low light and shallow dof at DVinfo.net

Alex Anderson · February 21st, 2015, 04:20 AM

I am still considering to get the a7s and I was wondering, if the a7s is so good in low light and it also has the full frame sensor, is there really a need to get any lens lower than an f4.0 ? Or, would I still need something like an f1.8 lens for those nice shallow dof shots?

Les Wilson · February 21st, 2015, 07:55 AM

In a word: Yes. But you can figure it out yourself. Distance to subject and focal length are factors in addition to aperture. You can use a DOF calculator specifying the sensor size of the A7 to compute the depth of field at a given distance between sensor and subject.

Alex Anderson · February 21st, 2015, 08:29 AM

that sounds good. I could save $800 since a 24-70, constant f4 lens costs $1200 and the constant f2.8 version costs $2000.

Les Wilson · February 21st, 2015, 02:12 PM

To be clear, You asked if an f1.8 lens is needed for nice shallow DOF and I said yes. The 24-70 constant f2.8 is a benchmark lens. But in my experience, for a nice creamy bokeh, you'll want something under f2. The point of the DOF calculator was for you to see the field size of an F4 vs f1.8. Keep in mind it takes distance ahead and behind of the field before it gets real blurry as opposed to just mildly OOF.

Alex Anderson · February 22nd, 2015, 01:34 AM

I should have been clearer and asked if an f4 can make a good bokeh shot. I appreciate you took the time to explain. Thank you, Les.

February 21st, 2015, 04:20 AM	#1
Alex Anderson Major Player Join Date: Dec 2008 Location: NYC Posts: 261	low light and shallow dof I am still considering to get the a7s and I was wondering, if the a7s is so good in low light and it also has the full frame sensor, is there really a need to get any lens lower than an f4.0 ? Or, would I still need something like an f1.8 lens for those nice shallow dof shots?

February 21st, 2015, 07:55 AM	#2
Les Wilson Inner Circle Join Date: Jan 2004 Location: Boca Raton, FL Posts: 3,014	Re: low light and shallow dof In a word: Yes. But you can figure it out yourself. Distance to subject and focal length are factors in addition to aperture. You can use a DOF calculator specifying the sensor size of the A7 to compute the depth of field at a given distance between sensor and subject.

February 21st, 2015, 08:29 AM	#3
Alex Anderson Major Player Join Date: Dec 2008 Location: NYC Posts: 261	Re: low light and shallow dof that sounds good. I could save $800 since a 24-70, constant f4 lens costs $1200 and the constant f2.8 version costs $2000. Last edited by Alex Anderson; February 21st, 2015 at 09:44 AM.

February 21st, 2015, 02:12 PM	#4
Les Wilson Inner Circle Join Date: Jan 2004 Location: Boca Raton, FL Posts: 3,014	Re: low light and shallow dof To be clear, You asked if an f1.8 lens is needed for nice shallow DOF and I said yes. The 24-70 constant f2.8 is a benchmark lens. But in my experience, for a nice creamy bokeh, you'll want something under f2. The point of the DOF calculator was for you to see the field size of an F4 vs f1.8. Keep in mind it takes distance ahead and behind of the field before it gets real blurry as opposed to just mildly OOF.

February 22nd, 2015, 01:34 AM	#5
Alex Anderson Major Player Join Date: Dec 2008 Location: NYC Posts: 261	Re: low light and shallow dof I should have been clearer and asked if an f4 can make a good bokeh shot. I appreciate you took the time to explain. Thank you, Les.