Rodenstock 105/5.6 with floating element

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Macro_Cosmos
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Post by Macro_Cosmos »

ray_parkhurst wrote:
Macro_Cosmos wrote: I wouldn't be willing to pay that much for the lens. I want to see some Rayfact 3.5x lenses getting into the surplus market...
Image

Regards,
MC
Looks like one popped up this morning:

https://www.ebay.com/itm/263520648351
Yeah, I saw that yesterday. $2500 though, nah.
It's 1.2kg, it requires what like 600mm of tubes... I'll give it some serious thoughts before placing an offer.

ray_parkhurst
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Post by ray_parkhurst »

Macro_Cosmos wrote: Yeah, I saw that yesterday. $2500 though, nah.
It's 1.2kg, it requires what like 600mm of tubes... I'll give it some serious thoughts before placing an offer.
I've seriously considered it, though the 18.3mm object / 64mm image circle does not meet the needs of my camera-pan system. I need to have ~21mm minimum on object side. The lens certainly would work for object-pan stitching, and that's what I'd consider it for.

The big question mark is how far it would need to be stopped-down for best performance. Apparently there is a half-stop detent at f2.8, so best case the lens works well at f2.8. If not, the next detent is f4, which limits usefulness for me. But if f2.8 is optimum, this would give NA 0.14, a big improvement vs the 0.1 I am working with now. It is indeed intriguing...

Lou Jost
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Post by Lou Jost »

I wonder if it is telecentric.

ray_parkhurst
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Post by ray_parkhurst »

Lou Jost wrote:I wonder if it is telecentric.
Given its f/2.4 max aperture I doubt it's telecentric.

Have you ever seen a commercial telecentric lens which has an adjustable aperture? All the ones I've seen are fixed. The aperture needs to be relatively small to have good telecentricity, but large enough to still have good resolution, so it seems there is probably an optimum, and the lenses I've seen are probably set to that optimum.

On a topic of terminology, I used "camera-pan" above, while in another thread I used "image-pan". Is there any standard usage for these concepts? If not I think I prefer "image-pan" and "object-pan". Any thoughts?

Lou Jost
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Post by Lou Jost »

Ray, I have a Sill Optics 1x telecentric lens which has an adjustable aperture. Also, when we use a waterhouse stop to make a lens combo telecentric, there is freedom to choose its diameter, and I use adjustable ones now.

I think "image pan" is ambiguous. I like to specify what is moved. Object, lens, axis, or sensor pan. But I don't know if there are standards. Ah, that reminds me, there are standard terminologies for view cameras: rear-standard vs front-standard shifts.

ray_parkhurst
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Post by ray_parkhurst »

Lou Jost wrote:Ray, I have a Sill Optics 1x telecentric lens which has an adjustable aperture. Also, when we use a waterhouse stop to make a lens combo telecentric, there is freedom to choose its diameter, and I use adjustable ones now.

I think "image pan" is ambiguous. I like to specify what is moved. Object, lens, axis, or sensor pan. But I don't know if there are standards. Ah, that reminds me, there are standard terminologies for view cameras: rear-standard vs front-standard shifts.
The view camera terminology may work, though I think I like "sensor-pan" best.

ray_parkhurst
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Post by ray_parkhurst »

Macro_Cosmos...I downloaded the Rayfact 3.5x lens spec from the Rayfact website, and it looks a bit different from the one you showed, mostly in the specifics of the aperture, but also in the image circle. The one you show says 60mm, which is inconsistent with the 18.3mm object size and 3.5x magnification. The one from website also specifically calls out f2.4 for the image circle, while the one you posted seems to imply you must stop down to f2.8, and that it has a f2.8 click stop.

I have asked the seller if the lens he is selling has a click stop between f2.4 and f4.

If the spec you showed is an older one, and the 64mm at f2.4 spec is a newer one, it may be there was an update to the lens to improve performance.

Image

RobertOToole
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Post by RobertOToole »

Macro_Cosmos wrote:Yeah, your observations are correct. The linos and the HR Digaron/Alpa Macro Switar is pretty different. The Linos shows a better MTF. One mistake people make with MTF charts is comparing graphs from different manufactures (i.e. Zeiss to Canon to Nikon). Since Rodenstock is owned by Linos which is owned by Qioptiq, which is owned by Excelitas Technologies... under the AEA Investors... whatever. They use the same standards when it comes to MTF charts.

Some manufactures which I won't name use MTF charts generated by the optics engineering software... yeah, pretty misleading.
Rodenstock lens MTF charts have been discussed on the forum a few times and from what I remember Rodenstock Germany (before they changed hands) and the US distributor at the time have said a few times online that Rodenstock MTF lens graphs are simulations of an ideal lens performance. They went on the say that you can expect a production lens to be within 10% of that ideal performance.

Current information from what I have read is that Leica, Zeiss and Sigma use measured MTF from an optical bench with prototype lenses. Sigma usually posts both measured and simulated on their website.

All other lens manufacturers share MTF lens charts that are calculated from idea based on a computer simulation.

Robert

basingset
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Re: Rodenstock 105/5.6 with floating element

Post by basingset »

Hi there! As someone else said, the three incarnations available correspond indeed to the same lens. I have not used this lens myself, but a friend of mine has, and he said it is pretty good quality.

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