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Author Topic: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar  (Read 7440 times)

epines

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Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« on: November 28, 2014, 05:02:26 pm »

Second time trying to post this:

I've read that these two lenses are identical, but I just downloaded the MTF charts from the Alpa website, and they look notably different (and better for the 48mm Helvetar). Can anyone confirm that they are different lenses? Has anyone used / compared them both? Is the Helvetar much better wide open than most of the new-generation large-format lenses?

I'm currently using the 47mm Digitar on an Arca Swiss 69 FC, but I would consider eventually switching to Alpa if the 48mm Helvetar is that much better. I'd love to use it with film and digital for travel shooting.

Second question: I want to be sure I'm reading the MTF charts right. If the x-axis is the distance from the center of the image circle, what are the units of measurement? It can't be mm, since I know these lenses don't have image circles of 200mm. Since I'm using a 36mm x 48mm sensor, where can I find the 30mm mark (corner of that sensor)?

For some reason I'm unable to attach the MTF charts here, but you can PM me if you'd like to see them.

thanks

ethan
« Last Edit: November 28, 2014, 05:17:00 pm by epines »
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epines

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #1 on: November 28, 2014, 05:16:43 pm »

The MTF charts are here:

www.ethanpines.com/files/ClientFiles/Lenses_Schneider47mm_digitar_mtf+tech_info.pdf

www.ethanpines.com/files/ClientFiles/Lenses_Schneider48mm_helvetar_mtf+tech_info.pdf

Looks like the x-axis on the 47mm Digitar chart represents 30mm, and the x-axis on the 48mm Helvetar chart represents 49.5 mm. Does that sound correct?  
« Last Edit: November 28, 2014, 05:18:18 pm by epines »
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ErikKaffehr

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #2 on: November 28, 2014, 06:36:34 pm »

Hi,

Those curves are calculated very different ways, so they are very hard to compare.

The Schneider 47 curves are  20/40/60 lp/mm while the Apo Helvetar curves are at 5/10/20 lp/mm and cover a larger format.

So, you would compare top curve for the 47 mm lens to the bottom curve of the 48 mm lens diagram and keep in mind that horizontal axis goes to 30 mm on the 47 mm and to 49.5 on the 48 mm.

Apertures are also different f/5.6 and f/22 for the 48 mm lens but f/5.6, f/8 and f/11 for the 47 mm lens. The former values may be more typical for large format film and the later more relevant for MFD.

I don't feel like a great expert in interpreting Schneider MTF data…

Best regards
Erik

Second time trying to post this:

I've read that these two lenses are identical, but I just downloaded the MTF charts from the Alpa website, and they look notably different (and better for the 48mm Helvetar). Can anyone confirm that they are different lenses? Has anyone used / compared them both? Is the Helvetar much better wide open than most of the new-generation large-format lenses?

I'm currently using the 47mm Digitar on an Arca Swiss 69 FC, but I would consider eventually switching to Alpa if the 48mm Helvetar is that much better. I'd love to use it with film and digital for travel shooting.

Second question: I want to be sure I'm reading the MTF charts right. If the x-axis is the distance from the center of the image circle, what are the units of measurement? It can't be mm, since I know these lenses don't have image circles of 200mm. Since I'm using a 36mm x 48mm sensor, where can I find the 30mm mark (corner of that sensor)?

For some reason I'm unable to attach the MTF charts here, but you can PM me if you'd like to see them.

thanks

ethan
« Last Edit: November 28, 2014, 07:13:23 pm by ErikKaffehr »
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RomanN.

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #3 on: November 29, 2014, 02:38:37 am »

both are the same schneider lenses. The apo digitar 47mm is the Super angulon 5,6/47 mm (105°) - not the 120° xl- simply relabeled as usable for digital use: therefore Digitar. The Apo name was added later- sounds better. Alpa is known for good selected lenses- that means you get always Schneider or Rodenstock lenses in good quality, what does not mean that common Schneider - Rodentsock lenses were worse.
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Chris Livsey

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #4 on: November 29, 2014, 04:26:58 am »

Alpa is known for good selected lenses- that means you get always Schneider or Rodenstock lenses in good quality, what does not mean that common Schneider - Rodentsock lenses were worse.

If they are not worse, none inferior may sound better if your post is intended not to (understandably) imply criticism of those not selected, on what criteria are they rejected?

ALPA selects the finest digital lenses from Rodenstock and Schneider and brands them as their own named exclusive lenses,http://www.linhofstudio.com/products/Alpa-Lenses-Digital

Would imply some superiority but is that based on the model selected or the individual lens?
« Last Edit: November 29, 2014, 04:29:14 am by Chris Livsey »
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ErikKaffehr

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #5 on: November 29, 2014, 04:55:51 am »

Hi Chris,

There is a natural variation in lenses. It is both about manufacturing tolerances but also differences between batches of optical glass. I was not aware of this until Stefan Steib (of Hartbley.de fame) pointed out to me that different samples of lenses can vary in focal length.

Also, there is a significant variation of optical performance between samples.

Alpa may select lenses or specify stricter tolerances than what is normally accepted by Schneider. I would also presume that Alpa wants to keep focal length variation within tight limits, as a spread of focal length may reduce the accuracy of the focusing method Alpa uses.

It doesn't mean that those lenses not selected are less good.

Just a note, many 'may's in this post…

If you are interested in sample variation in medium format, this article is a bit aged, but still interesting to read:
 
http://www.josephholmes.com/news-medformatprecision.html

It is very much possible that tolerances are much tighter now, though.

Tolerances is part of the business. Lens Rentals has written a lot about sample variations. They normally test something like 30 lenses before drawing to much conclusions.

Best regards
Erik


If they are not worse, none inferior may sound better if your post is intended not to (understandably) imply criticism of those not selected, on what criteria are they rejected?

ALPA selects the finest digital lenses from Rodenstock and Schneider and brands them as their own named exclusive lenses,http://www.linhofstudio.com/products/Alpa-Lenses-Digital

Would imply some superiority but is that based on the model selected or the individual lens?

« Last Edit: November 29, 2014, 05:13:21 am by ErikKaffehr »
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Chris Livsey

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #6 on: November 29, 2014, 06:37:36 am »

WARNING TECHNICAL_ LOOK AWAY NOW IF OF A NEVOUS DISPOSITION :o

Erik

Sample variation is inevitable of course in any manufacturing. Rolls Royce Aero engine engineers were appalled during WWII that they were asked to use paper shims for fit rather than machining.
Even Leica were rumoured to select the Summicrons destined to be close focus examples based on quality.

The Joseph Holmes link has somewhat passed into MFD folklore.

This doesn't however get to the bottom of the question: On what criteria do Alpa select?
On the after the shot capability:This plug-in for Adobe Photoshop® (as well as Photoshop Elements® - but not tested - please start Photoshop CS5 in 32bit mode when using the LC) is able to correct the distortion of ALPA lenses from Schneider, Rodenstock and Zeiss easily, quickly and at ultimate quality level.
http://www.alpa.ch/en/products/tools/alpa-tools/alpa-lens-corrector-product.html

The selection may not be necessary  ;D

They also rather contradict the digital lens argument themselves: There is no invariably correct attribution of a lens to digital or analog use. http://www.alpa.ch/products/lenses.html

Do the manufacturers , who presumably test individual lenses, select out, do ALPA give a minimum acceptable spec they will accept ?
This is just curiosity BTW and apologies to the OP but we haven't got to page 2 yet  :)
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ErikKaffehr

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #7 on: November 29, 2014, 08:03:03 am »

Hi Chris,

I guess that you need ask Alpa, or perhaps Steve Hendrix may chime in with an explanation. Steve used to be well informed and happy to provide good information.

Best regards
Erik




WARNING TECHNICAL_ LOOK AWAY NOW IF OF A NEVOUS DISPOSITION :o

Erik

Sample variation is inevitable of course in any manufacturing. Rolls Royce Aero engine engineers were appalled during WWII that they were asked to use paper shims for fit rather than machining.
Even Leica were rumoured to select the Summicrons destined to be close focus examples based on quality.

The Joseph Holmes link has somewhat passed into MFD folklore.

This doesn't however get to the bottom of the question: On what criteria do Alpa select?
On the after the shot capability:This plug-in for Adobe Photoshop® (as well as Photoshop Elements® - but not tested - please start Photoshop CS5 in 32bit mode when using the LC) is able to correct the distortion of ALPA lenses from Schneider, Rodenstock and Zeiss easily, quickly and at ultimate quality level.
http://www.alpa.ch/en/products/tools/alpa-tools/alpa-lens-corrector-product.html

The selection may not be necessary  ;D

They also rather contradict the digital lens argument themselves: There is no invariably correct attribution of a lens to digital or analog use. http://www.alpa.ch/products/lenses.html

Do the manufacturers , who presumably test individual lenses, select out, do ALPA give a minimum acceptable spec they will accept ?
This is just curiosity BTW and apologies to the OP but we haven't got to page 2 yet  :)

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epines

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #8 on: November 29, 2014, 11:41:30 am »

OP here. Well, this has gotten lively. Thanks to everyone for the informative responses.

I also received a reply from Alpa directly. They confirm that the lenses are optically identical. Andre says: "... the MTF charts of the Helvetar 48 are those for film use (and image circle of 98 mm @ f5.6/123 mm @ f11) and 5/10/20 lp/mm. Those of the Digitar 47 XL is a) for digital use at 20/40/60 lp/mm but only for 60 mm of image circle. Here you see the problem with MTF charts… comparability."

The Helvetar also has "an extended front mount for harmonized 67 mm filters threads and therefore a better shading function through this barrel."



dchew

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #9 on: November 29, 2014, 12:06:01 pm »

Chris & Erik,
At the risk of spreading more anecdotal information on the web, I visited Alpa in early October. Although I did not ask specific questions about their testing criteria, per se, they did show me the equipment they use. Impressive stuff; not Lens Rentals impressive, but pretty nice. I suspect they primarily check mounting accuracy, and in the process flag any noticeable decentering or other issues. I doubt they have unique specifications associated with Schneider / Rodenstock directly. But they obviously would for Seitz, their manufacturer. Those specs would be associated with the mounted lens, not the raw product from SK/Rodi.

Dave

Hi Chris,

I guess that you need ask Alpa, or perhaps Steve Hendrix may chime in with an explanation. Steve used to be well informed and happy to provide good information.

Best regards
Erik




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Chris Livsey

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #10 on: November 29, 2014, 12:55:06 pm »

Dave
That is very interesting, thanks for the post,. A personal visit is worth a lot to gain an understanding of and a feel for a company.
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Steve Hendrix

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #11 on: November 29, 2014, 02:38:15 pm »

It is not as complicated (but no less important) than one might think. There is an inspection of every lens that Alpa receives from Schneider and from Rodenstock. The lenses are used to photograph real world subject and the results are then compared to reference files from lenses that Alpa maintains in their inventory. Anthony Festa and I participated in this testing during our recent visit to Alpa. What we saw from the conclusions was that several lenses did not appear to meet the reference lens quality and were designated as "go backs".

Compared to buying a stand alone (unmounted) Rodenstock or Schneider lens from a generic source, this process removes the occasional poor performer, which as some have noted and described above, can occur as a result of numerous variation factors. So if someone ordered a Rodenstock or Schneider lens generically, there is a possibility they could have received one of these lenses, and perhaps wondered why the results were good, but maybe missing a certain wow factor. Some likely don't even question it. Expectations and results certainly vary with individual photographers as much as lenses vary themselves, so I'm sure every day someone somewhere has purchased a lens that really isn't as good as it could be, but continues happily (perhaps blissfully unaware) using it.

So the process is not complicated when you get down to it, but a critically important step considering the amount of measuring and checking tolerances that goes into the lens mount, camera body, digital back mount by Alpa for the optimal complete solution.


Steve Hendrix
Capture Integration
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Doug Peterson

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #12 on: November 29, 2014, 03:29:13 pm »

It is not as complicated (but no less important) than one might think. There is an inspection of every lens that Alpa receives from Schneider and from Rodenstock. The lenses are used to photograph real world subject and the results are then compared to reference files from lenses that Alpa maintains in their inventory. Anthony Festa and I participated in this testing during our recent visit to Alpa. What we saw from the conclusions was that several lenses did not appear to meet the reference lens quality and were designated as "go backs".

Compared to buying a stand alone (unmounted) Rodenstock or Schneider lens from a generic source, this process removes the occasional poor performer, which as some have noted and described above, can occur as a result of numerous variation factors. So if someone ordered a Rodenstock or Schneider lens generically, there is a possibility they could have received one of these lenses, and perhaps wondered why the results were good, but maybe missing a certain wow factor. Some likely don't even question it. Expectations and results certainly vary with individual photographers as much as lenses vary themselves, so I'm sure every day someone somewhere has purchased a lens that really isn't as good as it could be, but continues happily (perhaps blissfully unaware) using it.

So the process is not complicated when you get down to it, but a critically important step considering the amount of measuring and checking tolerances that goes into the lens mount, camera body, digital back mount by Alpa for the optimal complete solution.


Steve Hendrix
Capture Integration

This is true for both Arca Swiss and Cambo as well as for Alpa. Perhaps you could clarify if you feel there is anything which Alpa does differently in this regard. Perhaps Arca should start referring to the 4Xmm "Arcagon" or Cambo the 4Xmm Cambogon.
« Last Edit: November 29, 2014, 03:35:13 pm by Doug Peterson »
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ErikKaffehr

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #13 on: November 29, 2014, 04:01:46 pm »

Steve,

Thanks for chiming in. I was aware of your recent visit to Alpa and hoped you would offer some insight. Thank you very much!

Best regards
Erik

It is not as complicated (but no less important) than one might think. There is an inspection of every lens that Alpa receives from Schneider and from Rodenstock. The lenses are used to photograph real world subject and the results are then compared to reference files from lenses that Alpa maintains in their inventory. Anthony Festa and I participated in this testing during our recent visit to Alpa. What we saw from the conclusions was that several lenses did not appear to meet the reference lens quality and were designated as "go backs".

Compared to buying a stand alone (unmounted) Rodenstock or Schneider lens from a generic source, this process removes the occasional poor performer, which as some have noted and described above, can occur as a result of numerous variation factors. So if someone ordered a Rodenstock or Schneider lens generically, there is a possibility they could have received one of these lenses, and perhaps wondered why the results were good, but maybe missing a certain wow factor. Some likely don't even question it. Expectations and results certainly vary with individual photographers as much as lenses vary themselves, so I'm sure every day someone somewhere has purchased a lens that really isn't as good as it could be, but continues happily (perhaps blissfully unaware) using it.

So the process is not complicated when you get down to it, but a critically important step considering the amount of measuring and checking tolerances that goes into the lens mount, camera body, digital back mount by Alpa for the optimal complete solution.


Steve Hendrix
Capture Integration
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Steve Hendrix

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #14 on: November 29, 2014, 04:17:32 pm »

This is true for both Arca Swiss and Cambo as well as for Alpa. Perhaps you could clarify if you feel there is anything which Alpa does differently in this regard. Perhaps Arca should start referring to the 4Xmm "Arcagon" or Cambo the 4Xmm Cambogon.


Doug -

I was providing feedback specifically to the matter of what is different about a lens coming from Alpa vs a lens purchased "off the shelf". Cambo and Arca Swiss also receive the same lenses from Rodenstock and Schneider and those lenses of course undergo an inspection as well.

Capture Integration sells and supports Cambo, Arca Swiss, and Alpa products. The point of my response was not to compare the processes of each company nor claim an advantage for how Alpa inspects. Since the referenced manufacturer for this thread was Alpa, I answered specific to Alpa.

Regarding naming conventions, there are specific reasons and references for Alpa's lens naming, so your remark about Arcagon's and Cambogon's seems pointless (or perhaps not, since DT doesn't sell Alpa products).


Steve Hendrix
Capture Integration
« Last Edit: November 29, 2014, 04:26:55 pm by Steve Hendrix »
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RomanN.

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #15 on: November 29, 2014, 04:27:08 pm »

This is true for both Arca Swiss and Cambo as well as for Alpa. Perhaps you could clarify if you feel there is anything which Alpa does differently in this regard. Perhaps Arca should start referring to the 4Xmm "Arcagon" or Cambo the 4Xmm Cambogon.

According to Cambo: that was indeed so. Cambo saled at the beginn of digital era Schneider and Rodenstock lenses under the name Cambonar.
This was before the name Digitar or Apo Sironar Digital was introduce for largeformat lenses that are recommendet for digital use. So the first "for digital" labeled Super Angulon 47 mm was named Cambonar 47 mm. It is still the same lens that will be sold as Apo Digitar xl 47 mm.
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Steve Hendrix

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Re: Alpa 48mm Apo Helvetar vs Schneider 47mm Apo Digitar
« Reply #16 on: November 30, 2014, 10:59:55 pm »

Just as a follow up, since someone did privately message me and demanded that I explain how a 48mm Helvetar lens was technically superior to a 47mm APO Digitar (when in fact neither I nor anyone else ever made such a claim in this thread):

The branding of lenses is a practice that is not exclusive to Alpa. As has been pointed out, Cambo has engaged in this as well as other companies, Sinar would be another notable example. In Alpa's case, the branding serves several purposes:

*Enables Alpa to identify a lens that has come through the Alpa office in route to distribution. There are counterfeit exercises at play in some countries, and also being able to identify a branded lens from an off the shelf lens that has been mounted has some benefits.

*In at least some of the cases, while the optical formula is no different - and it has not been implied anywhere by Alpa that is is different - the filter thread and shade extension itself has been altered, typically to extend and optimize the shading and to maintain more of a standard filter thread, for example 67mm instead of the standard 40.5mm on the SK 72mm, which is in fact 74.9mm focal length, resulting in the 75mm Helvetar, with 67mm filter thread.


I hope this provides some clarity for everyone.


Steve Hendrix
Capture Integration

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