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01-02-2010, 01:24 AM   #1
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About S and L teleconverters

Question is: "How S and L schemes affect image quality?"

More detailed info:

I have "Hama Auto Teleconverter 2x for Pentax-K" which looks like Pentax S teleconverter (by size). S means short lenses as I know. For long lenses (longer than 300mm) Pentax has L teleconverter.

The problem is, that when I use mine teleconverter with 300mm lens, I get ghosty image. It is like in milk.

Is this an effect of conbining S-type teleconverter with long telephoto lens or not?

01-02-2010, 03:32 AM   #2
axl
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I would more say that the milkiness is effect of "Hama" converter.
A good TC doesn't have massive effect on IQ. It softens the shot a bit but not to milky stage. But you need good lens and good TC.
The difference between S&L TCs is how the elements are placed so they are optimaly deployed. There are some physical limitations as to why S or L won't work with lenses not intended for, as far as I know.

BR
Peter
01-02-2010, 06:36 AM   #3
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I can't claim any expertise beyond owning a variety of TC's but my understanding is that:

1. The 2x-L is uniquely designed for fairly small set of Pentax lenses and is physically incompatible with virtually all other lenses.

2. Virtually all other Pentax-relevant TC's are "S-type".

3. TC's are often designed for optimal performance with specific lenses: the Sigma line is another example.

4. TC/lens matches can be quirky: some are amazingly good; others, very disappointing.

5 There are a lot of crap TC's out there.
01-02-2010, 08:41 AM   #4
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1.4x-L and 2x-L converters have a protrusion sticking out of the end that attaches to the lens and will hit the rear element of most Pentax lenses before the K-mount can connect.

S converters do not have this and will work with any Pentax lens using a K-mount.

Tom

01-02-2010, 04:32 PM   #5
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Not much difference on digital

In addition to what Tom says:
The L-converters can be used with all Pentax prime lenses 300mm or longer, and with the very rare F/FA 250-600mm and K135-600mm zoom lenses. Autofocus won't work with any lens.

The S-converters are designed for shorter-than-300mm lenses, but can be used on any Pentax lens except the K/A 15mm and K18mm. No autofocus with these either.

The manual warns that the use of S-converters on longer lenses might result in vignetting (darker corners in the image) but since the digital CCD is smaller than the analog film frame this becomes less of a problem with digital bodies.

I use my 2X-S with my A*600mm lens and the results are fully satisfying, just as they are with shorter lenses like the A*200mm. I also have a 1.4X-L to use with the 600mm lens and of course this works very fine too, but I can't use this converter with any of my other lenses.

All the Pentax original converters, including the Pentax-F 1.7X AF adapter, are of very good optical quality.

Have a look at Bojidar Dimitrovs site Pentax Teleconverters

For other makes you'll just have to ask or try before you buy, there are some that only work with some lenses of the same brand (I think this is the case with Sigma), some that are very good and others that are simply unusable if you have any demands at all. Probably your Hama falls within the latter category.

Kjell
01-02-2010, 05:08 PM   #6
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QuoteOriginally posted by bilybianca Quote
The L-converters can be used with all Pentax prime lenses 300mm or longer ... Kjell
I'm afraid that's not quite accurate, Kjell. I know the 2x-L is physically incompatible with the DA*300 and suspect that might be true of some other 300mm Pentax lenses. It might be accurate to say that it can be used with all Pentax prime lenses longer than 300mm but I don't know that for sure.
01-03-2010, 03:40 AM   #7
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QuoteOriginally posted by dadipentak Quote
I'm afraid that's not quite accurate, Kjell. I know the 2x-L is physically incompatible with the DA*300 and suspect that might be true of some other 300mm Pentax lenses. It might be accurate to say that it can be used with all Pentax prime lenses longer than 300mm but I don't know that for sure.
You're absolutely right about this. It can't be used on the "small" 300mm lenses A* f4.0, F*/FA* f4.5 and probably not with the M300mm f4.0. My manual was printed before the DA era, so it doesn't mention the DA lenses at all but your experience with the DA* 4.0 sounds very logic.
It can be used with the "big" 300 mm lenses A*/FA* f2.8 and all the longer than 300 mm lenses. It can also be used with the A* 200 mm Macro lens.

Thanks for notifying and correcting.

Kjell
01-03-2010, 06:13 AM   #8
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QuoteOriginally posted by dadipentak Quote
I'm afraid that's not quite accurate, Kjell. I know the 2x-L is physically incompatible with the DA*300 and suspect that might be true of some other 300mm Pentax lenses. It might be accurate to say that it can be used with all Pentax prime lenses longer than 300mm but I don't know that for sure.
There are some limitations. It can't be used with the K 300/4, too.

The L tcs can be used with the A 400/5.6 (my own experience) but apparently (from info in an older discussion) not with the M 400/5.6. The L tcs can also be used with the Tamron 300/2.8 60B (my own experience) and deliver perfect results.

Ben

01-03-2010, 07:16 AM   #9
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I use the 2x-L with the A*400 f/2.8.
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