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04-23-2011, 07:15 PM   #1
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is this possible?

hi everyone

I was looking at a pentax M50 macro f4 and was wondering if it is possible to put a teleconverter on to make it around 100mm and then put on a macro extension to get closer?

thanks

04-23-2011, 07:24 PM   #2
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That would probably kill the IQ- but hey, it is possible

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04-23-2011, 08:36 PM   #3
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I don't think this will work for you, while possible, it probably won't be workable. You start with an f/4 lens, add a 2x TC and now you have an f/8 combo. When you add the extension tubes, you will have even less light getting to the view finder. How would you focus it? You would need so much light on the subject, that it just doesn't seem a good solution. And as Adam said, the IQ will most likely be bad.
04-24-2011, 03:02 AM   #4
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No, you don't want to do that. Unmatched TC's generally suck. TC's in macro usage eat light. For 100mm macro, get a cheap bellows and a cheap 100-105-110mm enlarger lens.

04-24-2011, 01:48 PM   #5
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But say you have all that stuff, why not try it.

My setup was to use a US $20 bill as a target. I got pretty close to the minimum focus distance of the M50/4 for the first shot, with just a little leeway to focus with the focus ring, not moving the whole tripod up and down. K-7, ISO 100, f8, 0.25 sec.:



Then I dusted off a Zykkor 2X TC, which I've never used for anything. It's safe to assume that it is not a hidden gem based on a Leica design. A little fiddling with the tripod was necessary to get the minimum focus distance again. I adjusted exposure by trial and error for a similar histogram, but with different content in the frame (more light tones) it didn't end up 2 stops darker. Shutter speed was 0.3 sec.:



Then I put on 48mm of extension tubes, the closest I could get to 50mm. Now that I think about it, I don't know the best position of the TC. In this case, the order was lens, TC, tubes. More small height adjustments, and 0.7 sec. shutter speed:



I would have agreed with all the armchair statements above, but results are decent anyway. Unless your target is stationary or extremely well-lit, the TC will make things difficult. But it doesn't kill IQ like you'd think. Maybe lower contrast. Focusing isn't easy.

Maybe someone smart can figure out magnification ratios.
04-24-2011, 05:04 PM   #6
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QuoteOriginally posted by Just1MoreDave Quote
But say you have all that stuff, why not try it.

My setup was to use a US $20 bill as a target. I got pretty close to the minimum focus distance of the M50/4 for the first shot, with just a little leeway to focus with the focus ring, not moving the whole tripod up and down. K-7, ISO 100, f8, 0.25 sec.:



Then I dusted off a Zykkor 2X TC, which I've never used for anything. It's safe to assume that it is not a hidden gem based on a Leica design. A little fiddling with the tripod was necessary to get the minimum focus distance again. I adjusted exposure by trial and error for a similar histogram, but with different content in the frame (more light tones) it didn't end up 2 stops darker. Shutter speed was 0.3 sec.:



Then I put on 48mm of extension tubes, the closest I could get to 50mm. Now that I think about it, I don't know the best position of the TC. In this case, the order was lens, TC, tubes. More small height adjustments, and 0.7 sec. shutter speed:



I would have agreed with all the armchair statements above, but results are decent anyway. Unless your target is stationary or extremely well-lit, the TC will make things difficult. But it doesn't kill IQ like you'd think. Maybe lower contrast. Focusing isn't easy.

Maybe someone smart can figure out magnification ratios.
thanks! they look great to me, maybe someday I can afford the equipment to try it out myself
04-25-2011, 12:47 AM   #7
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Can you try with a reverse ring? or is it too close working distance?

I use M28f2.8 reverse and full set of extension tubes.
Focus using moving camera, at f2.8 by holding the aperture lever of the lens and shooting at f22. flash 1/64 with radio trigger.
04-26-2011, 10:50 AM   #8
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QuoteOriginally posted by hoanpham Quote
Can you try with a reverse ring? or is it too close working distance?

I use M28f2.8 reverse and full set of extension tubes.
Focus using moving camera, at f2.8 by holding the aperture lever of the lens and shooting at f22. flash 1/64 with radio trigger.
At first I was going to say I don't have a reversing ring. Then I remembered I have a Kiron Reverse-Mate, with a K-mount on one end and a 55mm filter thread on the other. I had to fool around with step rings to mount the M50/4 to it. The lens has a small front element, deeply recessed in the front, so it may not be a great choice for reversing. But here's my first try anyway. I didn't use extension tubes, lens focus was at infinity (vignetting at other settings), actual focus was by moving the tripod column (maybe not perfect), f22, 2 sec., ISO 100, same bill, about the same working distance as with the TC:



04-26-2011, 11:02 AM   #9
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OMG! Abraham Lincoln's ghost in the upstairs left window!


I think the image with the lens reversed is better than with the TC.
04-26-2011, 12:50 PM   #10
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thanks very much for the info everyone.
ok another unusual question. could you put a telephoto extender on first then the macro lens to make it like a 100mm macro (assuming I use my 50mm f4 macro lens)

thanks and cheers
04-26-2011, 03:29 PM   #11
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QuoteOriginally posted by slip Quote
thanks very much for the info everyone.
ok another unusual question. could you put a telephoto extender on first then the macro lens to make it like a 100mm macro (assuming I use my 50mm f4 macro lens)
Not exactly your situation, but I regularly use a Sigma EX 180 f3.5 Macro with a Pentax F 1.7x Auto Focusing Adapter to get a 305mm f6 macro lens. The Sigma is a 1:1 macro to start with, and with the AFA, I can actually get @1.9:1 at a slightly closer Minimum Focusing Distance. I can get the original 1:1 magnification at a greater working distance though (at 15" from the front of the lens opposed to @10" with the lens alone), and that's important for shooting creatures. I shoot handheld and with flash all the time, BTW.

With your 50 f4, I believe that you get 1:2 magnification, and with a 2x TC, you should get 100mm and at least 1:1, but at f8, the viewfinder would be pretty dark, and you'd be limited to very bright conditions just to focus. You should be able to get good exposures with flash though.

If you want a more usable relatively economical solution, I'd look into an MF 50 f1.4 or 1.7 standard lens and a Tamron 2x Macro Focusing TC. This would give you a 1:1 100mm f2.8 or 3.5 lens, and the optical quality is better than most of the 2x TCs out there. The wider max aperture would be a lot easier to focus, and you'd have a nice fast 50 mild tele lens to boot.

Here's a good comparison of this combo against a considerably more expensive modern dedicated 100mm macro:

www.jr-worldwi.de: Photography

Scott
04-26-2011, 07:41 PM   #12
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QuoteOriginally posted by snostorm Quote
...If you want a more usable relatively economical solution, I'd look into an MF 50 f1.4 or 1.7 standard lens and a Tamron 2x Macro Focusing TC.
It's a Vivitar, not Tamron. Sorry, I'm only nitpicking because it's the beginner's forum - obviously you know, just typed the wrong thing.

These can be cheaper without electrical contacts. If your 50mm doesn't have them, your TC doesn't need them either.

QuoteOriginally posted by slip Quote
thanks very much for the info everyone.
ok another unusual question. could you put a telephoto extender on first then the macro lens to make it like a 100mm macro (assuming I use my 50mm f4 macro lens)
Isn't that what I did in the second shot?

Anyway, most of these bandaid solutions are not very cost-effective. A 2X teleconverter of reasonable quality, or the Vivitar 2X MFTC, is maybe $30-50. That means squinting through a dark viewfinder. It really makes focusing a chore.

Just last year I bought a slightly beat-up Tamron Adaptall-2 SP 90mm f2.5 macro for $80, with a K adapter. I forget what an 01F 2X teleconverter goes for, but you can start cheap and build a nice manual-focus macro system around that. A Pentax 100/4 is what, $100? A Raynox is maybe $40. I would go with one of those if I needed a longer FL or more magnification. Sell the M50/4 for $50 if it doesn't do the job.

What I did with macro stuff is accumulated a lot of lenses and accessories without a goal/subject in mind. It is much easier/cheaper to start with subject and go to lenses that do the job.
04-27-2011, 03:51 AM   #13
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QuoteOriginally posted by Just1MoreDave Quote

Isn't that what I did in the second shot?
I am very new to these terms so please be patient with me

thanks everyone so far

cheers
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