The Distance Between Raynox and Mitutoyo Lenses, Mag. Change

lonepal · Post by **lonepal** » Thu Mar 23, 2017 2:01 am

Hi. I am lurking for a long time on the site. I red lots of toppics about using Mitutoyo lenses. There are informations bu it all spreaded across the forum and also there are things that I am not really sure about. I just wanted to combine all related information into this toppic.

I ordered a Mitutoyo M Plan APO 10/0.28 lens and it will arrive like after 2 weeks. I already made a system with a Pentax bellows, adapters, a reversed DCR-150 and an iris according to my friend's system.

There are many informations on the web about the distance between raynox and the mitutoyo but there is not a certain information.

My questions;

1) What should be the exact distance between the dcr-150 and mitutoyo 10X? Because the lens is infinity type does the distance between the tube lens and the lens itself matters?
2) I want to use the mitutoyo 10X at lower magnifications. I red that I can use the 10X @5X with a 100mm lens with an APSC camera. I have an APSC Canon camera already (EOS 100D). Should I use a dcr-250 or shortening the bellows is enough? I mean any IQ difference between using a reversed dcr-250 and shortening bellows?

Help on this toppics will be appreciated.

nathanm · Post by **nathanm** » Thu Mar 23, 2017 9:00 am

Lots of people on the forum can offer advice on this. In principle you are correct that the distance between the infinity objective and the tube lens should not matter.

In practice I have found that I get the best results having it be very close - as close as I can.

Also, I have had better luck with a different tube lens for lower magnification than simply refocusing, but other people on the forum may have more experience with that.

I focus the tube lens at "infinity" by putting the camera in live view and focusing on a distant object (tree across the street) with just the tube lens and no objective.

lonepal · Post by **lonepal** » Fri Mar 24, 2017 5:09 am

nathanm wrote:Lots of people on the forum can offer advice on this. In principle you are correct that the distance between the infinity objective and the tube lens should not matter.

In practice I have found that I get the best results having it be very close - as close as I can.

Also, I have had better luck with a different tube lens for lower magnification than simply refocusing, but other people on the forum may have more experience with that.

I focus the tube lens at "infinity" by putting the camera in live view and focusing on a distant object (tree across the street) with just the tube lens and no objective.

Thanks for the information nathanm.

I need clear results/benchmarks.
Other than solid data are just advices like you said, but we do not know which one is better.
I could not find if aynone made a comparison about this, but I am sure someone think of that before me.

ChrisR · Post by **ChrisR** » Fri Mar 24, 2017 5:35 am

but I am sure someone think of that before me.

Maybe something like it, - but it's a lot of work

Shortening the focus of the tube lens takes it away from its design point. If you try it, you get quality drop and vignetting, as expected. But I doubt you'd go to the trouble to post the result on a forum.

lonepal · Post by **lonepal** » Fri Mar 24, 2017 5:41 am

ChrisR wrote:
but I am sure someone think of that before me.
Maybe something like it, - but it's a lot of work
Shortening the focus of the tube lens takes it away from its design point. If you try it, you get quality drop and vignetting, as expected. But I doubt you'd go to the trouble to post the result on a forum.

Thanks Rick.
Be sure I will try it with 10X by reducing the magnification to 5X.
I will also inspect the raynox-mitty distance/IQ relationship.

I am waiting my 10X to arrive.
I may need your help about comparisons.

nathanm · Post by **nathanm** » Fri Mar 24, 2017 8:06 am

Here are my tube lens tests http://www.photomacrography.net/forum/v ... 150a1e4480

However I did not try taking a single tube lens and racking the focus over a wide range. I don't think anybody on the forum has done that systematically and posted a result.

For better or worse, a lot of the results we want in macro photography can only be determined empirically - theory only takes you so far - testing is the only way to really find out.

But testing lenses isn't why most of got into this - we like to make pictures of things other than resolution targets.