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Closeup Filter (ex. Canon 250D) and focal distance
Does the use of a closeup filter (threaded into the front of a lens), in addition to providing obviously greater magnification, does it also increase the focal distance and therefore decrease the depth of field..

I am hoping that this is true, so that if I use a closeup lens on a point and shoot (such as my Panasonic FZ8) then I could reduce dof and therefore have a blurrier background (better bokah?) which for my purposes would be desirable..

The problem right now is that the FZ8 like many point and shoots focuses best in Macro Mode when at full wide (efov = 36mm) and so has too much depth of field even at f2.8. I am hoping a closeup filter would extend the focal length which is needed to reduce depth of field, as I am already shooting a full aperature..

Thanks..

Peter F...

Comments (9)

I'm not familiar with the FZ8. I use a H2 with M3358 close-up. The lens will give you less DOF. In fact, I noticed that I had to push F all the way up to F7 orf F8 to get a DOF that is necessary for getting flowers and bugs entirely in focus. I think that will not be different with the FZ8. It will give you a blurred background..

I think with the close-up, you will more often get the problem that too much is blurred, in stead of to little..

This is a good example at F6. See how the background is blurred and how the animal is not entirely in-focus in the rear, because there isn't enough DOF. I should have raised the F here a little..

Presonally, in this picture, I don't mind. But it gives me a headache sometimes.....

Edit: The H2, using the close-up lens, will focus best when in full-zoom. I believe this is the case with the FZ8 too. It also means that you can give your subject some extra distance. Helps alot with bugs....

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

Good luck, shooting with a close-up lens is great fun!.

Erwin.

Don't blame me for just getting started....

Sony H2Sony A300.

My Pbase is finally online:http://www.pbase.com/ed197907/..

Comment #1

I can only speak for my 250D/A710IS combination, but the depth of field appear to be the same between the cameras macro mode vs the lens..

The first image below is the camera only. The second image is with the 250D lens. The angle of the camera in relation to the ruler is the same in both shots. However, without the lens I needed to be about two inches away from the ruler. With the lens I was about 8-9 inches away from the ruler. You can see that the DOF is about the same..

This is in line with what Ive read about DOF. For a given camera, regardless of focal length, when the subject is the same size *in the frame*, the DOF for the selected aperture is always the same (although the way the background is blurred will be different...sometimes softer sometimes harsher). It doesnt matter what the distance to the subject is..

So it doesnt matter if youre at 36mm, 200mm, or 400mm...if you frame a subject so that it appears to be the same size in all three frames and keep the same aperture, then the DOF will be the same..

Most macro/DOF complaints Ive read here are about DOF not being deep enough. Even at F8 my DOF with or without the 250D is about 2 inches with the scene below..

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window..

Comment #2

With all due respect,.

Your comparison is not correct in my opninion. In the first shot you used an apperture of 2.8, on the second (the shot WITH close-up lens) you used an aperture of 4.8. If you get the same results, that proves my point that with the close-up lens, you get a shallower dept of field, because you need to zoom in further to get the same subject-size. Higher F-stop means more DOF..

You also shot both pictures from a different corner, resulting in a totally different shot. The 2 inches DOF is perhaps the same, but in order to get there you took a completely different pictures..

And besides, even if DOF is the same, the nice thing about the close-up lens is that it gives you more blur in the background..

Greetings,Erwin.

Don't blame me for just getting started....

Sony H2Sony A300.

My Pbase is finally online:http://www.pbase.com/ed197907/..

Comment #3

EDirkx wrote:.

In the first shot you used an apperture of 2.8, on the second (theshot WITH close-up lens) you used an aperture of 4.8..

Sorry, I used the wrong images. My assessment was based on the two images below. The ruller appears to become blurred near the same spot on both images..

I would agree that there a difference. It just doesn't appear to be that much. I wish I knew the proper way to account for the 250D in DOF calculations so we can know for certain what to expect in DOF..

A710 Macro f/8.

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

A710 250D f/8.

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window..

Comment #4

Thanks for the data! It shows what I expected. The closeup lens (250D) reduced the depth of field at the same aperature setting, which is what I want to achieve. The fact that for the same image size on the LCD can be achieved while at greater distance is a bonus..

Have you found any reduction in image quality when useing the 250D?.

Thanks..

Peter F...

Comment #5

PeterNMIF wrote:.

Have you found any reduction in image quality when useing the 250D?.

No, the image quality is the same. It's a very good lens...

Comment #6

PeterNMIF wrote:.

Thanks for you help on this!.

No prob..

Here's a sample taken with the 250D. The first is the scene. The second image is a 100% crop..

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Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window..

Comment #7

I agree, when using a good close-up lens like the Canon 250D there is no loss in image quality. Amazing pieces of glass really..

Greetings and have fun shooting!.

Erwin.

PeterNMIF wrote:.

Thanks for you help on this!.

Peter F..

Don't blame me for just getting started....

Sony H2Sony A300.

My Pbase is finally online:http://www.pbase.com/ed197907/..

Comment #8

PeterNMIF wrote:.

Does the use of a closeup filter.

Errr.... to be honest, "filter" is not really the right term. What you are talking about is properly known as a "supplementary close-up lens"..

(threaded into the front of a lens),in addition to providing obviously greater magnification, does italso increase the focal distance and therefore decrease the depth offield..

The supplementary close up lens works by temporarily SHORTENING the focal length of the lens it is mounted on, NOT lengthening it..

Shortening f-length with supplementary lenses works like spectacles in short-sighted people; it has the effect of allowing the camera to be in focus when it is moved closer to the subject. Put another way, it is the moving CLOSER that makes the subject bigger in frame the add-on lens just makes sure the picture isn't blurred when you do it..

DoF is reduced in the larger image, unless you stop down more to cancel it..

If image size doesn't change (like the ruler example shown elsewhere in this thread) DoF will remain the same, too. This is because effective DoF is as much linked to image size as it is to aperture.Regards,Baz..

Comment #9

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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