Rodenstock Rodagon 105/5.6 field curvature at 1:1 ratio?

[Kuja]

Hello everybody,

I'm in the process of digitizing my film archives and I'm trying to get the best possible results.
I've been using my Canon 5Ds with a lens adapter and a vintage slide duplicating rig, consisting of bellows and a film holder.

Something similar to this:




For this kind of use, the best possible flat field performance is the paramount. Low chromatic aberrations are also desireable

The lens that I'm using at the moment is a Pentax SMC 100mm f/4 Macro.
The Pentax is very sharp in the center with the film grain structure that is clear and defined.
In the corners the grain is still visible, but is progressively getting mushier towards the extreme corners, where it is kind of OK and acceptable, but could be better.

I have an oportunity to buy a Rodenstock Rodagon 105/5.6 enlarging lens for a fair price, but it is very hard to find any info on the net describing its flat field performance in the 1:1 range.

Does any forum member have the first hand experience with the Rodagon 105/5.6 in this kind of application - 1:1 copy work that requires the best possible flat field performance and low CA?

Thanks in advance,
Aleksandar

PS
This is the exact model of the lens in question:

[Ray Parkhurst]

[monopix]

No experience with that specific lens but I used another similar one (can't remember exactly which) and it was 'just' acceptable at f/11. I then changed to a Zeiss 100mm f/2.8 Makro Planar - WOW! What a difference. At f/2.8 it blew the enlarger lens out of the water. The Makro Planar may not suit you as it's a Contax/Yashica mount but I think the lesson is, find a lens designed to go to 1:1 and, if it's a Planar design, all the better. The other thing with a true macro lens is, you won't need the bellows which makes the setup much easier and less opportunity to get misalignment of the planes.

[eggplant]

[Ray Parkhurst]

[Kuja]

Thanks for the replies!

I bought it anyway, since the price was ok (around $40).

I have read on this forum and elsewhere that some people are using this lens for film "scanning" with very good results, so I thought that it was worth a try.

The lens is coming in tomorrow, so we'll see. If the results are not good for negative copy work, I'll use it on my enlarger.

I will also try the Sigma 70mm ART macro lens that is receiving rave reviews.

[Kuja]

Sigma 70mm ART macro on test:

https://www.closeuphotography.com/1x-test-2020/2019/12/13/1x-magnification-test-2020

[Kuja]

[Ray Parkhurst]

[quote="Kuja"]
One of the often mentioned lenses for 1:1 duplicating work is the Apo Rodagon D 75/4, but I decided to give the Rodagon 105/5,6 a chance after reading encouraging posts such as this:

[Kuja]

Thanks a lot Ray!

What would be your recomendations for a lens for film copy work?

Apart from copying 35mm film, I'm also planning to copy my 6x6 and 6x9 medium format negatives, and I even have a small quantity of 4x5" negatives.

I do not have thousands dollars to spend on some exotic glass like your Printing Nikkor.

Even Apo Rodagon D 75/4 is on the verge of being too expensive for me, and it is said that it is designed exclusively for 1:1 copy work, so it might not work so well for 6x9 negatives which will require lower magnification to fill my camera's 35mm FF sensor.

What do you think of the Sigma 70mm/f2.8 Art Macro lens that I mentioned earlier?

[Himself]

Try a Contax S-Planar 100/4. It's a dedicated bellows lens.
Maybe a bit cheaper than a Printing Nikkor.

[Ray Parkhurst]

[Kuja]

My new Rodagon 105/5.6 has finally arrived!

I couldn't wait so I did a quick and dirty test.

Since I don't have a M39 adapter for my macro bellows yet,
and the Rodagon has a standard 49mm filter thread, I have mounted it reversed.

I guess that at 1:1 ratio, reversed or not makes little or no difference.

[Kuja]

After my initial excitement about getting the Rodagon 105/5.6,
I must admit that my heart had sunk a little bit after reading the comments here.

But after the quick test, I must say that I'm (extremely) pleasantly surprised!!!

The Rodagon 105 is much better than my Pentax 100/4 macro!

I don't know how much better are the true 1:1 duplicating lenses since I have no experience with them,
but the results I got from the humble $40 Rodagon on my 50 megapixel Canon 5Ds,
to my untrained and inexperienced eyes, leave nothing much more to be desired.

I have discovered that the best aperture is f8.
The center of the negative is almost equally good at f5.6 and f8, corners are better at f8 and practically equal to the center,
at f11 there is a slight drop in quality across the frame.


Here is the downsized full test negative "scan" in Capture One software:

(Please bear in mind that these are JPEGs with compression, that the film is not perfectly flat in the film folder, that I have used a 2.5 sec exposure since the light source was the ceiling light (and very diffused at that), ...and that in these poor light conditions my focusing could be better.)





Here are few 100% crops close to the central portion of the negative.

(If you are reading this on a smaller screen, please click on the photos and use the "+" zoom loupe in order to view them at the full resolution!)

It seems that the actual taking lens and/or my focusing technique were not that good at the time when I took this photo,
so the Rodagon is digging out all of the existing detail/information from the negative and more (in form of the film grain):








... And here are the extreme corners, all four of them.

Notice the film grain structure, and how sharp are the film perforations, tiny dust hairs, dirt particles and specks on the clear film base.

To my eyes, this looks great!

When I was printing these negatives 30 years ago on traditional B&W photo paper, I wasn't able to get such good results.

50 mpix file gives a 19x29 inch (around 50x75cm) print @300dpi.










Notice how sharp are the edges of the mask of the film holder on the left side of the photo :

[Ray Parkhurst]

[Kuja]

Maybe also a sample to sample variation could play a role, and this Rodagon might be a really good one?

I see that someone wrote with a graphite pencil "105,9" on its barrel,
as if the lens' focal lenght was precisely measured.
Maybe it went through some process of selection, who knows.

The most important thing is that I'm very happy.

Now I only have to build a scanning rig for medium format negatives.
From the same seller I also got a fabulous vintage multi-format Durst Setoneg film holder, that will serve as the base for it.

[Kuja]

Thank you all for your help!

Special thanks goes to member @ForenSeil, whose posts inspired me to get the Rodagon 105/5.6.