Re: Best 2X TC for K mount
> Well, I guess, "S" and "L" just stand for short lenses versus Long > lenses, but the "L" converters themselves are quite "Long" too :-) I've always assumed that the "L" stood for "long" TC and the "S" for "short" TC, rather than referring to the focal lengths of the lenses to be attached. (However, I honestly don't know what Pentax's intent was...) >>The "snout" to which you refer- is that cause for incompatibility >>with certain lenses of a more conventional focal length, like a 80-200? >> > Yes, you have to be very carefull when trying it on a new lens, measure > first, then measure again! Very good point. One really doesn't want to find out "the hard way" (by "snout to rear element contact" that an "L" TC isn't compatible with a particular lens - . (I did provide measurements and measuring hints in another post in this thread.) Fred - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
RE: Best 2X TC for K mount
On Thu, 11 Apr 2002 09:41:45 -0400, TM wrote: >You've answered a question of mine before I've even asked it- >I was always wondering what the differences were between the -S >and the -L convertors. Thanks. > Well, I guess, "S" and "L" just stand for short lenses versus Long lenses, but the "L" converters themselves are quite "Long" too :-) >The "snout" to which you refer- is that cause for incompatibility >with certain lenses of a more conventional focal length, like a 80-200? > Yes, you have to be very carefull when trying it on a new lens, measure first, then measure again! >Are there any differences in brightness between the two? I am not sure, I have not seen a Pentax 2x S, I do know the "L" ones are brighter (larger lens diameter) than most other converters I have seen. I have the 1.4 and 2x APO AF converters by Sigma, and they are visibly smaller and cause vignetting on long lenses using larger apertures. (otherwise they are very good) Regards, JvW -- Jan van Wijk; http://www.dfsee.com/gallery - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
Re: Best 2X TC for K mount
Me thinks you`re not using the right stuff. Last weekend I used my 1000/8 SMCT with a full set of Asahi extension tubes, a Vivitar 2X Macro Teleconverter and an LX on a Bogen 3051 with a 501 video head and got a close up of an owls face, you can see every feather around its beak, and focusing was not that difficult, I don`t know, maybe I just got lucky. The photo will be in the upcoming PUG. I wouldn`t forget about it. Steve Larson Redondo Beach, California Pål Audun Jensen wrote: Pentax made a 2X-L converter dedicated to the longer A* series ED lenses. It works OK with these lenses. Otherwise, no non-dedicated 2X converter gives great results, and many of us, myself inculded, find that 2X converter never give good results. I never got acceptable result with the 2X-S converter. Getting sharp images with 1000mm lens without ED elements is almost impossible to start with. Getting good results with a 2X converter is impossible according to the laws of physics. It will also be impossible to get sharp images due to vibrations. You need at least two heavy duty tripods. At last, it is virtually impossible to focus an F:16 2000mm lens critically. So forget about it! Pål - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
Re: Best 2X TC for K mount
JCO: >Did Pentax make a high performance >K mount 2X teleconvertor for long lenses? >I want one to try on my SMCK 1000mm >F8. Pentax made a 2X-L converter dedicated to the longer A* series ED lenses. It works OK with these lenses. Otherwise, no non-dedicated 2X converter gives great results, and many of us, myself inculded, find that 2X converter never give good results. I never got acceptable result with the 2X-S converter. Getting sharp images with 1000mm lens without ED elements is almost impossible to start with. Getting good results with a 2X converter is impossible according to the laws of physics. It will also be impossible to get sharp images due to vibrations. You need at least two heavy duty tripods. At last, it is virtually impossible to focus an F:16 2000mm lens critically. So forget about it! Pål - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
Re: Best 2X TC for K mount
> Did Pentax make a high performance K mount 2X teleconvertor for
> long lenses? I want one to try on my SMCK 1000mm F8.
The best Pentax TC's for long lenses (but only for lenses that can
fit their "snouts" into the K-mount end of the lens) are the "L"
models (A 1.4X-L and A 2X-L). I don't know offhand if either of
these would fit into your K 1000/8, JCO.
The "S" models (A 1.4X-S and A 2X-S) are also good TC's, if the "L"
models won't fit. However, I really don't know how well they would
work with a 1000mm lens - I've not used either with any lens over
300mm.
In general, the 1.4X models (both "L" and "S") have a greater chance
of causing vignetting, but only with certain lenses.
The 6-element T6-2X is (in my tests) just as good a TC as the
7-element A 2X-S, but (again), I've never used it with a 1000mm lens
(and Pentax, in the user manual, doesn't seem to suggest its use
with lenses over 300mm).
In the event that the "L" models might fit, I'm going to append a
little treatise I posted to the PDML back in 1999, with the
measurements of the "L" TC's "snouts", below. (I apologize for its
length, but I tend to be verbose, and at least it's not OT - .)
Fred
+
Safe "X" (safe use of 2X-L and 1.4X-L with non-Pentax lenses)
As far as I know, there have been 6 Pentax rear converter
(teleconverter) models, and each has been designed primarily for
use with certain lenses, or for certain ranges of lenses. [Note:
In the original post I did not include the Takumar-A 2X TC, which
is not SMC and may not actually even be made by Pentax.]
The (oldest) T6-2X is specified for K-mount prime lenses between
135mm and 300mm. While it can be safely mechanically coupled to
shorter or longer lenses, or used with various zooms, Pentax does
not recommend this (presumably for optical reasons).
The (newest) AF Adapter 1.7X is specified for most manual focus K,
M, and A lenses having a maximum aperture of (usually) f/2.8 or
wider (for sufficient light for AF use).
The 1.4X-S and 2X-S ("S" for "short") designs seem to have the
least restrictions in recommendations, being safely usable with
most Pentax lenses from 300mm down to, say, 20mm or so. They can
be safely coupled with longer lenses, but apparently corner
vignetting will generally result.
The most "dangerous" rear converters are the 1.4X-L and the 2X-L
("L" for "long") models, because their front elements project
forward beyond their mounting flanges into the rears of any lenses
mounted to them. Obviously, only certain lenses, which usually are
the lenses longer than 300mm, can safely mechanically couple to
these teleconverters (and apparently vignetting is reduced by the
use of these converters, as compared to the other models).
However, what about the use of all these various rear converters on
non-Pentax lenses?
It would seem to me that, in general, all rear converters except
for the "dangerous" 1.4X-L and the 2X-L converters could be used on
most of the various 3rd-party K-mount lenses that are analogous in
specifications to the recommended Pentax lenses. (However, I would
be careful in the case of any lens with a protruding rear element.)
But how about the 1.4X-L and the 2X-L?
Intuitively (and my own intuition has ~never~ steered me wrong
before - ), it would seem that any of the longer 3rd-party
lenses could benefit from the avoidance of vignetting that the
1.4X-L and the 2X-L can provide, if only (and this is a big "if")
the protruding front teleconverter element does not contact the
rear element of the lens, or otherwise interfere with coupling.
For example, say you have your basic Tamkigma (?) after-market
400/4.5 lens - can you risk using one of the "L" rear converters
with it, or should you "wimp out" and settle for one of the "S"
designs? Well, you could go to the trouble of obtaining one of the
"L" models, and carefully (!!!) measure and test to see if it will
couple without damage, and then sell it when you find that it
won't. (Or, maybe you can hold onto it until your long-lost rich
uncle dies and bequeaths his A* 400/2.8 ED [IF] monster to you -
.)
Or, instead, you can rely in advance on the measurements taken by
"yours truly", who wondered the very same questions about using the
two Pentax "L" rear converters with his Tokina AT-X 150-500/5.6
zoom, and who obtained the answers of "yes" and "no". (In brief, I
found that the 2X-L converter will couple safely to the Tokina
150-500/5.6, but that the 1.4X-L will not.)
The 2X-L's protruding front element extends 17.0 mm beyond the
mounting flange, and has a diameter of 31.5 mm for most of its
length, but widens to 33.0 mm for the final 4.0 mm portion closest
to the plane of the flange. These dimensions allow the 2X-L to
fairly comfortably fit inside the rear of the Tokina 150-500/5.6
lens (though there's not a whole lot of room to spare).
On the other hand, the otherwise smaller 1.4X-L has a larger
protrusion, which extends 21.0 mm beyond the plane of the mounting
flange, and which has
Re: Best 2X TC for K mount
> Did Pentax make a high performance K mount 2X teleconvertor for > long lenses? I want one to try on my SMCK 1000mm F8. If not > Pentax, who made the best one? I dont care about meter coupling, > I'll be using manual exposure. Although I've never tried it with a 1000mm lens, a really sweet non-Pentax TC is the Vivitar Macro-Focusing 2X TC. It's a really nice 7-element TC (among the best), with the added advantage of having a helicoidal focusing mechanism, which turns out to be very useful in turning many not-so-close-focusing long lenses into very long "semi-macro" lenses - . Besides the "generic" Vivitar Macro-Focusing 2X TC, which fits onto any K-mount lens, I also have a mechanically similar specialized 6-element Vivitar Series 1 "2X Macro Matched Multiplier" for the VS1 450/4.5 Aspheric Mirror lens. It turns the 450/4.5 lens (which focuses only to 3.5 meters, for 1:8 magnification) into a 900/9 lens that focuses to 2.67 meters, for 1:2.5 magnification - kind of a neat concept - . (Not exactly hand-holdable, though - .) Fred - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
RE: Best 2X TC for K mount
Rogier wrote: > That raises a quick question... > > Is there a limit to the usage of a teleconvertor? Wouldn't > putting a 2x tc on a 1000mm making it very slow? > > regards, > > Rogier Absolutely. Such a setup has really limited uses, I'd imagine. Filling the frame with a giant sunset/sunrise or moonset/moonrise is one possible application. Here's a George Lepp photo with a huge sun: http://www.leppimages.com/birds/b-pe-br-1050.htm I think he stacked teleconverters on a long lens to get this effect. Of course, the resulting lens is slow and magnifies camera shake, atmospheric instability, etc. It would be fun to experiment with, but probably pretty hard to use --Mark - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
Re: Best 2X TC for K mount
> I just dug out the Pentax user manual for the Rear Converter A's, > JCO, and it seems that: [snip] Gee, the net works in strange and marvelous ways. The above was from a follow-up post I made some time after submitting a couple of earlier posts to this thread (but which I haven't seen coming back from the PDML yet). ;-) Fred - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
RE: Best 2X TC for K mount
Jan, You've answered a question of mine before I've even asked it- I was always wondering what the differences were between the -S and the -L convertors. Thanks. The "snout" to which you refer- is that cause for incompatibility with certain lenses of a more conventional focal length, like a 80-200? Are there any differences in brightness between the two? Taka - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
Re: Best 2X TC for K mount
> Did Pentax make a high performance K mount 2X teleconvertor for > long lenses? I want one to try on my SMCK 1000mm F8. I just dug out the Pentax user manual for the Rear Converter A's, JCO, and it seems that: 1. The A 2X-S should work OK on the K 1000/8. 2. The A 1.4X-S will show some corner vignetting on the 1000/8. 3. Both the A 1.4X-L and the A 2X-l will work fine on the 1000/8. Since the two "L" models will indeed fit into the lens mount end of the 1000/8, and since these two TC's are specifically designed for many of the long lenses, I'd recommend using either of them over any other TC for the K 1000/8. The "L" TC's really seem to be sweet performers on the long lenses that can accept them (and I am basing that statement on personal experience with both "L" TC's on a few of my own lenses, plus almost universally favorable comments about their use on other long lenses here on the PDML.) The only down side would be the color clash - the battleship-gray of the "L" TC's will look a little funny on the back end of that big black 1000/8 - . Problems, problems... ;-) Fred - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
Re: Best 2X TC for K mount
Hi JCO, On Thu, 11 Apr 2002 02:45:14 -0400, J. C. O'Connell wrote: >Did Pentax make a high performance >K mount 2X teleconvertor for long lenses? >I want one to try on my SMCK 1000mm >F8. > I think the 'best' one quality wise would be the "rear converter-A 2X-L" This is a large (over 2 inches long) converter designed for the A* long lenses like the 300mm f/2.8 and the 400mm f/2.8. It has a large lens-diameter to avoid any vignetting with those lenses. I am not sure they will fit the 1000mm because they have a 'snout' that goes over half an inch INTO the lens you are putting it on. >If not Pentax, who made the best one? >I dont care about meter coupling, >I'll be using manual exposure. Bad luck here :-) These A converters (there is a 1.4X as well) have full coupling for any A type lens. I disadvantage is that they are expensive (well over $300 US I think) and are somewhat hard to find. B&H always used to have them new too. Regards, JvW - Jan van Wijk; www.fsys.demon.nl - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
RE: Best 2X TC for K mount
Yes, it will be a 2000mm F16! JCO > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED]]On Behalf Of Rogier van der Peijl > Sent: Thursday, April 11, 2002 3:00 AM > To: [EMAIL PROTECTED] > Subject: Re: Best 2X TC for K mount > > > That raises a quick question... > > Is there a limit to the usage of a teleconvertor? Wouldn't > putting a 2x tc > on a 1000mm making it very slow? > > regards, > > Rogier - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
Re: Best 2X TC for K mount
That raises a quick question... Is there a limit to the usage of a teleconvertor? Wouldn't putting a 2x tc on a 1000mm making it very slow? regards, Rogier >From: "J. C. O'Connell" <[EMAIL PROTECTED]> >Reply-To: [EMAIL PROTECTED] >To: <[EMAIL PROTECTED]> >Subject: Best 2X TC for K mount >Date: Thu, 11 Apr 2002 02:45:14 -0400 > >Did Pentax make a high performance >K mount 2X teleconvertor for long lenses? >I want one to try on my SMCK 1000mm >F8. > >If not Pentax, who made the best one? >I dont care about meter coupling, >I'll be using manual exposure. > >JCO >- >This message is from the Pentax-Discuss Mail List. To unsubscribe, >go to http://www.pdml.net and follow the directions. Don't forget to >visit the Pentax Users' Gallery at http://pug.komkon.org . > _ Meld je aan bij de grootste e-mailservice wereldwijd met MSN Hotmail: http://www.hotmail.com/nl - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
Re: Best 2X TC for K mount
I read somewhere (dont remember where) that 7 element converters are much better than 4 element ones (or was it the other way round ? :)) I guess thats not much of a help :D On Thu, Apr 11, 2002 at 02:45:14AM -0400, J. C. O'Connell wrote: > Did Pentax make a high performance > K mount 2X teleconvertor for long lenses? > I want one to try on my SMCK 1000mm > F8. > > If not Pentax, who made the best one? > I dont care about meter coupling, > I'll be using manual exposure. > > JCO > - > This message is from the Pentax-Discuss Mail List. To unsubscribe, > go to http://www.pdml.net and follow the directions. Don't forget to > visit the Pentax Users' Gallery at http://pug.komkon.org . - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
Best 2X TC for K mount
Did Pentax make a high performance K mount 2X teleconvertor for long lenses? I want one to try on my SMCK 1000mm F8. If not Pentax, who made the best one? I dont care about meter coupling, I'll be using manual exposure. JCO - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
