Manual lens taking blurry shots at infinity

The Darkroom

Hi, I've got a manual 14mm Samyang. When I take shots with small apertures like f/16 it's sharp when done up closest to the subject.

When the focus ring is all the way to infinity and I'm at the same apertures or larger like f/8 the entire scene is blurry.

Does anyone here have experience with this as to what I'm doing wrong?

Even at f/8 with the focal ring at infinity when a person is in the photo, they and the background should be sharp but they're not.

Photos are being taken at a shutter of 200 -250 - 400 shutter speed.

magicbastarder

are you able to confirm that the lens is stepping down correctly across the aperture range?
also, is the subject in focus in the viewfinder, but out of focus in the photo?

Heebie

Checking the diopter on your view finder is step one.
If the diopter is set wrong, you might very well see something as in focus but have it come out blurry.

Also, don't forget that the infinity focus is generally just a tiny bit back from where the focus on the lens stops moving, not where it stops.
I think it's marked on the lens. I'm not looking at mine right now.

The Darkroom

Ok so I think I've figured out my problem. I've just discovered the world of ''hyperfocal distance''. If taking a wide angle photograph where there is foreground to infinity, having the lens set to infinity does not put any of it into focus.

So if the subject is 10 feet away from me, I set the focal length to 1.19ft and so everything of 1.19ft and to infinity will be sharp. I think I have this right open to correction.

Here is the website I found that calculates it for me. http://dofmaster.com/dofjs.html

I would welcome any advice.

magicbastarder

The Darkroom wrote: »

If taking a wide angle photograph where there is foreground to infinity, having the lens set to infinity does not put any of it into focus.

i'm not sure i share that interpretation. if focused on infinity, infinity should be in focus, and focus should also stretch towards the foreground, based on aperture chosen.
plus, wide angle lenses are known for greater depth of field.

would be helpful if you posted a pic.

Heebie

There are apps you can get to calculate depth of field and hyperfocal distance etc.
Hyperfocal Pro does... Guess what. 
dSLR Tools does hyperfocal distance, golden hour, long exposures with ND filters etc.
Exsate Golden Hour does... guess what..

Effects

Heebie wrote: »

Checking the diopter on your view finder is step one.
If the diopter is set wrong, you might very well see something as in focus but have it come out blurry.

I wouldn't have thought that was the case. If the diopter is wrong shouldn't it just be out of focus and nothing ever sharp?

You set the diopter by looking at the electronic overlay, not whether the subject is sharp or not.

wersal gummage

Effects wrote: »

You set the diopter by looking at the electronic overlay, not whether the subject is sharp or not.

Could you explain what you mean by this please? I don't actually understand it. I have always set diopter by autofocusing on something obvious /high contrast, and then looking through the viewfinder and adjusting the diopter until the item is perfectly sharp. I've never had a problem and photos on laptop are sharp etc, but always interested to learn something new!

Thanks

Effects

wersal gummage wrote: »

Could you explain what you mean by this please? I don't actually understand it.

Your way works as well. But you set the diopter so that the numbers and focus markers in your viewfinder are sharp.
They are on the same plane as the reflected image you are looking at. You need your focussing screen to be sharp, not necessarily a point in the distance that you are focussing on, as your eye focuses on the screen. The autofocus isn't always correct anyway.

Heebie wrote: »

If the diopter is set wrong, you might very well see something as in focus but have it come out blurry.

If something is sharp on your focussing screen then changing the diopter isn't going to change the focus point.
If the screen itself is out of alignment then something appearing sharp on the focussing screen can be out of focus on the captured image. Diopter doesn't correct for this though.

Heebie

Effects wrote:

You set the diopter by looking at the electronic overlay, not whether the subject is sharp or not.

Yes, you do. What you're doing is focusing the viewfinder for your eye. If you get that focus wrong, it can correct for the image being out of focus, so the image would look sharp in the viewfinder, even though it wasn't in focus. It's a good idea to recheck your diopter often, and be sure that when you adjust the diopter, you're holding the camera against your face "exactly" as if you were taking a photo. (Consider the word exactly air quoted.. I know I've never been able to have it exactly right against my face while able to reach the adjustment!)
If it's a digital camera, you can probably, even with it in manual mode, hold the shutter button halfway down while you focus and the camera should beep and light up focus points when you've got it "right" as well.

Effects

It can't correct the out of focus image. For 20/20 vision and the diopter set to 0 the image is either in focus or it's not.
If the focus isn't sharp, then adjusting the diopter won't make it sharp, only adjusting the focus of the lens will do this.
If the focus is sharp, then adjusting the diopter will make it appear less sharp.

OldGoat

The Darkroom wrote: »

So if the subject is 10 feet away from me, I set the focal length to 1.19ft and so everything of 1.19ft and to infinity will be sharp. I think I have this right open to correction.

Everything from half your calculated HFD to infinity should be acceptably sharp. So, if your HFD is 1.19' then the infocus range is from .56' to infinity.

chisel

You need to adjust/calibrate your Samyang - this lens focuses past infinity. Its easy to do:

https://www.youtube.com/watch?v=gtt9bcJDU2U