Need advice re long telephoto lenses

Started Jan 29, 2013 | Discussions thread
Greyser Veteran Member • Posts: 4,952
Re: Need advice re long telephoto lenses

Some time ago I posted similar answer in PF forum Birding group. Not messing with crippled PF links there is direct copy-paste version below. Please note that some of my points are already discussed somewhere above.

Here you go:

First of all let's agree on one thing: a prime lens is always better than zoom. I wouldn't talk about zooms here. Someone may comment on it.
I also won't talk about good quality MF lenses paired with Pentax 1.7x AFA converter. Despite the fact that AFA is exceptional tool, it won't give you shot to shotAF stability and action style shooting speed. Sooner or later you'll be thinking about upgrading to regular AF lens. There are too many limitation in a crippled AFAFA offerings.
In 300mm range there are a few options. The best IQ is considered to be delivered by DA*300/4. However, it is SDM lens (a bit slower AF maybe, and possibleSDM failures with older versions at least) and it doesn't work well with existing teleconverters (Note: Pentax may deliver SDM compatible TC this year).
F* or FA* 300/4.5 are also exceptional lenses. They are both light, fast enough, great with TCs (instant upgrade to 420/6.3), and are very capable to deliver outstanding image quality.
There are a few 300/2.8 lenses available (Pentax and Sigma). Both are great, but expensive, bulky and heavy. My opinion here is. If someone is OK with spending $3K-$4K on 300/2.8, Sigma 500/4.5 is always a better choice.
Among many birders 400mm is considered as an optimal FL. It's OK for small birds and a bit long, but still useable for large ones. It depends on the average weather conditions how fast the lens do you need. However, for the Pentax users there are only two good AF lens choices: very expensive (and not as sharp as 300mm sibling) FA*400/5.6 and very rare, but unbelievably great old Sigma 400/5.6 TeleMacro (77mm filter size only). They both are a bit slow but compact and lightweight.
Then there is Sigma 500/4.5. It is amazing lens, but the price tag is $5K. The new Pentax 560/5.6 is even more expensive, and it is still unknown how good/bad is it.
I never saw FA*600 in my life. So, let me stop here.
Good luck,


Addition thoughts from my today perspective:

Before owing Sigma 500/4.5 I was using exclusively FA*300/4.5 standalone or with the best selected 1.4x TC. This choice used to give me more flexibility over slightly sharper DA*300/4 and I chose FA* over DA* deliberately for more freedom of TC use.

Now when I have the 500/4.5 I may swap my FA*300 for DA*300 to get better sharpness at shorter end.

 Greyser's gear list:Greyser's gear list
Pentax K-01 Pentax K-5 IIs Pentax K-3 Nikon D500 Pentax K-1
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