potential Issues using Mf on DSLR

mybike · Joined: 29 May 2009 Posts: 60

This is a shot taken indoor with the pentacon using flash at 1 / 160 sec
f-5.6, iso 200

this is to know your impressions

Alphan · Joined: 17 Jun 2009 Posts: 28 Location: Malaysia

Try holding the lens to the body without the M42 adaptor. Pack some shims or just plain cardboard that is thinner than the M42 adaptor. The idea is to get the lens closer to the camera body than would be with the adaptor. Keep reducing the thickness of the shims until you get the infinity focus correct. If the thickness reduction is only very minimal (less than an mm), you can possibly tapper the M42 adaptor to avoid the hump as you mention in upper photo.

dnas · Joined: 14 Nov 2008 Posts: 488 Location: Japan

I'm wondering, HOW are you focusing?
There is no split prism on the glass focusing screen. When you took the original shots, did you focus by eye in the viewfinder, or did you just set the focus on infinity? Sometimes the diopter adjustment can interfere with your focusing accuracy, done by eye.

Some adapters allow focus PAST infinity, so that any slight difference in tolerance will allow you to focus any lens to infinity. This means that setting a lens to infinity will not get sharp focus at infintiy.

mybike · Joined: 29 May 2009 Posts: 60

Thanks alphan, dnas

alphan: i post a pic without adaptor, keepin in my hands and leaning it on the camera.
Now I got the focus at infinity!
So it's the adaptor? I think so.
Sorry, dnas. i always try to put the right focus using the wiewfinder and i saw that the adapter does not allow me to focus past infinity with the pentacon., but yes with the other lens in my sign (zenit, etc)

Don't really know why...seems the pentacon has a different flange focal distance

Alphan · Joined: 17 Jun 2009 Posts: 28 Location: Malaysia

Would removing the adaptor thickness by 0.5mm get you to infinity focus? If yes, then you should considering sanding the part of adaptor touching the 0.5mm flange you mention in your photo.

BTW, is it just foggy or the lens got soft focus or both?

mybike · Joined: 29 May 2009 Posts: 60

Thx for suggestions alphan, but do you think sanding is a solution? i never considered it. could be helpful?

the previous pic has been made in difficult weather conditions with misty fog not enough, actually, to understand the panorama
thsi one is better, it will be far 300 meters around from my position, so its' good to evalue if ther's correct f ocus past infinity.
Using only my left hand, keeping the lens .
So, I think fortunately the lens is still good (Pentacon is amazing)
and I have to find a soluition to use for the long distance Wink

Sorry if seems in poor conditions but probabily the compression of pics here is not the best...on my display are better don't know why everytimes I cannot see the same result when upload pics on the forum , any suggestions?

Alphan · Joined: 17 Jun 2009 Posts: 28 Location: Malaysia

Use the test without the adaptor to find out the negative thickness of the adaptor (how much is the adaptor thicker by). If minimum, then you can sand the adaptor but bear in mind that this adaptor may not be used on other M42 lens as they will all go beyond infinity.

It would be easier for you to test by focusing to infinity then shoot at something covering both near and far such as down the street. I shot mine on the fence to determine the "in focus" position.

Others with other suggestions, do chip in.

mybike · Joined: 29 May 2009 Posts: 60

Hello EB

I settled down everything now , it correctly works with my big happyness.
I opened the lens again, I remove the "cap" at the top of the lens
The part of the lens at the top, was not screwed at all, till the end.
I screwed it, so the lens became shorter inside, the lenghth decrease
Thath's why it did not focus past infinity, cause the problem was inside, not outside. So, I did not need to sand or use cardboard to solve this problem

I sorted it out , fortunately in the best way...very good. Thanks lads, for all of your help and sorry if I was not able to use the correct words in english to explain what happened, ready to try again to explain it back in a better way

By e all Wink

Paolo

Alphan · Joined: 17 Jun 2009 Posts: 28 Location: Malaysia

Glad you solved the problem. Now show us the pics? We would love to see the results.....

mybike · Joined: 29 May 2009 Posts: 60

Of course mate, it's been 5 days I keep shooting with my lens! Wink

thanks for your msg,. here some sample taken with canon eos 350d
THe kind of subject choosen was not so easy especially for a MF lens, but i tried to do the best, of course sometimes imissed the focus , i had to make a lot of tests bifore getting the right distance
Anyway, i am quite sactisfied to use it, even if it's difficult to use for sport. Iwanto exploit it a little;)
ciao

I start with an exhibition last sunday in my town, milan, water ski. my friend had the canon 70-210 with f/2.8, and me with the pentacon...i tried to do the best but of course cannot compete;)
all pics (more or less) had f8, iso 200, 1/1000-1250 time exposure
sunny day, shootings at about 3 p,m.

kansalliskala · Expire: 2016-12-30

Can you draw a diagram of the lens and put it to "Equipment Care and Repair" -section. Doesn't have to be very fine art ..

mybike · Joined: 29 May 2009 Posts: 60

WHY not?
if this could be helpful. I am going to upload the diagram. It's not fine art, really, hope the users understand

bye Wink

kuuan · Expire: 2014-12-26

potential issues using MF on dSLR?

'potential' is an understatement,
the main issue certainly will be that you like it so much so you can't stop buying ever more lenses -
and spend much of your time online in this forum discussing them Laughing

mybike · Joined: 29 May 2009 Posts: 60

I think so...
I am already thinking to a new grandangle Wink