Teleconverter 1,4 with a 55-300 lens will it work ok


JasonB757

Link Posted 02/02/2020 - 16:37
hi guys

new to this, will the above work, i have the 55-300 but for aircraft its just a little short, is it worth getting the teleconverter as i can t afford buying the 150-450 zoom after my K1 Purchase

any ideas?

thank you

johnriley

Link Posted 02/02/2020 - 17:11
The converter is for APS-C format, so you might find that in full frame mode there is quite a bit of vignetting. The 55-300mm lens is also unlikely to be at its best at 300mm and a 1.4x converter.

If you engage crop mode on your K-1 then the 300mm becomes an effective 450mm, so maybe that would be the best route to take?
Best regards, John

vic cross

Link Posted 02/02/2020 - 17:36
To Jason and John. using a 300mm on a crop doesn't actually make it a 450mm. all it does is make the picture in the middle of a 450mm therefore you might as well just crop the vignetting after and get the same result with same number of pixels either way so the resolution of the picture is the same. It does not magnify it to a 450mm all it does is take the middle pixels from the picture and makes it look like a 450mm.
SO. Just use the 300mm and crop it.
I hope I've made my self clear. OR have I made it more complicated than it is????????????????????????
CHEERS Vic.
Born again biker with lots of Pentax bits. Every day I wake up is a good day. I'm so old I don't even buy green bananas.

johnriley

Link Posted 02/02/2020 - 17:43
Quite right Vic, but it does indicate the crop which could be helpful. I have used the K-1 that way just the once, but of course we'd be better off using a K-3 under those circumstances. More pixels!
Best regards, John

jeallen01

Link Posted 02/02/2020 - 19:04
Success would also depend a LOT on WHICH teleconverter you buy as the "quality" of the results really does vary. Reputedly, the current model Pentax 1.4x HD WR tele-converter is supposed to work very well with many Pentax lenses.

Will also depend on which camera body you use - so which are you using?
K-3 II, K-3 and a K-70 from SRS (having now relegated the K-30 /"K-50" to a backup body) , & some Sigma and Pentax lenses (and a lot of old 35mm gear!)

JasonB757

Link Posted 02/02/2020 - 20:54
iam using the K1 MARK 2

JAK

Link Posted 03/02/2020 - 00:36
There's several versions of the 55-300 lens as well to add in to the mix!

If you want something longer (and less expensive than the150-450), the now discontinued Sigma 150-500 maybe worth tracking down.

Had you spotted this thread: https://www.pentaxuser.com/forum/topic/lenses-for-aviation-photography-59877 ?
John K
Last Edited by JAK on 03/02/2020 - 00:46

jeallen01

Link Posted 03/02/2020 - 08:53
Also bear in mind that adding any tele-converter to a slow-focusing lens will make it even slower, and that's especially true for any of the non-PLM versions of the 55-300 range - been there, tried that and gave up very quickly, especially at airshows!

The latest 55-300 PLM version focuses MUCH faster and more accurately, BUT it has a slightly smaller max aperture, and tests on the US forum tend to support the contention that any "improvement" in image quality is marginal at best, even with the best T/C!

As for the 150-500 Sigma, I had an HSM version and one of the main reasons I sold it (it's now in Russia!) was that it was very slow to focus even without a converter attached - mainly due to the fact that it has a very long "focus throw", i.e. the distance that the internal elements move between the "close" and "far" distance.

A much better alternative is, I understand, the 50-500 "Bigma" which has a much shorter focus throw, although finding one in Pentax mount will be a challenge - they go for around 600-700 from UK sources if you are very lucky, but for around 950 you can get one from Japan fairly easily (or occasionally in the UK).

PS: Not having a Bigma, the only lenses with which I will reasonably happily use a T/C are my very old Sigma 70-200 F2.8 and 100-300 F4, and then only with the matching Sigma T/C - all difficult to find, and now totally out of support and spares from Sigma Imaging.
K-3 II, K-3 and a K-70 from SRS (having now relegated the K-30 /"K-50" to a backup body) , & some Sigma and Pentax lenses (and a lot of old 35mm gear!)
Last Edited by jeallen01 on 03/02/2020 - 09:07

ilovesaabs

Link Posted 03/02/2020 - 09:48
Jason didn't say which teleconverter he'd get - if he is after the Tamron PZ 1.5 then that 's a full-frame version and some variants have the PKAF2 contacts for SDM/Powerzoom.

I had the 55-300 briefly while the DA*60-250 was getting its' new motor - I was so glad to get the DA* back to be honest. I can't remember how the DA55-300 looks at the camera end but the DA* doesn't vignette noticeably; I wonder if the angle of view on the DA at 300 mm is such that the crop doesn't impact on the image and the camera can be used in FF mode. Then you can crop, effectively getting more megapixels than adjusting the camera to crop (16MP) mode,
AKA Welshwizard/PWynneJ
Assorted Pentax/Nikon/Mamiya stuff

cbrog

Link Posted 03/02/2020 - 20:39
I sometimes wonder if chasing focal length is that necessary and whether high quality images cropped can be just as effective..?





This I captured with a Sigma 105 macro on my K3. ( Didn't have time to change the lens...).

JAK

Link Posted 03/02/2020 - 20:51
Judging by the angle of the plane it appears that you must have shot it down!
John K

cbrog

Link Posted 03/02/2020 - 20:55
JAK wrote:
Judging by the angle of the plane it appears that you must have shot it down!

Actually it frightened the life out me - I didn't hear or see it coming and it was very low!

Roger
Last Edited by cbrog on 03/02/2020 - 20:56

bforbes

Link Posted 03/02/2020 - 21:19
cbrog wrote:


Actually it frightened the life out me - I didn't hear or see it coming and it was very low!

Roger

"Should have gone to Specsavers" they do ear tests. How could you not hear a Merlin coming. But never mind it's a good shot of a icon
Barrie
Too Old To Die Young

http://www.pentaxphotogallery.com/artists/barrieforbes

jeallen01

Link Posted 03/02/2020 - 21:23
Great shot, although the prop is "too stationary" for my "liking" - slower shutter speed would have fixed that, but would have been more difficult to get that sharp. Anyway, don't think a T/C would have helped if it was that low, and would probably have degraded the image a tad.
K-3 II, K-3 and a K-70 from SRS (having now relegated the K-30 /"K-50" to a backup body) , & some Sigma and Pentax lenses (and a lot of old 35mm gear!)
Last Edited by jeallen01 on 03/02/2020 - 21:24

cbrog

Link Posted 04/02/2020 - 20:30
bforbes wrote:
cbrog wrote:


Actually it frightened the life out me - I didn't hear or see it coming and it was very low!

Roger

"Should have gone to Specsavers" they do ear tests. How could you not hear a Merlin coming. But never mind it's a good shot of a icon

I'll have you know I once spent 13 hours sitting behind four Merlins including a fuel and tighten up the loose bits stop on Malta There is a little bit of a story behind that picture which I didn't know when I originally posted it some three years ago. But I don't intend to bore you with that!

Roger
Last Edited by cbrog on 04/02/2020 - 20:32
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