Facepalm - when you make a "duh" mistake :)

bralex · Post by **bralex** » Mon Nov 05, 2018 11:30 am

I've been working on a new setup, not done yet, but imaging a ruler to get an idea of the magnification levels I'm getting with a Mitutoyo 10x objective and Raynox 150 tube lens. I'd been roughly expecting ~8x from the setup, and was struggling with why I was only getting 4.5x max. Looking at the ruler image vs. sensor size, dividing to get magnification. Just now I re-looked at the ruler - markings are at 1/2 mm, not 1 mm. I was getting 8-10x all along... Sometimes it's not easy being me!

lonepal · Post by **lonepal** » Mon Nov 05, 2018 12:18 pm

ChrisR · Post by **ChrisR** » Mon Nov 05, 2018 2:10 pm

Just to be clear, if your Raynox is focused at infinity, as its FL is 208mm, you should get

10 x 208/200 = 10.4x!

bralex · Post by **bralex** » Mon Nov 05, 2018 2:15 pm

Well, reversed. IIRC it's something like 0.84x reversed? Right now I'm just assembling the extension tubes, applying flocking, etc. Part of the setup is a helicoid focus adapter that I was messing with for different total tube lengths.

RobertOToole · Post by **RobertOToole** » Mon Nov 05, 2018 9:09 pm

bralex wrote:Well, reversed. IIRC it's something like 0.84x reversed? Right now I'm just assembling the extension tubes, applying flocking, etc. Part of the setup is a helicoid focus adapter that I was messing with for different total tube lengths.

Instead of applying flocking I use a method that takes 2 seconds and doesn't leave a mess or fall off later, and its cheaper.

What I use is called suede black paper from amazon, it comes in 8.5x11in sheets.

Set everything up and and before I thread the lens on, I grab a sheet, trim as needed, roll it up, insert into the tube assy and done.

Takes 2 seconds and almost no effort. Works 100% of the time.

I have a giant 20 foot roll of stick-on flocking that I haven't touched in a year.

Best,

Robert

RobertOToole · Post by **RobertOToole** » Mon Nov 05, 2018 9:11 pm

bralex wrote:I've been working on a new setup, not done yet, but imaging a ruler to get an idea of the magnification levels I'm getting with a Mitutoyo 10x objective and Raynox 150 tube lens. I'd been roughly expecting ~8x from the setup, and was struggling with why I was only getting 4.5x max. Looking at the ruler image vs. sensor size, dividing to get magnification. Just now I re-looked at the ruler - markings are at 1/2 mm, not 1 mm. I was getting 8-10x all along... Sometimes it's not easy being me!

I've calculated 23.5 across for a full frame sensor magnification and 35.9 for an APS-C sensor which didnt work either

rjlittlefield · Post by **rjlittlefield** » Mon Nov 05, 2018 11:18 pm

bralex wrote:Well, reversed. IIRC it's something like 0.84x reversed?

If the Raynox is focused at infinity, then the magnification will be the same either way around but different extensions will be required, forward versus reversed.

If the Raynox is not focused at infinity, then you can get a wide range of values, depending on both extension and on separation between objective and Raynox.

--RIk

Facepalm - when you make a "duh" mistake :)

Facepalm - when you make a "duh" mistake :)

Re: Facepalm - when you make a "duh" mistake :)