[stoppingdown]

During my latest three days in the Alps I was able to try the Marumi DHG 300 close up lens (+3) together with the SEL70200G, with an APS-C sensor. I am pretty pleased with it, as I was able to shoot ladybugs and other small insects, that were previously out of my reach, and there is no visible loss of quality:

 

http://stoppingdown.net/media/stillimage.../image.jpg

http://stoppingdown.net/media/stillimage.../image.jpg

http://stoppingdown.net/media/stillimage.../image.jpg

 

The "problem" was that I received the lens just hours before leaving and so I had to try it for the first time on the field, without preliminary exercise. I've understood basically nothing   about the focusing range of the combo at the different zoom settings, so I basically went by trial and error.

 

Now I'd like to do some rough lab measurement, so at the next chance on the field I'll waste less time. Do you think that it's worth while buying something like that:

 

https://www.amazon.co.uk/DSLRKIT-Focus-C...3_lp_img_3

 

or using a plain drawing ruler is ok? I realize that focusing on a plain ruler implies having an angle between the subject and the line of sight, so some correction is to be applied to measurements. But given that I'm not interested in precise readings, just a rough evaluation, it could be not a problem. Or not?

 

Thanks.