Gerd Waloszek       

Astronomy | GXR · GR · RX100 M1 · RX100 M4 · RX10 M3/4 · TZ202 · X Vario · M240 · General | Photos | Conf. Places | Calendars | Art

Ricoh GXR: Close-Up Lens Experiments (A12-50)

This page presents the results of a quick-and-dirty investigation into close-up lenses on the Ricoh GXR with A12-50 camera unit, which is already a lens with macro capabilities (up to 1:2 magnification). So why add close-up lenses to a macro lens? The simple answer is: For even more magnification. See what can be achieved.

Introduction

First, I bought a cheap set of Japanese close-up lenses identified as No. 1 to No. 3. I assume that the lens' numbers refer to their diopters. After initial tests, however, I did not use this lens set because I was disappointed with the achievable magnification (I did not want to stack lenses).

After I had bought a B+W +5 diopters close-up lens and a Marumi achromat with +5 diopters as well for my Leica X Vario and found out that they fared well on this camera, I was interested in how they would fare on the GXR A12-50. Luckily, I had bought a 40.5 to 43 mm step-up ring some time ago (I have forgotten why...). So I was able to attach both lenses to the A12-50 camera unit.

Magnification

Again, I applied the formula from dkpeterborough (L-Camera-Forum) to calculate the magnifications for my close-up lenses:

• Sensor width / object width = 23.6 [mm] / object width [mm] (The technical data for the A12-50 state a sensor width of 23.6 mm.)

The following calculations are based on test photos that I took to estimate the magnification (see below):

• No lens: 23.6 / 40 = 0.59 (should be 0.5)
• +5 diopters lens: 23.6 / 22 = 1.07 (B+W close-up lens or Marumi Achromat)
• +6 diopters: 23.6 / 21 = 1.12 (cheap close-up lens set)
• +10 diopters: 23.6 / 18.0 = 1.31 (B+W close-up lens and Marumi Achromat)

I am not sure whether +5 close-up lenses really achieve a magnification of 1:1, but they seem to come close. Stacking both +5 lenses seems to even go beyond 1:1.

Considering this result and the fact that some 1:2 macro lenses can be equipped with lenses that extend their magnification to 1:1, Ricoh could have developed such a lens to extend the A12-50's macro capabilities to 1:1. Regrettably they didn't...

Stacking Lenses

It seems to be possible to stack two lenses of higher quality without degrading image quality too much.

Quick Summary

With close-up lenses, the close-up capabilities of the Ricoh GXR A12-50 macro lens can be extended without much effort to a magnification of about 1:1. But for the sake of higher contrast and sharpness I would recommend to use better lenses or even achromats for this purpose.

Test Photos for Estimating the Magnification

For all photos the distance was manually set to 7 cm and the camera moved to achieve optimal sharpness. Please do not take the results too seriously.

Test Photos for Judging the Magnification Informally

I do present not larger versions of the photos below because they are presented here only for providing an impression of the achievable magnifications in real world situations. By the way, some of the photos are not sharp when viewed in original size...

Motif 1

Motif 2

For this motif, the cheap lenses suffer a lot from stray light. The Marumi achromat also fares better than the B+W close-up lens. But this difference may be also by chance...

Sample Photos

Here are a few sample photos where photos without close-up lens are compared with certain close-up lenses or combinations thereof.

Macro 1:2, no close-up lens

Marumi +5 achromat

Macro 1:2, no close-up lens

B+W & Marumi stacked (+10)

Macro 1:2, no close-up lens

B+W & Marumi stacked (+10)