Instruction: Generate an answer to the question by utilizing the information contained in the document.

Input:
Question: this is manual focus i presume, i didnt read everything lol, but will this work with the nikon D3100? how hard is it to focus? i have a 50mm, its hard
Document: From reading the other reviews, it seems like it is important to reiterate that this is a manual focus and manual aperture control lens. The mount is Canon EF-S compatible. You may need to read your camera manual to understand how to use the lens.Don't let the manual focus scare you too much. Using an 8 mm focal length lens, stopped down to f/11 or so, on a crop sensor camera, you can get everything in focus from 1 foot to infinity.
Pros:PriceGreat build quality for priceSharp at smaller AperturesGreat control of flaringFUN!Cons:Manual Focus, and no fucus confirmManual AperturePermanent HoodSoft below F5.6ishNotes:With no focus confirm, it's sometimes hard to tell through the viewfinder if you hit the mark, but almost everything you'll do with this lens will be focused to infinity or staged, so not really THAT much of an issue IMHO.For an amateur photographers with APS-C cameras, this is a great alternative to the Canon or Sigma fisheyes.
I use this on my Nikon D300 and it performs wonderfully, taking sharp photos with that unique fisheye look. The manual focus isn't an issue when I set the focus to infinite and unless I'm touching the lens to something, everything is sharp. The only downside is no little white dot to help when putting the lens on the camera body.
I have a Nikon d90 and its a manual focus with this lens. I thought it would honestly work a little better with my camera. There is nothing wrong with my camera and it will only work on the "m" stage. Other wise it will say "F--"
I'm returning this lens. Before I drop my review, some basic info: this lens will NOT auto-focus, that's a given. If you have a Nikon D90, it will NOT auto-meter. You'll have to put your camera on M mode and go fully manual. Also, you don't need to put the aperture at f/22 like other D lenses; you will need to use the aperture ring when metering. Everything will be in focus if you set your focus distance at 1 ft.
I love this lens!!!!! !People who complain that this doesn't auto-focus or work with aperture priority mode need to read the description and better understand their cameras, this lens isn't meant to do either.What it is meant to do is be a dirt cheap alternative to name brand fish-eyes.
This lens has a great feel and looks like a quality lens. I had a hard time getting pictures to focus. I did some research, most sites say you need to adjust the calibration. I didnt want to mess with it. Sold it.
this lens is amazing. perfect for skateboard filming/photography. the one and only downside is that its hard to focus because everything is so far away. great built quality. buy this lens! !
I love this lens for the viewing angle. If you want straight lines you need to keep the subject in the middle of the frame or it will warp, the all manual control is hard to work with an automatic camera. I find myself guessing and taking more shots because there is no light meter in the middle of my screen like how 35mm cameras have. Once you get your shutter / ap set it takes awesome photos! Wish it was more automatic but good photography is not easy.
I have a D3100 and wondered if the metering on my camera would work with this lens. I understand that it wouldn't on the D3000 but wasn't sure about the D3100. Any help would be appreciated.Sorry if this is a stupid question, I'm new to the world of SLR's and looked everywhere for this info but was unable to find it.
Answer: Yes, it is manual,yes it will be very easy to focus with it. (Basically, you just use the higher f-stop number, and everything is in focus = you do not need to focus it at all).And yes, it will fit D3100.PS. Read more :)