Panasonic G1+45-200 mm+Raynox 150 or 250

sagarmatha · Post by **sagarmatha** » Sat Apr 11, 2009 7:49 am

Does someone here have this combo?
If you set the zoom at 200 and put on Raynox 150/250 what horizontal reading on a yard stick do you get?

According to my calculations one would see about 18,5 mm (0.73 ") horizontally with Raynox 150 and 11 mm (0.43 ") with Raynox 250. Lens set at infinity.

Can someone carry out this little small experiment?

lauriek · Post by **lauriek** » Sat Apr 11, 2009 12:28 pm

I'm not aware of anyone here with a G1... Shame as I'm interested to see what that cam can do as well!

sagarmatha · Post by **sagarmatha** » Sat Apr 11, 2009 1:03 pm

on your site. I have to look more deep into them later.

Charles Krebs · Post by **Charles Krebs** » Sat Apr 11, 2009 1:49 pm

hmmm ... which "G" camera do you mean? The G1 had 7-21mm lens (equiv. to 34-102 on 35mm), the G9 has a 7.4-44.4mm lens (equiv. to 35-210 on 35mm), and the G10 has a 6.1-30.5mm lens (equiv. to 28-140 on 35mm).

The G1 sensor measured 5.3x7.2mm, the newer G9 and G10 sensor measures 5.7x7.6mm.

The Raynox DCR-150 is a 4.8 diopter (according to the Raynox site). This means the focal length is 208mm.

The Raynox DCR-250 is an 8 diopter. Which means the focal length should be 125mm.

If these numbers are plugged into a spread-sheet you get the following:
(lens at "infinity", zoomed to longest focal length)
using: Mag = (Lens FL)/(FL of attached CU lens)
using: x field size = (x sensor dimension)/(mag )

At least this is what I think the "numbers" yield. I don't have the camera or CU lens to actually try it.

sagarmatha · Post by **sagarmatha** » Sat Apr 11, 2009 1:57 pm

Give it another try with Panasonic G1, sensor size 18*13.5 mm

Charles Krebs · Post by **Charles Krebs** » Sat Apr 11, 2009 2:34 pm

.... yes, of course....
Can you tell I've never had a Panasonic camera!

Oh well maybe some Canon user will find that helpful.

Anyway, here's the same thing for the Panasonic G1

sagarmatha · Post by **sagarmatha** » Sun Apr 12, 2009 6:32 am

Thanks Charles. My figures are about the same.
I'm a bit confused about the saying that DOF is larger for a P&S camera compared to an ordinary DSLR. Example:
My Panasonic FZ50 at f/11 and 88.8 mm (400 mm 35 mm eq) has a magnification of 0.65 and a DOF of 0.57 mm whereas for a Panasonic G1 with 160 mm (35 mm eq) and f/11 and same magnification I get a DOF of 1.42 mm. All figures with Raynox 250.
Beats me all this fuzz about P&S. Seems I have been fooled.

rjlittlefield · Post by **rjlittlefield** » Sun Apr 12, 2009 8:02 am

sagarmatha wrote:I'm a bit confused about the saying that DOF is larger for a P&S camera compared to an ordinary DSLR.

That saying is an artifact of how the measurement is made.

DOF is actually determined by the cone angle of the entrance pupil, that is, the diameter of the entrance pupil divided by the distance from pupil to subject.

If you shoot both cameras at f/8, the smaller sensor camera will have more DOF. That's because the smaller sensor has a shorter lens, which at f/8 has a smaller entrance pupil and thus a narrower cone angle.

But if you stop down the lens on the larger sensor until its cone angle is the same as the smaller, then the DOF is the same also. It turns out that diffraction and noise effects all scale together so that both sensors can give the same final image in the same exposure time at the same light levels. But the aperture and ISO settings needed to accomplish this are quite different between the two cameras.

See http://www.photomacrography.net/forum/v ... php?t=4108 for more information. The back-and-forth discussion in that thread gets a bit confusing at times, but if you slog through the whole thing it should come out OK in the end.

--Rik

sagarmatha · Post by **sagarmatha** » Sun Apr 12, 2009 8:32 am

OK, I will read it through but what matters for me is the DOF at equivalent magnification!

rjlittlefield · Post by **rjlittlefield** » Sun Apr 12, 2009 8:39 am

All of my comments assume equivalent magnification, by which I mean that the same size subject area fills the frame of each camera.

The magnifications on sensor will of course be different by the ratio of sensor sizes.

--Rik

sagarmatha · Post by **sagarmatha** » Sun Apr 12, 2009 10:19 am

DOF revelation
Doing some small calculations I found out that the following relation holds:
DOF*sensor size=constant for a given aperture and magnification
Example:
Panasonic FZ50: relative sensor size: 5.0
Panasonic G1: rel. sensor size: 2.0
Full format camera: 1.0

So the DOF for G1 will always be 2.5 times that of FZ50 at a given magnification and aperture.
Comments?

rjlittlefield · Post by **rjlittlefield** » Sun Apr 12, 2009 10:58 am

That sounds correct, assuming that "aperture" means "effective f-number" and "magnification" means "field width at the subject".

At very low magnifications (landscape photography), the effective f-number is what's marked on the lens. DOF is inversely proportional to sensor size at same f-number setting.

At very high magnifications (microscopy), the effective f-number increases in proportion to the sensor size. DOF is constant at same lens setting, independent of sensor size.

In between (closeup & macro), the effective f-number varies in a complicated way with sensor size, at same lens setting and same subject field width.

If you try running the calculation in terms of the lens setting, you have to deal with this complexity.

But if you run the calculation in terms of effective f-number, then the complexity disappears and you're left with the simple relationship that you summarize.

That relationship is equivalent to saying "Same entrance cone, same DOF and same diffraction. Narrower cone, more DOF but worse diffraction, and vice versa." Sensor size doesn't appear in this form of the equations.

The more I have worked with this stuff, the more fond I have become of thinking in terms of the entrance cone. It gets the correct result with a lot less thinking, so it's easier and more reliable.

--Rik

sagarmatha · Post by **sagarmatha** » Sun Apr 12, 2009 11:15 am

Good. I have to think all this over. Must admit though that I feel a bit fooled by every bug shooter using P&S. I will definitely start thinking about acquiring a G1. Luckily the FZ50 I have I bought as used. I will use it as a good backup.
I'm not quite certain yet if I'll buy G1 or GH1. Is someone here doing video of insects?

rjlittlefield · Post by **rjlittlefield** » Sun Apr 12, 2009 12:08 pm

sagarmatha wrote:Must admit though that I feel a bit fooled by every bug shooter using P&S.

Before I came to photomacrography.net, all my macro work had been done with film SLR and then DSLR. When I got here, I started seeing pictures of flies with lots of DOF, labeled like "f/8". I was puzzled because I was used to having to stop down to f/22 to get similar shots, but I never gave it too much thought.

Finally somebody asked about the issues in upgrading from a P&S to a DSLR, and while trying to answer their question, I started to catch on.

Once the issue had my attention, I tracked down a lot of other writings, had some interesting discussions with experts in the field, did a lot of head-scratching, and had some more discussions with people who had contrary opinions.

Finally I figured out in my own head how the pieces fit together, to the point that it not only "makes sense" but predictions actually agree with experiment. (You'd be surprised how many people don't bother to check that last part.)

Then the challenge became figuring out how to explain it to other people so they don't have to struggle as much as I did. That part is still evolving.

--Rik

sagarmatha · Post by **sagarmatha** » Sun Apr 12, 2009 12:50 pm

So what is your equipment for taking photos up to life size?

Panasonic G1+45-200 mm+Raynox 150 or 250

Panasonic G1+45-200 mm+Raynox 150 or 250

Great photos

Charles!