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Oly 8mm f1.8 for Astro?

Discussion in 'Astrophotography' started by tradesmith45, Dec 26, 2015.

  1. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    Happy holidays all. I'm considering the new Oly 8 FE for night landscapes. Review sites are reporting significant field curvature, soft edges & CA wide open. Did a FlickR & mu43 search but didn't turn up any examples that could help me understand the performance of this lens. Looks really great stopped down.

    I currently own the Kowa 8.5mm whith is pretty good wide open & the M.Z 12mm f2 also good. Neither are perfect. Want a UWA f2 so I can use not so long exposures for dark foregrounds.

    Any of you shot a MW of similar w/ the the new FE @ f1.8 that you could post or better yet link the RAW in Drop box?

    Thanks!
     
  2. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    I've got the lens but I don't do astrophotography.

    Take a look at the photos I posted here Showcase - Olympus 8mm f1.8 PRO, specifically the first 2 shots. Both are at f/5.6.

    The flower shot was taken at a couple of inches distance. The edges are soft. Part of that is shallow DOF from close distance and part of it is probably field curvature at close range.

    The shot of the clouds and buildings was taken with focus on the clouds if I remember correctly though it may have been on the metal structure directly above. The buildings at the edges are acceptably sharp in my view and there's more detail that can be brought out if you want to but I didn't because it gave an "etched" look to things. I don't notice any problems I'd put down to edge softness or field curvature. I was standing about 20 metres from a street and the closest building, the tall one in the lower right corner, was on the other side of the street. That should give you an idea on distances.

    Sorry I don't have anything at f/1.8. I like my light too much so I need to stop down a bit to get my shots.

    I suspect the landscape elements in your planned MW shots are going to be as far or further away than the buildings in my second image, and not as bright and clear in your images as the buildings are in mine. If that's the case and you can't find problems from the issues you mention in that shot, you're unlikely to find them in the shots you plan on taking. There may be other images in that showcase thread which can give you a better idea of the lens' performance in the areas you ask about.

    As for CA, I always leave the correct CA checkbox ticked as a default in LR.
     
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  3. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    Surprisingly, no replies on this question. Since posting, have found a total of 4 images of the milky way w/ this lens. 2 of those were stacks of 10x+dark frame & show stack alignment problems. The other 2 are linked below. A full size jpg can be downloaded for 1 of these: Starry Night
    Sable Lightshow

    As you can see, there appears to be a bit more fringing than I see w/ the M.Z12mm f2 & modest astigmatism. Not too bad.

    I'd love to hear from others of you using this lens for starry night sky shots.
     
  4. Turbofrog

    Turbofrog Mu-43 Hall of Famer

    Mar 21, 2014
    I love the 7.5mm/3.5 FE for astro-landscape, and I imagine that the 8mm/1.8 is a pretty strict upgrade for that genre. 2 stops more light is massive.

    Remember also that the 12mm/f2 requires a shorter shutter speed (max 20s) to avoid star trailing, whereas you can get away with 30s on the fisheye. That's an extra half stop of light right there, so even if you stop it down to f2 or f2.5 to reduce aberrations, you're still on the level with the 12mm/f2.

    But for me, it all comes down to field of view. 12mm is nowhere near wide enough for astro-landscape for me. Even 11mm isn't wide enough. If you are willing to composite a separate Milky Way shot into the background and just use the foreground as a mask with the sky edited out, that's a different story, and so the narrow FL doesn't matter...but that doesn't feel as right, to me.
     
  5. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    I've similar goals about landscape astro except I really like to have lots of landscape in my images. So yes the 12 is too short except to do night panos. Do lots of those too. The Kowa 8.5 is wide enough (& looks to be sharper & almost no fringing compared to the M.Z8mm FE) but f2.8 requires really long times for dark foreground w/ current m43 sensors if there's only star light on foreground. I've found ISO800 about the max I want to use w/ minutes long exposures & Noise Reduction has to be turned so 2x that time.

    So getting enough exposure on dark land masses w/o impractically long times is pushing me to search for an f2 UWA option. Hence consideration of the f1.8 FE. I'd defish it using the method described by LonleySpeck. I expect I'd use a 2 image capture work flow - shoot the sky ISO1600, 30 sec stopped down to f2.2 & f1.8 for the foreground ISO800, 8 min if no moon.
     
  6. DoofClenas

    DoofClenas Who needs a Mirror!

    943
    Nov 9, 2012
    Traverse City, MI
    Clint
    Completely agree...The 7.5 3.5 is lovely at night, but having that 2 extra stops would be helpful.
     
  7. walter_j

    walter_j Mu-43 Veteran

    364
    Sep 10, 2013
    Hagwilget, B.C., Canada
    Walter
    Is the Kowa 8.5mm good for astro shots? F2.8 isn't very fast, so does anyone use it for astro shots? I'm tempted, but will hold off until I see what Oly has up their sleaves for fast primes.
     
  8. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    Yes Walter, it's pretty good for Astro. I've posted a bunch of images from it here. Here you can find several Aurora shot/ made w/ the Kowa: Best Aurora & Landscapes from Tombstone Trip

    The Kowa has some weakess in the extreme corners @ f2.8 but is very good every where else - very little CA or distortion. It's lighter than the 7-14 Pro & will hold screw in 67mm filters.

    Also did a mini review here
    Kowa Prominar 8.5mm vs. M.Z 12, 17, 9-18mm for Astro

    Be great if Oly made a fast UWA prime! But since fast for UWA is f2, I don't expect we'll see any f1.2 UWA.

     
  9. RKStarr

    RKStarr Mu-43 Regular

    Here is a (very rough and SOOC) image of Orion with my brand spanking new O8mm 1.8. I took a few test images which proved the lens to be promising for wide field astrophotography. This EM5/2 image is 60sec at f1.8 iso1600. Seeing was not ideal and moisture in the lower atmosphere was severe, as you can tell. This was a "sucker hole", ie.; a small break between more-or-less incessant clouds.

    I'll post more as conditions permit, but I thought you might find this rudimentary attempt as encouraging as I do with respect to the Oly 8mm lens.

    Cheers

    20160104-32-2.
     
    Last edited: Jan 9, 2016
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  10. wjiang

    wjiang Mu-43 Hall of Famer

    Hmm looks good just like the 7.5FE with more light and less noise!
     
  11. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    Thanks a bunch for posting this. Any chance you could put the RAW in Drop box so I could take a closer look? Not sure but the only color I'm seeing is maybe a bit of fringing in the corners. Is that right? Or is the Orion gas cloud visible once you steepen the tone curve?

     
  12. Turbofrog

    Turbofrog Mu-43 Hall of Famer

    Mar 21, 2014
    Looks pretty
    Seems to have nice resolution and quality considering the testing conditions!

    If you are doing astro and want to avoid star trailing, it does look like you will need to shoot at 1/30s, since the effect of motion blur does change the perception of sharpness in the stars. Still, that means that you can away with just ISO 3200 even on a hazy night. With a couple stacked images at ISO 3200 or even 1600, this looks like it will be a beast for landscape astro.

    Lenstip's review of the 8mm/1.8 was also very favourable. I was especially impressed by the lack of coma or other aberrations. Really a remarkable lens design when you think of it.
     
  13. RKStarr

    RKStarr Mu-43 Regular

    You're welcome.

    I took two 60 sec images that evening, and the other one is slightly better focus (and 800iso) Here is its .orf file:

    Dropbox - 20160104-33.ORF

    Please be aware that any strengths this rough image may exhibit are due to the EM5/2 and 8mm1.8, and any deficiencies are my own. I shy away from reading and posting "first images" or "first impressions" since those types of topics usually point towards operator deficiencies more than hardware strengths. Such is most assuredly the case here.

    And yes a 30 second image (or several) would have exhibited very little if any trailing, but my intent during this brief cloudless stretch under marginal seeing conditions was to get a sense of what an aperture of 1.8 could yield, not to make any keeper milkyway image. With any luck those will come in time.

    I am puzzled by what appear to be faint circular bands of purple with a center toward the upper left that appear as the image is pushed to any degree. Both 800 and 1600 iso images exhibit this. I was reminded of my disastrous attempts at night sky images with early panasonic sensors. If anyone has any thoughts I would love to hear them. In any case I will try this lens again at the next opportunity on both the em5/2 and em1.

    Other than that the only grumble I have with this lens (and I've had it less than a week so far) is the lack of focus clutch, as is found on the other pro lenses. Maintaining focus on stars would be a snap (*ahem*) if one could snap the focus ring to manual once sharp focus was achieved.
     
  14. walter_j

    walter_j Mu-43 Veteran

    364
    Sep 10, 2013
    Hagwilget, B.C., Canada
    Walter
    It isn't obvious that its a FE lens in vertical orientation. As for the circular bands, did you check the sensor for dirt? Or could it be flare from the side light? Thanks for posting. I'll keep an eye out for more shots from this lens.
     
  15. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    Thanks you so much! This is really helpful.

    I processed this in LRCC (6.1) which uses ACR 9.3. Even after applying modest tone curve adjustments & increased Vibrance, I see no faint circular bands of purple. Good news!

    Yes 60 sec. is long enough to yield visible star trails. But the image still demonstrates the lens is sharp @ f1.8 out to the edges. Fringing is there but mild & easily corrected in LR.

    Here's what I got.
    24024549020_fc0234859f_o. 20160104-33.jpg by tradesmith45, on Flickr

    Yes, I suspect this lens is hard to focus given it very wide angle. On my MZ 12mm f2, even w/ a clutch, its hard. I tested it in the day & discovered the focus by wire gave me only a single position where infinity focus was achieved. It appears the stepping motors use large enough steps that only one will work. So I use a fine tip black paint pen to mark the exact location where infinity focus occurs. The mark will ware off over time but its easy to reapply.

    Have you seen the tutorial over at Lonely Speck on a way to defuse w/o loosing so much of the AOV of an FE?
    The Best Method of Defishing a Fisheye Photo

    Thanks again.

    PS, oops, forgot to tun off the copyright watermark, sorry. This image is yours!


     
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