Lens tests

[BillN_33]

Your biggest issue is DOF and non-stationary subjects. Combine that with the fact that AF is never 100% consistent and you are going to get some misses.

But, from what I can tell the +4 in the last image looks good.

Suggest you do a side by side comparison of photos of a static test target taken with and without glass in the line of sight. One of the problems with glass is multiple internal reflection, which leads to confusion at the image plane. The side by side comparison will help you to decide whether the presence of the glass is the main source of your issue, or simply one more factor.

Thanks guys for continuing the debate on this issue

I accept that when taking shots with a 600mm f4 ..... the success rate can be low in anything other than ideal conditions - I have taken enough images with it to realise this.

I try to shoot at f8 as much as possible - realising that it will give me sufficient DOF to help with AF or MicroFocus inaccuracies

I have taken enough small bird images to realise that they seldom keep still and that there are usually micro movements at best

I want to get shooting through glass to the best level that I can as I have my set up by this window when it is not outside with me - it is just handy to sit by it for 10 or 20 mins at various times during the day.

We have lots of birds in the garden as we live in an ideal environment for birds in France

Thanks for all your suggestions ... it's work in progress as they say ...........

 

[sk66]

Based on the test image I saw (the back-focused one I embossed) I would expect you to be in the +5-10 range for AFMA. I think your +4 is probably good assuming the use distance is a bit longer than the test chart distance in that example (it might be good either way considering inconsistencies... I only saw the one test target).

Another thing I have found is that always starting AF from one end seems to be more consistent... the "sharpness" seems to have a "tolerance range," and the AF seems to tend to stop at opposite sides of that range depending on which direction it's coming from.

 

[AdamSi]

Have you tried using live view and timed release bill just to see if it looks the same as that will show if you are going to get any better by tuning?

 

[BillN_33]

Have you tried using live view and timed release bill just to see if it looks the same as that will show if you are going to get any better by tuning?

Thanks Adam

FoCal today, when and if the light improved - I bought it about a year ago and never used it - the upgrade is free - I have read thru all their latest stuff and it looks a lot easier to use on the Mac than it was, and it produces some interesting data - it is just that the distance needed to tune the 600mm + x 1.4TC is 20 x 840 = almost 17 meters .... but I also want to tune it at 7 metres and compare the results - so the light needs to be good and consistent

I'll try it first with a 50mm to get the hang of it

 

[BillN_33]

Thru the window glass shots from today

so the quality from my window seat is good enough for me - as these were taken at high ISO's in not particularly good light

ISO 1600

ISO 1000

 

[lost]

Hi Bill
If the glass you are shooting through is an opening window make a window replacement board with 4 turn keys and a hole cut for your lens fix some heavy duty material around hole for a lens sleeve you now have no draft and a centrally heated Hide.
Regards
Richard
P.s just refreshed the old thread showing the window board Boxing Day in the Hide is the thread name I tend to use a towel and bean bag to fill the hole

 

[BillN_33]

Hi Bill
If the glass you are shooting through is an opening window make a window replacement board with 4 turn keys and a hole cut for your lens fix some heavy duty material around hole for a lens sleeve you now have no draft and a centrally heated Hide.
Regards
Richard

Thanks Richard - very good idea - the window is only about 1 mtr by 500cm, so it is practical - a job for next Spring

just reading thru your thread - I have used a kind of perspex material in one of our barns - I think that I will give that a try ........ easy to cut a hole in the centre and also semi see thru and I can add camo netting