How can I control the aperture on a selfmade tube lens in my camera?

[AllEx]

I`m performing macro with microscope objectives and I have made 2 selfmade tube lenses



based one on the Rodenstock Apo Gerogon 150mm and one on the Raynox 250 DCR. These lenses are consisted Of various rings (step up & down), extencion tubes. and a focusing helicoid.
As you can asume no conection between the camera (D800) and the lenses can acheaved.
My question is whow can I interfear in the cameras sircuit that decides the F number (sometimes it apeared, on the top screen, F number 45).

[Manfred M]

These appear to be manual lenses with no electronic communications or mechanical linkages with the camera body, so I'm not quite sure I understand your question.

I assume you are shooting 100% manual mode? If this is the case, it really doesn't matter what the camera is showing as it will not have any impact on your image at all. The only way to change the aperture is to use the aperture ring on the Rodenstock lens (I believe this was an enlarging lens, so should be adjustable). I'm pretty sure that the Raynox is nothing more than a supplementary lens, so has no aperture control, so there is nothing to change the aperture settings on it.

[AllEx]

Thank you, your answer is exactly what I expected. It is just that I have to folow some functions and that number up there confused me somehow. I should have thought that it could only be an arbitrary one.

[loosecanon]

The microscope objective sets the effective aperture, all the other glass does is provide a means of changing the focus and widening the image circle. It will not provide a means of changing the depth of field. The best image quality is to just use the microscope objective, on say a bellows for focusing. That said some objectives are designed for infinity focus, whilst my Leica objectives are 160mm.

[AllEx]

I don`t know how that number, that is sowing in the control panel of the camera, is decided by the cirquit of it, but certainly it can`t be the effective aperture (other times it is so small that it is inposible to be that) of corse using bellows is a very versatile solution in order to take advandage of several types of objectives that require deferent lengths of tubes (tube lenses) behind them as to imitate the use of the accordingly equal tubes and eyepices of the microscopes.

[Dave Humphries]

Hi Alexander,

Having watched your linked video*, I was wondering whether you just wanted to be able to insert the calculated f number in to the shot's EXIF data? I think this should be possible in PS CS6, but I don't know how myself. If not, there may be other means, although I'm not sure I really see much benefit, unless the images are 'official research' rather than just hobby shots.

Either way, it is only something worth doing in post production, I wouldn't be concerned about what's visible through the viewfinder when shooting, your exposure settings are going to have to be on 'Manual' and set by trial and error anyway.

* by the way, I'm afraid your video has one or two technical/terminology errors, and lots of English spelling problems, possibly the result of translation software used.

All the best, Dave

[AllEx]

Hi Dave,
In order to insert the f number into the EXIF data of the photo might more shuitable program be the " Exif Pilot ". But that is not the case in my search for it (I use in the case of the Rodenstock the minimum that is avalable, no 9, on the lens and in the case of the Raynox what the camera says, I know that it is not having any explanation but at least in that case the numbers that the camera gives are more sensible and they work).

I perform my macro shots only with focus stacking, in order to calculate the step I use the fomula : 2cn(m+1)/(m*m) were n is the f number c the circle of confusion and m the magification. I know that it is not making sence to use that f number but so far it works.
The calculation of the step is a rather tricky busines. Always one has to experiment a lot and I do so.
I always shoot manual.
I don`t clame to be the altimate english speaker, you 'l have to exquse me since it isn`t my native language and though I have a respect in it I do not possess it. Of corse the spelling of the mashine no mater however I even more prossesed it in a voice manipulation program, did not manage to give the right esens in some parts. I apologise for any mistake, but I don`t have the nesesary verbal fluency to do it otherway.

With respect,

Alexander.

[Dave Humphries]

Hi Alexander,

In order to insert the f number into the EXIF data of the photo might more shuitable program be the " Exif Pilot ". But that is not the case in my search for it (I use in the case of the Rodenstock the minimum that is avalable, no 9, on the lens and in the case of the Raynox what the camera says, I know that it is not having any explanation but at least in that case the numbers that the camera gives are more sensible and they work).

I perform my macro shots only with focus stacking, in order to calculate the step I use the fomula : 2cn(m+1)/(m*m) were n is the f number c the circle of confusion and m the magification. I know that it is not making sence to use that f number but so far it works.
The calculation of the step is a rather tricky busines. Always one has to experiment a lot and I do so.
I always shoot manual.

It sounds like you have things under control above.

I don`t clame to be the altimate english speaker, you 'l have to exquse me since it isn`t my native language and though I have a respect in it I do not possess it. Of corse the spelling of the mashine no mater however I even more prossesed it in a voice manipulation program, did not manage to give the right esens in some parts. I apologise for any mistake, but I don`t have the nesesary verbal fluency to do it otherway.

I completely understand that English is not your native language, but you are presenting your video to the world in English (not Greek), so I'd suggest that it ought to be as accurate as you can get it. For typed words; a simple spell checker (with its language set to UK English or US English) in a document program (such as Word), or an e-mail program, or even a web browser could help a lot I feel. Type the text in to one of those first, correct what you can, then copy and paste it out of there and in to your video editor (or whatever does the captions).

For example, in my web browser (FireFox) I have an Add-on Dictionary installed, it shows which words you have probably mis-spelt (in your reply to me above) and when I right click and view the options for correction, it gets about 50% correct with the first option offered. Agreed; some of the others it does not - and you may then struggle to know which to choose, but if the number of errors were reduced by half, surely that is a good thing and not that difficult.

Since your video is intended to be educational, it ought to be of as high a quality of content as possible and I think it could be much better for not too much extra effort.

As an alternative idea, perhaps you could ask an English speaker to proof read your script, ideally after you have used the spell checker on it though.

If you don't think it's worth the effort, that's fine.


On the technical accuracy front, that video starts off stating that the term "Aspect Ratio" is used to express magnification (timestamp 0:35 to 0:53), this is not so. What you are defining is the Magnification ratio. Aspect Ratio is the ratio of width : height of an image.

It is a shame it is incorrect, since I thought some of your other graphics were quite clear and explained things well, but a lot of people will stop watching the moment they find something they know not to be true, losing faith. Additionally, some unusual terminology (e.g. "tube lenses", which I take to mean just normal fitting lenses used on DSLRs) and the errors in spelling (e.g. "mast" instead of "must"), do not inspire confidence in your presentation either.

I was brought up and trained in industry that if a job's worth doing, do it right, I must not be lazy.


I don't care much whether you think it is worth fixing this video, or even if you create another with the same problems, but if this is part of a study course you are completing, I suggest you might want to address these issues - I'm only trying to help you.
Not to mention others that may believe what you say, if they know little about macro/micro photography when they watch it.

I have to admit that you may face practical challenges of which I am unaware, I imagine that a Greek keyboard looks nothing like mine and that, along with similar language incompatibilities, may make your task far harder than I think it is.

All the best, Dave

[AllEx]

I find that your suggestions are positive, and only intend to improve my work. I was not against that from the first moment, and I'm sorry if I gave that impression.
The ways you propose are something that I'll consider and I'll imply in the future.
Thank you for your thoughts that will enhance my future work.
With recpect,
Alexander.