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Teleconverter recommendation
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PostPosted: Mon May 25, 2020 8:17 pm    Post subject: Teleconverter recommendation Reply with quote
I have a Canon EF 70-300mm f/4.5-5.6 DO IS USM lens and I would like to extend its range by adding a 1.4x or 2x teleconverter.
I'm looking for recommendations as I have no experience with AF converters. I do know that Canon's converters are not compatible.


PostPosted: Mon May 25, 2020 9:14 pm    Post subject: Reply with quote
Nice lens. I had to laugh at Canon using "Diffractive Optics elements" as marketing fluff though...

I think the reason there's no Canon TC for this lens is use costs lens stops, affecting auto focus and image stabilization. AF TC works better on faster lenses.

Not much help, sorry. Maybe Sigma has AF TC for one of its Canon-mount telephotos that will work. Replying to watch thread here. Smile


PostPosted: Mon May 25, 2020 10:08 pm    Post subject: Reply with quote
I have very good experiences with the Tokina made Kenko Teleplus AF converters which I have for Minolta AF/Sony-A and Pentax KAF.
Particulary the DGX MC4 1.4X converter delivers excellent results if the used lens is good as well and AF functionality incl. conversion of lens data in EXIF is working fine, at least on my Sony cameras.
The DG Teleplus MC7 2X converter may be already troublesome with certain lenses in both my Minolta and Pentax versions; i.e. the AF may not work correctly, particlularly with slower lenses.
For AF usage I would therefore rather recommend to stick to the 1.4X versions.


PostPosted: Tue May 26, 2020 8:37 am    Post subject: Reply with quote
visualopsins wrote:
Nice lens. I had to laugh at Canon using "Diffractive Optics elements" as marketing fluff though...

I think the reason there's no Canon TC for this lens is use costs lens stops, affecting auto focus and image stabilization. AF TC works better on faster lenses.

Not much help, sorry. Maybe Sigma has AF TC for one of its Canon-mount telephotos that will work. Replying to watch thread here. Smile


What's marketing fluff about DO? I believe the image quality is inferior to spherical optics but the size of the lens can be more compact, and potentially deliver better image quality over a lens of simpler and shorter construction. The DO designation lets people know what they're really buying at least. I really like their prime lenses with that technology.

As for OP, the Kenko MC7 is a generic converter and should work with any lens but Canon lens protocols are proprietary so check compatibility with your camera and lens first. My MC7 reports the EXIF correctly doubled.

I also have a Kenko 1.5x Teleplus MC DG. Despite this being the updated model of the Teleplus SHQ, the updated 'DG' (Digital Gate IC) does not correct the EXIF as you suppose it would.
This TC is reportedly closer to a 1.3x crop and therefore slightly under 1 stop loss of light. It uses the same optics as the 1.4x model it was sold under, as multiple brand names. This is probably the only option for your lens in order to retain autofocus, but apparently the 7-element MC7 is much better than the MC4. I can't say, I know my MC7 is good but haven't tested my 5-element 1.4x. The newer MC-4 1.4x is 4 elements only, per Kenko's specs. The specs for mine come from the expired B&H listing and the Kenko literature of the SHQ model, stating it as 5 elements in 4 groups.
This seems to be the updated version for pros, with 5 elements: https://www.bhphotovideo.com/c/product/674565-REG/Kenko_PRO3001_4XDGXC_Teleplus_PRO_300_DG.html/specs

I suggest taking a look here to check what's available among the many different models made as it is not worth buying a new one: http://technoclopedia-canon-eos.com/index-mob.htm?/frames/lens_accessories_conversion_tele-mob.htm


PostPosted: Tue May 26, 2020 4:31 pm    Post subject: Reply with quote
Thank you for the information gentlemen, I think a 1.4x converter is the way to go.


PostPosted: Tue May 26, 2020 7:16 pm    Post subject: Reply with quote
Teemō wrote:
visualopsins wrote:
Nice lens. I had to laugh at Canon using "Diffractive Optics elements" as marketing fluff though...

I think the reason there's no Canon TC for this lens is use costs lens stops, affecting auto focus and image stabilization. AF TC works better on faster lenses.

Not much help, sorry. Maybe Sigma has AF TC for one of its Canon-mount telephotos that will work. Replying to watch thread here. Smile


What's marketing fluff about DO? I believe the image quality is inferior to spherical optics but the size of the lens can be more compact, and potentially deliver better image quality over a lens of simpler and shorter construction. The DO designation lets people know what they're really buying at least. I really like their prime lenses with that technology.



Fresnel is what is being bought. DO confuses imho.


PostPosted: Wed May 27, 2020 7:55 am    Post subject: Reply with quote
visualopsins wrote:
Teemō wrote:
visualopsins wrote:
Nice lens. I had to laugh at Canon using "Diffractive Optics elements" as marketing fluff though...

I think the reason there's no Canon TC for this lens is use costs lens stops, affecting auto focus and image stabilization. AF TC works better on faster lenses.

Not much help, sorry. Maybe Sigma has AF TC for one of its Canon-mount telephotos that will work. Replying to watch thread here. Smile


What's marketing fluff about DO? I believe the image quality is inferior to spherical optics but the size of the lens can be more compact, and potentially deliver better image quality over a lens of simpler and shorter construction. The DO designation lets people know what they're really buying at least. I really like their prime lenses with that technology.



Fresnel is what is being bought. DO confuses imho.


The Canon lens is considerably more complicated than a Fresnel lens, and D.O is the term used in academia also. I see the Fresnel as just one design (with one element, usually plano-convex) like the Gauss lens or the Angénieux or the triplet which can all be modified into more advanced lenses.
It's really patented for 1 or more spherical lenses and 2 curved fresnel lenses all bonded together to overcome all of the problems of a less-complicated Fresnel: https://cpn.canon-europe.com/content/education/infobank/lenses/multi_layer_diffractive_optical_element.do

'Frensel' would turn a lot of potential customers away, the kind of people who don't read reviews but are interested in having a shorter lens while 'Diffractive Optics' either confuses or fascinates. Laughing


PostPosted: Wed May 27, 2020 10:18 pm    Post subject: Reply with quote
Teemō wrote:
visualopsins wrote:
Teemō wrote:
visualopsins wrote:
Nice lens. I had to laugh at Canon using "Diffractive Optics elements" as marketing fluff though...

I think the reason there's no Canon TC for this lens is use costs lens stops, affecting auto focus and image stabilization. AF TC works better on faster lenses.

Not much help, sorry. Maybe Sigma has AF TC for one of its Canon-mount telephotos that will work. Replying to watch thread here. Smile


What's marketing fluff about DO? I believe the image quality is inferior to spherical optics but the size of the lens can be more compact, and potentially deliver better image quality over a lens of simpler and shorter construction. The DO designation lets people know what they're really buying at least. I really like their prime lenses with that technology.



Fresnel is what is being bought. DO confuses imho.


The Canon lens is considerably more complicated than a Fresnel lens, and D.O is the term used in academia also. I see the Fresnel as just one design (with one element, usually plano-convex) like the Gauss lens or the Angénieux or the triplet which can all be modified into more advanced lenses.
It's really patented for 1 or more spherical lenses and 2 curved fresnel lenses all bonded together to overcome all of the problems of a less-complicated Fresnel: https://cpn.canon-europe.com/content/education/infobank/lenses/multi_layer_diffractive_optical_element.do

'Frensel' would turn a lot of potential customers away, the kind of people who don't read reviews but are interested in having a shorter lens while 'Diffractive Optics' either confuses or fascinates. Laughing


Maybe. Smile

DO combined with https://www.vision-systems.com/home/article/16737312/lenses-and-optics-variable-focus-lenses-uses-sound-to-shape-light could be in the next gen of smartphone cameras -- zoom lenses...
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