TC for A* 300 f/4 or M 400 f/5.6

Discussion in 'Pentax' started by, Nov 11, 2011.

  1. I'm looking to get these two lenses for a pretty nice price from someone unloading their old "junk" and may sell one off once I've gotten to try them a little. I'm curious what the conventional wisdom is about a TC for one of these is. Did Pentax make one specifically to go with one of these? Like the 1.4 maybe? A quick look at eBay and there are tons of cheap 2x converters (I already have a Vivitar 2x that is so-so) and a handful of 1.4x or 1.7x TCs from Pentax and Sigma that are going for a LOT ($450-550) of money! So I'm thinking those must be the good ones and they are in high demand.
    I think I will probably just try them on my Vivitar and see if it's acceptable for the time being if I want to go longer.
    Anyone got any more info or leads on better deals? Thanks!
  2. stemked

    stemked Moderator

    I can say, in general that the Pentax 1.4X-S is a very good TC. I've been happy with both the optical and build quality of the TC. It is not autofocus of course.
  3. Hey Matt

    A good TC coupled with a fine prime will provide very acceptable results most of the time. The A* line of lenses are
    still excellent. Never handled the 300mm f4, but I've owned the A* 200mm f2.8 for years. It's fantastic and I still get
    unsolicited offers for it from knowledgeable photographers. I have used it with the last modern Kenko 1.5x TC that also
    works with SDM and have no issues. I wonder if the premium for a Pentax or Tamron TC is worth it? 

    I think Sigma TCs only work with Sigma glass. The only good 2x TCs I've seen are Canon and that's not gonna help

    Using a long M lens is a bit of a PITA to me as there are that many more controls to dicker with while you are
    balancing and stilling the whole rig. Plus you gotta focus. 

    I believe Dave Hollander has a fair amount of experience and wisdom around this. 

  4. I believe Dave Hollander has a fair amount of experience and wisdom around this.​
    I'll cop to experience: wisdom, not so much.
    My basic premise is that both the lens and TC have to be high quality or it's a waste of time and money. Those are both well-regarded lenses: I've owned the A* 300/4 (loved it's compactness but found the DA* sharper) and got decent results with it when combined with a Tamron 1.4x TC. They're somewhat slow lenses but, given good light, I think you could expect good results using a Pentax 1.4x-S or Tamron 1.4x or, perhaps, Kenko 1.5x. The AF 1.7x would be pushing it, I think (also, the 1.7x is expensive and the AF--while kind of cool--doesn't really offer much advantage over catch-in-focus.) I have a Pentax 2x-S but wouldn't recommend it with these lenses.
    Actually, although I do prefer A and AF lenses, I don't find fully manual lenses much more bother--probably because I really don't take full advantage of the functionality contemporary equipment offers.
    I hope this is helpful.
  5. Someone locally was selling a Pentax 1.4xS that I considered buying for my Pentax A 400 f5.6. If I'm not mistaken some internet research revealed that this teleconverter was not well suited to longer focal lengths (hence the "S" designation I suppose ;-). Might be worth confirming that before buying if you come across one for a decent price (the one I saw was fairly priced).
  6. I have the 1.7x Pentax AF and it works optically relatively well, while mechanically it has some limits, since I have to sort of prefocus manually the 300mm FA 4.5 since the focus excursion of the multiplier is not sufficient. I can provide some test pics if needed.
    I also have the old Sigma 80-200 f2.8 EX and its dedicated 2x, I can provide some pics also for that. The coupling is mechanically perfect (although there are now some problems with the electri contacts), the results are reasonably good, but there are more lenses in the path and it shows a bit on contrast and aberrations vs the 300mm.
  7. If I'm not mistaken some internet research revealed that this teleconverter was not well suited to longer focal lengths (hence the "S" designation I suppose ;-)​
    Right, the L TCs were designed for Pentax lenses in the 300-1200mm range which have recessed rear elements. The A*300mm is not one of those.
  8. Thanks for all the info. I've sent the money so now I just need to wait for the package. I'm thinking I'll probably sell the 400 and keep the 300. I have used M lenses (I have the M 100 f/4 Macro) and I'm getting better at it but I do prefer A lenses. That combined with the presumably better image quality of the A* seem to indicate that if I'm only keeping one that should be the one. I'll try my Vivitar 2x converter just for grins once I get it but I don't have very high hopes for that!

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