[Shakey]

In a previous post I mentioned that I have the Pentax 55-300 WR and I also have the 1.4 converter which in theory turns this lens into a 420MM.

I'm looking at the Pentax 150-450 and the Sigma 50-500.

People have said that the 1.4 converter does not work with the Sigma and I've also read that the sigma does not produce sharp images at the long end. So is my current set up of the 55-300 with 1.4 converter a equal or better option...and save myself the cash? What woud be the positives of owning this lens?

The Pentax 150-450 with the converter would turn that lens into a 630 if I've done the math correctly. I don't need the low end on the sigma (50mm). I've read mixed reviews on this lens and it is significantly more expensive than the sigma. Again, am I wasting money based on what I already have? What would be the positives to owning this lens?

I'm a hobbyist looking to grow my skills and have some enjoyment by being able to spend time taking wildlife photos.

[normhead]

You seem pretty focused on the 150-450. What body are you planning to use it on, and what zoom ranges do you already have covered? The minimum aperture of the 150-450 with the 1.4 is ƒ8. That's what I'd be worried about. You need a lot of light just to lock focus. In bright sun you won't have an issue. Under a canopy you may have big issues.

A K-3, DA*300 F4 and 1.7x gives you 510 and ƒ6.3, a much more useful aperture. After years of A-400 F5.6 use, I cringe when I see folks talking about sticking a TC on a ƒ5.6 or smaller aperture lens. Sure you can do it, and you'll get nice images, but things will be harder than they need to be.

[boriscleto]

I use the Sigma 150-500 and never use it at anything less than F/8. I would be thrilled to have 630 and F/8, but I can't justify $2500 to $3000 to get there. If I really felt a need for anything better than the Sigma I would be changing systems. With really cheap P-TTL flashes hitting the market I will be investing in a flash extender this year...

XT Flash Extender Kit

[normhead]

I use the Sigma 150-500 and never use it at anything less than F/8. I would be thrilled to have 630 and F/8, but I can't justify $2500 to $3000 to get there. If I really felt a need for anything better than the Sigma I would be changing systems. With really cheap P-TTL flashes hitting the market I will be investing in a flash extender this year...

XT Flash Extender Kit

There's a difference between shooting at ƒ8, and "lens only opens to ƒ8." Your AF system is designed for ƒ2.8. ƒ8 is really stretching it.

[boriscleto]

There's a difference between shooting at ƒ8, and "lens only opens to ƒ8." Your AF system is designed for ƒ2.8. ƒ8 is really stretching it.

I never really had any problems with the 55-300 and the cheap 1.4x I was using it with. If it was too dark to focus it was too dark to shoot. Lacking an affordable flash I wasn't shooting under the trees anyway. It's all a matter of luck to get the birds at the right level with enough light anyway...

[normhead]

I never really had any problems with the 55-300 and the cheap 1.4x I was using it with. If it was too dark to focus it was too dark to shoot. Lacking an affordable flash I wasn't shooting under the trees anyway. It's all a matter of luck to get the birds at the right level with enough light anyway...

You might think it's too dark to shoot, Tamron 300, @ƒ2.8, ISO 640, 1/80s, pushing the limits, and shooing in the dark.

[geomez]

I've never used that sigma but I do have the Pentax 150-450 and it's a killer lens. I've never tried to do sharpness tests because it seems sharp at all apertures. It is probably my favorite Pentax zoom lens and the only complaint I have is it's size and weight.

When I was in the market for this lens I was faced with the same dilemma you've presented. In the end I felt there were too many IQ caveats with the sigma based on nearly every review and forum mention. That and the lack of WR AW on the sigma pushed me towards the Pentax. If you can get beyond the sticker price you won't be disappointed.

[biz-engineer]

I've used the DFA150450 in o the K3 and the K1 with and without TC.

On the K3 sensor, the DFA150450 with TC isn't so great:
- AF works well, even with F8 wide open, but AF tracking gives up if using more than 9 point.
- It is hard to get motion and vibration free shots given the 24Mpixels of the K3.
- My copy of the DFA150450 peak sharpness with TC is from f10 and f14.
- Ok for doing HD videos.

On the K1, the larger sensor give a bit of room (when not cropping) for the DFA150450 with TC (at 630mm/f8), using higher ISO in full frame more is less an issue compared to K3.

Basically, I'd recommend the DFA150450 on the K3 without TC. And with TC on the K1 FF ES mode when speed isn't a limitation (static shots).

[Shakey]

I'm really not set on any particular lens - like the Pentax 150-450 as normhead mentioned. As a matter of fact I have been looking for the Sigma 150-500 but it is no longer available. Obviously I'm learning a lot from you guys with the amount of questions I've asked so thank you for your thoughtful advice.
What I don't want to do is be cheap and buy something I'll later regret - then you end up spending more anyway to finally go out and buy the item you should have bought in the first place. I also don't want to overspend and buy something I don't need, but just don't know it yet....if that makes sense.
I keep thinking about the Pentax 150-450 only because it makes me feel a little "safer" in that I shouldn't have any issues in using it with my K-3. However, in the end will it put me any further ahead than using what I have (55-300 with TC) ?
In the end I don't want to jump the gun and buy something I'll regret either way.

[biz-engineer]

In the end I don't want to jump the gun and buy something I'll regret either way.

The problem with long lenses is that there is no such thing as cheap , long and good, unless you are lucky to find a good copy of a second hand lens (like norm with the Tamron 300 f2.8). Usually, cheap long lenses are slow or not so sharp. You can get a Sigma or Tamron long zoom but you nearly always get sharpness drop in the long end. Usually, the longest focal length that's still priced around $1K and reasonably fast is about 300 f4 or 400 f5.6 (DA300+TC) (same situation for Nikon: 300f4+TC, and Canon have the 400f5.6 for around $1K), if 400mm is long enough for you. Beyond that 400mm, you have the 500mm and 600mm primes, prices increase rapidly. There is the Kowa Prominar solution, deliver fantastic image quality from what I've seen (they compare directly with Canon FL lenses), with 350mm, 500mm and 800mm, is price around <$2500, but it is manual focus, although it is easy to manually focus (I've tried one), and they have the adapters for Canon, Nikon and Pentax. There is also one DA560 Pentax currently discounted at SRS microsystems (UK dealer) at about $3.3K (about 20% cheaper as anywhere else), or there is the Sigma 500 f4.5 around $4K+ if you can find one.

[normhead]

I keep thinking about the Pentax 150-450 only because it makes me feel a little "safer" in that I shouldn't have any issues in using it with my K-3. However, in the end will it put me any further ahead than using what I have (55-300 with TC) ?
In the end I don't want to jump the gun and buy something I'll regret either way.

It's a really safe purchase, as long as you are willing to deal with the weight and price. As long as you are young and strong, I don't think you ever regret a lens like that. I'd love to see someone put a 1.7x on it, on a K-1.

[lichih]

So I went looking for a review on the Pentax 150-450

You Tube

You Tube

Its probably more well done than some other reviews on this lens.

The images looks amazing. You should email the guy and ask him question on the lens since he seem to be really knowledgeable in wild life photography.

cheers!

[noelpolar]

mmm... the more I think about it the more the DFA 150-450 makes sense for a variety of situations. A friend has a sigma 150-500 and a 55-300..... the DFA is a significant step up from them.

1/12th crop of K-1 and DFA at 450

[Kunzite]

So I went looking for a review on the Pentax 150-450

Wait, is he praising the AF tracking abilities of a Pentax?

[Shakey]

So I went looking for a review on the Pentax 150-450

Pentax HD PENTAX D FA 150-450mm Hands-On Field Test - YouTube
Its probably more well done than some other reviews on this lens.

The images looks amazing. You should email the guy and ask him question on the lens since he seem to be really knowledgeable in wild life photography.

cheers!

Thank you for the link