Is the Panasonic 8mm/3.5 worth trying over the Samyang 7.5mm/3.5?

perpetualjon

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I've been having trouble working with my Samyang 7.5mm fisheye lens getting it to be completely in focus. Here's an example of what I've been shooting:
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In using the LCD to focus, it's hard to see when I'm on target. I usually take about 5-10 exposures of every shot slightly varying the focus each time hoping to get just the right amount. However, even that gets dubious results. It gets even harder when I'm dealing with bright sunlight. I got one of these guys to hopefully solve that problem:
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--While it DID help me work in bright sunlight, I found that the resolution of the LCD just didn't let me know if I was in focus or not. When I was able to fill my eye with just the screen, I realized this.

Even considering getting one of these (around $250):
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--But with a screen resolution of just 800x480, I might as well just look at the screen that comes with the camera since I'll still not be able to tell when I'm fully in focus.

So, my next idea is to go with the Panasonic 8mm. It has the same f-stop and I just lose a small amount of wideness compared to my 7.5. Do you think the AF will allow me to work more efficiently and manage to finally get my shots in focus with the least amount of effort? Maybe I'm doing something wrong and just need some help with the procedure of working with a manual fisheye lens...

I'd love to hear your thoughts on this!
 
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I hardly ever focus the lens per shot, rather set it to f8, roll the focus point slightly off infinity and forget about it, allowing the deep depth of field to do its thing. I do enable focus-peaking as a reality check but find I only need to change focus if I'm right on top of something. What f-stop was used for your sample shot?
 

perpetualjon

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I think I was on a f8 or 10 when I did that shot. It was pretty bright out so it may have been up to 11 even. I have a GH3 so I don't get focus-peaking (boo).
 

fmfche

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I think I was on a f8 or 10 when I did that shot. It was pretty bright out so it may have been up to 11 even. I have a GH3 so I don't get focus-peaking (boo).
Usually at about f5.6 or higher you start getting 'stars' from this lens, maybe open and close the aperture a few times while observing from the rear element(easier to see). Sticky aperture blades from rokinon/samyang/bower have been known to happen

example of flare: https://www.flickr.com/photos/89804205@N03/14062057497/

Other than that the advice about infinity/just before works great, just to to be aware if you are getting very close to your subjects (2-3ft)
 

perpetualjon

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I get those flares to the extreme! Here's a couple examples recently:

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Both shot at ISO 125 with either a 1/50 or 1/100 shutter speed. Mind you, I was aiming for a lens flare in the shot and developed the images accordingly.

I looked at the blades of the aperture but they look just fine to me...
 

fmfche

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Ok after I posted I was thinking it was pretty unlikely. Your shots looks pretty good imo!
 

fmfche

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Well thanks!! I guess what bugs me is that all you other contributors have images that are sharp all the way to the edge with the same lens!
Have you done any distortion correction? The first image at the top looks a bit like it. The only other thing I can think of is a decentering issue or another optical lens defect but I don't have the experience to make that judgement

The reason I say this is because in the image with the guy in the camo shirt the building on the far left has an outline.

Take a look at this article for more info: http://www.lensrentals.com/blog/2012/05/testing-for-a-decentered-lens-an-old-technique-gets-a-makeover
 
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I'm thinking there might be something wrong with your lens -- that first shot has very deep DOF in the center of the photo, as you can see with the building and palm tree behind the subject's head, but very quickly defocuses as you move out from the center -- it's really not an edge-loss thing at all. If I didn't know better I'd have expected you to have used some tilt-shift-like post-processing to get that effect.

Maybe you can borrow someone else's lens and compare shots? Or conversely try the same lens on another body?
 

perpetualjon

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Well, unfortunately, that test the link mentions doesn't work on ultra-wide lenses so I can't test it for sure. I AM going to try this lens on my GH2 and see if I get the same result...
 

letsgofishing

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There's definitely something strange going on - I've shot hundreds of images with mine and they are all perfectly sharp. I shot at f5.6 or f8 and focus the lens at just before infinity - works every time...
 

perpetualjon

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Just did a test with a shot in my backyard at f22 with ISO 120 and shutter at 1/30. I'm still getting blurry fringes... Maybe it is the lens after all. I cannot imagine how I would make this image any sharper in settings...

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perpetualjon

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Sigh... Maybe I should just wait until 2015 and pick up a Olympus 7-14 f2.8 pro lens. I'm sure it will kill me in the pocketbook but it may be the perfect wide zoom lens for my kit. It would at least also bring autofocus to the fisheye shots I'm doing now... Hell, if I buy the Panasonic 8mm lens now, I'll probably be more than half way there to buying the new Oly when it comes out.

Then again, I HATE waiting...
 

fmfche

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I would try to warranty it, could definitely be a manufacture issue. Worth the shot over the price of a new lens at least!
 

wjiang

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Heh, with the deep DoF and the keyline focus peaking 'hack' on the E-M5 I've never missed the lack of AF with the Samyang. You should at least try and get a warranty replacement, if you still don't like it you can sell it - I'm sure a good copy will make a decent sale.
 

perpetualjon

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Well, since the lens was purchased back in December of 2012, I'm pretty sure that ship has sailed. Also, through my research, I've learned that this family of brand names (Samyang, Rokinon, ect) are notorious for denying warranty claims, just never getting back to you, or just making it near impossible to find. I have also now read from other users that have had the same problem occur with their wide angle lenses from this same manufacturer. I think I'm going to just try and buy another one (used this time) but I'm really leaning towards the Panasonic 8mm now more than ever...
 
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