JensR

Lives in United Kingdom Bath, United Kingdom
Works as a Mechanical Engineer
Joined on Nov 23, 2003
About me:

Hi,

thanks for stopping by!
If you want to see what I'm up to, send me a message :)

My 'plan':
Talk Pentax into a digital Electro-Spotmatic! (This needs some work...)

-------------

Older Signatures:

'LBA knows no bounds, and seeks no justification...' (Jim King, 2005)
http://www.jr-worldwi.de/photo/index.html - Photography, Tech and Geek stuff :}

'Why is everyone answering rhetorical questions?' (Me, 2005)

'Well, 'Zooming with your feet' is usually a stupid thing as zoom rings are designed for hands.' (Me, 2006)

'I only trust those photos I have faked myself.' (Me, 2007)
http://www.jensroesner.de/

--=! Condemning proprietary batteries since 1976 !=--

'I don't want them to believe me, I just want them to think.'
Marshall McLuhan

Comments

Total: 135, showing: 41 – 60
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On article Sigma 85mm F1.4 Art DxO results: a new king is crowned (249 comments in total)
In reply to:

falconeyes: Bokeh set aside, this is the first 1:1 MTF comparison of Sigma 85/1.4A vs. Nikon 105/1.4E
-> https://www.dpreview.com/reviews/lens-compare-fullscreen?compare=true&lensId=sigma_85_1p4_dg_hsm_a&cameraId=nikon_d810&version=0&fl=85&av=1.4&view=mtf-ca&lensId2=nikon_105_1p4_e_ed&cameraId2=nikon_d810&version2=0&fl2=105&av2=1.4

The figures for the 105/1.4E have been stunning, but the 85/1.4A is almost a new all time record (it just failed to beat the Otus 55/1.4).

Unfortunately, both the 85 and 105 have shorter focal lenghts than claimed: 80mm and 95mm. I.e., there relative difference in focal length is closer to the claim: 19% rather than 24% difference.

have these focal lengths really been measured at infinity or at test-chart distance?

Link | Posted on Feb 2, 2017 at 19:07 UTC
On article Sigma 85mm F1.4 Art DxO results: a new king is crowned (249 comments in total)
In reply to:

Fred Joseph: Measured focal length of 79.7mm???? What does that mean? Is the lens short-changing the owner by 5mm?

Many lenses reduce focal length when focusing close (internal focus). Unless they specified "at infinity", they might have shot a test subject that was relatively close and calculated the focal length from that. (Sorry, I cannot access their review now to find out if that's the case.)

Link | Posted on Feb 2, 2017 at 19:06 UTC
On article Adobe Creative Suite 6 has been officially retired (351 comments in total)
In reply to:

robbinsbox: The last results from adobe showed subscription model working for them.
Dont really like it myself and have been playing with Affinity which will be fine as a PS replacement.
But how to replace LR, whıch ıs the one I use most of the tıme.

Edward, that is interesting I will have to try and see what happens. It definitely must be "phoning home". I agree, version 5 was completely quiet on my netports. But starting with 6.0 (when they introduced the CC version and made the standalone version kind of hard to buy or even find on their website) things have definitely become a lot more big brother is watching you!

Link | Posted on Feb 2, 2017 at 18:51 UTC
On article Adobe Creative Suite 6 has been officially retired (351 comments in total)
In reply to:

robbinsbox: The last results from adobe showed subscription model working for them.
Dont really like it myself and have been playing with Affinity which will be fine as a PS replacement.
But how to replace LR, whıch ıs the one I use most of the tıme.

Edward, I do not use Lightroom mobile (it actually says my Trial expired, but I never even trialled it knowingly), but it is (was?) my understanding that you need be signed in to LR/Adobe in order to fully use LR, even locally?
I guess your approach makes sense, I just didn't realise this was an option.

Link | Posted on Feb 2, 2017 at 05:25 UTC
On article Adobe Creative Suite 6 has been officially retired (351 comments in total)
In reply to:

robbinsbox: The last results from adobe showed subscription model working for them.
Dont really like it myself and have been playing with Affinity which will be fine as a PS replacement.
But how to replace LR, whıch ıs the one I use most of the tıme.

Why replace Lightroom? I really like the software, but Adobe's licensing scheme is taking away rights from users. Recently my PC crashed and I somehow got signed out of my standalone copy of LR. No biggie, I thought. I then applied an LR update. Only to find after restarting that Adobe's license server thought I was running one copy of LR too many and reverted me to a trial license. I had to engage with Adobe customer service, who, after their chat crashed a few times, were quick and helpful, to be fair to them.
However, this sort of hiccup with the standalone I find troublesome for what problems might surface if LR goes subscription only. Therefore, it is great to have other options available.

Link | Posted on Feb 1, 2017 at 12:56 UTC
On article Adobe Creative Suite 6 has been officially retired (351 comments in total)
In reply to:

robbinsbox: The last results from adobe showed subscription model working for them.
Dont really like it myself and have been playing with Affinity which will be fine as a PS replacement.
But how to replace LR, whıch ıs the one I use most of the tıme.

ACDSee has come a long way, wow, thank you for the heads-up!

Link | Posted on Feb 1, 2017 at 02:02 UTC
In reply to:

belle100: Can we also have versions for Nikon F-mount please.

There is a Leica-M autofocus adapter that uses a miniature gear motor. It is possible. Whether it gives the performance people would expect from a Nikon lens, I don't know...

Link | Posted on Jan 25, 2017 at 00:18 UTC
In reply to:

Robert Zanatta: What is "auto ramping"?

Fascinating, I am a MechEng and it is great to see the range of things you can do with a PID :) You say outliers (I guess clouds temporarily blocking the sun and similar things) are removed. So I am guessing the algorithm needs a few images to stabilise? Something between 5 and 10 shots, maybe?

Would your algorithm also cope with the camera rotating from lit area to shade? Or would the camera's auto exposure mode be better, because the range is not large enough to cause problems?

Link | Posted on Jan 13, 2017 at 06:41 UTC
In reply to:

Lee Saxon: Are they just aping the appearance of the Canon, like the new Voigtlander 58 does the Nikon Ai ? Or does it actually rip off the optical design? I'm not a *huge* fan even of the former, but if it's the latter DPReview should not be promoting it (even if the patent is technically expired).

"Yongnuo already sells 35mm F2 and 50mm F1.8 lenses in Canon and Nikon mounts with each mount having a corresponding barrel design to match of the camera brand’s own. "

This and the different optical formula hint at "just aping the appearance".

As to your last point, where do you draw the line what is okay to promote? Sigma reverse-engineering the EOS protocol? Sigma coming up with a mount that is basically a clone of the EOS mount? Metabones reverse-engineering two protocols to steal camera sales from Canon and lens sales from Sony? (Or give Canon lens sales and Sony camera sales, who knows...)

Link | Posted on Nov 2, 2016 at 23:02 UTC
In reply to:

Angrymagpie: Fantastic idea! We need more of these. Maybe an adapter where you can slide in different grades of ND filters and other filters instead?

I had that idea and DIYed IR and ND adapters. Without a proper machine shop, I wasn't able to manufacture a light-tight way of switching out the filter, so I sealed the filter into the adapter.
It works okay, but the glass has an effect on corner sharpness of wide angle lenses. Which is unfortunate, because I hoped this kind of filter could be used for extreme wide angle lenses that cannot take a filter. It should still be useful for telephoto-lenses, as the angle of incidence will be reduced and the glass has less effect.

Link | Posted on Oct 27, 2016 at 22:51 UTC
In reply to:

Henrikw: eeerrrr.....any pictures showing the result of this setup?!?

The project has a website and some scientific papers linked. From the ones I looked at, this one has the clearest picture. But don't expect too much beauty, this is science first and foremost:
https://arxiv.org/pdf/1401.5467v1.pdf
via http://www.dunlap.utoronto.ca/instrumentation/dragonfly/

Link | Posted on Oct 26, 2016 at 15:00 UTC
In reply to:

Donnie G: You want to do drone photography, then get a permit or license. Good idea. :))

Under this law, there is no drone photography in Sweden. The only permit is a surveillance permit. Police, fire-fighters and maybe (unlikely) security services.
And these drone operators don't do "photography".
A professional photographer will never get a permit in Sweden as the law stands now.

Link | Posted on Oct 25, 2016 at 03:15 UTC
In reply to:

Nigel Tafferham: Is it me or is the headline VERY misleading ?

Not at all what I thought, but seems to suppress IR thus enhancing visible light, correct ?

Some cams supposedly have weakish IR suppression filters on sensor, this should especially help those cams.

But unless visible spectrum is very evenly suppressed as in 'ND filtering', what is so special ?

Why just US ? Not so cheap either !!

Francis, from having used modified cameras for 12 years and currently using an all-spectrum Sony Nex5, I find it a bit hard to believe that there are many without a filter. CCD and CMOS sensors are both very sensitive to IR, without *any* IR filter, you have strong colour shifts.
So I did a bit of google and it seems Red cameras have IR cut filters as I suspected, but you can pay them to get a modified camera, which is a great service: http://www.red.com/learn/red-101/infrared-cinema

Edit: I can believe that the IR-cut filter of video cameras is weaker than in our "normal" cameras, but I am sure there is one.

Link | Posted on Oct 8, 2016 at 13:54 UTC
In reply to:

Nigel Tafferham: Is it me or is the headline VERY misleading ?

Not at all what I thought, but seems to suppress IR thus enhancing visible light, correct ?

Some cams supposedly have weakish IR suppression filters on sensor, this should especially help those cams.

But unless visible spectrum is very evenly suppressed as in 'ND filtering', what is so special ?

Why just US ? Not so cheap either !!

Yeah, selling poorly neutral ND as warming is a clever marketing ploy, I suppose and those other colours are IMO just a more or less failed attempt to correct the warm cast.
I was giving an overview of ND filter issues, as it seemed to pertain to your questions.

Link | Posted on Oct 5, 2016 at 18:51 UTC
In reply to:

dbo: I am using a B&W ND110 and I also have the big stopper for my LEE system. So far I encountered issues if at all on uwa lenses. In order to prevent unnecessary vignetting I use slim filter versions or the wa adapters for my LEE system.
This HOYA series looks like quite high framed filters I would probably not use for uwa lenses.

Agree to many that a comparison of high quality NDs would be appreciated.

Lee system: Huge-ish adapter that attaches to a lens and then you can slide one or multiple rectangular filters into the filter holder.

Link | Posted on Oct 5, 2016 at 15:57 UTC
In reply to:

Nick Spiker: I was very excited to see this, as I shoot a TON of IR photographs, then very disappointed as they don't even have spectral ranges or transmission curves, not even on their website, even more surprised because they currently make the only anti-reflective coated IR pass filter. :(

Nick, just to be sure: These are visible-light ND filters with reduced IR transmissibility. I

I, too, was looking for proper IRND that are not scientific-levels of money. You can get some IR long exposures from using a higher wavelength-cut-off, such as 1000nm instead of 720nm - but depending on the camera you might have problems and it might not create the IR colour you want.

Link | Posted on Oct 5, 2016 at 15:55 UTC
In reply to:

Nigel Tafferham: Is it me or is the headline VERY misleading ?

Not at all what I thought, but seems to suppress IR thus enhancing visible light, correct ?

Some cams supposedly have weakish IR suppression filters on sensor, this should especially help those cams.

But unless visible spectrum is very evenly suppressed as in 'ND filtering', what is so special ?

Why just US ? Not so cheap either !!

Not just you, but to be fair, it is not just dpreview, Hoya's text is misleading - I guess they don't expect any people to actually take infrared photos.

As to your question: It is a common problem that ND filters have higher transmissibility in the IR spectrum. As this is not a magic cut-off between visible and IR, this means that (roughly speaking and using example numbers) a 10 stop filter can be 10 stops for green, 9.99 for blue and 9.9 for red. So you will get a warming effect.
On modern cameras, the false colour from increased IR percentatge is usually miniscule, as the IR cut filter is so strong. Again, roughly speaking, the IR cut filter is about 12 to 14 stops.
So most of the ND colour cast will come from red bleeding through. Individual cases can vary, as we are talking about two different filters interacting. And in any case, a sharper red/IR cut-off will help with both colour shifts.

Link | Posted on Oct 5, 2016 at 15:53 UTC
In reply to:

nir-vana: Dear Tamron.
We, Sony FE system users have:
FE 50/1.4
FE 50/1.8
FE 55/1.8
FE 50/2.8 macro
Mitakon 50/0.95
Loxia 50/2
Samyang 50/1.4 MF
Samyang 50/1.4 AF
Slrmagic 50/1.1
But we don't have any decent telephoto option for E-mount.
I hope you realize that our system becomes much more popular than A mount.
I hope to have native Supertele for my A7RII
Nir

haha, no problem! :) I'm sorry for getting sliiightly exasperated :D :D

Link | Posted on Sep 3, 2016 at 15:26 UTC
In reply to:

nir-vana: Dear Tamron.
We, Sony FE system users have:
FE 50/1.4
FE 50/1.8
FE 55/1.8
FE 50/2.8 macro
Mitakon 50/0.95
Loxia 50/2
Samyang 50/1.4 MF
Samyang 50/1.4 AF
Slrmagic 50/1.1
But we don't have any decent telephoto option for E-mount.
I hope you realize that our system becomes much more popular than A mount.
I hope to have native Supertele for my A7RII
Nir

No! You misunderstand! This is not a *macro* extension tube! Seriously, read up on flange focal distance before you are spewing this non sense any further!
The extended barrel would just bridge the difference of flange focal distance between the SLR and MILC cameras. There is NO negative impact on the image quality! None!
Mount the lens on an SLR, flip the mirror up. Got that? Works fine, right?
Now, next to that, you take another copy of that lens and align it with the first. You also take a MILC and align it so that its sensor is in the same plane as that of the SLR. See the gap between the rear end of the lens and the flange of the MILC? That's what you need to bridge with a light-tight tube, the barrel extension.
Compare the two set-ups: The distance of the lens rear element to the sensor has not changed! The image cast onto the sensor is identical!
You do know that there are reputable lens makers who do exactly that? They offer the same optical formula for SLR and MILC.

Link | Posted on Sep 3, 2016 at 12:42 UTC
In reply to:

nir-vana: Dear Tamron.
We, Sony FE system users have:
FE 50/1.4
FE 50/1.8
FE 55/1.8
FE 50/2.8 macro
Mitakon 50/0.95
Loxia 50/2
Samyang 50/1.4 MF
Samyang 50/1.4 AF
Slrmagic 50/1.1
But we don't have any decent telephoto option for E-mount.
I hope you realize that our system becomes much more popular than A mount.
I hope to have native Supertele for my A7RII
Nir

You are right, and I mentioned that (albeit not in great detail). The reason I did not go into great detail was that poppyjk said that the *optical* formula would have to be reworked, which is wrong and *that* was my main point.

Link | Posted on Sep 3, 2016 at 02:58 UTC
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