Iris placement.

[AllEx]

iHow can I place an iris ring in a self-made tube lence (extreme macro), since the ones I found are having threads only in one side of them.
The overal size of the tube, can not be lower than,let`s say 42mm, therfore the lazer threads of 30 mm and the 30mm tubes Thorolabs use, or someting similar, is out of the question.

[Manfred M]

It's hard to give you a response to a written description.

If you are trying to reduce the amount of light hitting the sensor, a neutral density filter is a lot easier to implement. If you are trying to increase depth of field, either a fixed hole or a series of holes of varying diameter either on a slider or turret would be a lot easier to implement than installing a diaphragm mechanism that is not the right size / construction.

[AllEx]

I`m just trying to decrise the f number because it is taking place in the equesions that determine the step size. A neutral density filter would be capable to give me the nominal reduction of the f number??
[I`m using Raynox lense, the 150 DCR & the 250 DCR that are wide open causing me to use f=2.8 that giives me very small steps (meaning swalow DOF) that resalts in a very large amound of them]

[AllEx]

I`ve looked it out, a neutral density filter only gives stops of darkening the picture, I don`t supose that are equivalent with f stops, as soon as it`s not acomplished through the same mechanism although the resalt is the same.

[dem]

I`m using Raynox lense, the 150 DCR & the 250 DCR that are wide open causing me to use f=2.8 that giives me very small steps (meaning swalow DOF) that resalts in a very large amound of them...

Why don't you simply stop down the lens you are putting the Raynox on? Why not use say f/16 instead of f/2.8? What camera/lens are you using?

[george013]

I`m just trying to decrise the f number because it is taking place in the equesions that determine the step size. A neutral density filter would be capable to give me the nominal reduction of the f number??
[I`m using Raynox lense, the 150 DCR & the 250 DCR that are wide open causing me to use f=2.8 that giives me very small steps (meaning swalow DOF) that resalts in a very large amound of them]

The f-number is a relation between the focal length and the diameter of the aperture:
f-number= diameter aperture/focal length.
A peace of dark glass doesn't change that.

The Raynox lenses you mention are snap-on lenses. You mount them on the on-camera lens. They are meant to work in combination with another lens. I don't think you can use them as a single lens for that's what I read out of your post.

Off topic. May I ask you about Thessaloniki. I'm there in the end of the month.

George

[AllEx]

dem it all about hand made tube lenses that in the end they have the Raynox. They are not convencional lenses.there you can see one:

It is not a normal lens, it is made to maintane the proper distance between the camera sensor and the microscope objective lens that we atach in the frond of the tube lens. In the uper tube I can control the aperture because it is based on the rodeenstock witch has aperture manual adjastment.
When it is based on a Rodenstock as you know I cant adjast manualy the aperture as it is wide open, that`s why I`m seeking for an iris to plase in the back of the microscope objective.
George I think I answer to your suggestions.
As for Thessaloniki witch is the capital sity of the Greek region of Macedonia (50% of the teretory of the ancient one the other 20% is in Bulgaria and the left 30% is in the slave region, who`s residennts (with match dare) call themselfs Macedonians.
Anyway I could write a book on that topik, you will find there lots of ancient monuments as long as you wish to see them, a good temperatures (I hope) and a pleasand modern city.
Since I`m a hundicup stack in my bed for the last 15 years I`m not in the position to suggest you any modern places, even if the crisis ruined the country there still lots of beutyfull sites to see. I wish you a pleasant trip hear keep in mind that the term "filoxenia" is the Greek term that means to treat the foreigner as a friend.

[george013]

I don't know what would happen with the dof if you move the diaphragm to the front. Normally I would say it will get less but I'm not sure.

About Thessaloniki, I'm running away from Kingsday in Amsterdam and decided to go there. I didn't know anything about Thessaloniki so I started reading, first a roman of Victoria Hislop, "The small paradise", dealing with it's history in the 20th century. A city with about equal amount of christians, jews and moslims. First the moslims diappeared out of the city after the greek-turkish war, the exchange of people. And then during the second world war the jews. Now reading "Salonica, City of Ghosts: Christians, Muslims and Jews 1430-1950". There's another roman I'm looking for "birds without wings"from Louis de Bernieres. Hoping to get some info about the turkish view.
I'm staying there with Labour Day. I'm trying to get some information what's going on there on that day. I'm leaving next day. Do you have some info or a link where to search. In latin charcters. I'll send you a private message.

George

[Manfred M]

Take a look at how different apertures have been implemented in the past. Here is a modern reproduction of the Petzval 85 mm lens with a very simple way of changing apertures from a mechanical standpoint. This might be far simpler than what you are proposing.

https://microsites.lomography.com/petzval-lens/

[AllEx]

Unfortunately Manfred the smaller FL we use in tube lenses is 100mm therfore the 85mm lens you propose can not be used.
I`ll have evntualy to run deep staks of many imagies (700 -800 frames).

[Manfred M]

Unfortunately Manfred the smaller FL we use in tube lenses is 100mm therfore the 85mm lens you propose can not be used.
I`ll have evntualy to run deep staks of many imagies (700 -800 frames).

I'm not proposing the lens at all, but rather suggest you look at how the diaphragm has been implemented in it. It is far simpler solution than using a modern bladed diaphragm approach.

[rudi]

iHow can I place an iris ring in a self-made tube lence (extreme macro), since the ones I found are having threads only in one side of them.
The overal size of the tube, can not be lower than,let`s say 42mm, therfore the lazer threads of 30 mm and the 30mm tubes Thorolabs use, or someting similar, is out of the question.

Hi Alexander,
I am not yet in that stage off "extreme macro" so I can not give you any personal experience. But, AFAIK manual iris rings do have threads on both sides (https://www.ebay.com/itm/IRIS-DIAPHR...-/140547138653). To be sure, ask the people at http://www.photomacrography.net/
they are very experienced in this matter.

[AllEx]

I am a member of that site since 2015 I only thought to ask that one as I thought that it would be more apropriate for that mater. In fuct the tubs based on the Raynox lenses are made under the guidance of that site.
Thank`s anyway

AllEx

[AllEx]

I am a member of that site since 2015 I only thought to ask that one as I thought that it would be more apropriate for that mater. In fuct the tubs based on the Raynox lenses are made under the guidance of that site.
Thank`s anyway

AllEx

In my first visit to your post Rudi I didn`t notice the ebay link. That is exactly what I was aiming with my visit to the forum. |n the end I feel that I owe you a big thank you, yesterday I was looking for somethink like that all day.
Thank you very much.

AllEx