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12-22-2011, 11:14 AM   #1
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Extension tubes and catch-in-focus

Hi guys! My extension tube arrived yesterday, and i attached my M 50mm 1.7 lens to it, and everything works fine, except that i can't use catch-in-focus with it. Is there a solution for that?
Thanks!

12-22-2011, 11:36 AM   #2
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Is the flange of the tube (where it makes contact with the camera body) anodized, painted, or bare (chrome)? If it is NOT bare, try a piece of aluminum foil between the extension tube and the camera body, covering the electrical contacts on the lens mount to ground the contacts. If that works, try to cover just pin #7. If that works, scratch the paint on the tube to ground that pin.

12-22-2011, 11:36 AM   #3
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Most likely the mount part of the tube does not short the contacts as a chromed lens base would. You can test this with a strip of aluminium foil slipped between the body and the contacts. If the latter works you might consider aluminium tape or removing the coating from the base of the tubes. [edit: SOldBear beat me to it .]
12-22-2011, 11:36 AM   #4
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Well you don't tell us what type/brand these extension tubes are. If they are black anodized at the rear, there might be a solution in sanding down to the bare metal where the mount should shorten the camera body contacts.

Anyway, do not expect too much use of CIF in macro work. Scenes are usually pretty low-light and low-contrast making it hard for CIF to work properly

12-23-2011, 05:23 AM   #5
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CIF and extension tubes

Agree with Stone G. CIF is a bit slow to respond as well - I assume that you intend to slowly move the lens forwards or backwards until the image is focused. Having tried this approach, I can say that you are better off a) using Liveview to check focus, b) using a sliding rail system that you can move the camera on, which is fixed to a tripod and a ring flash or light

Macro work with extension tubes is difficult - can be done but is a pain to get right. Lighting is the killer issue really. To get around that, I bought an old but perfect 1.7 50mm SMC Takumar lens - now I can at least focus at F2 (F1.7 is soft), which improves the lighting issues a lot but DOF then measures about 3 millimetres - so, you get rid of one problem and introduce another.
12-23-2011, 05:38 AM   #6
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Thank you all. I'll try every tip here.
I will only use this setup at daylight, obviously, and perhaps like that it will work. Let's see
12-23-2011, 08:01 AM   #7
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QuoteOriginally posted by GabrielFFontes Quote
I will only use this setup at daylight, obviously
There's no reason not to have some fun with tubes at night. I shot these two awhile back, at about 4am, moonless night. I used a small LED flashlight held against the lens barrel/tubes to get focus, and the pop-up flash to get the shot. I can't remember if I used a diffuser on these or not, but I'm thinking not.





50mm F/2 on 68mm extension, resulting in about 1.45:1 magnification fully focused in. Handheld of course. Nothing spectacular, but still fun stuff.

Quick edit: On second thought, I may have only been using 2 of the 3 tubes, so somewhere around 1:1. Not using CIF, I haven't even begun to experiment with CIF yet. It's not really needed at this magnification.

Last edited by Philoslothical; 12-23-2011 at 08:16 AM.
12-23-2011, 09:07 AM   #8
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Philoslothical, for sure you can use it at nighttime, but CIF won't work, probably!

12-23-2011, 09:24 AM   #9
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With a strong LED light source, it just might. The small flashlight I'm using is generally enough for the AF confirmation to light up. Whether I can stand still long enough to make use of it is another story. I tend to lean in and grab the shot on a more instinctive and visual level, which is hit or miss of course.

In theory, I'd think if you can get an AF lock, even momentarily, that should be enough for CIF to fire, shouldn't it?
12-23-2011, 10:05 AM   #10
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It should, i guess...the system just uses the AF lock, right?
Also, a macro light ring should be great for that too...maybe i'll buy one some day, but i should get a true macro lens first
12-23-2011, 10:11 AM   #11
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It should need the AF lock for a much shorter time than we do, so yeah, it's worth a try.

I've thought about a ring light for this, but haven't got to it yet. My humble little flashlight will do for now (budget is more of a concern lately). A true macro lens would be MUCH easier to use than a short prime on tubes. No light loss to get 1:1 would be a big step up, plus they're renowned for their flat field sharpness. There would be little point using tubes with one to push it further though, as you would need more extension to counter the longer focal length, and you'd end up sacrificing any light gain in the process.
12-29-2011, 10:08 AM - 2 Likes   #12
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Hi guys. I know its a simple process, but i made a little tutorial just to help people.
PS : The final result can be much much better than mine, but i was doing it with one hand, because i was also taking the pics. That is why the pics are so bad
You will need only a scissor, duct tape (or some other kind of tape) and aluminium foil
So here you go






Hope it helps someone
12-29-2011, 11:24 AM - 1 Like   #13
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It's an el cheapo generic set of extension tubes, just scrape off the black coating and be done with it. Each time you mount and dismount the tubes from your body, you are going to leave behind minute amounts of adhesive residue on the mount which may cause more problems later. It's not like you are trying to preserve a $200.00+ set of extension tubes in it's original glory.
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