Which lens and close up filter?

[Jonny]

Guys,

I am looking at getting a close up filter soon so i can feed my photography bug whilst i am stuck indoors looking after my four year old. I have tried to take her out and about but she just won't allow me any time to take any decent shots and i am finding it frustrating.
I am thinking there will be lots of intresting 'small' things around the home i can start shooting whilst she is happily glued to the TV. So the question is which should i get?

My lenses are listed in my sig at the bottom so which will make the best lens for macro stuff and which filter should i buy to stick on it?

many thanks in advance for your much needed guidance.

[Scottes]

All of your lenses take different filter sizes. So you'd want to get the biggest close-up lens you can get (72mm I think for the 28-135) and step-down rings which will allow to put a 72mm filter onto a lens with a 58mm (75-300) filter size. So a 72-to-58 step-down ring will let you put the 72mm close-up lens onto the 75-300mm.

In actuality this is all I would do is these two lenses. The others are too short to make close-up lenses worthwhile, in my opinion. But I have seen people do great things with them on short lenses.

I don't really like close-up lenses because you get stuck at a certain distance from the subject. They have a very narrow focus range, so you have to be with 18 to 20 inches from your subject and that's it.


A problem you might have is that good close-up lenses, like the Canon 250D and 500D, are made for different lens lengths. The 250D is appropriate for your 28-135, but not so appropriate for the 75-300 at 300mm. The 500D was designed for long lenses like 300mm. I can't find a 72mm 250D for 72mm, so you'd probably need to go for a 500D in 72mm, for $115, or just use the 75-300 with a 58mm 500D for $83.


You can get inexpensive kits, like this (http://www.bhphotovideo.com/bnh/controller/home?ci=1&sb=ps&pn=1&sq=desc&InitialSearch=yes&O=S earchBar&A=search&Q=*&shs=hocus58&image.x=0&image. y=0) Hoya kit for $81 for 72mm, or $45 for 58mm. Though the Hoya kit is very good for a diopter kit, it's going to degrade the images. A kit like this give you lots of flexibility because it has 3 lenses at different powers of magnification. You can stack a +2 and a +4 to get a +6. At the cost of even more image degradation....


Another option is extension tubes. Tubes are hollow tubes which go between the lens and the camera. They kinda change the focal length of the attached lens and allow the lens to focus much closer than normal. They add a little magnification, too. Since there's no glass there's no image degradation. Your 75-300mm can focus as close as about 5'. With tubes you can get that down to mere inches, and since you're so much closer the magnification can be huge.

This set of Kenko tubes (http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=71515&is=REG) costs $129 and can be used with any lens except the 18-55mm.

I like tubes a lot as I find them extremely versatile.

[Jorge]

Hi Scottes

Is there a formula for calculating the change in minimal focus distance when using tubes? How much e.g would the minimal focus distance for the 70-200/f4L (noamally 3,9' ) be with 36 mm?

[Scottes]

There's a formula somewhere, but it's not too easy to find. I know that I have it in a John Shaw book at home.

See if this helps: http://www.bobatkins.com/photography/eosfaq/closeup.htm
Not a formula but a nice table with concrete info.

Let me know if you need more and I'll try to find that formula.

[Jon]

1/fl = 1/f1 + 1/f2
where fl = lens focal length, f1 = subject distance, f2 = image distance (which will be focal length + extension tube length when at infinity)

A 25 mm extension tube on a 50 mm. lens will bring it to 1/2 life size with the lens focussed at infinity.

[Jonny]

thanks so much Scottes for a lengthy, detailed reply. It is much apprieciated.

jon

[Scottes]

1/fl = 1/f1 + 1/f2
where fl = lens focal length, f1 = subject distance, f2 = image distance (which will be focal length + extension tube length when at infinity)

A 25 mm extension tube on a 50 mm. lens will bring it to 1/2 life size with the lens focussed at infinity.

This is NOT correct. To correctly *estimate* the magnification one must know the distance from the nodal point to subject, and nodal point to film/sensor plane.

Case in point 1: Using my 100-400mm at 400mm and a 36mm tube the tube gave me a 27% magnification of height and width. This formula computes that to 9%.

Case in point 2: Using 36mm on my 70-200 @ 70mm gave me what I measured at 1.7:1, NOT 1:2 like this formula implies. My measurement was obtained by shooting a ruler and finding that I can take a picture with 20mm filling the image width.

The formula also does not take into account the minimum focusing distance, which greatly affects the image magnification, too. And internal focusing lenses - like both mentioned - completely and totally mess up the simple formula above.

Use the chart and hope your lens is on it.