[richandfleur]

Thanks for the info guys.

[Kiwigeezer]

A 2x teleconverter will cost you two stops of light. This need not be an immediate issue regarding noise but the AF system can be challenged. If you take a lens like to 55-300 which is an f/5.8 at the long end, it becomes a 600/11.6 with a 2x converter. Technically, f/8 is the upper end for the AF system to work in an uncompromised manner. However, that is not a hard barrier and the main issue will be slowed-down AF in less than ideal light conditions.

If I were interested in those teleconverters, I'd ask how many elements they are using. Very elaborate 2x teleconverters can have 10 elements. Very good ones use 6 or 7. There are some that only use 4 (or less?). The less elements, the worse the correction. A less than very good teleconverter will introduce problems of its own; however even a perfect one will magnifier problems of the original lens. So if a 55-300mm is already struggling on its own, the teleconverter will amplify all its issues. Also note that if a lens requires stopping down to f/11 at the long end to get really sharp, this translates into f/22 with a teleconverter. This isn't ideal, neither for sharpness (diffraction) nor for noise. This is not to say that a teleconverter cannot be useful, but they make more sense when they are of very good quality and paired with excellent lenses that can withstand the extra scrutiny.

With today's high MP cameras, it often makes sense to just achieve the magnification by cropping. Cropping is essentially applying a digital teleconverter with zero optical aberrations. They only issue is that you can run out of pixels, but with a mediocre teleconverter, you typically cannot capitalise on your original pixel count that much either because adding cropping often reveals image quality problem caused by a less than very good lens + teleconverter combination.

BTW, the teleconverter offered probably only supports screw-drive AF. You may be able to find some that support AF for lenses with a built-in motor, but I think these are rather rare.

Yep, that's the "obvious limitations of 2x TCs" I made reference to. I put this post on because, in some circumstances, some may find this useful -wide-open at 300mm it seems to perform adequately for me. For $38 I won't lose any sleep when it doesn't.

[richandfleur]

Moon shots is what I'd be in for.

Debating improved resolution vs simply scaling in photoshop and interpolating pixels.

[Class A]

For $38 I won't lose any sleep when it doesn't.

Fair enough.

I sold my cheap bargain teleconverters because their results just weren't that hot.

Debating improved resolution vs simply scaling in photoshop and interpolating pixels.

Yes, that's the million dollar $38 question.
If you need more pixels than cropping would yield and the teleconverter offered is of high quality (i.e., the price does not reflect the effort that went into its construction) then the optical solution could be the better one.

[Kiwigeezer]

Moon shots is what I'd be in for.

Debating improved resolution vs simply scaling in photoshop and interpolating pixels.

I'll have a crack at the moon with my Pentax 55-300 and let you know. The supplier (Littles) appear to have a stock of these so they'll hang around for awhile yet.
Will dust off my Siggie 135-400 when I've got some time and try coupling with that. It'll be a better test.

---------- Post added 07-06-17 at 10:41 PM ----------

I'll have a crack at the moon with my Pentax 55-300 and let you know. The supplier (Littles) appear to have a stock of these so they'll hang around for awhile yet.
Will dust off my Siggie 135-400 when I've got some time and try coupling with that. It'll be a better test.

Moon will be interesting -bright enough to allow stopping down significantly, but if anything'll highlight CA's it would I think?

[Transit]

I'd make an offer but don't want embarrass myself. You put a price on it.

60 bucks, I've even got the box, one careful owner

---------- Post added 6th Jul 2017 at 11:24 PM ----------

I answered the Ricoh survey, suggested they dump Littles...

[Kiwigeezer]

60 bucks, I've even got the box, one careful owner

---------- Post added 6th Jul 2017 at 11:24 PM ----------

I answered the Ricoh survey, suggested they dump Littles...

I'm on a TC roll...if Awa doesn't want your Viv I'll take it.

[MarkJerling]

60 bucks, I've even got the box, one careful owner

---------- Post added 6th Jul 2017 at 11:24 PM ----------

I answered the Ricoh survey, suggested they dump Littles...

Good one! I'll do the same!

[Transit]

I'm on a TC roll...if Awa doesn't want your Viv I'll take it.

ok Mate

[following.eric]

Yes, great images from NZ, indeed!

For some of them, I'd love to learn where they were taken. Would it make sense to post a respective question on Flickr?

Great bird shots too!
Transit's duck looks more earthbound than the humming bird, but it is sharp as a ... tuck (sic).

Ya maybe on Flickr would be best because I'll see which one it is right away

[richandfleur]

I answered the Ricoh survey, suggested they dump Littles...

That survey doesn't seem legit.


Not many questions and on a basic survey platform like surveymonkey?

[Kiwi645hauler]

I'll have a crack at the moon with my Pentax 55-300 and let you know. The supplier (Littles) appear to have a stock of these so they'll hang around for awhile yet.
Will dust off my Siggie 135-400 when I've got some time and try coupling with that. It'll be a better test.

---------- Post added 07-06-17 at 10:41 PM ----------


Moon will be interesting -bright enough to allow stopping down significantly, but if anything'll highlight CA's it would I think?

Definitely have a good go with the 55-300, when pointing at the moon directly, if it is full/new you should still be able to use around 1/125 -1/250th shutter speed and around f8, but the best moon conditions to photograph are when it is the moon is a little older, and is between 1/4 and 3/4 and the waxing gibbons (half illuminated buy not yet full) that way you get the terminator (line between light & dark) and that area can provide some really neat detail in craters and ridges.
I photograph the moon reasonably regularly using a 300mm lens and i get some really nice pics (non from a pentax so i wont post them here haha)

---------- Post added 07-06-17 at 03:11 PM ----------

That survey doesn't seem legit.


Not many questions and on a basic survey platform like surveymonkey?

Sometimes less is more, they will get a lot more people answering such a short survey, and by providing an email address, if they have concerns or want more information, they can contact you via that channel for more indepth questioning

[richandfleur]

Yeah my thoughts though was whether the survey was even from Pentax at all?


Agree, the moon is usually brightly illuminated, so you're talking daylight exposure settings, despite taking the photo often at night. I'm hoping this would do well with the teleconverter linked on trademe. Can't find much about that specific brand though, Kepcor?


I shot this with an older teleconverter that I have. Just wondering if these new ones (that support AF) would have better optics.

You Tube

You Tube

[Transit]

That survey doesn't seem legit.


...

oh well... who ever is running it might attend to Littles

[Kiwi645hauler]

I am pretty sure it is legit as i found the link to it on twitter as well via the Ricoh Imaging feed and it was tweeted by them.