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06-13-2013, 03:05 AM   #31
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Hi Christo,

I did not answer your inquiry about the sensor cleaning. Here is what I do or have done:

1] I have all the Nikon and Canon digital cameras ever released to the marketplace. I can count on one hand the number of times I have ever cleaned a sensor.
2] Debris and dust can be removed with a puffer squeeze bulb, an electrostatic brush that picks up the dust or a pressurized can of quality air that leaves no deposit.on the sensor surface.

In my lab, I have also used vacuum systems and ultrasonic devices to clean the surface of the sensor. These devices can be expensive and are generally used on critical projects, not standard camera sensors.
There are several kits that describe how to do it yourself . As long as no free flowing solution gets into the camera, you will be ok.
I always recommend that a plain glass or microscope slide be used to develop the best technique for both lens and sensor cleaning.

Best Regards, Mike

06-13-2013, 01:49 PM   #32
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That's an amazing collection of lenses! Do you have a top 10 favorite? Any general advice for us just starting out in photography?

Regards,
Eric
06-13-2013, 04:30 PM - 1 Like   #33
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Hi Eric,

Thanks for commenting.
I have so many favorites, that it is best that I show you a portion of the Nikon collection that I started on over 50 years ago. Many of the newer Nikkors were not seen in this image because they were at my testing afacility being evaluated.
So, this is about 70 % of all the Nikkors that I currently own.
As for my other collections, this image represents about 25 % of all the other lens that I own from the "M" Leica rangefionder lens to medium format up to 6X7. Beyond that I have a special collection of very unique lens, too.

My general advise to you follows:

1] Buy a simple camera that has the basic features that the more expensive cameras have..
2] Invest in a quality lens, since the image information that passes through that lens is responsible for the image output.
3] Use your lens often, under many conditions to become familiar with both the lens and the camera.
Try to resist the temptation to buy "new" all the time, since many lens built years ago are much better than those made today.
4] Concentrate on learning the basics about taking pictures.
I started out over 56 years ago using all manual lens and cameras. I taught myself how to judge the correct exposure, f-stop, shutter speed and ASA film speed (ISO setting , today) for a wide range of lighting conditions.
While I own all the modern DSLR cameras in the Nikon and Canon line up and most of the high end mirror-less cameras, I still set my focus, exposure speed, ISO and f-stop manually. My results turn out better than any pre-programmed mode, auto focus mode or other multitude of features that I find useless. Now, by using the Aperture priority mode as a "teaching guide" , you can learn how to better judge a scene brightness, etc..I demonstrate this to my students. When we are out for a photo session, I will tell them what their camera will select , knowing the ISO and f-stop. The light meter in their cameras confirms my judgment everytime to within a 1/3 of a f-stop or a fraction of a shutter speed selected.
Mastering the camera and lens is fun to do, as you will take plenty of images.Keep records or voice recordings of what you . This will help you review all that you have accomplished.
5] Last point for now, start with several parameters being set once in the camera. Do not make changes all the time, as this will shortcut your learning experience in the field.

For example, if I go outdoors to image butterflies, I pre-set the exposure to 1/2000 second or faster, using my lens of choice set wide open. The ISO is pre-set to 100 or 200 depending upon the camera that I use. The lens being set wide open assures me tthat my lens is not compromised by stooping down too much. The limited DOF is good, because I want to isolate the butterfly. Now, the shutter speed is set fast because some butterflies move very quickly. I do not have to use fast shutter speed because of hand motion blur, because I have trained my self to hand hold any lens at a slower shutter speed than what any Image Stabilization routine can furnish. I know this because I have put on demonstrations showing that I can regularly hand hold an image stabilized 200mm lens with the IS set to OFF at 1/8 second without any blur. The same lens is hit or miss by 1/25 second. Image quality often suffers from IS features built in the lens, and you are better off buying a better lens without IS because of the cost savings alone. Now, to control DOF without using the f-stop, I use various working distances, focal length lens and perspectives when shooting any subject.

Best Regards, Mike
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06-13-2013, 04:46 PM   #34
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Thank you for the advice Mike! What older lenses would you recommend for Pentax?

06-14-2013, 03:58 AM   #35
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Hi Eric,

I have evaluated every Pentax lens made from the screw mount days to the present. From my own collection, I would consider the following manual focusing lens:
Note: this is not an all inclusive list, but one that is intended to be a good starter set for somebody with limited experience.

1] 28mm F/2.8
2] 50mm F/2 and/or the 50mm F/4 macro lens which is more versatile.
3] 85mm F/1.8
4] 300mmF4 A* or the 400mm F5.6 A* , you can really develop your skills on precise focusing and hand holding these focal lengths steady.

The above lens cover a good range of working distance. The exposure might not be automatically coupled to the camera, but you will be able to develop you skills to manually set up the camera to the proper ISO and shutter speed.
The f-stop should be set no lower than F/8 on the telephoto lens, and F/5.6 on the shorter focal lengths.

I use all my Pentax lens via an adapter that I have machined in my shop or one that I purchased on the Canon DSLR line and mirror-less camera line. I do not own a Pentax body, since there are other cameras that provide all the functionality that I require for the lens that I adapt to them. My Nikon cameras will not properly focus the Pentax line of lens until I use the medium format 645 or 6X7 Pentax lens. I do not recommend any adapter that uses a simple lens to provide Infinity focus on a lens to focus with a different camera.

Best Regards, Mike
06-14-2013, 05:17 AM   #36
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Mike,
Impressive collection.
From your recomendations I see you make a lot of emphasis on not stopping down the lens too much. I guess this a precaution to avoid diffraction issues?
I understand that for APS-C sensors with 16Mpx (what current Pentax DSLRs use), diffraction might set in between f/8 and f/11. This depends on many variables (which I don´t understand completely). For example, higher wavelenths (yellow, orange and red colours) are more prone to diffraction. And at the same time, as the green channel has double the resolution of the red and blue channels (bayer array), the latter will require a higher f stop before diffractions limits their resolution.

This is quite confusing becouse it makes it very difficult to establish a "working range" for each lens or shooting conditions and it is always of preference to have enough depth of field than avoiding diffraction. But I see you place some lmits:
QuoteOriginally posted by PhotoMike Quote
The f-stop should be set no lower than F/8 on the telephoto lens, and F/5.6 on the shorter focal lengths.
Users reportedly state several lenses offer best quality / contrast / resolution between f/8 and f/8, but this contradits with theorical diffraction limits for this sensors. I found this to be true for the M50/4 macro, which you named. In my very unscientific test, I found the best result at f/11. Could you expand a little more on this?

Here´s a well writen article if anyone is interested (not intended for you, Mike )
Diffraction Limited Photography: Pixel Size, Aperture and Airy Disks
Diffraction Limited Photography: Resolution, Color & Micro-contrast

Regards and thanks for your detailed answers,
Francisco

Last edited by carrrlangas; 06-14-2013 at 05:21 AM. Reason: Added links
06-14-2013, 05:59 AM   #37
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Hi Francisco,

What you reference about sensor technology and how it matches up with various optical systems is quite complex. I have been studying this field ever since the first CCD and later CMOS devices were born.
I worked closely with many US companies in the development of such devices and their test evaluations, too. While much has changed over the past 30+ years , the science remains the same whether the device is 0.1 megapixels or 200 megapixels. Matching sensors to lens is one area that my business consults in often. Many times it is for sensitive application areas in research or the security field.

All my best lens are shot wide open because that is where they furnish the most useful information by design. Even my F/0.75 to F/1.2 lens can form the proper exposure using low ISO and the highest shutter speeds .

If a lens NEEDS to be stopped down because of quality issues, then it is not well corrected optically, out of tolerance, or alignment..

After F/8, a $2000 lens exhibits little advantage over a $200 lens. I test lens all the time, and my results are absolute. It is one side to theoretically calculate optical behavior, but the reality is proven in the formal lab environment..

When I fulfill a multi-million dollar contract, I have complete agreement in the theory (design and optical physics) and the facts revealed from the lab testing.

As for your non-scientific findings on the Pentax 50mm F/4 macro working best for you at F/11 does not address any hardened parameters. When I test a brand name lens, it is often across a larger sample size than one , ten or even 100. There are manufacturing variations and quality control issues , too. Beside this, I do not address "personal preference" factors about a lens , only the facts that are derived from scientific test procedures. For example:

1] Most people do not know what to look for in an image to really know if the lens is performing properly.
2] Many people are pleased by setting their lens to F/11 or F/16, etc. because everything generally looks focused. When smaller images are viewed, this is the case because the finer details are lost in the presentation anyway.
3] Some people want more DOF, which I as said is really a level of compromise to the lens performance of a good lens.
4] Others enjoy the "soft" look, so f-stop works well to satisfy that preference
5] There are special effects that are carried out by stopping down lens to F/22 and beyond. The diffraction effects on point sources produce interesting and often colorful effects from the iris blades interfering with the incoming rays.
Using F/22, and ISO can allow for longer exposure times that reveal the waterfall motion by blurring the movement. Longer timed exposures at dust can show a smoothing effect across a waterway or mountain top from fog that is present.
I have engaged in these and many other special effects, without having to stop down the lens, using quality ND filters that force longer exposure periods.

I certainly know all there is to know about the Pentax 50mm F4 macro lens.The design is known, the characterization from the lab testing is known, and in many cases the internal assembly, including each element or group of elements has been measured.
This level of "reverse engineering" is NOT done because I had ever planned to copy a design and go into production against any company that was selling such lens. It is for the knowledge gained and the flexibility to modify or repair a lens that is not up to standard for a certain application. My copy of the Pentax 50mm F/4 macro does perform optimally at F/4 to F/5.6 without exception.

Best Regards, Mike

Last edited by PhotoMike; 06-14-2013 at 06:14 AM.
06-14-2013, 06:14 AM   #38
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QuoteOriginally posted by PhotoMike Quote
All my best lens are shot wide open because that is where they furnish the most useful information by design. Even my F/0.75 to F/1.2 lens can form the proper exposure using low ISO and the highest shutter speeds .

If a lens NEEDS to be stopped down because of quality issues, then it is not well corrected optically, out of tolerance, or alignment..
QuoteOriginally posted by PhotoMike Quote
Using F/22, and ISO can allow for longer exposure times that reveal the waterfall motion by blurring the movement. Longer timed exposures at dust can show a smoothing effect across a waterway or mountain top from fog that is present.
I have engaged in these and many other special effects, without having to stop down the lens, using quality ND filters that force longer exposure periods.
Mike,
Amazing answers.
This makes me re-think the way I use most of my lenses, being used to look for the "sweet spot" on each of them.
Also, I am thinking most of my lenses must have quality issues. Stopping them down 1 stop generally enhances contrast and resolution (even without great impact on DoF)
I though that lenses were designed so that bigger apertures will work better at close focusing distances so you need to close the aperture when focusing near infinity. From your explanation, this seems to be another misconception I should not care about?

Thanks again for your time and detailed anwers. This is truly good information not only for me but lots of readers.

Regards,
Francisco

06-14-2013, 07:49 AM   #39
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HI Francisco,

There has always been many misconceptions about camera and lens over the years.
This is good news for the manufacturers because most of their products are readily acceptable by users that do not know what to look for in a quality
lens, or are motivated by "the pride of ownership" to show off to their new equipment to fellow users.
If a lens really did have a "sweet spot", then it should be sold as a fixed f-stop lens. The term "sweet spot" always makes me smile as there is no such thing
in optics. Most of the time, it is the user that determines the results obtained. The choice of subject matter, the lighting condition present are a few of the many factors that
contribute to a lens behavior.

As for lens with quality issues , with the exception of a few lens produced including custom assemblies, all lens have some level of issues. Even the expensive ED, L, SD, ULD and other specialized glasses used in such lens,
there exist some issues.

Best Regards, Mike
06-14-2013, 08:09 AM   #40
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QuoteOriginally posted by PhotoMike Quote
Hi,

I have been involved with photography for 56 years now. I have earned several advanced degrees in Physic, Photography , Optics and Astronomy.

When it comes to application photography from the film days to the digital era, I have covered most fields in science, sports, commercial, private functions, and general photography using a very wide range of cameras and lens.
I have operated several small specialized optical design, and manufacturing companies and currently have a full optical testing facility that I use to continue to accurately test every lens available worldwide.
I continue to consult for various agencies and develop new imaging systems for specialized work, too.
My personal lens collections tops the collection shown here, since I own most every Nikon,Olympus, Canon, Leica, Pentax and Carl Zeiss lens made for 35mm format and all the Hasselblad, Mamiya RB67 and 645 lens, Pentax 6X7 and Pentax 645 , and Bronica lens made as well as numerous third party lens . I also own over 100 telescopic systems, specialized one of a kind optical systems, and many unique microscopic systems too.
Note: these are not idle collections, as I use all that I own on a rotational basis. The cameras range from the best Point and Shoot, all the Nikon and Canon DSLR ever made, every mirror-less camera along with a large number of film cameras from the past. Since I have a optical lab, all of my equipment is full working order, both mechanically and optically. Whenever a lens needs a coating or even replaced due to damage, I can service it myself, with the help from my co-workers.
Please feel free to contact me concerning anything about lens, cameras, accessories or just to introduce yourself.

Mike

With all my experience and investments in my life long enjoyment, I always wake up the next day anxious to learn more !

Welcome! definitely interested in seeing your camera collection!

Sound like you are able to fix camera too? I have Pentax 67 that needs services....:P
06-14-2013, 12:27 PM   #41
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Hi LFLee,

While it is most likely that the Pentax 6X7 could be fixed, my business is not setup to work on any product directly with the consumer. The majority of repairs that we do is for contract type work, where repairs and modifications are completed in
our facility. My business has not ever sold photographic equipment to the consumer, or have we ever been an Authorized dealer or Repair Center for any product.
Some examples of the cameras that I own are seen on Page 2 of my postings.

Best Regards, Mike
06-14-2013, 12:38 PM   #42
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I almost got me a headache reading through your introduction and the following posts!
Impressive background ad collection you have too !

So, here's the deal:

Focus shift with a Carl-Zeiss T*Planar 85/1.4 at F1.4, .... how would you "deal" with that ?
Have you ever work this out on that lens? I.E.: find a solution so that the lens can be used at that aperture without the shifting?

I am ready to send that lens and the camera I usually mount this lens with: a Pentax K7. It is going to be sent to a pro shop which takes care of high end photographic material (Hasselblad, Phase One, Canon, Nikon, Pentax, ... etc.)
but before I do send it in, I would like to have your thoughts on such "focus shift" with the Zeiss lens.

Of course, the shift occurs at the wide aperture and disappears as I stop it down. This is also a "known issue" with this particular lens.

Cheers, and welcome aboard!

JP
06-14-2013, 12:55 PM   #43
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Hi JP,

Thanks for the greeting.
The Carl Zeiss T* 85mm F/1.4 lens is a fine lens that I use at F/1.4 to F/2 maximum. I own all the Carl Zeiss lens.The only issues that I have had to address was with the lens ability to reach Infinity focus on either the Nikon or Canon bodies.The lens mount was removed and 0.0007 inch was machined off the brass ring to fix the issue,. All the lens work fine now.

Best Regards, Mike

Last edited by PhotoMike; 06-14-2013 at 03:15 PM.
06-15-2013, 11:11 AM   #44
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Going to the beach (Atlantic Ocean side ) in the early morning often provides interesting activities to record.
On this day, I was armed with my Nikon D3X and the outstanding Hasselblad 350mm F/5.6 SA ( Superachromat )lens.
The medium format lens with an adapter works well with all my Nikon , Canon and mirror-less cameras.
The lens is so well corrected, that there are few lens in its class at the longer focal lengths. When I shot this hand held image
using the 24 megapixel full frame Nikon camera, my Nikon D800E was at my laboratory in a test setup for another job.
However, the increase in resolution seen from using the Nikon D800E, 36 megapixel full frame camera, would not be
seen at this level of compression and posted size. I generally use the Hasselblad "SA" lens for scientific imaging due to
their extended spectral correction for focus. The Infinity focus for the UV to near IR spectral range remains the same. Not
many lens come close to this level of performance.
Prior to getting to the beach, I had preset the ISO to 200, and exposure to 1/2500 second based upon my experince at shooting during the morning hours at the beach .
The lens was shot wide open at F/5.6, since any stop down would be a compromise to its performance. For a lens costing in excess of $10,000, it is ridiculous to limit its
design intent.
Focusing is done manually.

Mike
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Last edited by PhotoMike; 06-15-2013 at 11:19 AM.
06-17-2013, 10:38 PM   #45
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I used an adapter on my Canon 5D Mark II to allow the use of the Pentax 645 400 mm F/5.6 EDIF lens on the body. This lens is all manual, with excellent optics. The build quality is essential to keep the elements aligned, and this lens will continue to provided many years of regular service over many new "auto-focus, image stabilized, electron iris, plastic constructed lens produced today. This 400mm F/5.6 lens is relatively light weight to easily hand hold, as I did for this beach shot.
The use of plastic in today's lens is a way that manufacturers manage weight issues, increasing speed of their autofocus due to the under sized motors now employed. Battery life is better with light weight lens , as the smaller motors draw less current.
However, I am not concerned about those features. I want a lens that remains aligned and is not effected by environmental or accidental issues that might occur.

As often the case with any of my quality lens , I shot this image wide open at F/5.6, using ISO 200 at 1/2500 second hand held. I preset all the settings in the camera, which was in manual mode. The focus is swift because the 400mm uses "internal focusing" (ED-IF). As soon as I see a subject of interest, I have the shot. Since the balance of the lens is very good, I can hand hold it down to 1/60 second of second on a regular basis without any motion blur introduced by myself. Therefore, I have no need for any image stabilization systems. In my optical testing facility , image stabilization systems often provide compromised image quality when turned on. I find it humorous that in some reviews that I have read, people complain about 25mm focal length lens "down-graded " because they are not image stabilized. I have shot 25 mm lens hand held to 1 second exposures when necessary.
I do invest much money into the highest quality optics and cameras, but not because of the "features" the manufacturers offer. They can keep all the "hype", as I have been taking images long enough not to require anymore than the basic manual controls.
As for a light meter, I had preset my settings at the beach without ever using the metering system provided by the Canon Full Frame DSLR.

Mike
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