PDA

View Full Version : EX 25mm Extension Tube



fotogmarc
12-16-2008, 05:59 AM
Hi guys
Looking for some input for the Oly extension tube. The price is pretty reasonable these days.
Specifically looking to use it with the kit 14-142mm and 40-150mm lenses.
Any experience passed along would be appreciated

jekostas
12-16-2008, 11:33 AM
To be perfectly honest, I'd probably look at getting the 35mm F3.5 macro first.

In terms of using the extension tube with the kit lenses, it won't focus at less than 20MM on the 14-42, but otherwise it shouldn't be too much of a problem. According to Olympus' website, it should give a 1x magnification ratio at ~25MM on the 14-45MM, I'm not sure what it would be for the 14-42 because the documentation isn't up. I would think that it would be similar. I'll be honest that I haven't had a whole lot of time to use that extension tube, just an extended store demo.

Phill D
12-16-2008, 11:45 PM
fotogmarc you asked a question I was about to ask too. I'd been thinking of a macro lens at some point but was leaning towards the 50mm rather than the 35mm due to the f2 aperture & the low light abilities it would have for indoor & concert use. As the 50mm is ~340 here and the 35 is only ~140 thats a big difference. However the 25mm extension tube is 100 so my thoughts were that the tube would give me some macro usage as I saved up for the 50mm in the longer term. So I had the same overall question as yours is the extension tube worth it for macro? or are the dedicated lenses better. At about 100 it actually seems a bit expensive to me for a metal tube without any glass. I just thought of another advantage of the tube it can be used with a range of lenses. So what differences/advantages would this give? Sorry even more questions :o

jekostas
12-17-2008, 12:49 AM
Well, it's not just a piece of metal, the electronics for focus and aperture control are there as well. Since the "kit" Olympus lenses don't have aperture controls or true manual focusing, this is rather important (the 14-42 and 40-150 are both focus-by-wire systems that use the internal focus motor instead of physical movement of the elements tied to the focus ring).

The reason macro lenses exist is bokeh, not close focusing. Macro lenses will generally give a better differentiation between subject and background, and a nicer rendition of the background than with standard zooms. This is more important for the 4/3s sensor, as the smaller sensor and corresponding smaller aperture and DOF in the lenses becomes an issue for subject separation. The kit 14-42 is a workable macro lens, but it shows noticeable DOF deficiencies compared to the kit lenses from the Nikon and Canon stables. An extension tube will exacerbate this problem because of the increased distance from the sensor to the aperture.

You're also going to get a slight drop in available light because of the increase distance from rear element to sensor. You're going to have to do a lot more with exposure compensation, as sometimes the camera's available metering systems won't be able to compensate.

If you're mostly doing indoors macro shooting, neither of these are a really big deal since light and subject controls are mostly constant. Outdoors for bugs/flowers/twigs/trees/leaves, etc. you're going to have to do some work.


Phill, if you're looking for concert and basic indoors macro, the extension tube and something like the Sigma 30mm F/1.4 would probably be a better choice, actually. The Olympus 50mm f/2.0 is a superior lens optically, but it has a somewhat slow and grindy focus mechanism.

fotogmarc, if you can deal with the exposure and DOF issues I outlined, by all means go for it. It might be a good idea to take the 35mm F3.5 out for a spin as well, just to see the difference. I've used this lens before and it is a truly excellent lens for the price.

Phill D
12-17-2008, 11:53 PM
Hmm Sigma 30mm hadn't considered that I'll have a look thanks.

fotogmarc
12-18-2008, 12:10 AM
Appreciate the input.
I've been looking at the macro lenses for a while. The 35mm does seem to be a bargain, but I'm worried about having to get too close to the subject (70mm equiv.) The 50mm and the Sigma are a little out of my price range for now. The reason I was looking at the tube is it can be used with any and all 4/3 lenses, so if I do get a macro later on it'll give me greater close ups.

Thanks

Still looking.

raven15
12-18-2008, 12:51 AM
I thought depth of field was a problem with macro, and macro lenses were usually stepped down quite a bit to have enough of the subject in focus? Oh well, I have shown no talent or inclination for macro :o so no worries for me.

I am hoping for the Sigma f/1.4 30mm for Christmas from my parents. Whether my dad's photographic sense or my mom's financial sense wins out will determine if I get it or the Oly 25mm pancake.

jekostas
12-18-2008, 12:00 PM
I thought depth of field was a problem with macro, and macro lenses were usually stepped down quite a bit to have enough of the subject in focus? Oh well, I have shown no talent or inclination for macro :o so no worries for me.


Well, yes and no. A lot of times with a lot of subjects yes, you're going to be stepping down the aperture for better DOF, but there are some subjects where you want as shallow a DOF as possible.

A couple examples off of the top of my head are getting the engraving or hallmark on the inside of a ring, or trying to isolate the maker's mark/signature on a watch or pocketwatch movement. While these may not be the standard macro subjects, they are pieces I tended to photograph with frequency.

Edit: I should mention that a lot of macro photography, especially outdoors, isn't just depth of field related, it's related to subject separation from the background. The difference between a good and a poor flower picture, for example, is how well the background is blurred out and how well it frames the subject. That's the reason good macro lenses exist, for that separation.