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07-07-2007, 10:40 PM   #1
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Focus distance between object and 50/f1.4 with extension tube/macro adaptor

Hi

I have a Pentax K100D and a 50/f1.4 pentax lens.

I would like to make close-up type "macro" shots and find that if I use the 50/f1.4, I am unable to get very near to the subject. A friend of mine has a DA 14/f2.8 lens and he says he is able to get up real close (up to 5cm of the subject) and yet focus perfectly.

I would like to know if it is possible for me to achieve this using extension tube and/or macro adaptor on the 50/f1.4. Or is it necessary for me to get a DA 14/2.8 as well. This lens is not exactly cheap, imho.

Any advice would be appreciated.

Thank you.

07-07-2007, 11:11 PM   #2
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Welcome to the Pentax Forums raider

What size is the lens cap. From what I understand a tube will make the object appear larger, however up won't be able to get any closer to the object.

However if the lens cap is 49mm and I believe also 50mm (there might be 1 or 2 more sizes available as well) you can get a reverse ring.

You then screw this ring onto the filter threads, and use it to put the lens on your camera backwards.

They don't work properly with all lenses, but they will often allow you to do what you want at an affordable price.
Kenmore Cameras has a used 49mm adapter for a whopping $4.50, here's the link
Kenmore Camera used equipment
It's about 1/2 way down and called a PK>REVERSE 49MM

I was going to buy it, but decided to save up for a dedicated macro lens instead.
07-07-2007, 11:25 PM   #3
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Thanks little laker

I have given some thoughts and feel that the reverse ring might not be suitable for me....I would still prefer the tube/macro adaptor approach

By the way, this is the picture taken by my friend who is using a DA14/2.8 (photo taken at very close distance to the subject) which I am desperately trying to duplicate with my DA 50/f1.4. I am not sure if it is possible at all.

Thanks

Last edited by raider; 01-11-2009 at 09:03 PM.
07-08-2007, 12:44 AM   #4
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I have a set of Vivitar extension tubes, and they work pretty well for me. And i have used them with my M 50 f1.4 and you can get REALLY close, as a matter of fact, you HAVE to get really close, anything more than less than a foot away and you can not focus on anything, lol There is a very small focusing area with the extension tubes, but they do what they are advertised to do !

here are a few samples with the 50mm and a 20 mm extension tube
https://www.pentaxforums.com/forums/post-your-photos/8030-few-more-extension-tube.html

07-08-2007, 01:26 AM   #5
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Would this extension tubes help in macro photography?
07-08-2007, 02:27 AM   #6
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Thanks for the info.

When you say close, can u get like 5cm away from the subject like using a DA 14/2.8?
07-08-2007, 05:09 AM   #7
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here are a few sets on ebay And yes you have to get REALLY close
eBay: ASAHI PENTAX AUTO EXTENSION TUBE ' K' SET (item 180137312248 end time Jul-09-07 17:52:05 PDT)
eBay: Vivitar AT-1 Extension tube kit 12mm,20mm,36mm Pentax (item 290134889132 end time Jul-08-07 12:19:18 PDT)
07-08-2007, 05:11 AM   #8
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QuoteOriginally posted by Deni Quote
Would this extension tubes help in macro photography?

i think those are for medium format cameras, not K mount

07-08-2007, 05:42 AM   #9
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yes ex tubes will let you shoot macros. a macro converter will do the same. for 1:1 magnification using a 50mm lens you will need to use 50mm of ex tubes. IIRC magnification is equal to mm of ex tubes/mm of lens. i have a set of tubes that are a total of 63mm. divide that by 50mm lens = 1.18X. using a 28mm = 2.25X.
if you get a set of tubes be sure to get a set in K mount with the aperture linkage in them. that way you can view the subject wide open and hit the green or AE-L button to get an EV. otherwise you will have to use the lens stopped down. macro needs as much DOF you can get and at f8 and above the VF gets pretty dark in stopped down mode.
you can make a reversing ring out of a body cap and adapter ring glued to it.
07-08-2007, 09:07 AM   #10
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QuoteOriginally posted by little laker Quote
What size is the lens cap. From what I understand a tube will make the object appear larger, however up won't be able to get any closer to the object.
A teleconverter will make an object appear larger at a given distance from the lens by increasing the focal length of the lens. Very often it will also increase the minimum focusing distance though. As a result TCs aren't seen in macro work very often (except for the speciality Vivitar Macro TC) because they add extra optics and slow down the lens.

An extension tube will allow you to focus closer in, fundamentally allowing the object to appear larger.

The extension tubes may or may not allow you to focus in to within 5 CM, but keep in mind that due to the longer focal length of the original poster's lens, the subject will be the same size at 10-15 CM as his friends' lens at 5.

As another person mentioned, you will get 1:1 magnification with the lens focused to infinity when the extension tube length equals the lens focal length (50mm for a 50mm lens), but you can of course move the lens from infinity focus to get even closer.

For macro photography, most people tend to prefer longer lenses (50mm and longer) because they allow for greater working distances. Many of the extension tubes will produce undesirable effects with shorter lenses in addition to the issues with "too close" working distances.
07-08-2007, 05:19 PM   #11
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Thanks for the explanation

QuoteQuote:
The extension tubes may or may not allow you to focus in to within 5 CM, but keep in mind that due to the longer focal length of the original poster's lens, the subject will be the same size at 10-15 CM as his friends' lens at 5.
Let me understand this correctly - if I add an extension tube to my 50/f1.4, I can then aim the lens at the subject with the separation distance being approximately 10-15cm and yet the image is at the same size and perspective as the DA14/f2.8? The perspective is important to me as my friend's DA14/f2.8 can make small size object look like a lifesize object (refer the tasmanian devil pic)

QuoteQuote:
you will get 1:1 magnification with the lens focused to infinity when the extension tube length equals the lens focal length (50mm for a 50mm lens), but you can of course move the lens from infinity focus to get even closer.
If I add the 50mm extension tube to the 50/f1.4, I will get 1:1 macro which is great. But what is unclear to me (yet) is the separation distance between this setup and the subject. Is this going to be at approx 10-15cm or much more?

Lastly, if I get the normal macro lens such as the pentax 100mm/f2.8, how far away from the subject do I have to stand to get a lifesize picture from a small insect, for example? Can I use the 100/f2.8 to make the perspective of the image also lifesize as per the DA14/f2.8?

Thank you.
07-08-2007, 09:30 PM   #12
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As per the Pentax website, the minimum focusing distance for the D-FA 100 macro is 30 cm. The minimum working distance (disance from te front of the lens to the subject) is 13 cm. I'm sure someone else can answer your question as to distances for the 50mm + extension tubes.
07-08-2007, 11:39 PM   #13
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There's a link in and a photo this thread of a vivitar 2x macro extention/adapter. I wanted to get it for myself but they won't ship to Albania. I thought it might help you.
07-14-2007, 06:38 AM   #14
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QuoteOriginally posted by ivoire Quote
Heres another option, get a copy of genuine fractals:
This approach isn't really an alternative to real macro photography. It's a good way of keeping the edges smooth when you enlarge, but it doesn't create detail that wasn't present in the original. In the example shown, the enlarged version is nice, but it doesn't show the detail in the wings that you'd get by getting up close and having the image larger on the sensor.

Here's an example using a SMC-A 50mm lens and a 63mm extension tube. The spider was about 4mm across, including legs. This was hand held, focusing at a distance of a couple of inches. The pop-up flash on the K10D wasn't ideal lighting, but it illustrates that you can get up pretty close with a 50mm lens and the tube:

07-14-2007, 07:16 AM   #15
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QuoteOriginally posted by raider Quote
By the way, this is the picture taken by my friend who is using a DA14/2.8 (photo taken at very close distance to the subject) which I am desperately trying to duplicate with my DA 50/f1.4. I am not sure if it is possible at all.

Thanks
Sorry if I'm repeating what has already been said and it may just be stating the obvious, but I thought I should point out: as mentioned you can use reversal or extension tubes to get closer with the 50mm... however you would not be able to duplicate that shot, because it was taken with a wide-angle.
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