Extension tube question

IMHO the focal length of a lens with extension tubes stays more or less the same, if the lems does not change its focal length with focusing without extension tubes.

 

By enter, if you mean on an EXIF, it would be the same. You could specify the extension tube you were using. If you are talking about flash calculations each extension tube has some light loss based on the length of the tube. Look in the spec for the particular length you are using. For myself, I would just calculate it based on the focal length of the lens and then based on the historgram result, add an EV correction in your camera. Keep it consistant for that that particular extension tube.

 

The focal length of the lens stays the same. All you are doing is altering the nearest focussing point and consequently the reproduction ratio.

Best wishes. Bob F.

 

Of course. Extension tubes are just focusing aids, like focusing helicoid or bellows. When I mount a lens into Linhof bellows, it does not change the focal length whatever the extension is. Otherwize, would they state the focal length for the lenses that are meant to use only with bellows?

 

Being a user of a PB6 - Extension Rings - Reversal Ring etc.etc.etc., what is it that you are wanting this equipment for? Without this information it is going to be very difficult to answer any of your questions. Also please note that I am in the UK and will not be answering any questions untill tomorrow.

Best wishes. Bob F.

 

you can use PB4, it gives interesting possibilities, especially w/Bellows Nikkor 135 lens; or with F/M39 adaptor and longer enlarger lenses

 

I have looked at the photo of the Chinese Latern and the Reproduction Ratios seem to range from about 1:3 to a maximum of 3:1. All these are easily obtainable with the PK/PN extension tube set and a 24mm lens. In fact if you have one with a 52mm thread, then buy a BR-2A reversing ring and watch by experimenting with various combinations your R/R rise to about 8:1.

As you are going to lose any coupling to metering etc. then it does not matter which of the older lenses you use, as long as they have click stops that allow you stop and lock down manually. You are going to have to experiment to find out what your f stop - flash output is going to be, but once you have found the combination then it generally remains stable for most R:Rs.

To be honest I really think that you are trying to run before you can walk and would suggest you might like to try a close-up lens or close-up attachment lenses and learn the basics of micro/macro photography before trying to get to grips with the intracacies of Photomiography.

Nikon produce an excellent free brochure called Nikon and The World of Close-up Photography. Get one from the Nikon offices in your country and read it. This will give a mass of useful information including what equipment you need to get the various Rep/Ratios.

Hope this helps.
BW. Bob F.

 

Kenko makes a set of extension tubes that maintain metering and AF. They can be stacked to give you quite a bit of extension.

 

The Novoflex rail will be excellent for extension tubes, but will not be necessary with Nikon Bellows.

Go to Ebay for the Kenko Tubes. They list more than you will ever need.

BW. Bob F.

 

I use Ebay for almost 100% of my purchases in respect of Camera Equipment and virtually everything else. You just have to use your commonsense and once you become familiar with the procedure you can soon spot a scammer.
Very pleased you have obtained some tubes. Good luck and keep in touch.

BW. Bob F.