Oly 45 1.8 with Pana GTC1 converter... works !!!

Started May 17, 2012 | Discussions thread
MT Senior Member • Posts: 1,943
Thanks MICKSH6

Thanks! You likely saved me some hassle. I have one on order to be shipped Monday from a NY source. I'll call and cancel tomorrow.

Essentially I had hoped for a 90mm 1.8 equivalent (180mm in 35mm equivalence) but 2.5 to 2.8 stops less light is a non starter for me. I was hoping for a poor man's solution to the upcoming 75mm 1.8 Oly prime and was willing to suffer a bit of resolution loss. But the low light loss is too much as it really, as you noted, not much better than the 40-150 zoom that I already have.

Thanks again! Your type of posts is what makes this forum great and helped me transfer from the Sony NEX system to MFT and it has been the right move for me.


micksh6 wrote:

MT wrote:


I read your post with interest. You posted a link and then took it off (edit?). Anyways, from your post I take it that you have the tele converter and actually tried it on your own camera. Would love to hear your comments. I'm trying to figure out your comment about 'useless toy' - whether it is sarcasm or whether you really mean that.

I didn't edit my recent posts in this thread.

Sure, I got one, few hours ago. I preordered this converter long before, hoping that Panasonic would exceed design specs, but they didn't.

What kenw and Great Bustard wrote about front element size is true, but I only knew outer diameter - 53mm, this might allow close to 50mm front element. I would have liked 90mm F2.5 AF lens too, if front element was smaller. The reality is that rear element size matters too and Panasonic made it ridiculously small.

Panasonic is not to blame, they did what they promised (although IMO it's overpriced). This converter will work on any slow zoom and will provide aperture about F4.8-F5.0 at 42-45mm. Oly 45mm will allow just a bit faster aperture than F5.6, but not even F4.5. Pana X or Oly 12-42mm zooms will not reduce aperture.

The reason I called this expensive toy is that for very little more than $130 one can get Oly 40-150mm zoom. This zoom is about as fast at 90mm (F4.9) and pretty sharp. And it can go longer than 90mm, you know.

Oly 40-150mm zoom was on sale for $100 last year, I thought everyone who wanted cheap tele got it. Now it costs more, $160 refurb at Cameta, but still, IMO, way better value than this converter for $130.

This converter on Oly 45mm will have hard time beating 40-150mm zoom in image quality and it won't have wider aperture. That's the point.

Use case of this converter is probably a lady with small purse carrying GF3 with X collapsible zoom and this thing, with no room for 40-150mm. Pretty limited usage, isn't it? And this breaks IBIS on Oly (Pana OIS will probably break too, neither like being fooled about focal length).

Now, I haven't measured sharpness of this this thing. All above assumed the converter doesn't degrade sharpness in way non-pixel-peepers can see on regular cat photos, which I can trust is true.

I will shoot resolution chart in the next couple of days, and some test shots, just out of curiosity, I need to do some other tests anyway.

OP could have noticed that converter doesn't keep F1.8 aperture. Camera measures around 2.5-2.8 stops less light with it attached. It is even worse than rear-mounted 2x teleconverters. Worst part is that DOF becomes wider as well. Background blur is nonexistent, just like with 90mm F5.0 lens.

On the contrary, other, larger front mounted teleconverters, like mine TCON-17 do not require more exposure (within 1/6 stop granularity). And TCON-17 does provide more background blur, so it really makes 75mm F1.8 lens. But, TCON-17 is too big and heavy.

I guess, there can be no miracles, no cheap fast long AF lens for people. Have to wait for Oly 75mm F1.8 then.

See the rear element of this converter. The filter ring is 37mm, there is Oly lens cap for comparison. The rear element is tiny, good for F5.6, but not enough for much faster aperture.

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