Hin's Photo Corner

I got this old zoom lens knowing that it is a auto-only M42 lens. I had the previous experience in altering an auto-only diaphragm into manual diaphragm m42 lens. It is equivalent to switching to M in most of the M42 lens with A/M switch. For manual stop-down, one has to use M setting as most of the current digital bodies don't have the mechanics to depress the aperture pin for the proper stop-down.

Every lens is different and this one does not come as a surprise in terms of difficulty. I first found the aperture pin not working even upon full depress into the lens. I later found a stuck linkage between the pin the aperture diaphragm. Once I get the pin to work properly, I added a little hollow insert using a fragment of a pen refill tube to make the pin pressing on the aperture diaphragm control at all time.



But once I get the stop-down mechanics working with manual diaphragm opening with the aperture ring, I found another issue and it is something that I have not dealt with before. The old M42 lens leaks oil likely from the helical housing in the focus and zoom compartments.

The lens has potential and I start liking its strong build and unique character that little is known about it.



It works quite well when stop downed properly. And here are some test shots done with Pentax K20D












Impressions & Notes

• It is a bummer to be able to fix a lens with aperture issues and stop short in fixing it completely due to the oil leaking from the lens helical to aperture blades
  
  
• The oil and wet blades don't affect the lens performance immediately as I find no issues in the test pictures but it is something to be less desirable
  
  
• The zoom lens has internal moving part for the zooming. Upon changing from 80mm to 200mm or vice versa, the lens does't extend or retract to a different length.
  
  
• Bokeh and sharpness are found decent. The lens perform quite evenly across the range though I prefer to shoot in 180mm instead of 200mm as I think sharpness is better in 180mm.
  
  
• This M42 zoom can work straight in Av mode in my Pentax K20D from f/4.0 to f/11. In wide open shot in f/3.5, I usually dial in +0.3 to +0.7 Ev.
  
  
• Contrast is sometimes low when I shoot into objects with harsh lighting. It seems lacking on coating like the SMC in Pentax. The contrast is usually a easy fix in post processing.
  
  
• I have decided to move on and sell it for cheap to others with full disclosure on the wet blade with oil issues
  

Related:

• Soligor 200mm Tele-Auto f/2.8 m42
  
• Pentax genuine M42 adapter
• Pentax K-x and M42 lens
• M42 adapter with inner ring for Auto-only M42 lens
  
• Pentax K20D
• Hin's Camera Gear
  

I bought this adapter from my good friend Alex in http://forum.mslenses.com/ and I asked Alex to charge me the regular he charges for his other clients. I got it shipped for $17.00 from Hong Kong, similarly priced like other 3rd party adapters.

This 3rd party adapter has an important function that is not found in all adapters that I have used. Not even the genuine adapter has the added feature: it works with M42 lens that does not have the A/M switch. When one uses an M42 lens, one has to switch the Auto/Manual diaphragm to manual so that the pin on rear is depressed while allowing the blades and diaphragm to close down for the stop-down metering to work in Pentax dSLR or the other K-mount in SLR cameras.

In the K-mount with KAF2 on Pentax K20D or something similar, what is missing is a mechanism to hold the auto-mount diaphragm governing pin in place for the blades to close down in stop-down metering. And this adapter has the extra ring on the back that is designed to depress the pin down, effectively serve as an M switch in a normal Auto/Manual diaphragm switch. I was quite pleased to try it out on a recent LBA purchase of a Lentar 200mm f/3.5 auto-mount m42 lens. You see the pin on the end in photos next to this paragraph. I have another auto-mount m42 lens that is exactly like this with a pin that all of my Pentax K-mount bodies can't handle the stop-down metering without alternation. There are several ways to do the alternation and the most prominent one has been using tube to place under the pin to shorten the pin which allow the diaphragm to go freely upon stop-down metering.

The new adapter from Alex works extremely well for the auto-mount lens that I have just purchased. There is no known label on the adapter and I will share my experience with the adapter when time allow. So far, it has work quite well for me when I mount it on 2 lens: one lighter with a 35mm f/2.8 and one quite heavy with my new Lentar 200mm auto-mount M42 lens. The later one misses the switch for Auto/Manual diaphragm switch. And the adapter comes in handy for my use.


Impressions & Notes

• Mounting is exactly the same mechanics as the genuine and 3rd party adapters
  
  
• The extra inner ring is designed to work with auto-mount diaphragm m42 lens without the Auto/Manual (A/M) switch that are found in most M42 lens. Some older version of M42 lens seem not to have the A/M switch and by default they go into Auto-diaphragm which will yield problems for Pentax dSLR with KAF2 mount.
  
  
• The adapter comes with dismount or removal tool similar to Bower or other 3rd party adapter
  
  
• The machining on the adapter can be improved. I will communicate to Alex to see if the machining on the metal edges on the adapter can smoothed out with finer edges.
  
  
• Though the adapter comes with removal tool, I found myself very surprised that I can actually dismount the adapter using my two fingers as shown in next picture. This is a big feature not to be missed for those auto-only m42 lens that don't have the A/M switch for auto and manual diaphragm settings.
  
  
  I can dismount with two fingers
  similar to genuine m42 adapter
  
  
• I need to test it more. But as of my first impression, the adapter works beautifully for two m42 lenses that I tried. It work well with the auto-mount m42 lens

Links:

• m42 adapter with inner flange -- mflenses forum member hk300
• alexcwyuen@hotmail.com -- email contact
• Disclaimer: I don't endorse the product as I generally recommend the use of genuine Pentax m42 adapter. This adapter has one unique feature with the inner flange that helps to work with auto-mount m42 lenses that lack the A/M switch. The inner flange depresses the aperture pin making it manual diaphragm as in switching to M in the A/M switch.
  

Related:

• Articles labeled M42 Adapter
  
• How to mount and dismount genuine adapter
  
• Pentax M42 Adapters
• Warning on 3rd party adapter
• How to convert M42 lens to K mount lens
• Custom settings on M42 lens
• Informative M42 mounting YouTube video
  
• Hin's Camera Gear