Diopter for D70 lens in Ikelight Housing

[c-dog]

Hello,

Can someone tell me where I can buy the +4 diopter close up lens that is required for the 18-70 lens kit on my D70 in the ikelight housing. I just got the housing and realized that this item is needed.

Ikelight says it is needed with my port for any lens that cannot focus to 12". I do not fully understand what is going on here. Would all of the pictures be out of focus with out the diopter or just the close up shots? Also, some of the shots that I have taken above water without the diopter include parts of the black lens hood. Will this go away with the diopter?

Thanks for your help, sorry if this item has already been discussed.

 

[dbh]

I can't remember if the 18-70 is a 67mm or not.

http://www.bhphotovideo.com/bnh/controller/home?O=158&A=details&Q=&sku=10146&is=REG&addedTroughType=categoryNavigation

W/O the diopter you will not get the lens to AF at all. It will just hunt.

Do not use the lens hood underwater.

HTH,
Dave

 

[scubaho]

B&H photo has them.

 

[AUTiger]

Your not actually taking a picture of a reef scene. You're taking a picture of the virtual image of the reef scene created by the dome. Thats why you have to be able to focus at 12".

I don't have an answer for your question. I need a diopter myself - I'm about to order a Tokina 12-24 and 8" dome for my D80. Please post what you end up buying and where you ordered it from.

From the Ike website:

Requirement for +4 Diopter

A lens behind any dome port will see a subject underwater as an apparent or imaginary image a few inches in front of the dome.

A lens that can focus as close as twelve inches will NOT need a + diopter close-up lens when used with an Ikelite dome port. The + diopter close-up lens is only required if the lens can not focus as close as twelve inches.

The apparent image position will vary depending on the water. The actual setting may range from 11.75 inches in Truk Lagoon to over 12.25 inches in the Caribbean.

The Ikelite dome is a 3" radius which is sometimes referred to as 6" which would be the diameter of the complete sphere. This size was chosen to avoid the buoyancy and size disadvantage of a larger dome. Rather than utilize something like a compass sphere, the Ikelite dome is designed and molded specifically for underwater photography.

Multiple focal length ("zoom") lenses usually will not focus close enough to provide full range operation behind any dome without adding a +4 diopter close-up lens. This close-up lens looks like a filter and is available from most camera stores.​

 

[c-dog]

Thanks for the info. I ordered it from the previously attached link.

Thanks again.

 

[joewr]

Hi,

As AUTiger said, what you are actually focusing on is a virtual image. The reason for this is that the dome is a lens itself--due to its curvature. Thus, it produces an image just in front of your lens. That is so close to your lens that it cannot focus on it. So, you need a close-up lens and that is exactly what a diopter "filter" is, a device that changes your lens to a close-up lens.

You can try this outside of your housing. Just put on the diopter and focus on near, small objects. Fun!!!

Most domes need a +3 or +4 diopter. It usually does not matter which because either will let you focus on the vitual image. However, it makes good sense to follow the mfg's instructions.

joewr

 

[frogfish]

I don't have an answer for your question. I need a diopter myself - I'm about to order a Tokina 12-24 and 8" dome for my D80.
.[/INDENT]

I have the same set-up and do not use a diopter for the above config

 

[joewr]

I have the same set-up and do not use a diopter for the above config

Hi, Frogfish,

I looked at your gallery and loved your photos--wonderful!

I am curious about your not needing a diopter for a dome, though. A flat port does not need a dome, but as far as I have seen, domes need diopters because they create virtual images too close for most lenses to focus on.

I have D100 with a Subal housing and use a variety of lenses. For my Nikkor 20mm and my Nikkor 28-80mm lenses, I use a dome and absolutely require a diopter.

Very puzzling...

joewr

 

[joewr]

I have the same set-up and do not use a diopter for the above config

Hi, Frogfish and AUTiger,

I think I finally understand--sometimes I am slow without the extra cup of good Peets Coffee...

I misunderstood Frogfish--many apologies. He has a Tokina with a much closer focusing distance. I do not have the exact close focus distance for the Tokina, but for a similar Canon lens it is : "Closest Focusing Distance: 0.24m / 0.79 ft." (http://www.fredmiranda.com/reviews/showproduct.php?product=221&sort=1&cat=27 ). This is less than 12" (obviously) and does not seem to need a diopter. Of course, that is proven by Frogfish' wonderful photos!

joewr

 

[frogfish]

Hi, Frogfish,

I looked at your gallery and loved your photos--wonderful!

joewr

Thank you for the kind comment - This actually encourages me to post some more recent attempts I'll work on it this week-end