Concerns and compensation

[smoke665]

If I were to use a 2x convertor with my 50 mm prime lens. Would there be any issues or adjustmental I should be aware of?

 

[robbins.photo]

If I were to use a 2x convertor with my 50 mm prime lens. Would there be any issues or adjustmental I should be aware of?

Well depending on the lens itself odds are good your 50mm won't mount on a tc. Most short focal length lenses won't

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[table1349]

Yes, TC's are designed for focal lengths of 100mm or more. The top quality TC's are designed to be used with top quality lenses. A TC will magnify the image, a 2x TC will cost you to f stops and most importantly they will cost you image quality. They magnify ever flaw in the lens. You don't say what system you use but if you are looking to by a top quality TC they will cost as much as a decent 100mm lens in most cases.

Example:
Canon EF X2 III - $429.00
Canon 100mm f2 - $499.00

For $70 more you get an f2 lens in the same focal length with good IQ.

 

[smoke665]

Sorry Pentax K30 (k mount). Pentax site was confusing. Didn't specifically say you could just recommend not to go below 50.

 

[robbins.photo]

Sorry Pentax K30 (k mount). Pentax site was confusing. Didn't specifically say you could just recommend not to go below 50.

I don't shoot pentax so can't be certain, but on the Nikon f mount the shorter focal length lenses the mount is not as deep as it is on the longer telephoto.

The tc is designed to take the deeper mount and won't accept the other. My guess is pentax is probably similar but maybe one of the pentax folks we have can weigh in.

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[Derrel]

First off, the TC unit MUST actually physically mate with any lens it is to be used with: many TC units have a forward-projecting element that sticks out from the TC unit's mounting flange, which means that "some" lenses will not even mount onto some TC units. So, there is that caution. OTHER TC units, such as some made by Kenko for example, have a fairly deeply-recessed front element on the teleconerter, and so those will allow mounting many types of lenses.

I've shot a few 50mm lenses with 2x TC units of various manufacturer and various vintages; the typical result is that wide-open the image quality has some veiling glare, which is a lowered contrast, and lowered resolution. Veiling glare is an actual term, an old term; MOST 50mm primes suffer from veiling glare when shot wide-open, and adding a TC will often tremendously add to this defect--almost to the point that the shot looks like it was made with say, the Lensbaby 2.0 effects lens.

Stopped down one stop, the image quality in terms of overall sharpness and contrast will usually be noticeably better--but NOT "great". Closed down another stop, or another two stops, image quality will probably be adequate for many uses. Adding the cheapest, crummiest 2x converter to a 50mm lens can give you a sort of dreamy look, which you might like for portraits; a really cruddy 2x + a-not-well-matched-to-that-converter lens lash-up it will often result in what looks sort of like adding negative clarity in Lightroom.

Be aware also that adding a 2x TC will usually affect the focusing performance of the lens. The best thing to do is to TRY IT and see how it works, for you, with whatever lens and whatever TC unit you have available to you; some of the old, manual focus, used $8 to $15 no-name TC units might be rubbish, but say, a high-grade, 7-element TC unit might be much better. I have a $19 Tokina 2x and a $299 Nikon 2x...one is very yucky...the other is much better in quality.

 

[smoke665]

Thank you, for the input. I have a couple (screw mounts) from back in the stone ages, that I found in a drawer. Actually used them quite a bit in my newspaper days, which piqued my curiosity as to the value of ordering one in the K mount. As some of the others have pointed out, after doing more research, I'm not sure if the cost savings (if any) would outweigh the trouble.

 

[smoke665]

Maybe some of the others on here have seen these, but it's a first for me. Since they screw to the front there wouldn't be any compatibility issues. Left one is a 52 mm 2.2 x converter, Right is a macro adapter. As cheap as they are it's questionable how well they would work, but at less than $25 for both, might be fun to play with.

 

[table1349]

Maybe some of the others on here have seen these, but it's a first for me. Since they screw to the front there wouldn't be any compatibility issues. Left one is a 52 mm 2.2 x converter, Right is a macro adapter. As cheap as they are it's questionable how well they would work, but at less than $25 for both, might be fun to play with.

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Probably only once. The reason no one suggests such things because of their quality, or lack there of. For a P&S they often are the only option and there are some fairly decent ones as well as being costly, for the P&S. Again, they still are not made for short focal lengths. Best suggestion, save your money and get a good 100mm or a 70-200. You will get far more use with either than you will those.