Prime?

Sorry, thought that I answered that in my last posting.

I want to be able to reach out further. The 55-300 is good and fine, but there are instances when reaching out further is desired. The Bigma (thank you whoever explained what THAT is) would be great, but I think that a converter will work. Not sure, tho, that's why I'm here.

I would really just like to take good pictures at a greater distance. Wildlife is that target.

Unfortunately zoom lenses are not the best candidates for maintaining quality when usinc TCs.

Also, you lose light and therefore need higher ISO settings to avoid camera shake.

The whole premise of a TC is a losing battle and most of the results are dire. Having sdaid that, there are some very expensive dedicated TCs that do offer high quality. They cost as much as an expensive lens though.

Been there, done that.

I started with cheaper 300 zoom lenses, then bought the 55-300, then added a Tamron x1.4 and then a Pentax AFA x1.7 - both excellent TCs - but they don't play nicely with the 55-300.

Your best bet to get to 500+ without that compromise is the older Sigma 170-500 (not super sharp but much better than a cropped 55-300) which is a more affordable price than the 150-500 or 50-500 or maybe the newer Sigma 100-420 is nearly there (there is an older 135-400 that you may be able to pick up cheaply).

The other option is a cheap Tamron BB 500 mirror (considered the best 500 mirror) - goes for around 100GBP - - but this is a fully manual lense and maybe not what you want (and of course the IQ is not up there with the Sigmas or cropping shots from the superb DA*300.

Bottom line is there is no cheap way to get excellent IQ at 500 without having a better quality lense as a starting point.

The reason I asked has been nicely explained above.

I agree that unless you are buying a very expensive matched teleconverter (ie one made by a manufacturer to work with a specific lens or group of lenses) the quality will suffer. And a matched converter is not cheap.

Ultimately a longer lens (or longer focal length) is not the answer. You have to contend with haze, camera shake, smaller apertures, etc. If you want better wildlife shots you have to learn to get closer to the wildlife.

None of us want to see you spend your money on something that will disappoint you.

This is mostly true - but not always possible. A longer lense is sometimes an absolute necessity.

I phrased that badly. I meant that if you have limited kit a TC isn't going to be the thing that makes the difference and you will have to learn to get closer.

Understood, and thanks everyone for the help. Unfortunately, getting closer to the wildlife is not always an option, just as carrying around the Bigma isn't.

Guess I'll just have to bite the bullet and save my money.

What do you mean by a 'limited kit'? The lenses I have are 18-55mm f/3.5-5.6 and 55-300mm f/4-5.8.

Limited by what lenses you have at your disposal, TC's generally work best on quality prime lenses.

John

Sorry, I simply meant that if you don't have long, fast primes (ie 400mm, 500mm f/2.8s) then you won't get the same effect by using a TC on a 55-300.

Unfortunately lenses like this don't come cheap. The Sigma 500mm sells for at least £3,500, if you can find it.

But don't fall into the trap of thinking that a long lens will automatically get you better wildlife shots. By itself it won't.

That's a little misleading considering Pentax don't currently make 400 or 500mm lenses and I don't know anyone who has a 500/2.8 - it would be absolutely massive (about the size of a small car) !

As I said earlier the AFA x1.7 works superbly on the DA*300 = 510mm for around £1,200

The Pentax 55-300mm works well with Pentax 1.4x and 1.7x converters.
The main problem with any long lens is holding it steady

Is that from personal experience ? It's not my experience at all - the zoom doesn't like TCs (this is well documented) and the IQ is awful.

You can still pick up a Pentax 400mm used. But you're right, not at f/2.8!

(of course Sigma do make a 200-500 f/2.8. It doesn't fit Pentax, it is the size of a small car and costs as much as a big car!)

I've already posted these two in some other thread, but can't remember the title. It was a similar query.
The first shot is without the 1.4x-s TC... Pentax 55-300mm only on K20D probably zoomed out a bit. 100ISO




This is with the Pentax 1.4x-s (both shots handheld) on the 55-300mm



The bokeh looks better as well.
The bird is a Lancashire Fence Sparrow that's
been reared on Meat and Potato Pies