4 Harley

Adalbert · Post by **Adalbert** » Wed Mar 28, 2018 4:18 am

Hello everyone,

Inspired by Robert, I have assembled new tube for my LU Plans.
It bases on the Harley clamps:
https://www.ebay.com/itm/49mm-Turn-Sign ... 5t&vxp=mtr
These clamps match to the cheap M42 macro-rings :-)

And the whole tube looks like follows:

This tube has a built in helicoid in order to be able to focus the LSA to the infinity.
The iris has been placed close to the LSA but I don’t know if this is the ideal position.

And installed on the slat looks like that:

BR, ADi

Pau · Post by **Pau** » Wed Mar 28, 2018 4:36 am

Nice construction!

Maybe an independent support for the motor will avoid transmitting its vibration to the camera.

The iris has been placed close to the LSA but I don’t know if this is the ideal position.

If you want it to stop the system the best position would be as close as possible to the objective. IMO placing it at the tube lens could be useful to cut glare but not to gain DOF

Adalbert · Post by **Adalbert** » Wed Mar 28, 2018 5:34 am

Hello Pau,

Vibrations are good for the cleaning of the sensor :-) but usually I flash on the second curtain.

Yes, the position of the iris is my problem.
I have already tested the iris in some positions but I haven’t realized any advantage

BTW, inside of the tube, between the microscope-lens and the tube-lens I have inserted the flocked light trap from Protostar.

BR, ADi

SebastianFg · Post by **SebastianFg** » Wed Mar 28, 2018 5:48 am

What advantage do you want to achieve?
Should be the first question.
BR Sebastian

Adalbert · Post by **Adalbert** » Wed Mar 28, 2018 6:08 am

Hello Sebastian,
You can find different stories about it on the internet.
E.g. increasing of the contrast or reduction of the reflexions, etc.
I have expected the increasing of the contrast during the exploration of the subject at least.
BR, ADi

Lou Jost · Post by **Lou Jost** » Wed Mar 28, 2018 6:45 am

Did you try putting the iris between the objective and LSA, so you can control depth of field?

ray_parkhurst · Post by **ray_parkhurst** » Wed Mar 28, 2018 7:32 am

I love the clamps, thanks for sharing.

rjlittlefield · Post by **rjlittlefield** » Wed Mar 28, 2018 8:18 am

A very nice solid setup! Thank you for the link to the clamps.

The iris should be positioned immediately behind the objective, as close to the objective as possible. In that position it can serve to reduce the effective NA of the objective, giving greater DOF although less resolution. This can be useful especially at the end of a stack with a deep subject, by making the far background less blurred so that it remains recognizable. See http://www.photomacrography.net/forum/v ... 7644#57644 and the surrounding thread for discussion.

A simple test for whether you have the iris close enough to the objective is to monitor the image brightness while stopping down. If stopping down the iris causes the entire image to darken equally, then the position is OK. If the corners darken more than the center, then the iris is acting partially as a mask and will be less effective. If the center does not darken at all, then it is acting entirely as a mask and will have no effect on DOF. In any of the latter cases, the iris should be moved closer to the objective.

--Rik

Adalbert · Post by **Adalbert** » Wed Mar 28, 2018 8:21 am

Hello Lou,
Yes, I have already tested the iris close to the microscope-lens.
Unfortunately it hasn’t had any influence on the picture I expected.
Neither increasing of the DOF nor improving of the contrast (only vignetting if closed).
So, I have moved it behind the LSA in order to reduce the reflections.
But I don't have any reflexion at all :-)
BR, ADi

ray_parkhurst · Post by **ray_parkhurst** » Wed Mar 28, 2018 8:23 am

I checked my array of cheap M42 extensions and most of them are 47mm diameter in the "flat" areas. Some are as small as 46mm. These clamps are rated at 49mm. What is the diameter of the extensions you're using?

Adalbert · Post by **Adalbert** » Wed Mar 28, 2018 9:15 am

Hello Rik,
This is a really nice feature, you have described.
Usually I’m not in in the room during the stacking-session (I get a headache because of the flash :-)
And I never touch the running system (I don’t want to destroy the stack).
For the blurring effect I prefer the PhotoShop.
BR, ADi

Adalbert · Post by **Adalbert** » Wed Mar 28, 2018 9:25 am

Hi Ray,
Sorry, I have forgotten to mention it

As you probably can see, there are some white rings between the clamps and the macro-rings.
These are the felt-pads I have stuck to the rings.
You have to choose the thickness you need.
BR, ADi

Macro_Cosmos · Post by **Macro_Cosmos** » Thu Mar 29, 2018 6:23 am

Thanks for those clamps, exactly what I was looking for!!!!!!!

Thank you so much!

Macro_Cosmos · Post by **Macro_Cosmos** » Thu Mar 29, 2018 6:24 am

Aaaaaaaand it's out of stock...

Edit: I found some!

mawyatt · Post by **mawyatt** » Thu Mar 29, 2018 1:11 pm

Adalbert wrote:Hi Ray,
Sorry, I have forgotten to mention it
As you probably can see, there are some white rings between the clamps and the macro-rings.
These are the felt-pads I have stuck to the rings.
You have to choose the thickness you need.
BR, ADi

Hi Adalbert,

Nice rings, how do you attach them to the clamps?

Best,