Jump to content

summilux 21/1.4 DOF


alexc
 Share

Recommended Posts

Advertisement (gone after registration)

I know it was covered before. Just wanted to clarify.

 

When I use aperture stop 5.6 from distance 3m according to DOF chart DOF is: 1,424 to ∞

However due to the crop factor of M8 the correct DOF is under aperture stop of 4 which is: 1,670 to 17,48.

 

Am I correct?

Link to post
Share on other sites

I know it was covered before. Just wanted to clarify.

 

When I use aperture stop 5.6 from distance 3m according to DOF chart DOF is: 1,424 to ∞

However due to the crop factor of M8 the correct DOF is under aperture stop of 4 which is: 1,670 to 17,48.

 

Am I correct?

I'll trust that you're reading off the lens correctly and not check that. But yes, you are correct that a good rule of thumb given the M8 crop factor is to read the depth of field as if your lens were one stop more open than it is.

 

David

Link to post
Share on other sites

Mmmmm. I don't get it. According to summaron 35 lens markings at f/5.6 it is 2.1 - 5.2 (not 1.46 - ∞). This is the same for all 35 mm lenses.

 

Using my spreadsheet I get for CoC = 31 micron 2.22 - 5.23 metres which coincides with the lens barrel. For the M8 it would then be CoC = 23.3 micron and 2.27 - 4.44.

 

The f/4 lens markings on the barrel indicate 2.3 - 4.5 which is close enough. So the rule of thumb to use 1 stop correction with the M8 is pretty much OK.

 

However the numbers listed by Alex© are completely different to my lens markings (& the calcuation). Weird.

Link to post
Share on other sites

Mmmmm. I don't get it. According to summaron 35 lens markings - snip -

Weird.

Blind as a bat it should have been 21 mm.

 

For 21 mm, f/5.6 @ 3m using my spreadsheet I get for CoC = 31 micron 1.38 - ∞ metres meaning the DOF chart (1.46 - ∞) is roughly OK. For the M8 CoC = 23.3 micron and the spreadsheet gives 1.58 - 33.35 metres.

 

This calculation includes diffraction, unlike the DOF calculator, explaining the slightly different numbers.

 

All is well after all.

Edited by SJP
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...