longest telephoto lens with min. f. distance of 55cm ?

[krasnicky]

Hi guys,
I have a question to all of you.
What prime lenses above 200mm focal length can focus an object 55cm from the lens?

I need to take a picture with CCD camera of an object 55cm away, but I need to magnify it as much as possible since I am interested only in a small central part of the picture.
So far I have found 180mm telephoto macro prime lenses from Cannon, Tamron or Sigma and also 200mm from Nikkor. I assumed to use 3x teleconverter insertion but I am wondering if I can find something better than this (even used and old).
Thanks a lot for any constructive comment and help!

Cheers
Daniel

[f6cvalkyrie]

Hi, Daniel,

maybe Nikkor has different 200mm models, but mine, a Micro-Nikkor 200/4 IF-ED focuses only to 71 cm
However, it combines superbly with the 2x teleconvertor TC-300 giving it a FL of 400mm and still focusing to 71 cm.

According to this source, and to some test shots I made some time ago, the IQ should be superb, and allow for cropping if necessary !

http://www.mir.com.my/rb/photography/companies/nikon/nikkoresources/teleconverter/index2.htm

But, if you need really to focus from 55cm, you'd need an extension ring.

I hope this helps,
Rafael

[Orio]

[Scheimpflug]

[krasnicky]

Thanks Rafael and Orio!
I think I need both a teleconverter to magnify the image and also an extension tube to get the right focus distance. Or to buy a long enough lens...
Does anyone of you know where I can find some rule or relationship to figure out what minimum focus distance I can get for a given lens with a given extension tube/bellows? Re-stating it I wanted to ask how does the m.f.d. change with a changing length of the extension tube?

Cheers
Daniel

[BRunner]

Another close-focusing telephoto is Sigma APO Tele-Macro 4/300. It focuses down to ~1m 1:3 macro on FF (tested by me). Or Sigma APO Tele-Macro 5.6/400 which focuses down to ~1,5m according to internet sources.

[Orio]

Give up the idea of teleconverter. It will degrade your image quality.
If some tube isn't enough to get the magnification you need, just add more tube.
Or buy a bellow.

[krasnicky]

Thank you!
You are right, at the end extension tube should do fine. I have a slightly different question now (sorry guys, but I am not a photographer). I have found out that angle of view of a lens is dependent on the focus distance. And that the angle of view for a lens is given for focused at infinity, but if I shoot with the same lens macro photos the angle might be different.
I have also read that it depends on the magnification but how can I know the dependence of magnification for a given lens? Eg. Canon 180mm macro I have found the angles of view (probably at infinity) and I know that at minimum focus distance it has 1x magnification, but what about being 10cm away from the minimum focus distance? How to find out the right angle of view?
Thanks a lot
Daniel

[AhamB]

How big is the object you have to photograph? With that information, you know how much you reproduction ratio (magnification) needs to be. At 1:1 your field of view will be 36mm wide and 24mm high (with a full-frame camera). At 1:2 it will be 72x48mm, etc. With a camera with a smaller sensor, the field of view will be smaller.

Once you know the needed field of view, you know the reproduction ratio and you can figure out the focus distance for the focal length you want to use. The simple formula for a lens used at infinity focus: RR = extension / focal length (both in mm).

You can also try this: http://home.comcast.net/~NikonD70/Tools/Simple_Close-up_Calculator/Simple_Close-up_Calculator.htm
It's a bit more sophisticated. Be sure to set the close-up lens power to 0 D (because you probably won't want to be using those).

[estudleon]

I agree with Orio.

But if your work accept the loss of IQ, the teleconverter can be one of the things to consider.

The teleconverter plus the tubes, one light and cheap way.

My personal option? Not teleconverter.

Rino.

[visualopsins]

Screw a +1 diopter on telephoto to give the required working distance, choose telephoto for magnification required. This is the combination with greatest light throughput (lowest f/#). Center sharp.

Is this an optics class question? It reminds me of the fellow with the problem of seeing 1 micrometer from 26cm away.

More information regarding the application will result in more specific designs.

[Arkku]

Do you need to be 55 cm away or can you go in closer? If yes, you could put a long lens on the camera and reverse a short one in front of it, this gives magnification equal to the ratio of focal lengths, so if you have a 200mm on the camera and a 50mm reversed you have 4:1 magnification already. But the working distance is only a few of cm.

As for teleconverters, yes, they introduce their own problems but they do maintain the minimum focus distance while increasing focal length, so if you specifically need a certain distance you could consider them, possibly combined with short extension tubing.

[ZoneV]

I want to add, that with lenses with IF (internal focussing) the focal length of the lens changes during focussing. The focal leghts the lens system has, are normaly not know - expext the one for infinity that is marked on the lens. Because of that, you can not calculate with these lenses when they are foccused with their IF on other distances than infitity :-/

[Gurdie]

How about an enlarger lens w. a tube or bellows?

[IAZA]

If maginification is your aim. Try attaching reversed lens to tele lens. But you have to be carefull in focusing and shaking.
I tried FD 55/1,2 SSC reversed + Nikon 200/4 AI, it give very close distance to object
sample, mosquito, I don't know how much magnification is
100% crop