Are you saying that all instruction I have read are wrong? They tell you to put the camera on a steady tripod so it does not move and then focus on different distances. Using a focus rail changes the distance to the object..right?
I tried the rail and it did not work!
Which is right and which is wrong? Please explain!

I can see the need for a focusing rail when using extension tubes, but not so much if you get a proper macro lens. On a macro lens you can adjust focus from close to infinity by turning the focus ring. I tried a focusing rail when I was exploring focus stacking. I set focus and moved the camera on the rail closer in steps, which only changed the aspect ratio so focus stacking was not possible! The right way to do it is to chose an aspect ratio and then turn the focus ring to different points. Then focus stacking works good. ( I got a Neewer rail on eBay and it worked good. You only have to be careful when you adjust the distance so the camera will not slide by its own weight!)
/Bosse
/Bosse
J

Thank You for your quick response!
I actually did a Google search and found that DOF depends on reproduction ratio, aperture AND focal length, but how the focusing distance affect DOF with different focal length and identical reproduction ratio can be neglected!
Tha was what I originally suspected but wanted to be confirmed.
Thanks again
/Bosse

That is not true! A crop sensor lens (Nikon Dx for example) on a full frame camera will give you dark corners because only part of the sensor, or film, will be used!
A full frame lens on acrop sensor camera will only use center part of the image thus creating a sharper image.
(I know some will disagree with this statement..LOL)
/Bosse

I have a Tokina 100 mm atx pro macro lens on my Nikon D7100. Shortest focusing distance is 11 inches at life size reproduction (1/1).
The depth of field is VERY shallow, only a few mm. If I chose a macro lens with much longer minimum focus distance, for example a 200 mm macro lens, and do a life size photo, will the depth of field be shallower or the same?
Or, in other words, do the focal lens on a macro lens affect depth of field so that a longer focal lens will be much more critical when it comes to focusing correctly ?
Will it mean that you have to compromise between depth of field and minimum focusing distance when you chose a macro lens?
/Bosse

I am sorry but I have to correct what you said. “Circle of confusion” has nothing to do with how much a certain lens covers the sensor! Do a Google search and it will be explained much better than I, with my limited English knowledge can explain.☺️

LOL...agree. I originally thought that comment was a joke. I am not so sure anymore.

My final thoughts:
Choice between 18-140 and 18-200...The 18-140 is definitely sharper and more balanced on a Nikon D7100 or D7200!
The 70-300 that was recommended is NOT a good walk around lens...it has no VR and is therefor hard to hold steady. It would need you to carry a tripod all the time! You also will miss the wide angle.
Between Nikon D7100 or D7200:
Both are very good cameras.
Ask yourself: Do I need WiFi..then the D7200 ( even if you can buy an WiFi adapter to th D7100)
Do you need the bigger buffer, do you shot long series at fast speed? D7200 is your choice.
If you don’t need WiFi or never shoot more than 4-5 frames of the same subject or seldom shoot sports the D7100 is your choice.
I never ever missed WiFi or bigger buffer so I chosed D7100. It is also cheaper if you can find a refurbished or used one in good condition. Your choice Dennis! Good luck!

Well, some drawbacks:
Everything is plastic,including the mount
No weathersealing
70 mm is for many way too narrow field to suite as a walk around lens, you need to buy an extra lens to get wide angle
I have never tried it but I am sure it is a good lens as you claim. I however do not agree that the 18-140 is soft and noticeably loses contrast at the long end.
We all have different opinions..LOL
my sharpest lens is an old 80-200 mm Ai manual lens which I bought on eBay for $3.20!

I have to correct myself. If you check critically you can notice SOME vignetting, but not as much as in your picture.
For practical use you can totally ignore it, or crop just a little bit. Overall this lens is,according to many testers, the best kit lens available of any brand!

Interesting. My first thought was that you put on the sunshade 90 degrees wrong, but you can only put in on the right way. Then I took a picture of a white wall ....not a slightest sign of vignettting! Must have been something wrong with your lens?? Did you use a non OEM sunshade? My lens is perfect!

I never noticed any vignetting! Have you updated the firmware?

This is why I purchased my D7100 with 18-140 mm lens! I strongly recommend this lens. As an avid amateur I feel no need to upgrade to FF.

Here is another comparison:

I live between Grand Rapids and Kalamazoo.