image only using..err. (excuse me while I go try remember my O-Level maths!) 8,043,520 pixels.. THINK! in the middle of that, about 1/3 of available; the rest of the frame black..... This bit of maths was what prompted me to get the higher, 24Mpix sensor D3200 over the 16Mpix D3100.. What I DIDN'T consider though was the viewfinder... fish-eyes make stuff SMALL very quickly as they go away from the lens; and if you are trying to peer at them through a smaller view-finder, and the image is only taking up a EVEN smaller part of that? Paying attention to what's in the frame and any 'critical' detail can be VERY hard...
2/ That 180 in all directions field of view... FANTASTIC; for five minutes I felt I had discovered all that the 12mm fish had been missing..... then it started becoming a 'chore'!.. remember what I just said about how hard it is to see small detail? Y-e-s.. so, imagine a black camera strap 'just' at the edge of the frame.... a very BLACK frame.. not till you get the pictures off the card a up on a 17" monitor do you notice that the edge of the frame isn't.. the side is your black camera strap in shot, the bottom, my black bike jacket and my black biker boots... Hint,, get a yellow strap and wear Hi-Vis / Day-Glo! (Do they do day-glo dockers? Could be Useful!)
3/ SO, the view-finder image is tiny and dark.. lets use the back-screen.. that's bigger and brighter, AND holding the camera further from your body.. you might not get so many unwanted bits in the periphery.... only now you are holding the camera at arms length and still squinting to see small detail on the screen, it's not a whole lot easier!
4/ Distortion.. I had a good idea what to expect from years with the 12mm.. and again, going full-round, I felt I was getting it in full measure; more of it across more of the frame, what I DIDN'T imagine though was JUST how much more 'critical' framing FOR distortion would become...
This is my uncle's tea-rooms*.. & having the lens in the bag when I dropped in on the way back from a classic bike scramble, thought I'd try it out on some more 'interesting' interior architecture.. pretty nice demo actually....
This was shot from the balcony over the main dining room, and I managed to get the horizontal beams pretty much dead centre, and the balcony's A-Frame cross beam slap on the bottom of the frame; I THOUGHT I was pretty much spot on centre of the room too and dead square.. but if you look I am off a bit, and the straight beam has't curved with the frame.
EXACTLY the same view-point, but camera tilted down only what, 10 degrees? TOTALLY changed the perspectives. In the first shot, a lot remained straight; in the second, almost NOTHING has stayed straight, everything has been bowed. They are two totally different photo's; but to get the different effects you have to be SO careful in framing, which as mentioned is difficult to begin with because of how much is crammed into such a reduced area.
5/ Exposure - Floor to ceiling wall to wall field of view; cramming SO much into the frame; the exposure range is usually huge; out-doors back to the sun, you can only turn maybe 30 degrees either way before you get direct sun on the lens; if you do manage to keep it behind you, though you still get every strong highlight glaring back at you, its nie on impossible to avoid hot-spots; and you have the same problem the other end with shadow & shadow detail.
With the 12mm on film cameras; this was always a pain. I had OM10 and OM4 bodies. OM10 had for its day, pretty good Centre-Weighted-Average metering, which was, for the most part, pretty reliable with most 'normal' lenses. The fish? Well, the CWA sample area was huge! So huge it was almost useless. As earlier comment about the change in perspective from a fairly small change of angle; tip the lens up a fraction and more sky would send the shutter speed up three stops, tip it down, cut out a little sky add a little shadow, would come down three! Six stop 'range' of suggested settings? WHAT do you pick? OM4 had very elaborate, for its era 'multi-spot' metering system; but, again, with such a large FoV, a 'spot' sample was covering as much scene as a CWA reading from a more normal angle lens; and being able to average multiple spot samples, only highlighted WHY the metering system was struggling.... in the end, I resorted to taking grey-card readings or spotting off paving slabs and stuff through another lens, or working to f/16 sunny! Which was one of the reasons I eventually re-mounted to M42.. to use either on a meter less Zenith or my Sigma Mk1 Richoc 'copy', with non-coupled TTL meter.
This then remains a point of interest to me, with the 4.5 full round on the D3200; and just how much 'smarter' or more precisely, 'reliable' modern 'evaluative' matrix' multi-spot metering may be, when similarly challenged? So far, which isn't very, I have to say, it does seem to be coping PRETTY well.. I haven't resorted to metering through another lens yet, which has to be 'good'!But for any-one unfamiliar with UWA and fish, it is worth noting, with the likely contrast range one will grab; it is very worth while paying attention to metering and being sceptical of cameras suggested settings.
6/ Fringing & flare - above pics have quite noticeable blue-fringes... er.. they're there; that's about all I can say about it! Its a true-fish lens, with bow front; you cant use front of lens filters or a hood, without intruding into the Field of view. Supplied lens cap, though is a two-piece job, push on metal ring, that slides over the lens body, with a conventional 72mm pinch-grip cap in the end. Remove only the pinch cap, the rig acts as a hood shielding the edge of the lens; but masking about 5 degree of view either side; you loose a little field of view and the fringes, and 'might' avoid a little flare; but as spot-lights pic; its going to be there on any hot-spot.
SO! while not completely new to fish; they are tricky, and going the whole hog, VERY tricky to get the best from. And far ore demanding than I expected. The 12mm, was 'relatively' tolerant to use.
If I knew then what I knew now? Well? 4.5mm is expensive.. and having stumped up for it; it DOES now make me question whether I would have been better to go the whole hog and go for an 8mm on a full-frame body... would have given me the full-round 180 FoV, and hopefully larger, brighter view-finder and or screen to help make framing easier; plus better potential selection of 8mm lenses; BIG chunk of cash to chuck at the job though; 8mm on crop, with a view to going Full-Frame with it? COULD be a good compromise to dive into the fish-pond; the cropped circle would make the masking issue less severe, and it would deliver a lot of fishy-flavour, as I had with the 12 on film; but wouldn't have take ME forwards, it would have merely begged the Full-Frame body.. so actually.. for ME, I think it wasn't such a bad choice. For other's? Well, its all compromise; and a 8mm on Crop could offer enough fishyness to explore their quirks and start experimenting with one; but you'd possibly feel you did't get it all ad want the full-fish, as I did.. which you'd all ready have, but only on a full-frame body. the 10's & 11's on a Crop sensor, I believe give full sensor coverage, and as such are more of a coventional UWA, with poor rectiliniar correction, than a 'fish', which may be good for packing in big scenes, but not really for exploring fish-effects.. offer more possibility on a full-frame body.. but, even there, while a little ore fishy than my old 12mm Panomar, they are still cropped-circle fish with just a bit more FoV on the diagonal.
Which begs some pondering; and the first conclusion, or at least strong suggestion IS if you want to get serious about UWA or Fish-Eye... you'd do well to get serious and go Full-Frame before you start! The bigger sensor makes any focal length effectively 'wider' (well, apart from the 4.5!.. at 8mm, you are getting the full circle on the sensor, so anything shorter just means a smaller circle!) So you don't have to chase SUCH short focal lengths to get as much FoV.
But full-frame cameras aren't cheap. And you can still get a lot of fish with a crop; you have to get down to 8mm to really start seeing it; but the Sanyang 8m is 'only' £250 ish retail, new. Compares to my old Panomar 12mm on film, while having such modern features as an actual focus control and wider range of apertures; and could offer the full-Monty of full-round on a full-frame if you upgraded later. The full-monty for DX is only available (at the moment) from the Auto-Focus and fairly fast f2.8 max aperture Sigma 4.5mm, retailing new at around £550. Its still 'cheaper' than going 'full-frame' and an equivalent grade 8mm. BUT it IS very fishy, and they are tricky to 'learn', as I'm fidig with 20 years of the 12 as preparation! Suggestig that an 8m is probably a pretty good compromise ad place to start for most.
On to;
Lens-Correction & De-Fishing; I am possibly repeating a lot of 'fishing ground' covered in the tutorial;
Understanding Fisheye lenses
, however; My Daughter sat watching tidy up some fish-shots from film yesterday and asked,
"WHY, use a Fish Lens only to take away the Fishiness?"
Its a VERY valid question.... its NOT an ultra-wide angle lens, it is a fish; if you didn't want fish, why didn't you use a rectilinear UWA in the first place?
Well; before Digital, reason was I didn't have an 'normal' UWA! As said anything wider than 28 was rare and tended to be expensive; might have bee lucky to find the odd 24, but that was about it.. and we did't have digital dark-room to stitch panoramas! These days, in digtal, little excuse. You want fish, use fish; you no want fish, no use fish!
Old fashioned way of 'de-fishing' was to crop, which was literally taking a pair of scissors to the print! (Or cranking up the head and dong a sectional enlargement in the dark-room) Loosing a lot of fishiness around the edges and getting something more akin to a UWA from the middle. Still as valid a way about it as any.. but, back to earlier comment about fish wasting available pixel resolution; you are already down to 1/3 of the pixels the camera could deliver; take a square out the middle of the image circle, as big as you can without getting any vignette left in the corers, and you are down to 2,200 by 2,200, less than 5Mpix from the 24Mpix the camera had available to start with! almost down to 1/5th from 1/3rd.
Fish-Eye Hemi? - It doesn't do a full rectilinear conversion; it only straightens on one axis, if I remember correctly. I down-loaded the trial version and tried it on a bunch of scanned film shots a few years ago, and unfortunately I have no hemi'd & unhemi'd versions of the same photo hosted anywhere to offer comparison; and demo went west log ago when I got a new PC, and not been able to get a 'new' demo working on my new one! Which is a pitty. Would like to give it ather go with some of the full-rounds.
Photo-Shop 'Lens Correction Filter'.. on the cropped circle scans, there's obviously no EXIF data to give it a correction profile to use; trying to force a profile on it gave some WEIRD results, though! I thought that was just 'cos it was a film scan though. Putting full-rounds from the 4.5 through it, though, it does pull profile from EXIF, BUT.. absolutely bludy HORRIBLE! It takes a ruddy great crop, to start with, then stretches the corners, and distorts EVERY-bludy thing! You can mess with the sliders to 'tune' the distortion, but SO FAR all I have managed to do, is get either square pictures that look like they were taken in hall of mirrors, or very soft 'crops' I could have got better just using the crop tool! Pre-Cropping the image circle to a square; game more promising results, didn't stretch the bottom of the circle out all the way to the edge of the original image frame.. b-u-t.. then over-corrected in the middle, giving a sort of 'reverse' fish distortion!
So, for me, at least, its back to the beginning, and either presenting 'as shot'; begging I get to grips with this tricky to use lens, and apply some pretty diligent 'clean in camera' discipline to get presentable round images straight from camera... or copping out by cropping out.... OR NOT using fish in the first-place, if I don't want fish!
And THAT I think Is probably the bottom line; if you want wide, go wide, and if you have to compromise on width to keep scenes looking 'normal', compromise the width... and having been hungry for FoV for SO may years.. I am starting to think that 'actually' that 'problem' of getting anything wider than a 28 on film, probably wasn't SUCH a bad thing! so 18 on a Digi-Crop, probably not far off as wide as you can practically and frequently use.... going through sets taken with a 28 on film, scanned and now actually seeing what is in the full-frame (2x3 ratio negs were almost always cropped when commercially processed to 5x7 prints), and how much detracting detail has 'cluttered' even those fairly conservative wide-angle shots; and I THOUGHT I was reasonably diligent at corner checking! Contemporary digi-pics, not a LOT different, and again, on review, I'm chucking or cropping over cluttered shots, or trying to clone out distractions, like dog walkers in Day-Glo! There's a lot to be said for keeping it 'tight', keeping it 'simple'and concentrating the viewers attention on the selected 'interest'.... but still all part of the great adventure that is photography!
Uncle's Tea-Rooms*; going to offer a cheeky plug! Its The Cow-Shed, Yew-Tree Craft Centre, Wooton-Wowen, Warwickshire (just off A3400 Birmingham-Stratford Road) He deserves it; I turned up on a big black motorbike, in black leather jacket & jeans, all likely to scare the natives, and he STILL gave me and my daughter a cup of coffee and some chocolate cake! And I'm NOT just saying this cos he's 'family', It was exceedingly GOOD cake, and exceptionally GOOD coffee! While his menu... having just been ripped off to the tune of £15 for two trays of chips and sausage and a couple of cans of pop at the classic bike thing, made me want to CRY!
