[snostorm]

So to search for this AFA 1.7X TC, do I look for just that: Pentax AFA 1.7X?

Hi Jacques,

The official name on the TC is "SMC Pentax - F 1.7x AF Adapter", but it's the only 1.7x TC that Pentax has ever made AFAIK, so I usually just look for "Pentax 1.7x" and see what comes up. Anything not made by Pentax isn't it.

Scott

[Ben_Edict]

Hi Ben,

I am enthusiastic about this lens! -- but I have subsequently obtained a Sigma EX 300/2.8 APO and an FA* 300/2.8, so the Tamron has been relegated to backup of the backup.

It must be noted that "LD" is the Tamron equivalent of Pentax "ED" glass elements and Sigma's "APO", but the Tamron does not control CA/PF as well -- in the case of these 3 models, at least. The Sigma controls CA/PF considerably better than the Tamron, and about the same as the FA*300/2.8 in this regard. The Sigma is a tad sharper, and the FA*300 is a bit sharper still, but the differences are really marginal, IMO.

I use the 300/2.8s + TC(s) in lieu of longer glass -- LBA in the super tele range gets very expensive very quickly. . . . . . and I've limited myself to this class of lens as the largest that I can physically handle on a daily basis. I'd love to have an EX 500/4.5, an FA*250-600/5.6, and an FA*600/4, but I'd gain little in usability with the Sigma at a cost of $3K-4K, and the two big Pentaxes are just way too big at @ 13 lbs -- and in addition to the cost of the lens, I'd have to put about another $1K into a new tripod and gimbal.

Here are a few examples of why I feel that I can stand pat with any of the 300/2.8s and TCs. These were shot with the DS, and it only gets better with the K20 or K-7. . .

This Cardinal shot was a lucky one -- handheld with the DS, SP 300/2.8 + SP140F 1.4x TC + P F 1.7x AFA (714mm f6.7). This is only lightly cropped, then resized from the original jpg.

For my purposes, I consider myself set out to 714mm. . .I think. . .

Scott

Very nice and good images. Your thoughts about useability reflect my own - as do your financial considerations. The 300/2.8 lenses are simply very versatile and much more cost effective than longer fast glass.

Ben

[StephenMerola]

Well the lens came yesterday. Wow. It is built like a tank. The lens came with both the front filter and clear rear filter. The front filter has some marks, but it is not bad. I already ordered a cover for the front. The seller included a Pentax K/M adapter which works nicely.

I took some handheld photos through the kitchen window and got some decent results. The PF and CA are there, but nothing too bad. This lens is pretty sharp wide open. I realize now that I need a better tripod though. I will also need a case for the lens.

[jpzk]

Hi Jacques,

The official name on the TC is "SMC Pentax - F 1.7x AF Adapter", but it's the only 1.7x TC that Pentax has ever made AFAIK, so I usually just look for "Pentax 1.7x" and see what comes up. Anything not made by Pentax isn't it.

Scott

Thanks Scott,
I am slowly building a "bird" gear, so this would be very handy.
Mind you, all I have for "distance" right noew is a DA*300 F4 and a Tamron 1.4X TC.
That does the trick for some situations but I wished I coudl sometimes get closer.
A 300 f2.8 still AF with a 1.7X TC, right?
JP

[Ben_Edict]

Well the lens came yesterday. Wow. It is built like a tank. The lens came with both the front filter and clear rear filter. The front filter has some marks, but it is not bad. I already ordered a cover for the front. The seller included a Pentax K/M adapter which works nicely.

I took some handheld photos through the kitchen window and got some decent results. The PF and CA are there, but nothing too bad. This lens is pretty sharp wide open. I realize now that I need a better tripod though. I will also need a case for the lens.

Sounds good - you will have a lot of fun with that lens. If you have some spare money, I would invest in the KA-adapter - makes shooting the Tamrons much easier.

Ben