Hyperfocal distance, DoF and other mysteries

[WhiteD3]

Please educate me:angel:

Love my new 10-20mm lens but I have a hard time focusing it in low light when doing landscapes. So I did some research and found a lot of users of this lens are not focusing on a subject at all (Landscapes), rather they are setting a focus distance on the lens of (say) 1m (the HFD?), FL at 10mm and f11 (or there abouts) on the basis that the DoF will go from very close (300mm) to infinity, and so everything will be in focus.

Checked these numbers on an online HFD calculator. All well and good.

So my question: Assuming this works ok, if I change the focus (but nothing else) to something say 5m away, does the near limit of 300mm change to 4700mm?

Or have I missed something fundamental?

Cheers.

[vnx205]

It doesn't work that way.

See what this site says.
Understanding Your Camera Lens's Hyperfocal Distance (http://www.cambridgeincolour.com/tutorials/hyperfocal-distance.htm)

The hyperfocal distance uses a similar concept, except its bounds are from infinity to half the focus distance (and the amount of softness shown above would be unacceptable).

Your nearest point in acceptable focus would be about a couple of metres.

[Cap]

Cambridgeincolour is an excellent site - can be very technical but understandable :)

The HFD gives you the greatest usable DoF for any given subject, if you want everything within half the HDF to infinity to be considered within the DoF (acceptably sharp - of course the COC (Circle of Confusion) dictates what is acceptably sharp!)

However, HFD really works for landscapes only as thats when you dont want boke to occur. It also really work when you dont have a horizon to focus on and/or if the foreground subject needs to be sharp.

Where confusion sets in is the line that some use, which is focus 1/3 of the way into the subject to get HFD. This isnt true as (the website above demonstrates) the DoF changes from the focal plane from a 30/70 range to a 5050 range, changing with focal length.

I wont rabbit on except to say that I have created a tiny spreadsheet to calculate HFD that I can use on the laptop... the formula again sourced from the net (not my own calculations).

[WhiteD3]

.........I have created a tiny spreadsheet to calculate HFD that I can use on the laptop... the formula again sourced from the net (not my own calculations).

I have done that myself but then got lazy and paid $2 for PocketDOF to run on my phone. Ran a random check of the calcs and it works:)

[WhiteD3]

However, HFD really works for landscapes only as thats when you dont want boke to occur. It also really work when you dont have a horizon to focus on and/or if the foreground subject needs to be sharp.

Yes, that's me. Sunrise over the ocean, trying to get the cloud on the horizon and foreground beach/rocks/trees acceptably focused.

[Cap]

Yes, for example, last weekend I too a shot of the beach with a strong foreground. Here what I did was muck around with my focus, it wasnt calculated by any means, but I did notice that the timber was def out of focus if I focused at infinity. What I did was turn the focus ring (manual focus selected) ever so slightly so that I just got the foreground sharp. However, you may notice that the background still has some level of detail, not completely blurred if I had focused on the timber itself (subject focusing).

hope this makes sense.... note that the highlights (blown) and b&w were purposely done to give the effect I wanted.

Note: for some reason the photos uploaded here are shot to ***** with blur!!! Dont know why this happens in the AULRO gallery.

https://www.aulro.com/afvb/images/imported/2010/07/1619.jpg

[Butts]

Stooge, I must say "stunning image" :cool:
Its got everything you WANT in an image. Great capture.

White D3, one of the better DOF references online:-

Depth of Field Table (http://www.dofmaster.com/doftable.html)

[mrapocalypse]

That is a stunning shot mate. And thanks for the info.. I learnt stuff. Always kind of did it but never really thought there were hard and fast rules.

[Cap]

That is a stunning shot mate. And thanks for the info.. I learnt stuff. Always kind of did it but never really thought there were hard and fast rules.

Thanks for the comments... I can see that being a poster size someday.

Actually, no real hard and fast rules, just another tool in the kit if you need to use it. Like the "Rule of thirds", its another tool but not something that MUST be used in every shot ;)

[Chucaro]

The quality of the optics it is very important as well
This sunrise is with the sun coming out just on the split in the Split Solitary island from the beach of the same name north of Coff Harbour
On the detail at full pixel resolution (jpg compressed) the light house in the island is reasonable sharp and the FG on the full image as well.
Tokina 12-24 f/4 @ 24mm
Aperture F/8

https://www.aulro.com/afvb/images/imported/2010/07/1585.jpg


http://www.aulro.com/app/data/500/medium/SapphireBeach14-Detail2.jpg

[WhiteD3]

Still have some work to do but I'm much happier with my latest effort re focus in low light.

http://www.aulro.com/afvb/camera-corner/73324-post-your-sunrise-sunset-24.html#post1285442

These were taken using two methods. The first method for almost total darkness was f11 and manual focus to a smidge over 1m on the focus ring. Once I had more light I used live view, zoomed in x10 and manual focused, keeping the fstop above 11 to maximise the DoF.

Thanks for your help and advice:)