Teleconverter and aperture

hammy · Nov 29, 2006

I've got a simple question here I've always wondered about

I have a 2x teleconverter that I regularly use on my 50mm f1.8

When using my teleconverter on my 50mm 1.8, does the aperture remain the same? In other words, is it a 100mm 1.8?

Nick Zentena · Nov 29, 2006

No. You lose 2 stops IIRC. The focal length is twice the length but the aperture size is the same. So the F/stop must change.

Ole · Nov 29, 2006

2x teleconverter -> 2x the aperture number (two stops). 1.4x teleconverter -> 1.4 times the aperture number (one stop).

It's simple, really!

David A. Goldfarb · Nov 29, 2006

You lose two stops, usually in addition to a little transmissive loss, which can be around 1/3-1/2 stop. You don't need to think about it if you are metering through the lens, but if you use a handheld meter or non-TTL auto flash, and if you shoot slides, you might want to run some tests.

hammy · Dec 1, 2006

Thanks.
That's what I thought.

Christopher Walrath · Dec 1, 2006

Yeah, I've found through personal lens tests that teleconverters do not begat the same image quality as a longer lens or a longer zoom on that lens. Of course you have to weigh whether you want to have one lens or four when in the field, what have you.

Helen B · Dec 1, 2006

Masochists may be interested in Dead Link Removed about exposure compensation with a teleconverter when used for macro.

Best,
Helen

keithwms · Dec 1, 2006

Helen B said:
Masochists may be interested in Dead Link Removed about exposure compensation with a teleconverter when used for macro.

Best,
Helen

Using a TC for macro? :confused: I guess you mean an extension tube; I wouldn't use a TC for macro. As for exposure adjustment with an extension tube, it's just a bellows factor issue.

naturephoto1 · Dec 1, 2006

Keith,

Yes the teleconverters can and are frequently useful for close-up or macro work. As an example this would allow the use of a lenses with or/without extension tubes, bellows, or even diopters. Helen is quite right about and quite knowledgeable about the affects of teleconverters and macro work. I would have to read what she indicates more carefully in the thread on the other site. However, if you are using a camera with an inboard meter, the through the lens metering should tend to make the appropriate corrections for exposure. Bracketing as is the usual procedure should yield good results. If however, there is no inboard metering, then you will have to make corrections.

Rich

Helen B · Dec 1, 2006

keithwms said:
... I guess you mean an extension tube...

Well, what would I know? I'm only a girl. My guess is that it would have been better to have looked at the thread before commenting. I did warn you that it was for masochists, though.

Best,
Helen

Lee L · Dec 1, 2006

keithwms said:
Using a TC for macro? :confused: I guess you mean an extension tube; I wouldn't use a TC for macro. As for exposure adjustment with an extension tube, it's just a bellows factor issue.

Keith,

I see you subscribed in October. Not to be condescending, but if you read through Helen B's other posts, you'll find that she's always meticulous and correct. I know there's a lot of underinformed and poorly worded junk on the web, but you won't see that coming from Helen.

Lee

keithwms · Dec 1, 2006

Helen B said:
Well, what would I know? I'm only a girl. My guess is that it would have been better to have looked at the thread before commenting. I did warn you that it was for masochists, though.

Best,
Helen

My comment had nothing to do with your gender, why bring that up? It's irrelevant.

I did glance at the thread and I indeed did not find it enjoyable, as you had predicted.

In fact,I posted my message because I know for a fact that some newcomers (boys and girls) confuse TCs with extension tubes. Simple.

keithwms · Dec 1, 2006

Lee L said:
Keith,

I see you subscribed in October. Not to be condescending, but if you read through Helen B's other posts, you'll find that she's always meticulous and correct. I know there's a lot of underinformed and poorly worded junk on the web, but you won't see that coming from Helen.

Lee

My comment had nothing to do with Helen, her gender, or her qualifications.

I think Rich responded to my post aptly, without resorting to issue of gender or my date of subscription.

Dave Parker · Dec 1, 2006

I have been using Teleconverters for macro work since about day one, and that was close to 30 years ago...works for me, your mileage may vary,, I guess I pretty much use anything that will allow me to get the shot, I have also been known to stack 2 or 3 teleconverters to get a shot..

Go figure.

Dave

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