The Raynox Macro club

[newarts]

Originally Posted by audiobomber

True, but the Raynox diopters are 43mm, not 39mm. DCR-150 Macro conversion lens for D-SLR camera.



AFAIK the true macro lens specs show working distance from the camera sensor to the subject. The Raynox specs show working distance from the diopter lens to the subject. At 1:1 on my long zooms, the Raynox 150 allows a real working distance (i.e. from the lens to the subject) easily double what I get with the D FA 100mm macro.

Sorry about the Raynox 150 diameter error; I remembered wrong I guess.

There are two distances commonly referred to regarding focus. One is "closest focus distance", the distance from the image plane to the subject. The other is working distance which is the distance from the "front" of the lens to the subject.

The closest focus distance can be precisely defined on an optics basis*, while the "working distance"cannot because of lens recesses, hoods, and the fact that real lenses are thick, not idealized "thin" lenses.

Regarding the working distance for the Raynox, the way a close-up lens works is that light from an object at its focal point leaves the lens parallel to the optic axis. The camera lens then sees these light rays as if they are coming from an infinite distance.

The camera lens focused at infinity forms an image on the image plane of the object at the close-up lens' focal point.

The Raynox DCR 150 has a strength of 4.8 diopters, or a focal length of 100/4.8 = 203 mm, about 8.2" not counting any hood or finite thickness of the lens.

I just measured the working distance with an FA 55-300mm lens and a Raynox DCR 150. With the zoom lens focused at infinity, the working distance at 55mm is about 8" and it is also about 8" at 300mm.

The working distance for a close-up lens with the primary lens focused at infinity is simply the focal length of the close-up lens.

The working distance is reduced a bit as the focusing ring on the primary lens is turned.

Dave

* Distance=Focal_length((1+m)^2)/m where m is magnification.

[audiobomber]

I agree with all that Dave. I was disputing your statement that "the working distance will be about 8.3", a little more than a 100mm macro lens at 1:1". The difference in working distance (lens to subject) is a lot more for a Raynox 150 than for a 100mm macro focussed at 1:1. Actually the working distance of the Raynox 250 on a long lens is pretty close to the 100mm 1:1 macro subject distance.

[adwb]

Thanks for the advice and suggestions every one.

Wasser, yes the 80-200 is definitely a defiant lens. It keeps telling me its better than the others and I have to kind of agree. It is in fact brand new although an old mfg date, and is easy to focus and nice and light. reproduction is over all very good.

I think, based on all the advice. I will get a adapter and a 150 and give that a try.

So last question any one know the best [cheapest] source of a 150 in the UK??

thanks again
Alistair

[newarts]

Originally Posted by audiobomber

I agree with all that Dave. I was disputing your statement that "the working distance will be about 8.3", a little more than a 100mm macro lens at 1:1". The difference in working distance (lens to subject) is a lot more for a Raynox 150 than for a 100mm macro focussed at 1:1. Actually the working distance of the Raynox 250 on a long lens is pretty close to the 100mm 1:1 macro subject distance.

Thanks for the clarification...

I estimated the 100mm lens working distance from theory. According to thin lens optics, the lens-subject working distance is:

Working_distance=Focal_length(1+1/m), which for a 100mm lens at m=1 gives 200 mm (a little less than the 203mm distance for the Raynox 150.)

In real life, actual working distance can be quite a bit less due to lens design, recess, hood, etc. I've a Macro-Takumar 50:4 in which the lens element is recessed 50mm from the front of the lens. Its useful working distance is only about 50mm at 1:1mag.

I've a simple (non-Internal Focus) 90mm Tamron macro lens which at 1:2 mag has an actual working distance of 9.5" (about 241mm); theory predicts 90(1+1/0.5) =270mm, so it is only off by a little bit when the 18mm lens recess is accounted for.

Internal focus lenses can be considerably different from theory because the actual focal length varies with the focus distance (the thick lens doesn't move, its internal elements move, making it hard to even define where the lens is in space!)

Photozone says the DFA100 at 1:1 has a working distance of 130mm (not 200mm), just like you say. Its effective focal length at 1:1 mag can be estimated from the focal distance equation:

Focus_distance=Focal_length((1+m)^2)/m ---- i.e. distance from image plane

The specs say the minimum focal distance for the DFA 100 is 300 mm which according to the above formula corresponds to an effective focal length of 300*1/(1+1)^2 = 75mm, for a working distance of 150mm from the "lens" (wherever that is!!) to the subject (just like you say.)

It looks to me as if the "100mm focal length" in the DFA 100's lens specification may be valid when the lens is focused at infinity, not when it is focused close.

Sorry for the exhaustive response, I thought it might be useful for others to see some of the reasons why things are less simple than thin lens theory predictions.

Dave

PS I just measured the glass' aperture on my Raynox DCR 150. It is 37mm.

[photolady]

Got another photo of my beetle for the club.

Click on the image to view it in a larger size

[adwb]

I don't know if any one is interested but I have Raynox lens set up on ebay 230393864884
and I am looking for a dcr 150 if any one knows of one available?
Alistair
Attached are two images taken with a dcr 250 one not good but ladybird not to bad for a newbe to macro
I want a150 to try to get a deeper dof

[audiobomber]

Here's a couple of shots I've posted elsewhere on the forum. May as well put them here where they belong. Tamron 70-300 and Raynox 250.

Click on the image to view it in a larger size

Click on the image to view it in a larger size

[res3567]

Raynox 150, F32, on board flash, ISO 800, overcast, Tammy 70-300 at about 275mm, my K100DS

[jon.partsch]

I got my Raynox 250 last night - inspired to purchase by this thread

This spider lives in my bathroom. It's body is about 3mm from mandables to the end of it's abdomen

Tamron Adaptall-2 80-210mm f/3.8-4.0 at f/11 and 105mm with Raynox DCR-250
Taken with K110D and built-in flash - Jpeg from camera, cropped and minor contrast enhancement only

[res3567]

Welcome the the forum and welcome to the club! Good pic; try a higher ISO and stop the lens down more the get more DOF. These add on lenses have very shallow DOF, unless that is the effect you are after.

Also there is a photo crituque section here if you want the advice of other photographers.

[jon.partsch]

Thanks Rob,

I have another photo (non-macro) that I took today that I will post in the crituque area.

I am a hopeless pixel-peeper, so shooting at f/32 and ISO 800 is really hard for me to swallow, but I will give it a try. There is a spider in my garden that I'd like to photograph.

The shallow DOF is really intense. I plan to pick up the Tamron 90mm f/2.8 before the rebate offer expires in December. I got the Raynox because someone here pointed out how easy it is to pull out of a pocket and slap on your lens if you come across a cool bug or something - Less chance of a shot wasted trying to fumble between lenses. I intend to use a dedicated macro lens for more "planned" shots.

[Bramela]

Received my Raynox 150, and as promised earlier, here are 3 of my first efforts,

K20d, M135/3.5 lens/Raynox 150







Its rather a fun exercise using the Raynox.