Extension Tube Problems

[TobyMac]

Hello all,

I recently purchased some extension tubes to get even closer macro work. They work really well but I have noticed some serious chromatic aberration in my shots when using them. I was wondering if anyone could share some post processing tips to fix it.

[Mike Buckley]

You'll probably get suggestions that are pertinent to your software if you explain the software that you use.

[TobyMac]

Ah sorry yes my mistake. I use photoshop cs6 mainly but also have lightroom to my disposal.

[FrankMi]

...and the camera and particularly the lens in use Toby? I am curious as I've used extension tubes with my D3100 and 18-55mm Nikon lens and not see this issue. I am processing with CS5.

[chauncey]

I generally use them on a macro lens as opposed to your 24-105 lens...that may be your problem.

[DanK]

It should not be a matter of processing. I have used tubes from 12 to 68 mm on countless shots with two lenses, and EF-S 60mm macro and an EF 100mm L macro, and I don't think I have ever had to correct for CA. I'd bet good money that the issue is the lens. The magnification will make CA more apparent, and the lack of a flat field may be a problem. I've used tubes a few times with a 70-200 f/4 IS, but I have never tried them with any other non-macro lens, including my 24-105.

[TobyMac]

I use the 24-105. However I also use them with a 100mm macro and it's fairly noticeable with that.

[DanK]

I use the 24-105. However I also use them with a 100mm macro and it's fairly noticeable with that.

That has me stumped. Can you post some examples with the 100mm? I'll post two randomly selected shots I did with the 100mm, a 50D, and a 36mm tube. Both processed in LR only, no adjustment for CA.

[Glenn NK]

This is puzzling as tubes are full of air not glass. The CA's would be a function of the lens would it not?

I have used the 24-105 with tubes, but mostly with the 100 macro (older Canon one), and have never seen any CA's with either. Although the more recent 100 Canon is better than its predecessor, the older one I have is excellent in this respect.

Strange.

Glenn

[tclune]

I'm just spitballing here, but it is not unheard of for extension tubes to be flexible. Is it possible that the CA is caused by the tubes drooping, causing the lens to no longer be orthogonal to the sensor plane?

[Glenn NK]

I'm just spitballing here, but it is not unheard of for extension tubes to be flexible. Is it possible that the CA is caused by the tubes drooping, causing the lens to no longer be orthogonal to the sensor plane?

Gee Tom, maybe they sold you rubber ones?

[Stagecoach]

I'm just spitballing here, but it is not unheard of for extension tubes to be flexible. Is it possible that the CA is caused by the tubes drooping, causing the lens to no longer be orthogonal to the sensor plane?

The flexing in the Kenko's is very significant and can be measured in millimetres when using a heavier lens and gets worse with the more tubes you use. Easy to get over if using a tripod but something to be aware of.

I'm a regular user of tubes but have never noticed any CA and would be interested to see one of your examples Tobias.

Grahame