Sharper Imagon Examples

[Frank Petronio]

I'm semi-interested in Imagons, likely because I found a deal on one... how sharp can you make an Imagon while still being wide open? I am not a fan of the extreme softness I see on some of the photos - does anyone have any examples?

I don't mean stuff shot at f/32, I mean wide open or f/8-11 range but with the least severe disc (which one is that by the way?)

I'm hoping it is almost "normal" looking ;-p

Thanks

[BrianShaw]

I'm not intimately familiar with Imagon but selected a Fujinon for the same reasons you enquire about. It was always my impression that it was easier to get sharp soft-focus with Fujinon rather than Imagon. For the Fujinon "wide open" is quite different depending upon which disc is in place. With a red disk wide open is actually rather stopped down, but the effect is a rather sharp soft.

I look forward to reading more knowledgable replies though.

[Bob Salomon]

With the Imagons up to 250mm in Copal shutter 3 disks are supplied, with the 300mm in Copal 2 disks are supplied. In all cases the disk with the smallest center hole will be the sharpest and with all of that disk's outside holes closed the Imagon is very sharp.

The softest and most halation will always be with no disk. The disk with the largest center hole will will be next softest with all outside holes open. With the outside holes closed it will become a litlle sharper with a little less halation. The next disk also gets progressively less soft with progressively less halation depending on if the outside holes are open or closed.

Since the Imagon effect is strongly influenced by lighting ratios and the character of the light the Imagon is normally used at a strong ratio of about 5:1 and with strong spectrals since that is what halos.

So, with the largest disk or wide open an Imaagaon will be at its softest. With the smallest disk with the outside holes closed the Imagon will be at the smallest H number and will be at its sharpest. Exactly the opposite of what you are asking for. A 200 or 250mm in Copal is an H 5.8 lens. The largest disk is H5.8 to 7.7. The 300mm in Copal is a H 6.8 lens and the largest disk is H 7.7 to 9.5.

[Mark Woods]

I own a 200mm & 300mm Imagon. I use them wide open most often and really enjoy the softness. The 200mm is supposed to be used for 6x9, but it covers my 8x10 and give a beautiful image. Using the most open disk considerably increases the sharpness. Bob's analysis is very accurate. Frank, with the widest open disk, the F/Stop is F/6.3 for the 300mm and F/5.7 for the 200mm. They're a single element lens and neither of mine are coated. The example is a scan from an 11x14 print made from an 8x10 neg with the 200mm Imagon. Have fun with it.

[Brian C. Miller]

I'm semi-interested in Imagons, likely because I found a deal on one... how sharp can you make an Imagon while still being wide open?

Frank, you can make a "zone plate" for yourself and experiment with it without buying a thing. The Fuji SF and the Imagon both use zone plates, and you can make one yourself. Just take some black paper, and cut some holes in it. For a f/5.6 lens, the center hole would be at the f/11 size, and punch out holes at the f/8 size. Sandwich it inside the lens, and see what you get.

[SergeiR]

Frank, you can make a "zone plate" for yourself and experiment with it without buying a thing. The Fuji SF and the Imagon both use zone plates, and you can make one yourself. Just take some black paper, and cut some holes in it. For a f/5.6 lens, the center hole would be at the f/11 size, and punch out holes at the f/8 size. Sandwich it inside the lens, and see what you get.

Cant vouch for imagon (although if its similar to 180mm SF on RZ i can) , but Fujinon is soft without disks. Amount of apparent softness is very different for different lighting situations.
And it gets pretty darn sharp once you crossing over into 11 and smaller

[Sevo]

I'm semi-interested in Imagons, likely because I found a deal on one... how sharp can you make an Imagon while still being wide open?

Not at all - that is, the softness is aperture controlled, the lens is sharp by f/11 (the size of the central hole in the aperture disks). Wide open, that is, with no disk attached, it is mushy indeed.

[Ed Bray]

With the Imagons up to 250mm in Copal shutter 3 disks are supplied, with the 300mm in Copal 2 disks are supplied. In all cases the disk with the smallest center hole will be the sharpest and with all of that disk's outside holes closed the Imagon is very sharp.

The softest and most halation will always be with no disk. The disk with the largest center hole will will be next softest with all outside holes open. With the outside holes closed it will become a litlle sharper with a little less halation. The next disk also gets progressively less soft with progressively less halation depending on if the outside holes are open or closed.

Since the Imagon effect is strongly influenced by lighting ratios and the character of the light the Imagon is normally used at a strong ratio of about 5:1 and with strong spectrals since that is what halos.

So, with the largest disk or wide open an Imaagaon will be at its softest. With the smallest disk with the outside holes closed the Imagon will be at the smallest H number and will be at its sharpest. Exactly the opposite of what you are asking for. A 200 or 250mm in Copal is an H 5.8 lens. The largest disk is H5.8 to 7.7. The 300mm in Copal is a H 6.8 lens and the largest disk is H 7.7 to 9.5.

I own a 200mm & 300mm Imagon. I use them wide open most often and really enjoy the softness. The 200mm is supposed to be used for 6x9, but it covers my 8x10 and give a beautiful image. Using the most open disk considerably increases the sharpness. Bob's analysis is very accurate. Frank, with the widest open disk, the F/Stop is F/6.3 for the 300mm and F/5.7 for the 200mm. They're a single element lens and neither of mine are coated. The example is a scan from an 11x14 print made from an 8x10 neg with the 200mm Imagon. Have fun with it.

I have a 200mm Imagon, I have not actually used it yet but it is currently in the Synchro Compur shutter of my 300mm Symmar-S. I understood that the greater softness was produced by using the most open aperture along with the peripheral holes also open, is this not the case? as the statements in red above seem to contradict the one in green.

If I do not use the supplied disks but were to use the diaphragm in the shutter, would this give a sharper result?

[William Whitaker]

...how sharp can you make an Imagon while still being wide open?

"Sharp" and "wide-open" seem to be mutually exclusive terms in the context of the Imagon. What is it you're looking for, Frank? Shallow DOF? Something a Commercial Ektar or a plasmat won't do?

[Bob Salomon]

Brian,

That is not how an Imagon works. That is how you control an Imagon.

The peripheral area of the Imagon casts an image as does the center on the image plane. The peripheral holes on the Imagon disk control how much of those peripheral areas will be used to make the exposure.

Lastly the Fuji places the disk inside their lens. The Imagon has no inside to place the disks in. The disks are positioned in front of the lens.

So your advice to Frank won't work if you want to try to simulate an Imagon.