Canon EF lenses on MFT cameras?

35 minutes ago, Architeuthis said:

This is interesting. Just yesterday, after watching the Wetpixel episode on WA macro tools, in a severe attack of GAS , I ordered the Zen DP-100 (Tokina version). I plan to use it with the Tokina and 0.71x speedbooster for WA macro. It will last until I have the dome here, but I will report on performance as soon as I have some results...

Wolfgang

You've got all the bits, you could try the 8-15 in the same setup I would imagine and put it to the test if 5mm difference in extension makes a noticeable difference.

Apologies @Architeuthis for inducing a bout of GAS!

The reason I brought up the question re: minidomes is I managed to pick up a second-hand as-new Zen DP-100-N120CR for less than half-price new; I just couldn't resist.

I reached out to Zen re: DP-100-N120CR compatibility with smart adaptors and this is their feedback:

"We have never tested the Viltrox EF-M1 adaptor so unfortunately we cannot make a recommendation when using the Zen DP-100-N120CR. We have only tested this combination when using the Metabones Speed Booster Ultra 0.71x Adaptor. With the speed booster, you would only need the 36064 N85 to N120 adaptor plus the DP-100-N120CR as the extension is already build into the DP-100-N120CR. An extra 5mm of extension is the recommended solution for the smart adpator. The smallest extension ring Nauticam makes is 10mm so I am afraid that would push the dome too far forward and cause vignetting. Again, we have never officially tested this so you are welcome to try, but I do believe you will see vignetting if you were to add 10mm of extension."

Question for the community: using a EF-M43 smart adaptor and 8-15:

If you were to go with the 36184 - 41.5mm n85 - n120 adaptor and Zen DP-100-N120CR the lens would be 1.175mm further from the dome than optimal.

Similarly, if you paired this 41.5mm adaptor with a 30mm N120 extension and Nauticam 140mm Dome, the lens would be 1.8mm further from the dome than optimal.

Do my calculations add up correctly? Would this variation from optimal positioning be expected to result in noticeable degradation to image quality/vignetting?

I think you can see where I'm going here. If I can find one port adaptor and one extension that supports both of these domes for the 8-15 adapted to MFT, I'd be very happy.

1 hour ago, joncroweucl said:

Apologies @Architeuthis for inducing a bout of GAS!

The reason I brought up the question re: minidomes is I managed to pick up a second-hand as-new Zen DP-100-N120CR for less than half-price new; I just couldn't resist.

I reached out to Zen re: DP-100-N120CR compatibility with smart adaptors and this is their feedback:

"We have never tested the Viltrox EF-M1 adaptor so unfortunately we cannot make a recommendation when using the Zen DP-100-N120CR. We have only tested this combination when using the Metabones Speed Booster Ultra 0.71x Adaptor. With the speed booster, you would only need the 36064 N85 to N120 adaptor plus the DP-100-N120CR as the extension is already build into the DP-100-N120CR. An extra 5mm of extension is the recommended solution for the smart adpator. The smallest extension ring Nauticam makes is 10mm so I am afraid that would push the dome too far forward and cause vignetting. Again, we have never officially tested this so you are welcome to try, but I do believe you will see vignetting if you were to add 10mm of extension."

Question for the community: using a EF-M43 smart adaptor and 8-15:

If you were to go with the 36184 - 41.5mm n85 - n120 adaptor and Zen DP-100-N120CR the lens would be 1.175mm further from the dome than optimal.

Similarly, if you paired this 41.5mm adaptor with a 30mm N120 extension and Nauticam 140mm Dome, the lens would be 1.8mm further from the dome than optimal.

Do my calculations add up correctly? Would this variation from optimal positioning be expected to result in noticeable degradation to image quality/vignetting?

I think you can see where I'm going here. If I can find one port adaptor and one extension that supports both of these domes for the 8-15 adapted to MFT, I'd be very happy.

Hi Jon,

No problem, GAS is fun and part of our hobby...

Your calculation for the DP-100-N120CR gives the identical result als mine in the table above - so it is probably correct...

Here are my calculations for the Canon 8-15 with 1x adapter and Nauticam 140 port:

My result for the 41.5mm extension is 1.2mm, but this difference is likely the 5.625mm I take for the additional length of the 1x vs. the 0.71x speedbooster. Your message from Zen says 5mm. I have measured the difference with an electronic caliber, I have both adapters here ; while the 1/100 and 1/1000 of a mm will differ with temperature, one can take 5.6mm as a fix value...

=> I think this different treatment by Zen is an indication how unimportant deviations in the 1/10mm range are in practice (but deviations will become more important at smaller dome radii, what is here the case). We both will check in the future in real live, this is the only way to find out, I am eagerly waiting for the domeport to come (What Chris says about purple fringing does not sound too good. With the 140 and 170 ports I cannot see any optical flaws with Canon 8-15 and also not with Tokina 10-17 (with speedbooster; with 1x adapter and especially with TC the Tokina is coming to its optical limits))...

=> Just a thought on the 41.5mm N85/N120 adapter: I do not see a reason why the Metabones or Viltrox 1x adapters should not fit into this extension, but the devil never sleeps. better to ask Nauticam whether they know if the adapters fit before ordering, just for safety.

I also changed my order from last night from DP-100-T to DP-100-N120: I realized that the domport in front of the macro object will be the same, no matter whether I use the canon 8-15 or the smaller Tokina 10-17 lens, no reason to optimize everything for the Tokina, which is optically not as good. This means a mispositioning of the Canon 8-15 of +2.4mm or -2.6mm, depending on the extension, but I take this risk. The Tokina with 1x I can house almost perfect with a 20mm extension, that I already have. In case IQ is poor with the Canon I can ask our local UW dealer in making a custom extension for me for reasonable money. He is quite good in this, he did a similar extension for me already in the past...

Wolfgang

Interesting to hear about custom extensions....

I'll get in touch with Nauticam to confirm if the Viltrox and Metabones smart adaptors can fit in the 41.5mm port adaptor. I expect this will be no issue personally, as I can remove the tripod mounting foot on the Viltrox. As you said, best to check!

Assuming positive feedback from Nauticam, I'm going to pull the trigger for the 41.5mm port adaptor with the DP-100-N120CR. At least that will get the system in the water for some testing. I'll be doing some shore diving in August and seal diving in the Farne islands in September, so it'll get a real-world test then.

If all works I'll be delighted to be able to take the 8-15 underwater with just the adaptor and minidome. Very travel and "relatively" budget friendly kit

I think the question to ask is if the focus gear is in the same relative position compared to the 34.7mm N85-N120 adapter.  The 34.7 adapter is setup so you can use the canon zoom gears when the lens is mounted on the speed booster or you can Wolfgang's gear adapter when using the smart adapter.  The important dimension is distance of the zoom gear from the camera body flange.  The 41.5mm adapter seems to made for adapting EF lens to the EOS M cameras.

On the subject of the purple fringing that appears to be an issue of using the Panasonic lens on an olympus body.   It is not reported on Panasonic bodies. 

I really think a 5mm difference is minimal based on looking at the ikelite system I linked it uses an 8mm fisheye behind a very flat dome port and the entrance pupil is probably 80-90mm in front of the centre of curvature of the dome.  The point is if an 8mm fisheye produces OK looking images in these conditions, being only 5mm you would think is less of an issue.  You can see the dome in side view here:  https://www.ikelite.com/blogs/photo-galleries/nikon-z7-and-8-15mm-fisheye-underwater-photos-with-compact-8-inch-dome

Good point, Chris. I'll be sure to ask Nauticam the same question re: positioning of the adjustment knob and gear meshing relative to each adaptor. 

My concern with using the 34.7mm N85-N120 adapter with the Zen DP-100-N120CR minidome is that the front of the lens will sit ~5.6mm closer to the port than is optimal. Maybe this is an irrelevance or indeed preferable to being 1-2mm further away?

Maybe all this fuss over a few mm amounts to imperceptible differences in the real world  the feedback from Zen gave me that undesirable sinking feeling, but then again they stated repeatedly they hadn't tested my specific combination, so were right not to make a specific recommendation.

10 hours ago, joncroweucl said:

Good point, Chris. I'll be sure to ask Nauticam the same question re: positioning of the adjustment knob and gear meshing relative to each adaptor. 

My concern with using the 34.7mm N85-N120 adapter with the Zen DP-100-N120CR minidome is that the front of the lens will sit ~5.6mm closer to the port than is optimal. Maybe this is an irrelevance or indeed preferable to being 1-2mm further away?

Maybe all this fuss over a few mm amounts to imperceptible differences in the real world  the feedback from Zen gave me that undesirable sinking feeling, but then again they stated repeatedly they hadn't tested my specific combination, so were right not to make a specific recommendation.

That was the point of the Ikelite link you are talking 5mm in front of optimal point, they are maybe 80-90mm in front of optimal point with the example I posted.  I know the 4"dome may cause additional abberations, but the only way to tell is try it out.

So there were no Nauticam dealers in my local region that stocked the 41.5mm port adaptor. I've gone ahead and ordered the 34.7mm adaptor and have managed to obtain the 3d printed extension for the zoom ring. Thanks for the design, Wolfgang.

To summarise; I'll be testing the Canon 8-15 FE with Viltrox EF-M1 Smart Adaptor on Panasonic GH5 in NA-GHV housing, 34.7mm N85-N120 port adaptor and Zen DP-100-N120CR minidome. If all the kit fits my initial tests will be limited to my bathtub.

I've not done and lens-dome testing before; I plan on making CFWA test shots with small SCUBA kit (15m reel, torch, boltsnaps etc.) with vivarium foliage stock to the walls of the tub to assess DOF and corner sharpness at different apertures.

Community; are there any specific assessments you'd be interested in seeing?

On 6/8/2021 at 3:35 PM, joncroweucl said:

Good point, Chris. I'll be sure to ask Nauticam the same question re: positioning of the adjustment knob and gear meshing relative to each adaptor. 

My concern with using the 34.7mm N85-N120 adapter with the Zen DP-100-N120CR minidome is that the front of the lens will sit ~5.6mm closer to the port than is optimal. Maybe this is an irrelevance or indeed preferable to being 1-2mm further away?

Maybe all this fuss over a few mm amounts to imperceptible differences in the real world  the feedback from Zen gave me that undesirable sinking feeling, but then again they stated repeatedly they hadn't tested my specific combination, so were right not to make a specific recommendation.

 

 

Here a report of my first photos taken with EM1II/Canon 8-15mm fisheye/1x Metabones/Zen DP100 (N120 version):

I took the Nauticam 34.7mm N85/N120 adapter plus a 30mm N120 extension ring. According to Zen's recommendation the total extension is 2.4mm too long and this should lead to slight vignetting @8mm. This is, however, not the case (and so I will not test the the 25mm extension ring, which leads to an overall extension of -2.6mm too short). I also did not notice any sign of puple fringing (as Chris reportes for the Pana 8mm fisheye behind the DP100 minidome), so this is likely really a phenomenon created by the Panasonic lens (it was my initial fear that the purple fringing is caused by the small minidome and not by the lens). A difference is also that one can leave the sunshade on the lens, when using the NA140, while one has to remove the shade when inserting into the DP100 minidome (with both domes one has to mount the lens separately from the front, when the camera is already in the housing (with 34.7mm N85/N120 attached) and then mount dome+extension).

I also must say the photos were taken in a nearby gravel pond with 3m - 4m of vis what is not ideal for judging sharpness of the image. My impression was that IQ is comparable to the Nauticam 140 dome, but the number of out of focus images is greater compared to the same lens in the Nauticam 140 dome. This MAY BE a homeopatic impression, because I always have in the back of my mind that the virtual image is nearer and smaller and so AF will be more difficult...

8mm, f 8.0, 1/200s, ISO200, 2*Inon Z330

I also had the impression that wrong positioning of the strobes, leading to backscatter, is easier with the minidome. Positioning of camera and strobes for WAM is easier. Here an example photo of a common sunfish (Lepomus gibbosus). I could have taken the photo with the Nauticam 140 dome as well, but is was easier with the minidome:

15mm, f 7.1, 1/160s, ISO200, 2* Inon Z330

The fish did not let me come close enough to really exploit the advantage of the minidome vs. 140. On July 15th I will go for two weeks to the Adriatic and hopefully there I will encount something more suitable (e.g. nudis in front of a nice background for WAM).

Here some test photos (uncropped) that may allow, to some extent, judging the IQ better:

8mm, f 5.6, 1/250s, ISO200, 2* Inon Z330

8 mm, f 6.3, 1/160s, ISO200, 2* Inon Z330

In the next post I will post two images that I took under similar conditions with the same camera/lens combination, but behind the Nauticam 140 dome...

Wolfgang

Here two photos taken with EM1II/Canon 8-15mm/Metabones 1x under similar conditions, but behind the Nauticam 140 dome, a week before at the same location:

8 mm, f 6.3, 1/160s, ISO 200, 2* Inon Z330

8 mm, f 9.0, 1/250s, ISO 200, 2* Inon Z330

More testing in much clearer waters is required to come to a final conclusion about comparing IQ between the NA140 and the DP100. Until now I am excited about the minidome, IQ is very good as far as I can judge under the given conditions (3-4 m vis)...

Wolfgang

Looks great Wolfgang, but the usual problem of small images, perhaps when you get to clear water you can post some corner crops as well?

On 6/23/2021 at 3:05 AM, ChrisRoss said:

Looks great Wolfgang, but the usual problem of small images, perhaps when you get to clear water you can post some corner crops as well?

 

I think one can see differences in sharpness in the edges between the two testshots, taken at f 5.6 and f 6.3 (ton and hanging brick). The image arse, however, not directly compareable, as the difference may be also just the different distances of the edges to the lens, and not produced by the minidome...

I will try to get shots in clearer waters and show crops of center and edges. At the end a careful comparison of test images at different apertures under standardized conditions, as proposed by Jon, will be the better means to finally judge IQ. I am eager to see these photos...

Wolfgang

On 6/9/2021 at 1:56 PM, joncroweucl said:

So there were no Nauticam dealers in my local region that stocked the 41.5mm port adaptor. I've gone ahead and ordered the 34.7mm adaptor and have managed to obtain the 3d printed extension for the zoom ring. Thanks for the design, Wolfgang.

To summarise; I'll be testing the Canon 8-15 FE with Viltrox EF-M1 Smart Adaptor on Panasonic GH5 in NA-GHV housing, 34.7mm N85-N120 port adaptor and Zen DP-100-N120CR minidome. If all the kit fits my initial tests will be limited to my bathtub.

I've not done and lens-dome testing before; I plan on making CFWA test shots with small SCUBA kit (15m reel, torch, boltsnaps etc.) with vivarium foliage stock to the walls of the tub to assess DOF and corner sharpness at different apertures.

Community; are there any specific assessments you'd be interested in seeing?

See below a limited summary of the equipment setup and and test results. This summary is not designed to be a comparison to other setups for the Canon 8-15 on m43, simply an investigation into the feasibility of this specific equipment setup.

https://www.flickr.com/photos/193329934@N02/albums/72157719526251695/with/51278536908/

The equipment fits comfortably. The extension built into the Zen DP-100-N120CR minidome removes the requirement to use a N120 extension ring. 

IMG_20210627_102210 by Jonathan Crowe, on Flickr

My experience is that the operation of using the knob on the port adaptor to adjust the zoom on the 8-15 was a bit stiff and clunky. @Interceptor121 and @Architeuthis, did you experience the same? I'm wondering if the dimensions of the zoom ring adaptor I had printed are a bit off and I'm experience sub-optimal performance.

With no extension ring, the positioning of the lens front element is 5mm closer to the glass dome that is determined to be optimal by Zen and Nauticam. This is because the 1x adaptor is 5mm deeper than the Metabones Speed Booster Ultra 0.71x Lens Adaptor that the Nauticam N85-N120 34.7mm Port Adaptor is designed for.

IMG_20210627_101826 by Jonathan Crowe, on Flickr

It is difficult to determine the impact on image quality and field of view, with this deviation from optimal entry pupil positioning, in the absence of comparison images captured using the 30mm N120 extension ring and N120 140mm dome.

With a recent opportunity to dive on the North Norfolk cost eliminated by poor weather and diving conditions, I resorted to the controlled photography environment of my kitchen sink.

IMG_20210627_163003 by Jonathan Crowe, on Flickr

The subject was a small spool with line positioned on a small ceramic bowl. The base of bowl was touching the dome shade. This was to simulate golf ball sized subject with interesting skin texture and facial features on a rocky outcrop. The bath mat has a very subtle rough texture and was positioned so the printed images were close to the corners of the frame.

I think the image quality is excellent. The depth of field necessary to resolve the texture on the bath mat is achieved at f8 and corner sharpness is not improved by stopping down any further than f11.

P1111054 by Jonathan Crowe, on Flickr

More images at different apertures are available at the Flickr link at the top of this post. I saw no point in testing the lens at 15mm in the sink as I could not position any suitably sized subjects and a reasonable distance from the port.

I'm happy with this setup as it delivers very good image quality and accomplishes my goal of fitting all my equipment in a IATA compliant carry on rucksack. This would have been very difficult/impossible if an extension ring and 140mm dome were substituted.

If I ever get a free house in the future I plan on testing the zoom range and IQ of the Canon 8-15 FE and the Panasonic 14-42ii behind the AOI-UWL-09 wet lens in the bathtub with subjects at different distances. There is very little analysis of the AOI wide wet lens on WetPixel, so I plan to make a contribution. I'll be diving off of the Farne islands in September 2021 so my objective is to have a better understanding of the capabilities and limitations of both lens setups before I go and deploy them in the real world! 

I'm happy to receive any thoughts, feedback or suggestions for further testing.

2 minutes ago, joncroweucl said:

See below a limited summary of the equipment setup and and test results. This summary is not designed to be a comparison to other setups for the Canon 8-15 on m43, simply an investigation into the feasibility of this specific equipment setup.

https://www.flickr.com/photos/193329934@N02/albums/72157719526251695/with/51278536908/

The equipment fits comfortably. The extension built into the Zen DP-100-N120CR minidome removes the requirement to use a N120 extension ring. 

IMG_20210627_102210 by Jonathan Crowe, on Flickr

My experience is that the operation of using the knob on the port adaptor to adjust the zoom on the 8-15 was a bit stiff and clunky. @Interceptor121 and @Architeuthis, did you experience the same? I'm wondering if the dimensions of the zoom ring adaptor I had printed are a bit off and I'm experience sub-optimal performance.

With no extension ring, the positioning of the lens front element is 5mm closer to the glass dome that is determined to be optimal by Zen and Nauticam. This is because the 1x adaptor is 5mm deeper than the Metabones Speed Booster Ultra 0.71x Lens Adaptor that the Nauticam N85-N120 34.7mm Port Adaptor is designed for.

IMG_20210627_101826 by Jonathan Crowe, on Flickr

It is difficult to determine the impact on image quality and field of view, with this deviation from optimal entry pupil positioning, in the absence of comparison images captured using the 30mm N120 extension ring and N120 140mm dome.

With a recent opportunity to dive on the North Norfolk cost eliminated by poor weather and diving conditions, I resorted to the controlled photography environment of my kitchen sink.

IMG_20210627_163003 by Jonathan Crowe, on Flickr

The subject was a small spool with line positioned on a small ceramic bowl. The base of bowl was touching the dome shade. This was to simulate golf ball sized subject with interesting skin texture and facial features on a rocky outcrop. The bath mat has a very subtle rough texture and was positioned so the printed images were close to the corners of the frame.

I think the image quality is excellent. The depth of field necessary to resolve the texture on the bath mat is achieved at f8 and corner sharpness is not improved by stopping down any further than f11.

P1111054 by Jonathan Crowe, on Flickr

More images at different apertures are available at the Flickr link at the top of this post. I saw no point in testing the lens at 15mm in the sink as I could not position any suitably sized subjects and a reasonable distance from the port.

I'm happy with this setup as it delivers very good image quality and accomplishes my goal of fitting all my equipment in a IATA compliant carry on rucksack. This would have been very difficult/impossible if an extension ring and 140mm dome we substituted.

If I ever get a free house in the future I plan on testing the zoom range and IQ of the Canon 8-15 FE and the Panasonic 14-42ii behind the AOI-UWL-09 wet lens in the bathtub with subjects at different distances. There is very little analysis of the AOI wide wet lens on WetPixel, so I plan to make a contribution. I'll be diving off of the Farne islands in September 2021 so my objective is to have a better understanding of the capabilities and limitations of both lens setups before I go and deploy them in the real world! 

I'm happy to receive any thoughts, feedback or suggestions for further testing.

The shorter extension means the field of view of the fisheye is getting reduced and the port will have additional barrel distortion. It would be difficult to notice this as the corners that are already compressed are affected so the only consequence is the loss of FOV. if this was a rectilinear lens the adverse effect would show more.

You can test that taking a shot dry in the sink and then keeping the camera exactly in the same point take the shot in water. The field of view will reduce and the lens will not longer have the fisheye diagonal

Probably the tokina set up is the most portable compromise considering it takes an acrylic port however I doubt the optical quality can compare with the canon. 

For sure this set up you have is good for WAM but I do not shoot any of that so for me this was not a deciding factor and as I have a 180mm dome for rectilinear I have given up the idea of just one bag for my equipment long time ago!

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.

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

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

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

On 6/7/2021 at 1:45 PM, Architeuthis said:

Hi Jon,

Initially I have considered the Zen DP-100 (for EM1II, but this should not make a difference), but I did not acquire it. Partially the reason was the right extension: The DP-100 comes with built in extensions for the Canon 8-15mm, Tokina 10-17mm or nothing (blunt N120 version). The Nauticam 34.7mm N85-N120 is made for the Metabones 0.71x focal reducer, while one wants to use the 1x Smart adapter with Canon 8-15mm. The Smart adapter is 5.63 mm longer than the 0.71x speedbooster, so none of the versions fit as they are. I made  a table with all N85-N120 extensions that I found available from Nauticam (used with or without additional available N120 extension rings) and calculated how much the deviation (in mm) is from the recommended one:

The closest match would be the 47mm N85/N120 extension together with the Tokina version (DP-100-N120T) with only 0.3mm deviation. I refrained, however, from ordering this combination, since I was thinking in case it would not work I have an extension and a domport that is not good for any of the lenses that I have. The 34.7mm N85/N120 adapter, that is designed for the Metabones adapter, gives 2.6mm deviation at the best. I do not know, how much worse IQ would be, but I think the smaller the dome radius is, the more effect on IQ per mm wrong positioning...

I am eager to hear what Zen support tells you. I also asked them and was told that fisheye lenses are very tolerant for wrong positioning and they recommend the 34.7mm N85/N120 adpater plus 25mm extension (as listed above) - but they cannot guarantee anything...

 

Wolfgang

P.S.: I see now, that Massimo has also answered. I agree that it is better to take the Tokina 10-17mm with the small DP-100: using the DP-100-N120T with 0.71x speedbooster and Tokina 10-17mm lens is the optimum and does not need any further adjustments...

 

I was looking at the useful table you made.  But I cannot understand where you have the 25mm extension and why under the Tokina version you number are negative then positive then negative then positive depending on the adapters used...  Sorry I am confused!

Hi nudibranco,

Sorry for the confusion. The numbers are the deviation from optimum (=extension recommended by the port table) in mm, when the lens is used with the 1x Metabones adapter. Negative means the overall extension is to short, positive means it is too long. Zero is exactly the optimum...

The calculations for the different versions of the DP100 port are done with different additional N120 extensions that are available by Nauticam, in order to get the closest match to the optimum. I did not include them in the table (I thought this would be less confusing, but here we are...).

The used additional N120 extensions were (ordered from the 34.7mm adapter up to the 55mm adapter):

DP100-N120: 25/20/10/10/10

DP100-CR: no additional extension throughout (=None)

DP100-T: 10/10/None/None/10(None would have been the better choice for this last case, but the 55mm adapter is not really of interest for this DP100 version)

This reminds me that I promised to post some photos, taken with DP100 and NA140 domeports, for comparison. I will do so in the next days, when I have time. I can say already now that under real live conditions, that vary a lot from motif to motif, the differences are too small to be recognized by me...

Wolfgang