[pure-silver] Re: Depth of Field (35mm vs. 4x5 or 8x10)
- From: DarkroomMagic <info@xxxxxxxxxxxxxxxx>
- To: PureSilverNew <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 29 Oct 2004 21:14:17 +0200
Michael
I'm not sure that I understand your question completely, but I will try to
offer some advise anyway. Maybe, I get you closer to a solution.
First, one needs to remember that perspective is not modified by using
different focal lengths. It is purely modified by viewpoint and subject to
camera distance. If you use the same lens with your 4x5, you'll get the same
image, but you won't fill the frame, and you've gained nothing. If you use a
longer focal length, you'll fill the frame better, but you loose DoF and
have to make up for it with a smaller aperture. Here is how I would approach
the issue.
1. Duplicate 35mm viewpoint and distance with the 4x5 camera.
2. Use any 4x5 lens that will fill the frame, or get as close as you can.
3. How far to close the aperture will depend on the 35mm vs 4x5 focal length
ratio you are using.
For every doubling of focal length, stop down by 2 stops to get the same
DoF.
If a 100mm lens filled the 35mm frame, then you need a 400mm lens to fill
the 4x5 frame. You will have to stop this 400mm lens down by 4 stops to get
the same DoF. If you are forced to use a 210mm lens with your 4x5 camera,
you are not filling the frame. You will fill a frame closer to a 6x6 or 6x7
camera. This will force you to enlarge the image twice as much as you would
have to do with the 4x5, but you will have to stop down by only 2 stops.
You will get the same perspective and the same DoF this way!
Regards
Ralph W. Lambrecht
On 10/29/04 8:52 AM, "Michael Healy" <emjayhealy@xxxxxxxxxxxxx> wrote:
> I'm wondering whether someone might be able to confirm or elaborate upon a
> couple
> questions I've been kicking around, regarding depth of field and lens length.
>
> About a year ago, I shot a 35mm image of a piece for my my partner's
> portfolio. This was
> cast glass, of several boat-like objects, each about 8-9" long, which she
> attached to a
> sheet of glass about 1 foot wide by 1.5 feet deep. I shot this piece on a
> sheet of black
> velvet, on 35mm film, using a 100mm lens. Depth of field was hairy, but I
> managed to
> get enough of it. The piece fills the frame very tightly. It is very dramatic
> and disturbing,
> and it has sufficient depth of field. One of the better images I've shot for
> an artist's
> portfolio.
>
> Some months later, I finally was able to purchase a 210mm lens for my 4x5
> camera. I
> wanted very badly to replicate this image for my own portfolio. So I tried to
> reshoot it on
> 4x5. It was a disaster. I spent several days replicating the shot, but I could
> NOT, for the
> life of me, achieve the depth of field I'd gotten on 35mm. After doing some
> research, I
> think I realized a couple things. The main problem seems to be that to achieve
> the same
> DofF in 4x5 as in 35mm, assuming a 4x5 lens that is equivalent to the one used
> in
> 35mm, one must station the 4x5 at the same distance from the object as was
> used in
> 35mm. IE, when I chose a 210mm lens (4s5) to replace the 100mm lens (135), I
> was
> wrong to move the 4x5 closer to equivalently fill the frame. I was wrong to
> conclude that
> this would produce the same result. Rather, the same result will be achieved
> by
> maintaining the same camera-to-subject distance. Of course this means that the
> object
> will appear no larger or smaller on the 4x5 image as it did on the 35mm image.
> As soon
> as one moves the camera closer (to fill the frame), one starts losing DofF.
> Those of you
> who have worked with 4x5, can you confirm this one way or the other?
>
> Stemming from this: Supposing this is the case, and supposing a client has a
> desire to
> see their close-up image on 4x5 instead of (yuk!) 35mm, I'm thinking: I shoot
> a closeup
> detail of a sculptural object in 4x5, and there's little DofF. I do it with
> 35mm, and I'm able
> to get plenty of DofF, but at the cost of a tiny image. Here's what I'm
> wondering. If I were
> to enlarge that 35mm slide, yes, it would show a loss of resolution; but if it
> already HAD
> captured deep depth of field, then wouldn't the enlargement retain the depth
> of field?
> And if I was unable to replicate this depth of field in 4x5, for having to
> move the camera
> too close, then wouldn't the 35mm enlargement's DofF be retained, and be more
> satisfactory visually, than the 4x5's shallower DofF? What I'm saying is, is
> it better to
> shoot 35mm and enlarge, w/ all its shortcomings, than to get a great 4x5 that
> never
> achieved satisfactory DofF? or will the enlargement of 35mm deplete the sense
> of DofF,
> and end up looking no better than the 4x5 with its inadequate DofF?
>
> I have to add that I am not talking about paper prints, and conventional
> viewing
> distance. I am talking about slides (or negs), and the actual level of detail
> that will come
> through under a loupe on a light table.
>
> One reason I am asking is that for some time now, I have had absolutely no
> available
> darkroom; so while it would seem to be easy enough to just shoot a 35mm neg
> and
> enlarge it for comparison to a 4x5 neg or slide, I don't have the luxury. I
> have no
> darkroom at all. So is there someone who already is familiar with these
> issues, that they
> can confirm or disagree, and explain one way or the other?
>
> Mike Healy
>
>
>
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