F5.6 Digital verses Film

[phili1]

I had a portrait shoot and I tought I would update my personal Photo. I still shoot Portraits with my film camera and check settings with my digital G3.

I tripod mounted the G3 and proceded to take 10 Pictures of me. When I got home and put it on the computer I was amazed that my background was totaly in focuse, where by my film a F 5.6 with lens at 105mm the background is always out of focus which is what I want. I never noticed this before, which leads me to believe it was done by Canon for sharper pictuers.

I was wondering those with the 10D, does it work like the EOS film system or does digital have a greater depth of field, or is just the Prosummer Cameras.

I was thinking of useing the G3 for my portraits but this means that I would have to shoot at F2.8 and there is no way I can turn down my lights for that.

Any comments from those who shoot studio set ups.

[WW50]

Phil...

That's just basic photography. Shorter focal length lenses exhibit greater depth of field at any given f-stop. If you were shooting with the G3 zoomed all the way in, you are still using a lens with a focal length of about 21mm.

Wendell

[phili1]

Wendel, I have been doing Photography for 30 years I know the basics.

My problem is that at 105mm film camera lens the background is out of focuse at 10 feet away. With the digital at 140mm the basics say it sould be out of focus but its not. I can accept this because its a fact. What I need to know is it the way prosumer cameras and the SLR work like a regular film camera or is it a total Digital situation. I was comparing apples to apples.

I was planning on using the G3 for Portraits with my Mono lights. Now if you travel with a muslim background you need the background out of focus or you have to bring a steam machine with you.

But before I plunk down $1500 bucks I need to know what to expect. The DOF at 20mm(105mm) should be 2 1/2 feet the background was 10 feet away and it supprised me.

[PacAce]

Wendel, I have been doing Photography for 30 years I know the basics.

My problem is that at 105mm film camera lens the background is out of focuse at 10 feet away. With the digital at 140mm the basics say it sould be out of focus but its not. I can accept this because its a fact. What I need to know is it the way prosumer cameras and the SLR work like a regular film camera or is it a total Digital situation. I was comparing apples to apples.

I was planning on using the G3 for Portraits with my Mono lights. Now if you travel with a muslim background you need the background out of focus or you have to bring a steam machine with you.

But before I plunk down $1500 bucks I need to know what to expect. The DOF at 20mm(105mm) should be 2 1/2 feet the background was 10 feet away and it supprised me.

Your DOF problem (or discrepancy, if you will) has nothing to do with digital vs. film. The reason you're seeing the wider DOF with your G5 is because you are not comparing apples to apples as you said you would like to do. What is say is 140mm on the G5 is the 35mm equivalent. The actual focal length of the G3 is really 28.8 mm. So, using 28.8 mm on any camera is going to give you basically the same DOF, give or take a few units, depending on the CoC value you apply.

So, to answer your question, if you were to take a 105mm lens and put it on the 10D you would basically get the same DOF as you do with the film camera given equal conditions in both (i.e. subject to distance, aperture, etc.)

[WW50]

Whoa Phil...I'm on your side buddy...my intent wasn't to say that you didn't understand the basics....

What I was saying is that we are working with a much shorter focal length lens....you are working with a 105mm lens on your 35mm camera and your G3 will be at about 21mm at fully racked telephoto. I would have been surprised if there was not a big difference in the depth of field.

Wendell

[phili1]

Do you guys know the Tom Hanks movie when he says stupid is as stupid says.

You made me go back and retrace my steps and I remembered after looking at the Exif. that I had metered my subject for my 35 mmm at ISO 100 and was shooting ISO 50 with the diftal so I closed down 1 stop, ther is my DOF change, so I feel like the saying.

You guys werer right I was not comparing Apples To Apples. Sorry.

[pradeep1]

Do you guys know the Tom Hanks movie when he says stupid is as stupid says.

You made me go back and retrace my steps and I remembered after looking at the Exif. that I had metered my subject for my 35 mmm at ISO 100 and was shooting ISO 50 with the diftal so I closed down 1 stop, ther is my DOF change, so I feel like the saying.

You guys werer right I was not comparing Apples To Apples. Sorry.

Three cheers to Phil for admitting his mistake and coming clean. :wink:

[submannz]

Yes I noticed this with my camera, and it was frustrating, I quite often blur the background in Photoshop after.

I have been told by an expert that the Canon Asperical lens is very very good, so seems to give a better DOF anyway.