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Architeuthis

Canon EF lenses on MFT cameras?

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On 6/29/2021 at 11:48 PM, joncroweucl said:

Thanks for the insights, @Interceptor121

I had the Panasonic Image App running and watched through my phone as I filled the sink to see if I could notice the FOV narrowing. I was so pleased to see that there was no noticeable difference that it didn't occur to me to take a before and after shot. I'll do it next time.

After some investigation I've determined that the interior ring of the dome port is just making contact with the face of the zoom gear extension ring. This is causing increased resistance when turning the knob on the port adapter and making changing the focal length difficult. I'm also concerned that persisting and accepting this situation will eventually lead to stripping the teeth from the port adapter knob gear.

I plan to file away the exposed face of the zoom gear extension, or ask my maker friend if he can amend the design of the extension for my port. I'll post an update once I've made progress.

Hi Jon,

The extension ring is not causing problems as I am using it. I guess (as you alraedy say) that the extension is just too short in your case. I shortened one extension collar, the one for the Tokina 10-17 with 1.4x TC, where my design is a bit too long (I did not want to redesign and order a new one). I used an abrasive tool similar to the one below to make it fit:

https://www.bauhaus.at/schwingschleifer/bosch-professional-schwingschleifer-gss-23-a/p/24795795?gclid=EAIaIQobChMIxNmGjevD8QIVjP93Ch1I1QMyEAQYAiABEgLrvfD_BwE&ef_id=EAIaIQobChMIxNmGjevD8QIVjP93Ch1I1QMyEAQYAiABEgLrvfD_BwE:G:s&s_kwcid=AL!11897!3!224895636698!!!g!297667046343!!947016865!47437589459&cid=PSEGoo947016865_47437589459&pla_campid=947016865&pla_adgrid=47437589459&pla_prpaid=297667046343&pla_prid=24795795&pla_adt=pla&pla_prch=online&pla_stco=

In addition, I drilled three threads (each in 120° distance from the others) into the extension collars. These are for grub screws that are thightened with allen keys, so that the collar is fixed firmly to the zoomgear and can not get loose during the dive...

 

Wolfgang

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Any updates on this with some blue water results and recommendations??

Also just to double check, how was the autofocus when comparing to a prime fisheye??

Thanks!

Scott

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Posted (edited)
On 8/11/2021 at 9:45 PM, ScottyR said:

Any updates on this with some blue water results and recommendations??

Also just to double check, how was the autofocus when comparing to a prime fisheye??

Thanks!

Scott

Hi Scotty,

I am back now since two weeks, but did not have time yet to postprocess the greatest part of my photos: a lot of work after the holidays and finally I got a summer-flu and am lying right now in the bed...

What I can say is just what my impression is now:

To have similar corner sharpness with the Nauticam NA140 and the Zen DP100 dome, the 100 dome requires 1-2 f-stops more (this statement I will be able to check after processing my photos).

With the NA140 dome (and the Zen DP170), I do not recognize a difference in AF compared to the Zuiko 8mm fisheye (I always use "C-AF" with my EM1II). I have the impression that with the DP100 the number of slightly out of focus photos is substantial (I never noticed such photos before with the NA140 dome)..

For me the NA140 will remain the main fisheye dome. I also never used the Zuiko 8mm since I have the Canon 8-15mm (and the Tokina 11-18mm). The DP100 will be for extreme CFWA (The NA140 is, however, quite small; the difference is not big)...

 

Wolfgang

Edited by Architeuthis
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