01-18-2020 02:04 AM
01-18-2020 03:54 AM - edited 01-18-2020 03:55 AM
Take a series of photos with the lens at different apertures against a plain white surface. Look carefully at the images and see if you can observe any noticeable dust marks. I would be surprised if you see anything. The lens has a focal length of 600mm, so back where the elements are it is very likely to be be massively out of focus. and thus invisible to the sensor.
If you DO see dust marks make sure your sensor is clean, or try a different lens and see if you ge the marks in the same place - that would suggest the sensor has dust on it, which WILL be noticeable.
01-18-2020 08:46 AM
Don't worry about it:
"So, this seems like a good time to do a blog post showing that 1) this big-ass fly had almost no effect on image quality, so that little dust speck you’re frantic about sure doesn’t, and 2) getting flies (or dust) out of a lens is a lengthy and difficult process that takes a long time."
01-18-2020 02:57 PM
"... there is like dust, it can be noticeable when you put it directly to the light."
Yes you do need to test it out. I doubt the dust will show up because it is not in focus inside the lens. However, if it is severe on the lens elements, enough it will block some light and that isn't good.
Midwest Camera Repair will service it.