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IQ of defished Sammy 7.5 images

Discussion in 'Native Lenses' started by pdk42, Feb 23, 2014.

  1. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    I know there are lots of threads on de-fishing the Sammy 7.5, but I couldn't find one that looked at the IQ of defished images that have been cropped to match equivalent rectilinear lenses. So, I thought I'd do a few experiments - nothing too rigorous, but I did draw some conclusions from it, so thought I'd post it for anyone else who's interested.

    The Objective
    To see how corner resolution is effected when Sammy 7.5mm FE images are de-fished to a rectilinear projection and then cropped to suit equivalent rectilinear lenses.

    Setup
    I used an E-M5 mounted on a tripod and took a shot of the inside of my conservatory on a sunny winter's day (excuse the mess!!). I took shots at f5.6 with the Sammy and the Oly 9-18 @ 9mm for comparison. The focus point was on the far wall, a distance of approx 4m away. I then defished the Sammy image using a Rokinon-specific profile in Lightroom that I was created by user "kenw" on DPR. The profiles can be found on this thread:


    Aside from de-fishing, the Sammy image has a minor WB change to match the Oly shot and a -0.25EV correction (again, to match the Oly lens). Other than that, there are no other changes in LR.

    Original Images

    Oly 9-18. 1/350th @f5.6
    Oly9-18.

    Sammy 7.5. 1/500th @f5.6
    RokFish.

    Defished and Cropped Images

    I then defished and cropped the Sammy image to various fields of view as follows:

    9mm (approx 90 degrees horizontal FOV):
    RokDefish9.

    7mm (approx 105 degrees horizontal FOV):
    RokDefish7.

    6mm (approx 115 degrees horizontal FOV):
    RokDefish6.

    The focal length equivalences are fairly approximate since the actual FOV will depend on the exact mathematical projection in use - and rectilinear lenses at these focal lengths will not be perfect projections. However, I think it's close enough for a quick comparison. Note that the uncropped horizontal FOV of the Sammy lens is about 132 degrees, but I didn't examine that since the defishing results in extremely wide images with significant smearing at the edges that is beyond what most would consider acceptable.

    Comparison of corner sharpness

    The following shows a 100% crop area near the bottom right hand corner in each of the images. Note that the size of the objects in the Sammy images are smaller since they are identical scale crops from an image with a larger field of view (so things look smaller!)

    Sharpness Comparison:
    RokCropComparison.

    To remove the magnification effects, I downsized the Oly 9-18 shot so that it matched that of the Sammy. Here is the comparison:

    Scaled comparison of Oly and Defished Sammy at 9mm
    9ScaleCompare.


    It can't be said that any of the corners are super sharp, but I think that the Rok defished images are actually pretty good - certainly no worse than the 9-18, even at a focal length approaching that of a 6mm equiv prime. Until my craving for a nice native 7 or 8mm prime is satisfied, I'm fairly happy that the defished Rok delivers, albeit with some extra time in PP.
     
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  2. broncophil

    broncophil Mu-43 Veteran

    243
    May 23, 2010
    thanks, i literally just got this lens this morning.

    do you know how i can add the profile to LR on my Mac Mini?
     
  3. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    You need to go to the directory where LR keeps local lens profiles. On Windows, it's here:

    C:\Users\[your username]\AppData\Roaming\Adobe\CameraRaw\LensProfiles\1.0\Downloaded

    I think on a Mac it's something like this:

    Macintosh HD /Users/[your username]/Library/Application Support/Adobe/CameraRaw/LensProfiles/1.0/Downloaded

    You'll have to do some fishing (no pun intended!).

    Once you've found it, just copy the .lcp files there and re-start LR. You'll then see the profiles in the LR panel:

    LRPanel.

    Oh - another thing, LR uses different profiles for raw and JPG files. So, you should download the profiles from here instead - this has JPG and raw versions:

    https://www.dropbox.com/s/yxb469wib0ceijr/fisheye_profiles.zip
     
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  4. Ricoh

    Ricoh Mu-43 Top Veteran

    906
    Nov 2, 2013
    UK
    Steve
    Excellent work Paul. I was actually on the hunt for a second hand wide angle, but seeing the comparison here, it has caused me to hit the pause button.
     
  5. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    The Sammy 7.5 is an amazing lens. Great sharpness, excellent colours and contrast, good build quality and not too expensive either. You can't lose really. Buy it used and even if you don't like it, you'll be able to offload it without losing anything - look on it as a rental!
     
  6. timg

    timg Mu-43 Regular

    74
    Jun 13, 2012
    Thanks for that Paul... Certainly food for thought, I've beed seriously considering swapping my 9-18mm+14-42mm for the panny 12-32mm+Samyang.

    Out of interest, what are the dimensions of the 9mm, 7mm and 6mm crops (just wondering how many pixels you lose)? Also, did you take a shot with the 9-18mm at a smaller aperture to compare to?
     
  7. Rasmus

    Rasmus Mu-43 Top Veteran

    656
    Nov 16, 2013
    Stockholm, Sweden.
    Interesting, I should try this myself, my Samyang spends most of the time in the bag. Corners at 9mm look rather sharp, at 7mm they look less so and at 6mm the smearing is rather visible.
     
  8. Rasmus

    Rasmus Mu-43 Top Veteran

    656
    Nov 16, 2013
    Stockholm, Sweden.
    By the way, could you please post some 100 % crops of those tree branches near the upper left corner? One of my pet dislikes about my wide angles is how they render fine branches on trees, especielly near the corners, they tend to look all smeared out and fuzzy.
     
  9. arch stanton

    arch stanton Mu-43 Veteran

    411
    Feb 25, 2012
    London
    Malc
    Big thanks - I absolutely love this lens for the great outdoors!
    How do you find the profiles you posted above vs the Nikon fisheye profiles? I use the 10.5mm one as a quick de-fish and slide the amount about to see how much fisheye works best - which varies from image to image.
     
  10. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    I've never used the Nikon profile, so I don't know, sorry. I have used the Sigma 8.5 profile though, and they are very similar.
     
  11. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    Tell you what - here are links to the raw files. You can do your own pixel peeping if you wish! Remember though that the trees are behind glass, so probably not a fair comparison.

    Oly 9-18
    Samyang 7.5

    You might need to right-click on the links and then do "Save As".
     
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  12. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    You can get an idea of the cropping from the non-fished image. Sorry, don't have the pixel sizes to hand (on my other computer!). Both shots were at f5.6. I also took shots at f8, but TBH, there is very little difference between them.
     
  13. RevBob

    RevBob Super Moderator

    Jun 4, 2011
    NorthWestern PA
    Bob
    I really like this little lens and tests like this just confirm it's quality. Rokinon makes some decent quality, reasonably priced lenses.
     
  14. wjiang

    wjiang Mu-43 Hall of Famer

    Thanks so much for doing this test and for providing the RAW! I've been dithering about getting something wider than 12mm for a long time now. I was always tempted by the Samyang fish-eye, but everybody said that if you were going to de-fish you might as well get a proper UWA. I was about to buy a used 9-18mm, but your test shows that I would lose absolutely nothing IQ-wise by de-fishing the Samyang. I've confirmed myself by de-fishing and pixel peeping with the RAW - the results are still sharper than I get with the O12-50, and although there is some minor C/A, it is much less than the 12-50 gives. It was quite nice to be able to play with the RAW and experiment with de-fishing using Hugin - it gives me much greater confidence about the versatility of a fish-eye. I actually found a General Panini projection with (50, 0, -70) to work quite well with this image - it leaves some barrel distortion (the verticals are straight though), but the overall view is no longer fish-bowl like and it preserves corner sharpness much better.

    Any tips on fish-eye composition with/without de-fishing in mind? I know of the trick to keep the horizon centred when keeping the fish-eye look, how relevant do you find this when de-fishing, taking the different projections into account?
     
  15. timg

    timg Mu-43 Regular

    74
    Jun 13, 2012
    Thanks for the RAW files! Going to have a play with those later :biggrin:
     
  16. arch stanton

    arch stanton Mu-43 Veteran

    411
    Feb 25, 2012
    London
    Malc
    I'm by *no* means good at this but I'm starting to get results I like - you really have to play about, and it's great fun :)
    The perspective suits spaces with circles in them really well, I have one of a circular Casino in Macao I love - I'm about 15 feet away and the perspective really improves the photo.
    As you say, keeping the horizon central minimises the fisheye effect, you can then crop to 3:2 for a nice landscape format and use the crop to move the horizon.
    De-fishing works well, LR lets you choose an "amount" of de-fish and I usually find myself leaving some fisheye in the perspective, my eye just prefers it. This probably looks like the Panini that leaves in some of the curved lines.
    I've recently found the horizon distortion can suit some scenes really well - I took one in the mountains a couple of weeks ago with a high, very curved horizon. I intended to de-fish but it gives a "little planet" effect that accenturates the height of the shot.
    I can post pics if people want - don't want to highjack the thread!
     
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  17. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Even if you have an UWA, a true fisheye is still wider and can be very useful.

    I occasionally do real estate photography, with the 4/3 Olympus 8mm fisheye and the 4/3 7-14mm.
    For small rooms, the 8mm FE can get close to full-room shots, whereas the 7-14mm cannot, even after de-fishing.

    Barry
     
  18. Curley

    Curley Mu-43 Regular

    Agreed. The fisheye can do what the UWA can do (with defishing), but the UWA can't do what the fisheye can do.

    That's why I'm about to sell my Oly 9-18 and keep the Rokinon 7.5mm fisheye. Since I got the fisheye and Oly 12-40, I never use the 9-18.

    But in addition to its great flexibility and sharpness, the Rokinon also delivers wonderfully vibrant colors.
     
  19. evilnim

    evilnim Mu-43 Veteran

    201
    Mar 27, 2012
    Birmingham
    Hey all.

    Sorry to resurrect an older thread, but I'd be grateful for a little help if anyone can provide....

    I've been reading all about the 7.5mm fisheye over the last few weeks, and am close to pulling the trigger. This thread has almost tipped me over the edge, as I've currently got the 9-18, but really want something a little different and a little wider. The 7-14mm is the obvious choice but for the price and the purple flare potential on my EM-5 (I'm aware not everyone has issues with that though). So I've turned to the Sammy.

    I like the fisheye look, and have never shot with one before. In terms of rectilinear adjustments, I thought I'd give the defishing profiles a shot in LR5 before buying with the (very kindly provided) raw file in this thread to see how I could manage it in my workflow, as it would be ace to get both fisheye and UWA use out of this nifty little lens.

    This, however, is where I've run into problems. I've scoured the threads here and on dpreview where kenw originally posted his profiles. I've downloaded the .lcp files and stuck them in the below folder in my mac first without a folder, then inside a new 'Samyang' folder.

    Macintosh HD /Users/[your username]/Library/Application Support/Adobe/CameraRaw/LensProfiles/1.0/Downloaded

    When I open up the develop module, I don't see the Samyang profile option, nor do I see a 'Panasonic' option. I've closed LR down and restarted it, and am now totally stuck.

    Appreciate that no-one may be able to solve this from afar, but thought I'd throw it out there and see what happens....

    Many thanks in advance.

    N
     
  20. evilnim

    evilnim Mu-43 Veteran

    201
    Mar 27, 2012
    Birmingham
    Sorted! Found the solution thanks to kenw pointing me in the right direction. Got a lot to thank him for!

    For anyone else who is struggling to install the lens profiles into LR 5.3 on a Mac running Mavericks, there is a secret 'Library' folder, only accessible by opening a finder window, and selecting 'Go -> Go to folder -> ~/Library/Application Support. Then follow the standard instructions to create a 'Downloaded' folder in '1.0' and stick the .lcp files in there.

    Love it