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11-23-2009, 09:17 AM   #1
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A gang of m42 macro tube questions

Hello,

I bought a super takumar asahi 105mm on Ebay thinking it was a macro lens, but apparently it is not. I really am interested in shooting things like insects or flowers at very close up levels, but I think I am going to need macro tubes to accomplish it.

If I want 1:1, do I really need to get 105mm of tubes? Won't that be too long for the camera body? I am curious about structural integrity at this point.

Moreover, this lens is a m42 lens, so I bought the genuine k adapter. However, do I need m42 macro tubes, or k mount tubes?

Does anyone have a suggestion for tubes?

Thank you in advance.

11-23-2009, 09:28 AM   #2
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I believe to get 1:1, you need to calculate it, as it depends focal length(big factor), minimum focus distance, etc.

www.peterforsell.com
Macro lens calculations

I am not sure how well the M42 K-mount adapter mounts to a K-mount tube, but I presume you could go either way:
lens -> m42 tubes -> m42-k adapter
lens -> m42-k adapter -> k-mount tubes.

In which I'd go with K-mount tubes for compatability with other lenses. I am not positive, I actually have both sets at home (someone thought the m42 tubes were part of a lens and sent it to me on ebay) so I can look into it if someone doesn't already know.

I don't think brand matters optically (as there is no glass), but length, build quality, ease of use (such as disconnecting the lens on a K-mount adapter), weight, etc matter.

I have cheap ebay k-mount tubes from China and the screw for releasing the lens fell out and the tread seems to have been stripped very easily, I am trying to get the seller to send me another one.
11-23-2009, 09:41 AM   #3
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Original Poster
QuoteOriginally posted by Eruditass Quote
I believe to get 1:1, you need to calculate it, as it depends focal length(big factor), minimum focus distance, etc.

www.peterforsell.com
Macro lens calculations

I am not sure how well the M42 K-mount adapter mounts to a K-mount tube, but I presume you could go either way:
lens -> m42 tubes -> m42-k adapter
lens -> m42-k adapter -> k-mount tubes.

In which I'd go with K-mount tubes for compatability with other lenses. I am not positive, I actually have both sets at home (someone thought the m42 tubes were part of a lens and sent it to me on ebay) so I can look into it if someone doesn't already know.

I don't think brand matters optically (as there is no glass), but length, build quality, ease of use (such as disconnecting the lens on a K-mount adapter), weight, etc matter.

I have cheap ebay k-mount tubes from China and the screw for releasing the lens fell out and the tread seems to have been stripped very easily, I am trying to get the seller to send me another one.
Thank you.

I was looking at PENTAX M42 SCREW MOUNT AUTO MACRO EXTENSION TUBES MINT@ - eBay (item 230395874790 end time Dec-04-09 20:50:11 PST)

but I am not sure it will work for what I am looking for.
11-23-2009, 10:20 AM   #4
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I have a manual for my genuine Pentax M42 tubes (that I'm selling ) and it says the 105 Tak can only do .65x magnification with 57mm worth of tubes. The bellows, on the other hand, can make the lens go over 1x magnification.

11-23-2009, 10:42 AM   #5
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QuoteOriginally posted by ryan s Quote
I have a manual for my genuine Pentax M42 tubes (that I'm selling ) and it says the 105 Tak can only do .65x magnification with 57mm worth of tubes. The bellows, on the other hand, can make the lens go over 1x magnification.
I would like to point out (from personal experience) that handheld macro at 1:1, especially of anything that moves even the tiniest little bit, is extraordinarily difficult.

I don't think the OP realizes that he has to manually stop down the aperture on these lenses prior to shooting. That has two effects: 1) it moves the camera, ruining focus in the process and 2) it makes the viewfinder damned near pitch black.

The only thing I can say about doing macro with a setup like this is that it "builds character". It is doable but unless a person is just a diehard curmudgeonly Luddite with a mile-wide streak of contrariness I would recommend skipping the aggravation and going for a genuine macro lens to begin with....preferably K-mount.

I think this is the first time I have ever suggested a K-mount lens, come to think of it.
11-23-2009, 10:55 AM   #6
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As usual, very informative. Thanks guys.

To be honest, I would prefer to go with a real macro lens, but everything I found on Ebay is $200+. I would love to see something in the $100s. Or is that just the nature of the macro game?
11-23-2009, 11:02 AM   #7
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QuoteOriginally posted by Dynasty Quote
Hello,

I bought a super takumar asahi 105mm on Ebay thinking it was a macro lens, but apparently it is not. I really am interested in shooting things like insects or flowers at very close up levels, but I think I am going to need macro tubes to accomplish it.

If I want 1:1, do I really need to get 105mm of tubes? Won't that be too long for the camera body? I am curious about structural integrity at this point.

Moreover, this lens is a m42 lens, so I bought the genuine k adapter. However, do I need m42 macro tubes, or k mount tubes?

Does anyone have a suggestion for tubes?

Thank you in advance.
To get to 1:1 you need extension tubes equal to the lens focal length. 1:1 is then achieved when the image is at 2 x the focal length.

As for the integrity, the 105 F2.8 takumar is a compact lens, people have put much worse on extension tubes

As for the type of tubes, it is fully up to you where you put the K adaptor,

I picked up a genuine set of pentax tubes for an M42 for $5 and they look like they never got used.
11-23-2009, 11:37 AM   #8
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QuoteOriginally posted by Lowell Goudge Quote
To get to 1:1 you need extension tubes equal to the lens focal length. 1:1 is then achieved when the image is at 2 x the focal length.

As for the integrity, the 105 F2.8 takumar is a compact lens, people have put much worse on extension tubes

As for the type of tubes, it is fully up to you where you put the K adaptor,

I picked up a genuine set of pentax tubes for an M42 for $5 and they look like they never got used.
As far as I understand, this doesn't take into account how much the lens will be moved away at closest focus, hence the minimum focus distance and magnification figures, but what FL is given? minimum, maximum focus distance?

11-23-2009, 11:39 AM   #9
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QuoteOriginally posted by Mike Cash Quote
I would like to point out (from personal experience) that handheld macro at 1:1, especially of anything that moves even the tiniest little bit, is extraordinarily difficult.

I don't think the OP realizes that he has to manually stop down the aperture on these lenses prior to shooting. That has two effects: 1) it moves the camera, ruining focus in the process and 2) it makes the viewfinder damned near pitch black.

The only thing I can say about doing macro with a setup like this is that it "builds character". It is doable but unless a person is just a diehard curmudgeonly Luddite with a mile-wide streak of contrariness I would recommend skipping the aggravation and going for a genuine macro lens to begin with....preferably K-mount.

I think this is the first time I have ever suggested a K-mount lens, come to think of it.
Great point, extension tubes will rob light in addition to having to stop down to get usable DoF.
11-23-2009, 12:54 PM   #10
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QuoteOriginally posted by Eruditass Quote
As far as I understand, this doesn't take into account how much the lens will be moved away at closest focus, hence the minimum focus distance and magnification figures, but what FL is given? minimum, maximum focus distance?
You raise some good questions, but they are much more important for a true macro lens, like the 100mmF4 than the 105 F2.8

The lens moves a little at minimum focus but not a lot.

I have a K 105 F2.8 which is similar

Without extension tubes it's minimum focus is 1.1 meters and the lens extension at minimum focus is only 11 mm, and maximum magnification ratio (at minimum focus is 0.11.

By comparison, the 100mmF4 macro extends a full 50mm to give 1/2 life size without extension tubes.

On the 105 mm if yoou go to 105 mm of extension tubes your working distance is 200-210mm and magnification ratio is between 1:1 and 1.11:1
11-23-2009, 03:58 PM   #11
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QuoteOriginally posted by Dynasty Quote
As usual, very informative. Thanks guys.

To be honest, I would prefer to go with a real macro lens, but everything I found on Ebay is $200+. I would love to see something in the $100s. Or is that just the nature of the macro game?
You could try to find a Cosina/Vivitar/Promaster/Phoenix plastic fantastic 100/3.5 macro for about $100 (including a "matched" close-up lens that's actually pretty good). There's also a KA-mount manual focus version.

Cosina AF 100mm f/3.5 macro (Pentax) - Lab Test Report/Review

A Pentax K or M 100/4 might also fit your budget. The biggest drawback is that you lose TTL flash.
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