[newarts]

I know how to calculate the resulting macro ratio with a Raynox on a lens when focussed at infinity. Is there a way to tell what kind of magnification adding a diopter will bring at minimum focus? (Obviously not valid for an internal-focus lens).

Magnification is the size of the image on the sensor divided by the actual size of the subject.

With just the original lens objects in focus at infinity have zero size on the sensor, hence zero magnification. As you turn the focusing ring subjects closer than infinity are in focus, hence there is a magnification associated with how close the original lens is to the subject in focus.

Sometimes the original lens' specification gives its maximum magnification ratio, like 1:4 or you can measure it by taking a photo of a ruler.

The minimum magnification of a closeup lens & main lens combo is when the main lens is focused at infinity; call it minimum_close_up_mag.

Minimum_close_up_mag=Original_focal_length/Close_up_focal_length

If the original lens is focused closer than infinity it has an original mag & the equation for total magnification is:

Total_mag=original_mag+minimum_close_up_mag(1+original_mag)

Say you start with a magnification of .25 & use a 2X closeup lens combo, The final magnification is

Total_mag=0.25+2(1+0.25)=2.75

Dave

PS your 16-45 has a maximum magnification of 0.25X at 45mm (according to http://www.dpreview.com/lensreviews/pentax_16-45_4_p15/).

Let's use a Raynox 250 with it; The minimum mag with the Raynox 250 on the 16-45 at 45mm is (I recall you said the Raynox' actual focal length is 109mm):

Min_mag=45/109=0.41X

The maximum mag is:

Max_mag=0.25+0.41(1+0.25) = 0.76X

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Last edited by newarts; 07-13-2009 at 12:11 PM.

[audiobomber]

PS your 16-45 has a maximum magnification of 0.25X at 45mm (according to Pentax DA 16-45mm 1:4 ED/AL Lens Review: 1. Introduction: Digital Photography Review).

Let's use a Raynox 250 with it; The minimum mag with the Raynox 250 on the 16-45 at 45mm is (I recall you said the Raynox' actual focal length is 109mm):

Min_mag=45/109=0.41X

The maximum mag is:

Max_mag=0.25+0.41(1+0.25) = 0.76X

Interesting. Thanks Dave.

[photolady95]

I got confirmation that this lens should be here today. I'll shoot some photos this afternoon and post them tomorrow, in Post your photos.

[newarts]

I got confirmation that this lens should be here today. I'll shoot some photos this afternoon and post them tomorrow, in Post your photos.

Yay!

I'm looking forward to seeing not only quality, but how the magnification range on the long zoom works out.

Dave

[usapatriot]

I have a DCR-250 and it works quite well attached to my DA 18-55 II lens, although the the latter mentioned lens does not have the zoom needed to really produce stunning macros. I'm sure if I had a longer lens it would work a lot better with the DCR-250.

[photolady95]

Well, I tried this afternoon but between the heat and the skeeters, I gave up. It's hard to slap skeeters and try to focus at the same time.

Though I did try before the skeeters hit, but couldn't get this to focus on anything. I guess I need some more instructions on how to use it first. Anyone want to see if they can make me see. I turned off autofocus, and one time I was actually able to see anything, I was about three inches from the subject.

[Marc Sabatella]

The 150 can only focus on objects between around 7 and 8 inches away (depending on where you have the focus ring). That is, focus on infinity to get 8 inches focus distance, set for minimum focus to get about 7 inches. Half those distances for the 250. Might as well set the focus first, before even pointing at your subject, rather than assumign you can set up and then focus. Instead, set the focus, then simply move forward or back until the subject comes into focus. Oh, and DOF is miniscule, so move slowly, or you might move right past the focus point.

[photolady95]

This is similar to my 135mm macro lens. On 1.5 I have to move up to get anything in focus. Thanks Marc. I'll try again tomorrow morning. I'd try tonight but it is getting stormy looking and I care not to get my equipment wet.

The Raynox is a sealed lens

[photolady95]

The Raynox is a sealed lens

Yeah, but I'm not weather sealed.

[res3567]

This shot was taken with my Raynox 250.


Put up yo dukes!

[res3567]

This shot is with my Raynox 150.



Step into my parlor.....

[audiobomber]

I took a few photos with the DCR-150 in the middle of this thread and finally found time to put them up. The photos below show the DA 16-45 on its own and then with the DCR-150 mounted. Note, these were just done as a test of magnification. I didn't use a tripod and it was a gusty day so the flowers were waving.

DA 16-45mm at f/8


DA 16-45mm with DCR-150 at f/8



The Picasa photos linked here Picasa Web Albums - Dan - Raynox 150 were taken with the 150 mounted on a DA 55-300mm lens. As discussed above, the DCR-150 on a long lens has shallow DOF compared to my D FA 100mm Macro, which makes it more difficult to handle. I like to use flash and f22-32 with the Raynox lenses (the Picasa photos were all taken with natural light).

[photolady95]

Rob nice capture but I really don't like eight legged creatures...ugh!!

Dan, nice capture on the yellow. I also looked at your album on the DCR-150. I like the bug and the purple flower. Nice crisp and clear on the steman

[audiobomber]

Dan, nice capture on the yellow. I also looked at your album on the DCR-150. I like the bug and the purple flower. Nice crisp and clear on the steman

Thanks, but I'm pretty disappointed with that yellow flower on this website. It doesn't pop the way it does in my laptop.

How are you making out with the Raynox, have you given it another try? I was thinking you might be best to try it on your 135mm, or at something less than full zoom on the 70-300, until you get more used to it.