Rollei RPX 25: Grain and Resolution

[RalphLambrecht]

Thank you very much Flavio.



Well, the absolute physical resolution limit of the D800 is the Nyquist frequency. That are about 100 Lp/mm with that sensor. With the best lenses you can reach about 90-95 lp/mm with it.



Acros 100 had set the benchmark for fineness of grain in that sensitivity class. But concerning sharpness and resolution, TMX and Delta 100 are better. Concerning the real speed of Acros: In the developers I have used for it it indeed had about 1/3 stop less speed compared to Delta 100 and TMX.

Best regards,
Henning

I get 98 lp/mm with my D800.

 

[Henning Serger]

Henning, can you post a characteristic curve of TMY-2 in ADOX HR DEV? If so, did you develop in accordance with the time/agitation regime specified for that film here:

https://www.fotoimpex.de/shop/images/products/media/63385_4_PDF-Datenblatt.pdf ?​

Thanks in advance.

Hello Sal,
sorry, I mixed things up in my post (writing faster than remembering ). I've successfully saved one underexposed TMY-2 with HR DEV last year (using data from the datsheet). But I still have to do the complete test routine with all sensitometry for that combination. I've mixed it up with ADOX FX-39 II I've mentioned in my post. This developer works very, very well with TMY-2: I've got record values in resolution with this film-developer combination, and very good sharpness. The results have an excellent 'plasticity', a kind of "3D-effect". Grain is of course visible, but looks very nice. No problem at all here, because TMY-2 is the most fine grained ISO 400/27° currently on the market.
Characteristic curve:
I prefer very good shadow detail, and I am using an enlarger with a mix-box and double condensor. Following my results (average values from several tests with my main used cameras; measured with a Heiland TRD-2 densitometer). ISO 200/24°; FX-39-II with 1+14 dilution; 14 min developing time; 2 inversions at the beginning, than 1 inversion per minute.
Zone I: 0,15 logD
Zone II: 0,30 logD
Zone III: 0,42 logD
Zone IV: 0,58 logD
Zone V: 0,72 logD
Zone VI: 0,90 logD
Zone VII: 1,06 logD
Zone VIII: 1,26 logD
Zone IX: 1,45 logD
Zone X: 1,64 logD

Best regards,
Henning

 

[Henning Serger]

I get 98 lp/mm with my D800.

Ralph, absolutely possible and not surprising.
Because,
1) If you remember what you've written in your book , in resolution tests with lp/mm test patterns there is always a kind of small "interpretation margin". Different people / reviewers - also because of different eye sight / power - set the limits whether a linepair is clearly separated or not a bit differently. And a difference of 95 lp/mm (my upper value) to your 98 Lp/mm is absolutely in between this interpretation margin. And I am always a bit more on the "conservative" side with my data.
2) Resolution is dependent on object contrast: If your test chart has a higher contrast than mine (which has 1:4, two stops), then that contrast difference can also result in higher resolution.
3) And of course the lens plays an important role: a) If your lens has higher resolution than mine (even with exactly same lens models results can be different because of sample variation) and b) Differences in focal length: Lenses have sample variation in focal length. A lens which is "officially" 50mm can have an effective focal lenght of maybe 48.5 mm, or 52mm for example. The 52mm sample will have a higher resolution (if all other performance factors are the same) compared the 48.5 sample because of this small tele effect.

Best regards,
Henning

 

[Nicoconut]

Hello Henning,

I may be a little late, but would you have any resolution figures about Ilford Ortho Plus 80 and Rollei Ortho 25 plus?
Thanks a lot!

Best regards

 

[Henning Serger]

Hello Henning,

I may be a little late, but would you have any resolution figures about Ilford Ortho Plus 80 and Rollei Ortho 25 plus?
Thanks a lot!

Best regards

Yes, I have test results for Ilford Ortho Plus 80:
With my test method (details see my explanations in the postings above) I've got a resolution of 80 – 90 Lp/mm.

I have not tested Rollei Ortho 25 plus. But photo chemistry manufacturer SPUR has tested it intensively. Their results:
- Ortho 25 plus has absolutely nothing to do with the former Rollei Ortho 25, both are completely different films
- Ortho 25 plus is not an ISO 25/15° film, but a 80/20° - 100/21° film
- Ortho 25 plus has much less sharpness, lower resolution and significantly coarser grain compared to the former Ortho 25
- both have completely different developing times.
But as so often, Maco Photo (Rollei-Film) is again misleading their customers: There is no new data sheet and any information at all about the changes and the fact that the successor is completely different material.

Best regards,
Henning

 

[Nicoconut]

It's definitely good to know about Maco Photo's behaviour; transparency isn't becoming the norm any time soon, it seems...

If you don't mind, Henning, have you ever tested film with medium format lenses following the same protocol?
The results reported on this website (https://web.hevanet.com/cperez/test/fourcameras.html) seem reliable and consistent with your T-Max 100 figures.

The related question is: would it be pointless to use 120 Adox CMS 20 II when it comes to raw resolution? If it were available thas is ! ^.^

Best regards

 

[Henning Serger]

It's definitely good to know about Maco Photo's behaviour; transparency isn't becoming the norm any time soon, it seems...

If you don't mind, Henning, have you ever tested film with medium format lenses following the same protocol?

Yes, I have also tested several medium format lenses with exactly the same methodology. The results were as expected: The resolution values have been a little bit lower (about 5-10% on average) compared to my 35mm prime lenses.The general rule is: The bigger the lens diameter, the lower the resolution (but as with most "general rules", there are some exceptions ).

The related question is: would it be pointless to use 120 Adox CMS 20 II when it comes to raw resolution? If it were available thas is ! ^.^
Best regards

I had also tested CMS 20 II in 120 (when it was available; but ADOX is working on bringing back 120 generally).
Well, would it be pointless? That totally depends on your individual purposes, and your intended images, how big you want to enlarge your pictures etc..
And for those who only use medium format, and don't have a 35mm camera, it of course makes much sense .

Best regards,
Henning

 

[Nicoconut]

The resolution values have been a little bit lower (about 5-10% on average) compared to my 35mm prime lenses

With a difference that small, it definitely makes sense to me to use CMS 20 II on medium format. According to what I read, I just thought: if a lens supposedly peaks at 120 Lp/mm, how can it exploit CMS 20 II potential? Or did I misunderstood something?
In any case, I will happily get some CMS 20 II when they bring it back, for sure.

Thanks a lot for your teachings, Henning!

Best regards

 

[Henning Serger]

With a difference that small, it definitely makes sense to me to use CMS 20 II on medium format. According to what I read, I just thought: if a lens supposedly peaks at 120 Lp/mm, how can it exploit CMS 20 II potential? Or did I misunderstood something?
In any case, I will happily get some CMS 20 II when they bring it back, for sure.

Yes, you did misunderstood something. You mixed up pure lens resolution and overall system resolution (a mistake most photographers make, by the way).
The pure lens resolution (called aerial resolution) is very high, and for a good 35mm or medium format prime lens much much higher than 120 Lp/mm, at least for the wider apertures up to f5,6. With smaller apertures then diffraction becomes the limiting resolution factor.
For example at f4 a very good prime lens has an aerial resolution in the range of 300 - 400 Lp/mm.
When you then combine your lens with a film or a digital sensor, you get the combined 'system resolution' which is lower than the pure aerial lens resolution.

Concerning your question and ADOX CMS 20 II in 120:
In my standardized resolution test I've got about 200 Lp/mm system resolution with this film in combination with the Mamiya Sekor C 2.8/80 for the Mamiya 645 Pro TL.
That is really quite a lot. You can enlarge these pictures as big as you want, the sky is the limit .

Best regards,
Henning

 

[Nicoconut]

Well, sky is high enough for my needs as an amateur, I guess!

Thank you very much for sharing your knowledge with us, Henning. It's been a pleasure!

Best regards