Please help me interpret this chart

[gasdockd]

I have been studying the compatibility chart for the ex-25:

http://www.olympus.co.jp/en/support/imsg/digicamera/compati/di004042e.cfm#etcl

If i were to use I use an ex-25 with a 50-200mm SWD, should I interpret this chart to mean that if I set a focal length of 200mm, that I should be able to focus on objects between 0.8 and 1.9 meters away with an expected magnification factor of .12-.35? The magnification goes up the farther away i get? I'm not sure that this makes intuitive sense to me, but I see that there are a lot of threads about extension tubes already. Maybe I can figure it out.

Apologies for the basic question, but having tried some close up work recently with my 50-200mm, I am trying to figure out whether an ex-25 will solve the problem of mInimum focusing distance while still giving me the magnification that I want.

Regards.

 

[Godfrey]

gasdockd wrote:
http://www.olympus.co.jp/en/support/imsg/digicamera/compati/di004042e.cfm#etcl

If i were to use I use an ex-25 with a 50-200mm SWD, should I interpret this chart to mean that if I set a focal length of 200mm, that I should be able to focus on objects between 0.8 and 1.9 meters away with an expected magnification factor of .12-.35? The magnification goes up the farther away i get? I'm not sure that this makes intuitive sense to me, but I see that there are a lot of threads about extension tubes already. Maybe I can figure it out.

The wrote the focus distances from near to far and the magnification values from small to large ... unfortunately, these two measures are opposites, so just invert one of them.

88.5 to 195.9 cm distances represent 0.35x to 0.12x magnifications (FourThirds) with this combination.
--
Godfrey
http://godfreydigiorgi.posterous.com

 

[gasdockd]

Thanks for the reply and the helpful clarification. On the focusing distance thing, am I correct to presume that with the ex-25 and the 50-200mm SWD, set at 200mm focal length, I should be able to bring into focus objects that stand between 88 and 195 cm from the front of the lens using the MF ring? Or does it mean that with focus set at its closest setting that I will be able to bring the subject into focus by varying the distance from the lens between 88 and 195cm? Maybe I'm asking the same thing in two different ways.

 

[RoelHendrickx]

And I have never really studied the focus distances and stuff like that.
So I am afraid I cannot help you with your actual question.

But I can tell you a few practical points :

• The EX-25 on the ZD50-200 is an excellent solution for close up work where you do not want to get too close to the subjects.
• AF does work, but MF is more practical.
• For finding focus, it is oddly less important to use the focus ring than the zoom ring. Most often, I have found that the best way to find good focus, is to use the ZOOM ring until the subject is in focus and then make a slow rocking motion (going back and forth with your body without touching zoom of focus rings) to acquire the best possible focus. This allows also to place the actual focus on different parts of the subject.

(All this applies to handholding. Work on tripod is obviously different!)

--
Roel Hendrickx

lots of images : http://www.roelh.zenfolio.com

my E-3 user field report from Tunisian Sahara: http://www.biofos.com/ukpsg/roel.html

 

[Godfrey]

Thanks for the reply and the helpful clarification. On the focusing distance thing, am I correct to presume that with the ex-25 and the 50-200mm SWD, set at 200mm focal length, I should be able to bring into focus objects that stand between 88 and 195 cm from the front of the lens using the MF ring? Or does it mean that with focus set at its closest setting that I will be able to bring the subject into focus by varying the distance from the lens between 88 and 195cm? Maybe I'm asking the same thing in two different ways.

You're asking the same thing in two different ways. The focusing range with the 50-200+EX25 combo set to 200mm allows subjects from 88 to 195cm to be focused. How you adjust the subject distance and focus setting is up to you

Normally, when I get down to macro magnifications between 1:5 (0.2x) and 1:1 (1x), I find it easier to lock the focus and adjust distance to subject with the camera/lens assembly on a geared focusing rail.
--
Godfrey
http://godfreydigiorgi.posterous.com

 

[gasdockd]

So I got a hold of an ex-25 and tried some shots in my office. Setup is the E5 with EX-25 and 50-200mm SWD, tripod mounted.

Subject is a paper clip on my desk, approximately 3cm in length.

Per the chart, when the focal length is set to 200mm, the farthest away one can focus is 195cm. By using a tape measure, I found that the 195cm refers to the distance between the subject and the SENSOR (marked by the ϕ on the side of the camera).

Example of 200mm focal length at 195cm distance:





The chart then states a minimum focusing distance of 88cm while at the 200mm focal length. Again this is from the object to the sensor.

Example of 200mm focal length at 88cm:





I then looked at minimum focusing distances for 100mm, which is listed as 48cm:





and 50mm, which is listed at 27.6cm. This sounds good except that given the length of the lens, plus extension tube, plus E5, the subject is almost touching the front element of the lens. And, given the MAXIMUM focusing distance of 28cm at this focal length, that gives a scant 0.4cm of space in which to bring something into perfect focus. I see this being very technically challenging without a macro rail, or nearly impossible on subjects that don't hold still:





What have I learned?

Well, I think that using the ex-25 on the 50-200mm SWD makes most sense in the intermediate to long focal lengths. Olympus specifies a minimum focusing distance of 1.2m for the 50-200mm SWD without the extension tube, so certainly at 100-200mm, the ex-25 could be useful. Once getting down towards 50mm, I think I'm better off sticking with my 50mm f/2.

I've also learned that it's worthwhile to delve into the technical nitty-gritty before investing money and time into into gear. Part of what I love about the hobby of photography is the intersection between these tremendously technical details and an entirely creative medium for artistic expression. What fun!

 

[RoelHendrickx]

Good examples.
Using the EX-25 with ZD50-200 makes indeed most sense at longer focal lengths.
About focusing technique : you should try the suggestions I wrote above.

So I got a hold of an ex-25 and tried some shots in my office. Setup is the E5 with EX-25 and 50-200mm SWD, tripod mounted.

Subject is a paper clip on my desk, approximately 3cm in length.

Per the chart, when the focal length is set to 200mm, the farthest away one can focus is 195cm. By using a tape measure, I found that the 195cm refers to the distance between the subject and the SENSOR (marked by the ϕ on the side of the camera).

Example of 200mm focal length at 195cm distance:





The chart then states a minimum focusing distance of 88cm while at the 200mm focal length. Again this is from the object to the sensor.

Example of 200mm focal length at 88cm:





I then looked at minimum focusing distances for 100mm, which is listed as 48cm:





and 50mm, which is listed at 27.6cm. This sounds good except that given the length of the lens, plus extension tube, plus E5, the subject is almost touching the front element of the lens. And, given the MAXIMUM focusing distance of 28cm at this focal length, that gives a scant 0.4cm of space in which to bring something into perfect focus. I see this being very technically challenging without a macro rail, or nearly impossible on subjects that don't hold still:





What have I learned?

Well, I think that using the ex-25 on the 50-200mm SWD makes most sense in the intermediate to long focal lengths. Olympus specifies a minimum focusing distance of 1.2m for the 50-200mm SWD without the extension tube, so certainly at 100-200mm, the ex-25 could be useful. Once getting down towards 50mm, I think I'm better off sticking with my 50mm f/2.

I've also learned that it's worthwhile to delve into the technical nitty-gritty before investing money and time into into gear. Part of what I love about the hobby of photography is the intersection between these tremendously technical details and an entirely creative medium for artistic expression. What fun!

--
Roel Hendrickx

lots of images : http://www.roelh.zenfolio.com

my E-3 user field report from Tunisian Sahara: http://www.biofos.com/ukpsg/roel.html

 

[BigScooter]

That closer focus distance can be a drawback with some lenses (50mm f2) where you have to remove the lens hood or the distance is just too short, I would think this could happen with the 50-200 @ 50mm. But it's always fun to take a closer look at everyday items, note the text in his collar.





--
And now for something totally different
Tim

 

[Godfrey]

...Per the chart, when the focal length is set to 200mm, the farthest away one can focus is 195cm. By using a tape measure, I found that the 195cm refers to the distance between the subject and the SENSOR (marked by the ϕ on the side of the camera). ...

Yes, this is normal. Focusing distances are nearly always quoted from sensor/film plane to subject. In most uses with the focusing range of most lens mounts, the distinction isn't significant, but when you're working in the macro range using close up lenses and extension tubes you have to be aware of the implications regards the length of the lens and camera.
--
Godfrey
http://godfreydigiorgi.posterous.com

 

[gasdockd]

very fine detail indeed. Good thing you didn't get the whole bill, else the secret service would probably be after you!

I find shooting flat subjects such as this to be easier since all the relevant detail lies in the same plane, more or less. I am trying to capture such close up details on three dimensional objects (flowers and small statues of Hindu Gods), and the very narrow depth of field, at such close distance, is proving to be my greatest challenge. But, I love the process of trying to figure it out. It makes a successful result so much more sweet when you have to work to get it.