DOF and Cropping take 2

Started Feb 11, 2014 | Discussions thread
Ian Stuart Forsyth
OP Ian Stuart Forsyth Veteran Member • Posts: 3,270
Re: DOF and Cropping take 2

awaldram wrote:

Ian Stuart Forsyth wrote:

awaldram wrote:

"Note that the above calculator assumes that you have a lens on the new sensor (#2) which can reproduce the same angle of view as on the original sensor (#1). If you instead use the same lens, then the aperture requirements remain the same (but you will have to get closer to your subject)."

Again exactly what I've been saying

So why would you interject in a conversation about the Equivalence between the formast in the discussion with GossCTP stating “that a FF F4 at 200mm is equivalent to a cropped 135 F2.7”

Because he was making statements that were unsure and based on a wrong premise your replies of 'perfect' it wasn't fair to GossCTP or any readers.

His statements were based of previous response by me and you so I didn't interject in my mind but was already involved in the conversation

And then you state

“But I Don’t see this as equivalent at all.”

Well even the site you provided see that they are equivalent here’s their calc

So if your site you provided see it as equalling then why interject.

I don;t see it as equivalent

As I explained whats important to me is shutter speed ,ISOt he equivalence is DoF and in my shooting useless.

And here lies your problem holding ISO across format is irrelevant as iso 100 on cropped is the same as iso 225 on ff

This is a simple question, of the 2 images captured below which will capture the most amount of light and which will have the most amount of noise in image.

A Full Frame 24mp camera with the current level of sensor technology using a 300mm F4 lens with a shutter speed of 1/300 and using iso 225

And a Cropped 24mp with the same level of sensor technology using a 200mm F 2.8 with a shutter speed of 1/300 using iso 100

Would you be so kind as to answer

This seem like your biggest issue with FF to cropped comparisons with regard to SS ISO DOF that and the end noise level will be , the answer is that they will have the same total light and thus the same noise in the image.

I would never go from an f2.6 lens on aps-c to f4 on FF just to maintain DoF the concept is alien and redundant.

But it you that has to hold the same DOF as the DOF in FF is to shallow for your taste

I feel as if you have a vague notion on how this work and your attempts at being vague is there to twist your posts to what is true at the end of the day .

Mmm interesting interpretation I don't think I've been vague at all nor changed my approach or 'facts' rather I think You and MC have chosen to be very selective on what you read what you quote and how you attempt to ridicule.

You do this because your insecure in your FF purchases and are seeking approval from others by beating the FF is best despite the obvious fact nobody cares.

I am not insecure, It’s not me but rather you that jumps into these threads and supplies incorrect facts and expect the people that know how this works sit back and allow you spread the incorrect information, Anytime the people that interject on how the physics in cropping an image and how it compares when its related to another format, even when a K5 is used for cropping the image to a small FOV you are the first to point out how it’s wrong. Time after time it’s you that is the first inline to give a fatally flawed correction to the people that truly know how the physics work. And at the end of the day when all said and done the final response from you is

"I don;t see it as equivalent

As I explained whats important to me is shutter speed ,ISOt he equivalence is DoF and in my shooting useless."

If you don't see it as equivalent ( even when your own site says it is and also I know of at least 3 more that clearly state this a true) maybe you should look at the links both MC and myself have given you so that with the knowledge from these sites you can give the truth. And stop presenting the false insight to how the physics of cropping an image circle works in the real world.

let be really clear

Let's be

DoF Equivalence is pointless a waste of time and shows nothing of any interest to a photographer of any format.

It’s not pointless, many time I have seen you here show a photo using something like a 100MM F2.8 and cropped such to a FOV of a 500 mm FF system and state that it’s still F2.8, lacking the knowledge to understand that its not a equivalent FF 500mm F2.8 lens and that it does not collect the same amount of light as a ff 500m F2.8.But rather it has the DOF, FOV and the same total light as a 500mm lens using F13. We have given you I know of 2 sites that can explain this to you but you have ignored them and still you love to give this advice in this area to people just starting to lean photograph and that’s not right.

Its better to give the correct advise to beginners that the wrong advise.

The only possible reason you;d bring it up again and again is to show you can shoot at a narrower DoF on FF than you can on APS-c with production lens... to which my answer is as always so what.?

Most people have to much DoF .!

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