Canon RF 100 macro port options

[darth mollusk 4]

I will be purchasing the Canon RF 100mm macro and have a few options to consider before I choose a port. I own the Aquatica AR5 housing. Ideally I would use the Aquatica mini macro port – but the tapered design will likely keep the lens ~3cm back from the port glass (the RF lens has a wider diameter than the EF lens the port was designed for).

1. Are there consequences to having 3cm of space between a 100mm macro lens and a flat glass port? Aquatica has a wide (not tapered) flat port option – but this will reduce my ability to get the strobes in close. 

2. I've heard some people have used a 100mm fisheye dome with a macro lens (this would be great for travel – one port for fisheye and macro options). Guessing this would impact how close I could focus on the virtual image (the RF 100 has an 11cm working distance for reference). Anyone here tried this with the EF 100 or equivalent? 

3. Curious if there are options available to use non-Aquatica ports on an Aquatica housing (I've seen a Sea & Sea adapter – though I'm not sure it's in production anymore). 

I will be talking with Aquatica (when we get a copy of the lens to test). I shoot with Aquatica for a number of reasons: I'm Canadian (having local contact is great – and I have a preference to support small local business) and I dive in cold, remote locations (Aquatica have a reputation for tough housings). I understand I would have a few more options available if I went with Nauticam... but there are always trade-offs. 

Edited June 7, 2021 by darth mollusk
corrected working distance...

[Tom_Kline 143]

"Back in the day" one had to have space between a macro lens and port because the lens extended when focused so this should not be too big an issue. The larger OD of a standard macro port will help with buoyancy since there will be a larger air pocket. It appears that the RF100 macro does extend a bit to get to 1.4x so that apparent extra space may end up being useful.

The main downside will be accessories that apparently require the camera lens to be right up to the port glass such as those made by Nauticam. For example, on their lens compatibility list, the older extending Micro-Nikkors are not included for the EWML. We will have to wait and see to when the new lens is available and in the hands of the housing and port manufacturers to get more specific info. A third party port manufacturer that may produce a port for the new lens and with an Aquatica mount is Saga. See: https://sagadive.com/product/frontales-conicos-de-aluminio-saga/   Note that they offer Aquatica now. I have one of their ports from this list for Seacam for the Nikon 105mmVR macro and it is quite nice.

[darth mollusk 4]

Thanks Tom! Good to hear there shouldn't be much of an issue with the air space – would be painful to lose that crisp image quality that comes with the 100 macro. 

In the short term I'm not too worried about accessory wet-lenses (1:1.4x with 45MP gives me plenty to work with... for now). I suppose the other consideration is that my port will be ~3cm closer to critters than it would otherwise need to be. Measuring the Saga macro port dimensions in PS it appears I could get the RF 100 within ~1.5cm of the glass (did not know Saga offered an Aquatica mount – great to have another option!)

So many epic salmon images on your website btw – nice work!

Edited June 6, 2021 by darth mollusk

[ChrisRoss 150]

Your working distance on the 100mm macro at 1.4x is 85mm so you lose 30mm of that working distance, so you might have 45mm of working distance allowing for port glass thickness etc even in a perfect fitting port.  The lens is not reported to extend when focusing, see this post: 

Always better to get a port that fits better and keep the working distance in that range.  While you could use a dome port with it, the extension needed to make it fit (let alone getting the dome placement correct would be near as big as the flat port. 

On the port diameter, the RF lens is listed at 81.5mm OD, the Canon 100mm EF lens is 77.7.  The 18430 port is also listed as supporting the Nikon and Sony macro lenses and the Nikon lens is listed 83mm OD, so the RF lens should fit near as well as the Nikon lens. 

[darth mollusk 4]

Thanks Chris! I had not seen that the working distance at 1.4x reduced to 85mm (makes sense). 

I estimated where the RF 100 would sit before bumping into the tapered side of the port by measuring dimensions in PS (including the standard 4mm width of the sidewall). I suspect the 18430 mini macro port 'supports' the Nikon lens, but still places it back 3 or more cm from the glass. Considering your very valid points re: working distance I want to be as close to that glass as possible. So far the best option appears to be the Saga (~1.5cm from the glass). Guessing the non-tapered Aquatica macro port would make it challenging to get the strobes in close enough at minimum working distance...

[ChrisRoss 150]

I'm wondering if the gains  made with the tapered port would be cancelled out with the loss of working distance??  Probably best to wait to have the lens in the hand to see how it fits - the specs suggest it will be very close.  You may have some flexibility with choice of extension ring as well to fine tune the fit.

[darth mollusk 4]

Just received an update from Backscatter: Aquatica will be machining a new mini macro port for the Canon RF 100. 

[Tom_Kline 143]

On 6/6/2021 at 3:29 PM, ChrisRoss said:

Your working distance on the 100mm macro at 1.4x is 85mm so you lose 30mm of that working distance, so you might have 45mm of working distance allowing for port glass thickness etc even in a perfect fitting port.  The lens is not reported to extend when focusing, see this post: 

 

According to this page the barrel extends: https://sansmirror.com/lenses/lens-database/lenses-from-camera-makers/canon-eos-rf-mount-lenses/canon-rf-100mm-f28l-macro.html

We will have to wait and see for a more detailed evaluation. The image of the lens nose is consistent with a portion of the lens extending as there are several parts here - the front end is not flush.

The reason I got the Saga port was for the 67mm threaded end. This enables fitting a range of optical add-ons, from the EMWL to wet diopters.

Edited June 7, 2021 by Tom_Kline

[ChrisRoss 150]

This page quotes barrel extension at 1x and 1.4x and the lens would appear to change length by 6mm between 1x and 1.4x being longer at 1.4x.  https://www.dpreview.com/articles/1449146848/closer-look-canon-rf-100mm-f2-8l-macro-is-usm?slide=2

the length is quoted as 148mm, flange distance is 20mm so at , focal distance is 280 and working distance is 112mm and 280 -20 -112 = 148mm, Doing the same at 1.4x you get a length for the lens of 154mm.  I expect that would be the extent of length change, looking at the videos is they are actually focusing the lens there is no visible length change in the videos.

 

[AndreSmith 15]

Slightly different question but still considering Aquatica and ports for Canon R5:

I see Aquatica lists an adapter for use with EF lenses:

8474 Port extension EF lenses to be used on Canon  R5            349.00 $

I am assuming this is simply to extend a port by the same length as the RF to EF adapter between the camera body and the EF lens. So really just a compensatory extension ring? So by the same logic if you already have extension rings that provide the extra length required you don't need the 8474 port extension?? If that is the case could someone please measure the 8474 for me . Trying to get that R5 underwater but have only EF lenses. Wont have any moola left for RF lenses after the housing purchase!

Thanks for any info

 

[ChrisRoss 150]

Flange distance for EOS EF lenses is 44mm and the flange distance for RF lenses is 20mm, so the RF-EF adapter is 44-20 = 24mm long.

The extension ring 48474 should be the same thickness but may not be exactly the same.

The port charts however are rather confusing the RF port chart on the bluewater website says that extension 48474 is required for the RF lenses as well as the extensions listed which seems odd.  This seems to imply the 48474 extension is not required when using EF lenses with the EF-RF adapter.   

This is certainly the case for Nauticam where it directs you to the EF port chart for EF lenses with RF adapter.  This means that the RF housings have the zoom gear drive at the same spot relative to the lens flange as the EF housings so you can use all the same extensions and zoom gears.  It also means the lens has been placed in the same spot relative to the housing flange so the same extensions are needed. 

If you have the housing already you can test this out - if the zoom gear still mates up it indicates Aquatica have designed things the same way and you can double check this by checking lens placement - the lens should look like it's in the same position relative to the dome.

You could also talk to the dealer you are getting the housing from or ask Aquatica who are normally quite responsive to confirm - they need to provide some guidance on how to select extensions when using the EF-RF adapter.

[AndreSmith 15]

Thanks Chris, appreciate your reply.  Yes it is a bit confusing! I don't have the housing yet so can't tell if the zoom gear lines up. I will try to get hold of Aquatica to clarify