Interest in New lens for wide FOV?

[Nodda Duma]

I am a lens designer. I'm interested in turning old designs into new products. I'm trying to determine a sensible starting point. You folks seem to be underserved. See this link

(there was a url link here which no longer exists)

but post here on this question:



What focal length to cover what format?

 

[Dan Fromm]

I am a lens designer. I'm interested in turning old designs into new products. I'm trying to determine a sensible starting point. You folks seem to be underserved. See this link

(there was a url link here which no longer exists)

but post here on this question:



What focal length to cover what format?

Suggestion. Why don't you ask for interest by format for lenses with focal length equal to the format's diagonal (in other words, normal for the format) and for lenses with focal lengths half the diagonal (cover 90 degrees on the diagonal). Always with coverage around 15% more than the diagonal to allow for small movements. The forum software allows questions like yours to be asked as polls (which format? a, b, ...)

 

[Nodda Duma]

I can look into that but what sub forum to place the poll into?

 

[LJH]

200-210mm for 7x17", please!

 

[norm123]

200-250 for 11 x 14

 

[Oren Grad]

Well, it would hardly be a "sensible starting point", but what the hey: 270 for 12x20. If you want to be more practical: as small a 150 as you can make that will cover 8x10, with a bit of wiggle room as per Dan.

 

[Old-N-Feeble]

I would be very interested in an affordable high-performance 150-165mm that would cover 11x14 (8x10 with lots of room for movements). The 150 SSXL can no longer be bought for less than $2000+ and I don't think the 165 SA is quite as good a performer as the 150 Nikkor-SW or 155 Grandagon none of which have the coverage of the 150 SSXL though the 165 comes close.

EDIT: What's the possibility (and added cost) if an aspheric element is used? Is there enough benefit to warrant the added cost? Also, a real benefit would be if the lens isn't too big and heavy... maybe an f/8.

 

[Nodda Duma]

Aspheres are useful if weight and length are significantly more important than cost. For polychromatic objectives, they don't necessarily reduce lens count and they only improve performance if a design is already extremely weight or length constrained. Manufacturing cost is increased (more complex polishing), and assembly cost is increased (tighter tolerances on tilt / decenter).

From my viewpoint, aspheres are just another tool in the optical design toolbox. Like any other tool, it is very useful in some cases and not so useful in others. I would avoid their use for LF optics because (a) you're not operating at a lens speed where they can help size/weight, and (b) the production volumes means just the aspheric lens itself would cost as much as a good used pickup truck.

You see them in fast SLR lenses because they help size and weight, and are produced in numbers that justify the cost of the (prototype ~$10k / production ~$100k) mold.

 

[Old-N-Feeble]

So do you think your 165mm will cover 11x14 (barely) and compete with the quality (to the corners) of the lesser 150 Nikkor-SW, 155 Grandagon-N or 165 SA and at a competitive price? Can it be designed so that an existing center filter will fit it? If so then I'm pretty excited about it. I do realize yours will be a more capable lens if it meets these criteria.

 

[Nodda Duma]

I seem to recall comparing performance to similar focal lengths and being satisfied with the comparison. For coverage, keep in mind the 165 is corrected for 8x10. You might not see the corners in 11x14. Somewhere in the other thread I reported the coverage size...I don't recall what it is off-hand.

My big concern is if there's room in the center for a filter. It's a pretty tight fit. I've been debating whether I should rescrub the design to make it more "filter-friendly", but I haven't circled back around to take a second look. I will get back to this when I can. Lately I've had to concentrate on some other work which has tied up my Zemax license.

 

[Old-N-Feeble]

Heh... I don't mean a filter in the center of the lens. I mean a center neutral density filter attached to the front of the lens that's darker in the center to equalize light transmission to the film. Though a "center-center" filter would be even better.