Q's about Rokinon 12mm f2.8 fisheye lens

blackstar

Senior Member
Have ordered this lens (Rokinon 12mm f2.8 fisheye lens, FF) from AMZ (on sale - 20% off on Prime Day). I'll use it with D3500. Before arriving, need helps to clear some potential obstacles when starting using it:

1. What is the correct focal length to calculate hyperfocal distance I should use with D3500 -- 35mm equivalent (~18mm) or real focal length (12mm)?

2. Can you set aperture by the aperture adjustment ring on this lens (no need on d3500 body)?

3. What is the reference line of distance scale below the focus scale ring? How do you use it to help focusing?

4. What is the best (preferred) ways to focus with this lens for different shots -- landscape, architecture (inside, outside), close-up, night sky (MW, etc)? -- e.g., set to the infinity mark or use hyperfocal distance for MW shots?

Thanks for your help.
 

480sparky

Senior Member
1. 12mm is 12mm is 12mm. You can't use the '35mm equivalent' any more than you could use the 'medium format equivalent' or the 'large format equivalent'.

2. I doubt it.

3. That's your depth-of-field reference.

4. Set your focus well before sunset.
 
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blackstar

Senior Member
Thanks, Sparky.

1. I entered 12mm (real) and 18mm (35mm equivalent) in the calculater and it came out the same hyperfocal distance: 2.61m. So this one resolved.

2. So how do I set aperture for my shot? Just set it from D3500 and forget about the aperture adj ring on the lens?

3. How do you read the DOF reference line? Example?
focus ring-s.jpeg

4. I mean for MW shots, you set on the infinity mark? or actually focus on the hyperfocal distance? And how about focusing other photo scenes?
 

480sparky

Senior Member
My guess is you'd have to dial the lens all the way down to f/22. Whether the D5300 allows non-CPU lenses, I don't know.

As for the DOF guide, the numbers on each side of the large white focus mark show you the approximate DOF on the focus ring.

Go to 1:30:

 

hark

Administrator
Staff member
Super Mod
Contributor
My guess is you'd have to dial the lens all the way down to f/22. Whether the D5300 allows non-CPU lenses, I don't know.

As for the DOF guide, the numbers on each side of the large white focus mark show you the approximate DOF on the focus ring.

Good point about the compatibility with non-CPU lenses. According to B&H, none of the D3x00 or D5x00 bodies are listed as being compatible, but it should come with the AE chip.

https://www.bhphotovideo.com/c/prod...m_f_2_8_ed_as.html/compatibility?sts=pi&pim=Y

You set the aperture to the smallest aperture. Some lenses have a switch (or lock) to prevent the aperture ring from changing. Then on the camera body, you set the aperture the same way you always do. So don't use the aperture ring at all. If the aperture ring isn't set to the smallest, you might wind up with ERR.
 

blackstar

Senior Member
Thanks, Sparky and Cindy.

For setting aperture, Sparky and Cindy's tip is what I heard (read) before. So it's confirmed. Tks

So the reference line of distance scale is for checking up DOF and used to set focus distance. Nice tool (mechanism) to make and implement the "zone" focusing. I call it "semi-auto" focusing (just set and go). It's probably the best way of focusing with this lens? Still wonder how accurate of all the numbers (both focuse adj ring and DOF reference line) are? And where and how do you find the real infinity point on focus ring? (I read so often that the ring stop point isn't the accurate point set for infinity.)
 

480sparky

Senior Member
Thanks, Sparky and Cindy.

For setting aperture, Sparky and Cindy's tip is what I heard (read) before. So it's confirmed. Tks

So the reference line of distance scale is for checking up DOF and used to set focus distance. Nice tool (mechanism) to make and implement the "zone" focusing. I call it "semi-auto" focusing (just set and go). It's probably the best way of focusing with this lens? Still wonder how accurate of all the numbers (both focuse adj ring and DOF reference line) are? And where and how do you find the real infinity point on focus ring? (I read so often that the ring stop point isn't the accurate point set for infinity.)

The reference marks are 'old hat' to us 'old farts'.
 
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