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04-15-2015, 08:50 AM   #1
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Can this be for real? Wow.

I am looking at something which claims to be a 3X teleconverter, brand name "Formula 5", M42 mount.

Oh. My. God.

The light loss is, I'm sure, going to be horrific. I'm tempted to spring for it (along with a cheap M42 telephoto lens) solely to see (a) if it works and (b) how it does.

Has anyone ever encountered anything like this before?

04-15-2015, 08:56 AM   #2
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Sounds interesting, though people even complain about 2x teleconverters. I'd be interested to see what you find out if you do buy it
04-15-2015, 08:57 AM   #3
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A 2X is pushing things. I really don't think a 3X would be worth anything.
04-15-2015, 09:24 AM   #4
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2x is do-able with a constant f/4 zoom, though it darkens my split-prism focusing screen.
Even my best 2x gives noticeable CA.
A 3x teleconverter would have to be magic to be worth the loss of light and IQ.

04-15-2015, 09:32 AM   #5
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You see them all the time with Spotmatics or other M42 cameras on Shopgoodwill. They don't really seem to have survived the transition to K-mount. Probably because 70-210 and 80-200 zooms were replacing the 135mm as part of the kit by then. The Korean 60-300s were popular in the 80s too.
04-15-2015, 09:33 AM   #6
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3x converters have been around for quite a while. Do a search for '3x teleconverter' and see for yourself.
Like all teleconverters, they are the poor man's way of increasing focal length. They will give you extra
reach but at the price of light loss and reduced image quality.
04-15-2015, 09:39 AM   #7
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3x were quite common at one time. I have a couple laying around in M42 but I've never used them. I kept them to take the glass out of to make extension tubes. But never got around to it.

IMHO mostly a gimmick as the light loss and IQ loss are horrific. Though back in the day when primes were about all you had a 2x and 3x TC gave you a lot of focal lengths for little money when added to your 135mm or 200mm. Not worth the effort today I don't think but if you want to make your 300mm a 900mm go for it.

04-15-2015, 10:02 AM   #8
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As mentioned above they have been around a long time. While I never used one (I used 2x sometimes/mostly with film--and results I thought were fine), the same general attributes/problems as with 1.4x and 2x TC, and its worsening with higher magnification (as in the trend of 1.4x to 2x), applies.
As I recall from reliable source(s) [for sure Blaker "Field Photography" and likely Lefkowitz "Manual of Close Up Photography"]:
1. Generally best in close up/macro,
2. Best with highest quality prime lens--can be terrible w/ lower quality zooms.
3. If optics/mechanics poorly made will be terrible, if well made likely can be pretty good/better than cropping (even at infinity).
4. Combining two TCs (e.g., 2x and 3x) quite satisfactory results in macro,
5. f stop reduction is consistent with magnifying image from the lens--1 stop if 1.4x, 2 stops if 2x, 3 stops if 3x.
6. And [not specifically from the source(s) mentioned] w/ high iso ability now they (and mirror lenses) likely are more viable alternatives, as except for minor diffraction reducing resolution, modest f stops (and higher shutter speeds) are now feasible.

---------- Post added 04-15-15 at 10:06 AM ----------


Last edited by dms; 04-15-2015 at 10:08 AM.
04-15-2015, 10:23 AM   #9
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I used to have a 3x TC in K mount back in the day, bought it with some lenses and never used it. I just bought a Kenko AF 3x which only auto focuses only on my f2.8 lenses, need to take it out for a test.
04-15-2015, 12:12 PM   #10
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I have a 3X in K-mount. Its not actually horrible, but I certainly wouldn't spend any huge amounts of money on one. As mentioned above, they work MUCH better with macro shots or anything really that's less than infinity shooting.

With infinity shots, lets just say "I hope you enjoy seeing every lick of dust hiding on that sensor of yours." Diffraction is also nasty (even wide open as even an f5.6 lens is going to shoot up to f11 (if I did the math right) and have an extra glass element thrown in. Adding those three stops means the things are only really useful with lenses that have wider apertures, and are decent at those wide apertures, because any little flaw or defect in either the TC or the lens is going to become noticeable, fast. Since you're also disconnecting the lens from the body by shoving the TC (which will likely have no contacts) in the middle, you're killing the ability to stop down meter as well. Its wide open or nothing.

Heres my particular beastie.



And here are some shots taken with it with the Bower 35mm f/1.4.



This is the same stack of change shot at MFD with the same lens, sans the 3X TC.


Note that the Samyang 35 isn't a macro lens, it just has a decent MFD of about a foot. I really should try one of the pseudo-macros (really, they're more close focus than anything) I have with this thing one of these days.


Last edited by Sagitta; 04-15-2015 at 12:28 PM.
04-15-2015, 01:31 PM   #11
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QuoteOriginally posted by Sagitta Quote
I have a 3X in K-mount. Its not actually horrible, but I certainly wouldn't spend any huge amounts of money on one. As mentioned above, they work MUCH better with macro shots or anything really that's less than infinity shooting.

With infinity shots, lets just say "I hope you enjoy seeing every lick of dust hiding on that sensor of yours." Diffraction is also nasty (even wide open as even an f5.6 lens is going to shoot up to f11 (if I did the math right) and have an extra glass element thrown in. Adding those three stops means the things are only really useful with lenses that have wider apertures, and are decent at those wide apertures, because any little flaw or defect in either the TC or the lens is going to become noticeable, fast. Since you're also disconnecting the lens from the body by shoving the TC (which will likely have no contacts) in the middle, you're killing the ability to stop down meter as well. Its wide open or nothing.

Heres my particular beastie.



Note that the Samyang 35 isn't a macro lens, it just has a decent MFD of about a foot. I really should try one of the pseudo-macros (really, they're more close focus than anything) I have with this thing one of these days.

I've got both thenvivitar 2x and 3x , bought both back in the early 1980's when I was young and foolish
04-15-2015, 02:26 PM   #12
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Cropping is a better alternative than a 3X converter.
04-15-2015, 03:36 PM - 1 Like   #13
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QuoteOriginally posted by Pål Jensen Quote
Cropping is a better alternative than a 3X converter.
Only if the crop is not severe. If the crop gets you into lost detail due to pixel resolution the TC is better simply due to the larger number of pixels
04-15-2015, 04:15 PM   #14
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QuoteOriginally posted by Pål Jensen Quote
Cropping is a better alternative than a 3X converter.
In my personal opinion, severe cropping is never a better alternative to anything. Its only viable if you physically can't get the shot due to lens limitation or inaccessibility to the subject.
04-15-2015, 06:27 PM   #15
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QuoteOriginally posted by Sagitta Quote
In my personal opinion, severe cropping is never a better alternative to anything. Its only viable if you physically can't get the shot due to lens limitation or inaccessibility to the subject.
No use for lots of pixels if they are fuzzy. Better with fewer sharp ones. Images get published from 1mp DSLR's....
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