Spyder Lenscal Question

[Bristolian]

Hi folks,

I've bought myself a Spyder Lenscal and am happy I know how to use it except for one thing - how to measure the calibration distance?

I'm okay with the 25 - 50x the focal length idea but is that distance measured to the front element of the lens, the lens mount or the focal plane of the camera? I think it should be the latter but can't convince myself which one is right

Thanks in advance

 

[Canon Bob]

Given that the advice is 25-50x the FL then the precise point of measurement becomes pretty insignificant I would have thought?

 

[realspeed]

Steve

You don't say what you are calibrating for. is it for a model shoot and getting eyelashes razor sharp? or is it for more general use.. I have a spyderlenscal and had it for some time.

All I can say is don't worry about which point in the camera to measure from that is irrespective against the distance your subject is.

Fix lens (prime) are not the problem telephoto lenses are however. So what I do is fine tune to max and then min mm lens range and split the difference between them taking a mid point.

One thing you may come to notice is the fine tune can alter anyway depending if it is a hot or cold day. I have recalibrated my nikon 24-70 mm lens several times since i have had it to the extent of +/-3 on the D810 fine tune scale. even then it may need tweeking in PP. the wider the lens mm length say 80-400mm is even more of a guess ,so hence the mid way mark is best

What can throw a reading out is not setting it up properly. Me? I set the lenscal on one tripod and the camera on another on a level plain and then even down to using a remote trigger release, usually a wireless one against a corded one. slightest movement is to be avoided, plus using correct camera settings of course

Not having a laptop I wire into the TV screen to get a larger picture of the scale and work from that, seems to work well.

The way I look at it is cameras and lenses are built to a tolerance so that they can work in hot or cold climates, so there must some movement in the lens and camera anyway

To sum up, don't get hung up on fine tune it will drive you nuts I should know

 

[Bristolian]

Given that the advice is 25-50x the FL then the precise point of measurement becomes pretty insignificant I would have thought?

After posting my question I was thinking about this and came to the same conclusion

 

[Bristolian]

Steve

You don't say what you are calibrating for. is it for a model shoot and getting eyelashes razor sharp? or is it for more general use.. I have a spyderlenscal and had it for some time.

This is just a general check on camer+lens focus accuracy without an y specific purpose in mind. I guess I'm looking to see if the kit is working properly so that when I get out of focus images I will know its me not the gear ... a craftsman and all that

All I can say is don't worry about which point in the camera to measure from that is irrespective against the distance your subject is.

Yes, I think you are correct about this. I just didn't want to waste my time doing it one way to then find I had to do it all over again.

Fix lens (prime) are not the problem telephoto lenses are however. So what I do is fine tune to max and then min mm lens range and split the difference between them taking a mid point.

All of my lenses are zooms so I was planing to do the checks at both ends and in the middle then work out the "average" and apply that with a slight bias towards the long end as that's where I tend to use the zoom anyway.

One thing you may come to notice is the fine tune can alter anyway depending if it is a hot or cold day. I have recalibrated my nikon 24-70 mm lens several times since i have had it to the extent of +/-3 on the D810 fine tune scale. even then it may need tweeking in PP. the wider the lens mm length say 80-400mm is even more of a guess ,so hence the mid way mark is best

Hadn't given expansion/contaction due to the environment a thought. You may well be right but I wouldn't have thought that the temperature differences found in the UK (winter to summer) would have much of an effect on plastics and glass that a pretty stable materials.

What can throw a reading out is not setting it up properly. Me? I set the lenscal on one tripod and the camera on another on a level plain and then even down to using a remote trigger release, usually a wireless one against a corded one. slightest movement is to be avoided, plus using correct camera settings of course

Not having a laptop I wire into the TV screen to get a larger picture of the scale and work from that, seems to work well.

The way I look at it is cameras and lenses are built to a tolerance so that they can work in hot or cold climates, so there must some movement in the lens and camera anyway

To sum up, don't get hung up on fine tune it will drive you nuts I should know

The lenscal will be sat on top of a very sturdy cabinet and the camera on a tripod on a good solid floor so movement shouldn't be an issue. I am also fortunate to have a laptop and USB cable to connect the camera so I think I have that side of things are sorted.

Thanks for your detailed reply

 

[realspeed]

Steve it is a pleasure to be able to pass on what I have found out. Don't forget to check every so often the calibration, it can alter with camera/ lens use.